A polypeptide chain (often
a secondary structure of a protein) arranged as a
long zig-zag.
1002.
Beta DNA (ß DNA)
Definition:
The normal form of DNA found in
organisms, which exists as a right-handed
helix.
1003.
beta human chorionic gonadotropin (beta hCG)
Author:Guo Li Definition:
This is a glycoprotein composed of two subunits and secreted by the placenta. It
is detectable 1 day after implantation of the a fertilized ovum and peaks at
60 to 90 days of gestation.
Normal level is less than 5 mIU/mL; 20-100 IU/L 1 to 2 weeks after
conception and 50,000 IU/L about 65 days after pregnancy then declines. In
molar pregnancy, it can be extremely high initially, (over 100,000 IU/L) but
declines with time.
In the first three weeks of a normal pregnancy, the serum beta hCG
approximately doubles every two days. The doubling time of hCG is considered
a more reliable method of evaluating an early pregnancy than a single
result.
1004.
Beta oxidation (ß oxidation)
Definition:
The oxidative breakdown of fatty acids into acetyl-coenzyme A by repeated
oxidation at the ß-carbon atom.
1005.
beta particle
Definition:
An electron or positron emitted from a radioactive nucleus during
beta decay.
beta thalassemia major: in this form of beta thalassemia, patients are homozygous for the defective genes: beta0, homozygous beta+, both are life-threatening.
beta thalassemia minor: patients are heterozygous for the defective gene; they have a mild anemia.
One of two major types of thalassemia, a genetically inherited disease, where one of the two types of
polypeptides making up the
hemoglobinprotein is defective or missing. Hemoglobin proteins are composed of four polypeptides -- two "alpha chains" and two "beta chains". In beta thalassemia, the beta chains are defective or missing (see also
alpha thalassemia).
The three classifications of beta thalassemia, in order of increasing severity, are thalassemia minor, thalassemia intermedia, and thalassemia major. Thalassemia major is also known as Cooley's anemia.
Symptoms include slow growth, jaundice, enlarged heart, liver, and spleen, thinned bones. Untreated children die young, usually of heart failure or infections. Thalassemia intermedia produces milder symptoms for the first two decades of life in most cases. Thalassemia minor may not produce any symptoms, though changes in the blood occur.
The protein which forms thick deposits, or plaques, in the brains of people with Alzheimer's disease, a disease where memory skills gradually deteriorate with age.
1009.
betadine
Definition:
A type of skin disinfectant.
1010.
betulinic acid
Definition:
This pentacyclic terpene is
found in the bark of birch trees, especially
the white birch (Betula alba). It is currently being
investigated as a treatment for malignant melanoma.
1011.
BglII
Definition:
A restriction enzyme that cuts DNA in a staggered manner wherever it finds the sequence "AGATCT."
1012.
bi-
Definition:
A prefix meaning "two" or "twice."
1013.
bicoid genes
Definition:
A group of genes which are important to the proper development of the head and thorax in the embryo of the fruit fly Drosophila melanogaster.
1014.
bidirectional replication
Definition:
A type of DNA replication where replication is moving along in both directions from the starting point. This creates two replication forks, moving in opposite directions.
1015.
biennial
Definition:
Refers to a plant that completes its life cycle in two years.
A change in the stability or in the types of solutions which occurs as a parameter is varied in a dissipative dynamic system. The change can be seen as a "bifurcation point" in a graph of the parameter being varied vs. one of the properties of the solutions.
A chronic disease of the liver characterized by the autoimmune
destruction of the organ. Patients affected are usually women from
40-60 years of age.
1027.
biliary endoprosthesis
Definition:
A tube inserted into a narrowed or blocked bile duct to improve
bile flow.
1028.
bilirubin
Definition:
A red-orange pigment found in bile which is formed when old red blood cells are broken down in the liver. It can also form from other types of
hemecatabolism. It has the chemical formula
C33H36N4O6. It is transformed from the green bile pigment biliverdin, which is directly formed from heme catabolism. Excessive bilirubin in the blood results in
jaundice.
Bilirubin is the by-product of breaking down hemoglobin that is measured in a blood
sample. The unconjugated form of bilirubin is also called indirect
bilirubin. After the liver adds a glucuronide to the unconjugated bilirubin,
it is called conjugated bilirubin, also called direct bilirubin. Conjugated
bilirubin is excreted into the hepatic ducts, the common bile duct and then
the bowel. Serum levels of bilirubin increase when there is excessive
breaking down of red blood cells, or when there is liver dysfunction.
Jaundice is clinically recognizable when total
bilirubin exceeds 50 umol/liter.
Normal ranges:
Total bilirubin 5.1-17.0 umol/L (adult) and 17-20 umol/L (newborn)
Indirect bilirubin 3.4-12.0 umol/L
Direct bilirubin 1.7 - 5.0 umol/L
1030.
biliverdin (dehydrobilirubin)
Definition:
A green pigment found in bile which is formed during hemecatabolism, mainly the breaking down of old red blood cells, within the liver. It has the chemical formula C33H34N4O6. It transforms into the red-orange bile pigment bilirubin.
1031.
binary acid
Definition:
This refers to any compound that acts as an acid and which is composed of hydrogen plus only one other element.
1032.
binary compound
Definition:
This refers to any compound that is composed of only two elements.
Increasing the activity of bacteria
that break down pollutants; a
technique used in bioremediation.
1045.
bioautography
Definition:
A chemistry lab technique to determine the concentration of a chemical substance such as vitamins or antibiotics by observing its effects on different test organisms' growth rates. A type of bioassay.
A field of ecology which deals with the study of communities of organisms and the interactions and relationships between the member organisms.
1051.
biocenosis (biocoenosis)
Definition:
A group of organisms in a self-sufficient community naturally occupying a small area with a uniform environment throughout.
In the field of paleontology, it is one of three types of fossil communities, which depends on the condition and completeness of the community when found. Biocenosis is the most complete type, able to offer the most information about what the community was like when it was alive.
1052.
biochemical mechanism
Definition:
This is the general term for any chemical reaction or series of reactions, usually mediated by enzymes, which produce a given physiological effect in a living organism.
1053.
biochemical oxygen demand
Definition:
The amount of oxygen aerobic
organisms need to carry out oxidative
metabolism in water
containing organic matter, such as sewage.
1054.
biochemorphology
Definition:
The scientific study of the chemical structure of pharmaceuticals and
nutrients and their effect on organisms.
1055.
biochip
Definition:
An electronic device that uses organic molecules to form a semiconductor.
A field of ecology which studies the effects of climate on what plants and animals are like, physically and behaviorally.
1059.
biocompatibility
Definition:
The ability to exist alongside living things without harming them.
1060.
biocybernetics
Definition:
The study of how communication and control occurs within the bodies of living things, between different parts of the body.
1061.
biocycle
Definition:
A biological cycle; repeated cycles of biological phenomena within the bodies of living things. Examples: menstruation in humans, the daily sleep cycle which, when disturbed, results in jet lag, and migration.
1062.
biocytin
Definition:
The amino acid residue formed when
biotin links covalently via an
amide linkage to a Lys residue.
Able to be decomposed by natural biological processes, such as by being
digested by bacteria or
fungi.
1065.
biodegradation (to biodegrade)
Definition:
The degradation, or destruction of, a chemical substance or substances by biological means (such as through microorganisms using it as a nutrient).
1066.
biodiversity
Definition:
The existence of a wide range of different types of organisms in a given
place at a given time.
1067.
bioelectronics
Definition:
The study of how electrons are transferred between molecules during biological regulation or biological defense. The movement of electrons is fairly important to the study of metabolism mechanisms.
1068.
bioenergetics
Definition:
A scientific field that deals with the application of thermodynamic
principles to organisms and biological systems.
1069.
bioengineering
Definition:
The science of developing and manufacturing artificial replacements for organs, limbs and tissues.
A branch of engineering in which live plants and plant parts are used as building material for erosion control and landscape restoration (this is in contrast to conventional engineering, in which only dead materials are used).
Adding nutrients or oxygen to increase microbial breakdown of pollutants.
1071.
bioequivalence
Definition:
Two different drugs which have the same potency and bioavailability, assuming equal doses.
1072.
biofeedback
Definition:
Information about certain bodily functions that are normally involuntary, such as pulse rate and blood pressure, that is given to an individual so that she or he can learn to affect or control them.
1073.
biofeedback
Definition:
A technique that allows a person to control, via methods such as visualization and relaxation, internal processes (such as heartbeat, blood pressure, brain wave activity. etc.) that are normally outside conscious control.
1074.
bioflavonoid
Definition:
A group of chemical substances found in many plants which help keep the cell walls of small blood vessels permeable.
1075.
biofuel
Definition:
A gaseous, liquid, or solid fuel that is rendered from raw biological
material (plants, sewage, dry waste, etc.) through combustion or
fermentation.
1076.
biogas
Definition:
A gas that is produced through anaerobic respiration; it
contains mostly methane and carbon dioxide with small amounts of water
vapor, nitrogen, hydrogen, or other gases.
1077.
biogenesis
Definition:
The theory that life always arises from previously existing life, and never from things which are not alive (as would be the case for the theory of spontaneous generation).
1078.
biogenetic law (recapitulation theory, "ontogeny recapitulates phylogeny")
Definition:
The theory that "ontogeny recapitulates phylogeny," which means that one can trace the evolutionary development of a species by studying the development of an individual embryo or young of that species. The theory is still used, especially in paleontology, but has been found to not be strictly true when applied to problems in biology.
1079.
biogenetics
Definition:
A form of genetic engineering; the science of adding or altering the genetic code of an organism to
achieve particular traits. This technique is becoming more and more important in agriculture as researchers seek to make crops that are resistant to pests.
1080.
biogenic
Definition:
Something which came about as a result of the activities of living things.
Something which is necessary for life processes.
1081.
biogenic amine (bioamine)
Definition:
A group of chemical substances which are made by cells and which alter various bodily functions (like vascular functions or nervous system functions).
Study of microbially-mediated chemical transformations of geochemical interest, e.g. nitrogen or sulfur cycling.
1083.
biogeography
Definition:
The study of the distribution of different species of organisms around
the planet and the factors that influenced that distribution.
1084.
biogeotechnology
Author: Definition:
The use of biological, ecological, and geotechnical engineering data to solve geological problems (such as erosion). Applied biogeotechnology focuses on using plants and human-made structures to control erosion, protect slopes, and restore environmental quality.
1085.
biohazard
Definition:
A risk of exposure to harmful bacteria, viruses, or other dangerous biological agents, particularly those found in genetic recombination studies or in clinical microbiology labs.
1086.
biohydrology
Definition:
The study of the interactions between the water cycle and plants and animals.
1087.
bioimplant
Definition:
An implanted prothesis made of biosynthetic material.
1088.
bioinformatics
Definition:
The use of computers in solving information problems in the life
sciences; mainly, it involves the creation of extensive electronic
databases on genomes, protein sequences, etc. Secondarily,
it involves techniques such as the three-dimensional modeling of
biomolecules and biologic
systems.
1089.
bioinstrumentation
Definition:
The use of machines and sensors to monitor physiological data from the body.
1090.
bioleaching
Definition:
The conversion of metals to a soluble form by live organisms such as bacteria or fungi.
A mechanical device for introducing foreign genes into plants by physical injection.
1093.
biological agent
Definition:
A disease-causing microorganism or virus, or other toxic biological matter, which is used as a weapon during war.
1094.
biological clock
Definition:
An internal biological mechanism which controls certain biological rhythms and biocycles, such as metabolism, sleep cycles, photosynthesis.
1095.
biological control (biocontrol)
Definition:
The agricultural use of living things, such as parasites, diseases, and predators, to control or eliminate others, such as weeds and pests, rather than by using chemicals (herbicides and pesticides).
1096.
biological engineering
Definition:
A type of artificial selection; the creation of plant or animal breeds that are agriculturally or industrially useful. Compare natural selection.
1097.
biological half-life (t 1/2)
Definition:
This is the time required for one-half of the total amount of a particular substance in a biological system to be consumed or broken down by biological processes when the rate of removal is approximately exponential. Toxic chemicals with a long biological half-life (such as some pesticides) will tend to accumulate in the body and are, therefore, more likely to be harmful. A substance with a short biological half-life may still accumulate if a portion of it it becomes tightly bound to bone or other tissues, even if most of it is quickly cleared from the body.
The process by which toxins such as pesticides build up in each
successive link in the food chain; for instance, a given population of
beetles may have very low levels of a fat-soluble pesticide, but the
pesticide will build to much greater levels in the fat of a bird that
eats those beetles, and the pesticide will reach greater levels still in
a human or panther that eats the beetle-eating birds.
1099.
biological monitoring
Definition:
This is the periodic examination of biological specimens for the purposes of monitoring their exposure to or the effects of potentially toxic chemicals to the environment. This is normally done by analyzing the amounts of the toxic substances or their metabolites present in body tissues and fluids. The term is also used to mean assessment of the biological status of populations and communities of organisms at risk, in order to protect them and to gain an early warning of possible hazards to human health.
1100.
biological oceanography
Definition:
The study of marine plants and animals and the way they interact with the marine environments. Similar to the study of marine biology.
Natural or artificial substances that enhance or restore normal immune defenses.
1103.
biological specificity
Definition:
The specific, orderly patterns of development and metabolism which define and characterize an individual and its species.
1104.
biological value (BV)
Definition:
The nutritional value of a protein, usually measured in comparison to the nutritional value of egg protein, which is the highest possible (BV=0.9 - 1.00).
1105.
biological warfare
Definition:
The military use of harmful biological agents such as pathogenicbacteria.
Agents, such as vaccines, that
give immunity to diseases or harmful
biotic stresses.
1107.
bioluminescence
Definition:
The production of electricity within the body which can be seen as visible light. Some organisms which have this ability are glowworms, fireflies, some jellyfish, some fungi, and some deep-sea fish.
1108.
biolysis
Definition:
The decay or decomposition of organic matter into simpler chemicals by organisms.
1109.
biomarker
Definition:
A pharmacological or physiological measurement which is used to predict a toxic event in an animal.
1110.
biomarker
Definition:
A specific biochemical in the body which has a particular molecular feature that makes it useful for measuring the
progress of disease or the effects of treatment.
1111.
biomass
Definition:
Plant material that can be converted into fuel.
A quantitative
estimate of the entire amount of living organisms in a particular
habitat; it can be measured in terms of volume, mass, or caloric energy.
1112.
biomaterial
Definition:
Any nondrug material that can be used to treat, enhance, or replace any
tissue, organ, or function in an organism.
1113.
biome
Definition:
A region which has distinct types of organisms, substrates, and climate, all interacting to produce a large, distinct, and complex biotic community.
1114.
biomechanical engineering
Definition:
This is the use of engineering/mechanical principles to solve problems in biology and medicine.
1115.
biomechanics
Definition:
The study of the body in terms of its mechanical structure and properties. Locomotion of the body is one of the more important things to which the mechanical laws are applied for study.
1116.
biomechanics
Definition:
This is the study of how living organisms move, grow, etc. in relation to mechanical principles.
1117.
biomedical engineering
Definition:
The use of engineering technology, instrumentation and methods to solve
medical problems, such as improving our understanding of
physiology and the manufacture of artificial limbs and organs.
1118.
biomedicine
Definition:
A general term which means research done in the fields of biology,
biochemistry, and
chemistry for application in medicine.
1119.
biometrical genetics
Definition:
The mathematical approach to the study of the inheritance of different phenotypes, or physical characteristics, as a result of plant or animal breeding.
1120.
biometrics (biometry)
Definition:
The statistical approach to the study of biology, especially to biological events like births and deaths, and other biological observations.
The calculation of life expectancy.
1121.
biomicroscopy
Definition:
The examination of tissues on a microscopic level. Could refer to the specific examination of the cornea or lens of the eye, using a corneal microscope and a slit lamp.
1122.
biomimetics
Definition:
A branch of biology that uses biological systems as a model to develop
synthetic systems.
1123.
biomolecule
Definition:
Any organic molecule that is an essential part of a living organism.
1124.
bionavigation
Definition:
The ability of certain animals to navigate by instinct to specific sites, apparently without using any landmarks. Examples are salmon returning to the same rivers where they were born, birds returning to the same nesting sites after annual migrations, or Florida green tortoises finding the same beaches upon which to lay their eggs.
1125.
bionics
Definition:
The study of the structure and function of organisms in order to apply this knowledge to the creation or modification of mechanical or electronic devices.
1126.
bionucleonics
Definition:
The study of how radioactive materials or rare stable chemical isotopes can be applied to biologic systems.
1127.
biopack (biopak)
Definition:
A container for living organisms used during biological experiments done in space; this container monitors the organisms' biological functions.
1128.
biophagous
Definition:
To feed on live things.
1129.
biophile
Definition:
A chemical element which occurs naturally in living organisms or organic matter, such as carbon, hydrogen, oxygen, and nitrogen.
1130.
biophysics
Definition:
The scientific study of the physics of organisms and biological structure
and processes.
1131.
biophysiologist
Definition:
A biophysiologist is a scientist who studies how non-human organisms function.
1132.
biophysiology
Definition:
Biophysiology is the scientific study of how non-human organisms function.
1133.
bioplast
Definition:
A mass of live protoplasm which is functionally independent of other living things. An amebiccell.
The strength of a chemical substance on the body; how well or how far it can act on a biological system.
1136.
biopotential
Definition:
The amount of energy in biologic matter available to transform into kinetic energy (the type of energy which is seen during activity), before this energy is actually manifested by an organism.
1137.
bioprocess
Definition:
The process of preparing a biological product (especially one involving genetic engineering) for commercial use.
1138.
biopsy
Definition:
To remove a sample of tissue from the body in order to examine it with a microscope for signs of disease, usually to help make a diagnosis.
The sample of tissue removed in order for it to be examined under a microscope for signs of disease so that an accurate diagnosis can be made.
Civil engineering methods incorporating organic materials to produce functional structures that are also aesthetically pleasing, provide wildlife habitat, and provide sites for revegetation.
1153.
biotechnology
Definition:
The industrial use of living organisms or biological techniques developed
through
basic research. Biotechnology products include antibiotics, insulin,
interferon, recombinant DNA, and techniques such as waste recycling.
Much older forms of biotechnology include breadmaking, cheesemaking and brewing wine and beer.
1154.
biotic
Definition:
Having to do with living things. Something that is caused by, or produced by living things. Having to do with the biological aspects of an environment (as opposed to geological, etc. aspects).
1155.
biotic community
Definition:
An aggregation of different species of organisms living and interacting within the same habitat.
A group of fossil species which are often found together in the same sites.
1156.
biotic potential
Definition:
The potential growth a population of living things can expect if it were living under ideal environmental circumstances.
A water-soluble vitamin (a member of the B complex vitamins) that
is important because it replenishes an
intermediate in the Krebs
cycle. It is also used in biochemistry to detect certain protein and
DNA interaction.
1159.
biotope
Definition:
The smallest unit of habitat where all environmental conditions and all types of organisms found within it are the same throughout.
The location of a parasite within the host's body.
1160.
biotoxin
Definition:
A toxin (a poison) which originates from a living thing (a plant, animal, fungi, bacteria, etc.)
The sequence of chemical reactions which a compound goes through in the body of an organism (including plants).
The conversion of a compound from one form to another by the actions of organisms or enzymes.
1162.
biotron
Definition:
A chamber used for biological experiments. In it, environmental
conditions can be completely controlled, thus allowing researchers to
test the effects of environmental changes on organisms.
1163.
biotroph
Definition:
An organism which cannot survive or reproduce unless it is on another organism. For example, fleas.
1164.
biotype (adj. biotypic)
Definition:
A population where all individuals are genetically identical.
A particular physiological or anatomical characteristic of an organism adapted to and living in a specific type of environment, distinctive from the same species of the organism adapted to a different type of environment.
1165.
bioultrasonics
Definition:
The use of ultrasonic sound for medical treatment or other biological purposes.
1166.
Biozzi mice
Definition:
Any genetic line of mice which has been bred to have unusually high or unusually low antibody responses to various antigens.
1167.
biparietal diameter (BPD)
Author:Guo Li Definition:
One of the ultrasound measurements of the human fetus (others are head
circumference, abdominal circumference, and femur length) which correlates
with the gestational age.
Divided, nearly to the base, into two parts. Compare bifid.
1169.
biphasic growth curve
Definition:
A particular type of growth curve seen in cultured microorganisms in
which they have two exponential growth stages separated by a plateau
phase. This double-hump curve is produced when the microbes are
cultured using two carbon sources, one of which must be used up before
the second can be used.
1172.
birth control (contraception, family planning)
Definition:
In general, birth control or contraception is anything that prevents a woman from becoming pregnant.
The most basic and cheapest form of contraception is abstinence (not engaging in sexual intercourse at all). However, abstaining from sex can cause great stress and frustration in some, since the human sex drive can be quite powerful.
A variation on abstinence is fertility awareness (also known as "natural family planning"). This method involves a couple avoiding intercourse during the times that the woman is most likely to be fertile. This method requires that the woman be very aware of her own body and her reproductive cycle; some estimate that this method has a 70%-98% rate of success, depending on the regularity of the woman's cycle and the specific monitoring technique used. Signs that a woman has ovulated (and is therefore fertile) include a sudden change in basal body temperature, changes in vaginal mucus, or a combination of the two. A woman is least likely to be fertile during her menstrual period and for a few days thereafter.
Barrier methods of birth control work by preventing sperm from reaching the egg. Barrier methods work best in conjunction with spermicides (creams or jellies that contain chemicals that kill sperm and sometimes disease-causing microorganisms).
Because barrier methods also prevent the exchange of body fluids to varying degrees, they are also useful in preventing the transmission of venereal diseases. Barrier methods include:
Other birth control methods work by altering a woman's hormones so as to render her infertile (male hormonal birth control is being researched). Hormonal methods include:
Depo Provera
birth control pills
Norplant
"morning after" pills
Other women may use intrauterine devices (IUDs), which work mainly by preventing the fertilized egg from implanting in the wall of the uterus. Other women use abortion (surgery to remove or drugs to induce the expulsion of an embryo or fetus) as a last-ditch effort at birth control.
If a couple wants no children at all, they may undergo surgery to render themselves sterile. In women, this procedure is generally a tubal ligation (cutting or blocking the Fallopian tubes, which carry the eggs from the ovaries). In males it is a vasectomy (cutting or blocking the tubes that carry sperm from the testis). These procedures can sometimes be reversed.
Previously known as 1,3-diphosphoglycerate (1,3DPG), this molecule is the
first molecule that generates ATP in
glycolysis. Its phosphoryl
group
generates a high-potential phosphorylated compound through a redox
reaction.
1,3BPG is also responsible for the production of an
allosteric effector of
hemoglobin,
2,3-bisphosphoglycerate (2,3BPG). In
this reaction, a phosphoryl group is transferred from 1,3BPG to the C-2
of 3PG. This yields 2,3BPG and a different 3PG molecule.
1175.
bithorax (bithorax complex)
Definition:
A group of genes (at least nine) found in the fruit fly genusDrosophila which codes for proper segmenting of the thorax (the middle body part of an insect, between the head and the abdomen) during the fruit fly's early development.
A stage in the development of a mammalian embryo just after the blastula stage, where the hollow ball of cells becomes two layers of cells - one layer, called the trophoblast, is at one end of the embryo and attaches it to the wall of the uterus so that it can receive nutrition during its development. The other is a single-cell layer which surrounds the blastocoele, the fluid-filled hollow part of the ball.
1180.
blastomere
Definition:
One of the cells of the early embryo, formed during the first few divisions of the newly-fertilized zygote.
An acute or chronic mycosis which usually affects man and animals (e.g. dogs). Blastomycosis is caused by a fungus called Blastomyces dermatitidis and occurs in North America, Africa and Israel. Infection apparently occurs by inhalation of spores from the fungus although B. dermatitidis has proved difficult to isolate from environmental habitats.
1182.
blastula
Definition:
A hollow ball of cells formed at the end of the cleavage stage of
embryonic development.
This is the time for the bleeding to stop from an artificially made superficial
incision on the forearm. The mechanism to stop bleeding involves vascular
contraction, platelet function, and the participation of the non-clotting
portion of the Factor VIII. Bleeding time may be normal in disorders of the
coagulation system. Normal range is 1 to 8 minutes.
Bleeding time is elevated in the following conditions:
decreased platelet count
decreased platelet function
increased prothrombin time
uremia
DIC
certain drugs: aspirin and other anti-inflammatory drugs
An agar-based medium which has
been enriched with sterilized, defibinated
blood (sheep, rabbit or horse). It is used for primary plating and
subculturing, especially to determine bacterial hemolysis.
1186.
blood clotting factor
Definition:
Any of a number of different protein factors which, when acting together, can form a blood clot shortly after platelets have broken at the site of the wound. The factors have Roman numeral names, like VII, VIII, IX, X, XI, and XIII. Defects in the genes which code for any of these factors result in genetic diseases like hemophilia, which results from a defect in the gene for factor VIII or IX.
1187.
blood count
Definition:
A numerical representation of the number of formed elements, such as red
blood cells or platelets,
found in a cubic millimeter of blood. The
number is obtained by counting the cells in an accurate volume of diluted
blood.
1188.
blood culture
Definition:
A preparation of blood, which is used either for general analysis or to
grow specific blood elements (such as white blood cells).
The main sugar that the body makes from the three elements of
food--proteins, fats, and carbohydrates--but mostly from
carbohydrates. Glucose is the major source of energy for
living cells and is carried to each cell through the
bloodstream. However, the cells cannot use glucose without
the help of
insulin.
1190.
blood glucose meter
Author:PharmInfoNet Definition:
A machine that helps test how much
glucose (sugar) is in the
blood. A specially coated strip containing a fresh sample of
blood is inserted in a machine, when then calculates the
correct level of glucose in the blood sample and shows the
result in a digital display. Some meters have a memory that
can store results from multiple tests.
A way of testing how much
glucose (sugar) is in the blood. A
drop of blood, usually taken from the fingertip, is placed on
the end of a specially coated strip, called a testing strip.
The strip has a chemical on it that makes it change color
according to how much glucose is in the blood. A person can
tell if the level of glucose is low, high, or normal in one
of two ways. The first is by comparing the color on the end
of the strip to a color chart that is printed on the side of
the test strip container. The second is by inserting the
strip into a small machine, called a meter, which "reads" the
strip and shows the level of blood glucose in a digital
window display. Blood testing is more accurate than urine
testing in monitoring blood glucose levels because it shows
what the current level of glucose is, rather than what the
level was an hour or so previously.
arterial presssure: systolic pressure is the peak pressure during each
heart cycle. Diastolic pressure is the minimum pressure during each
heart cycle.
the mean arterial pressure: is the average pressure throughout the
entire cardiac cycle.
the pulse pressure: the difference between the systolic and diastolic
pressures.
venous pressure: central venous pressure is the blood pressure at the
entrance of the superior vena cava into the right atrium of the heart.
The force of the blood on the walls of arteries. Two levels
of blood pressure are measured-the higher, or systolic,
pressure, which occurs each time the heart pushes blood into
the vessels, and the lower, or diastolic, pressure, which
occurs when the heart rests. In a blood pressure reading of
120/80, for example, 120 is the systolic pressure and 80 is
the diastolic pressure. A reading of 120/80 is said to be the
normal range. Blood pressure that is too high can cause
health problems such as heart attacks and strokes.
This is the microscopic examination of anticoagulated blood obtained from vein
pucture. The characteristics of red cells, white cells, and platelets are
observed for their sizes, shapes, numbers, color, morphologies, and the way
their group together. Certain presentation of blood smear may suggest
disease conditions.
A waste product of the kidneys. Increased levels of BUN in
the blood may indicate early kidney damage.
1198.
blood urea nitrogen (BUN)
Author:Guo Li Definition:
This is an indicator of glomerular filtration rate. However, because it is dependent upon the protein intake in the diet and renal function, it is an
insensitive indicator. At least 50 % of the kidney substance must be
destroyed before BUN is elevated.
Tubes that act like a system of roads or canals to carry
blood to and from all parts of the body. The three main types
of blood vessels are arteries, veins, and capillaries. The
heart pumps blood through these vessels so that the blood can
carry with it oxygen and nutrients that the cells need or
take away waste that the cells do not need.
1200.
blood-brain barrier
Definition:
A barrier made up of neuroglia
and capillary walls which limits the
movement of substances in the bloodstream into the brain.
A flower or bloom, esp. of a fruit bearing plant. A state or time of flowering, literally, and figuratively.
1204.
blunt-end DNA
Definition:
A fragment of a DNA molecule in which the ends of both strands are even with each other rather than one strand being longer than the other.
1205.
blunt-end ligation
Definition:
A lab technique to join together two pieces of blunt-end DNA, such as an insert into a cloning vector, which requires the enzymeligase because there are no single-stranded overhanging ends for the attachment to form more spontaneously, by itself.
1206.
bobbed
Definition:
The name for a variety of Drosophila (a fruit fly) mutation where the bristles (mostly on the back of the head) are very short and thin compared to normal fruit fly bristles. Also, the number of copies of genes encoding rRNA molecules are reduced.The mutant allele is located on the sex chromosomes and is recessive.
Normal oral temperature is 36.3° C to 37.1° C or 97.3° to 98.8° F. The rectal temperature is about 0.5° C or 1° F higher than the oral temperature.
1208.
body-centered cubic (bcc)
Definition:
A molecular structure in which a cube-shaped lattice is formed with one atom in the middle and four other atoms arranged around it as the corners of the cube.
A quagmire covered with grass or other plants; wet, spongy ground; a small marsh; plant community on wet, very acid peat.
1210.
boiling point
Definition:
This is the temperature at which the vapor pressure of a given liquid reaches atmospheric pressure (and thus starts to boil).
1211.
boiling point elevation
Definition:
This is the phenomenon of increasing the temperature at which a liquid boils by dissolving another substance in the liquid (for example, you can raise the temperature at which water boils by adding salt to it).
1214.
bone marrow biopsy
Author:Guo Li Definition:
This is obtained by inserting a hollow needle into the bone cavity (usually the
iliac crest or sternum). A specimen, after decalcification, sectioning, and
staining, is examined under low power microscopy. The staining
characteristics, number and morphology of cells may be suggestive and
sometimes diagnostic of certain blood related diseases.
Material effects, risks and side effects: prolonged bleeding time if the
patient has bleeding tendency, infection, the needle on the sternum may
suddenly go through the bone and puncture the heart or large blood vessels.
1215.
bone marrow harvesting
Definition:
A medical procedure which involves collecting healthy bone marrow which will
be stored and used in a future bone marrow transplant.
This is a technique to demonstrate abnormal metabolic activity in bone. The
procedure involves intravenous injection of the radionuclide which is
usually sodium pertechnetate (technetium Tc99m methylene diphosphonate)
which is taken up in areas of active growth in bone.
It is possible to
differentiate normal growth and excessive growth from the level of
radioactivity emitted. This method can detect metastatic tumor to bone from
the prostate, breast, lung, kidney, bladder and thyroid, arthritis,
osteomyelitis, and new fractures. Other methods include WBC scan and gallium
scan.
1217.
boom
Author: Definition:
A floating log or similar element designed to dampen surface waves or control the movement of drift.
1218.
Born-Haber cycle
Definition:
This is a mathematical description of the relationship between the electron affinity, heats of atomization, ionization energy and lattice energy of ionic compounds.
1219.
borrow pits
Author: Definition:
Excavations created by the surface mining of rock, unconsolidated geologic deposits or soil to provide material (borrow) for fill elsewhere.
1220.
botanist
Definition:
A botanist is a scientist who studies plants.
1221.
botany
Definition:
The scientific study of plant life.
1222.
bottleneck effect
Definition:
This is a type of genetic drift caused by the rapid decrease in a population's size due to a natural disaster (fire, flood, etc.) that results in a new mating population that is not genetically representative of the original group.
A very strong poison which affects the nervous system, made by the bacteriaClostridium botulinum. The poison causes the food poisoning known as botulism.
1225.
botulism (botulism disease)
Definition:
A type of food poisoning caused by the toxin botulin, which is made by the bacteriaClostridium botulinum. Symptoms of the disease include vomiting, stomach trouble and indigestion, abdominal pain, trouble seeing, and a barking cough.
1226.
boulders
Author: Definition:
Largest rock transported by a stream or rolled in the surf; arbitrarily heavier than 50 pounds and larger than 8 inches.
Substrate particles greater than 256 mm (10 inches) in diameter. Often subclassified as small (256 to 1,024 mm) and large boulders (larger than 1,024 mm).
A growth hormone found in
cattle; a version of this hormone is also found
in all mammals, including humans. Injections of this hormone
dramatically increase the milk production of lactating cows. In past
years, the hormone was very expensive because it could only be taken
from slaughtered cows, but in the early '90s researchers learned
how to genetically
engineered the bacterium E.
coli to produce it. Now, many dairy producers use the hormone,
but the practice is controversial because the use of bST may increase the
incidence of mastitis (udder infection) in cows, and the long-term
human health effects of the slightly increased hormone levels in the
milk from treated cows have not been established. See also
porcine somatotrophin.
A neuro-degenerative disease found in domestic cattle which is related to a number of other similar diseases found in other animal species, including humans. The most well-known of these other diseases are scrapie, found in sheep, and Creutzfeldt-Jakob Disease, found in humans. The family of diseases is caused by an abnormally-configured protein called a prion. The function of the protein in its normal configuration is not certain. The diseases are similar to Alzheimer's disease in humans, except the progressive loss of brain function is more rapid.
1229.
Boyle's Law
Definition:
This law states that the volume of a sample of gas is, at a constant temperature, inversely proportional to the pressure of that gas.
1230.
brachiopod (Brachiopoda)
Definition:
A phylum of invertebrate animals often grouped with two other phyla under the name "Lophophorates." General characteristics include: a pair of protective shells (giving them a superficial resemblance to the bivalves - i.e. clams), a stalk protruding from the rear called a "pedicle" which anchors the animal to the sea floor, and a lophophore (a ridge with many tiny tentacles on it, used to catch food particles floating by). Brachiopod shells come in many different shapes and sizes. Brachiopods were extremely abundant during the Paleozoic era (both in terms of numbers of individuals and numbers of species), but were practically wiped out around 300 million years ago during the Permian mass extinction.
A small bract-like structure borne singly or in pairs on the pedicel or calyx of a flower.
1235.
bradycardia
Definition:
Bradycardia is an abnormally slow heart rate. In healthy adults, the normal resting heart rate is about 70-80 beats per minute (athletes often have resting heart rates in the 60s and sometimes lower). In newborn babies, the normal heart rate is 120-160 beats per minute.
1236.
bradykinin (kallidin I, callideic I)
Definition:
In biochemistry, a
hormone with the chemical formula of C50H73N15O11 which causes muscle contractions in the lungs, uterus, and intestines, the dilation of blood vessels (resulting in lowered blood pressure), and pain.
In endocrinology, a hormone that forms in blood plasma which can dilate blood vessels, make one more sensitive to pain, and/or play a role in inflammation.
1237.
braided stream
Author: Definition:
Stream that forms an interlacing network of branching and recombining channels separated by branch islands or channel bars. (See also channel braiding.)
1238.
braiding of stream channels
Author: Definition:
Successive division and rejoining of streamflow with accompanying islands. (A braided stream is composed of anabranches.)
1239.
brain (encephalon)
Definition:
The center of the central
nervous system; a mass of nerve tissue in the
cranium that receives and transmits neural impulses and controls and
directs an organism's behavior and actions.
A definition of death based on the absolute and total loss of the
individual's brain function that is irreversible.
This definition of death is a medical definition which may differ from
religious, ethical, philosophical or cultural definitions of death.
Modern anesthesia techniques can render a person without brain activities
(flat EEG), totally paralyzed (with neuromuscular blocking agents), and with
no cardiac (heart) activity (with cardioplegic solutions), such as is the
case when a patient is undergoing extracorporeal circulation during cardiac
anesthesia. In this case, despite that the patient physically resembles that
of a dead person, the condition is reversible.
Therefore, to declare brain death, one must follow a protocol of clinical
testing as well as preclude anesthetic causes and hypothermia.
This is a technique to demonstrate the pattern of blood perfusion of the brain.
The procedure involves intravenous injection of the radionuclide such as
technetium 99m pertechnetate, mercury-210, or radioiodinated albumin. This
method can diagnose cerebral hemorrhage, cerebrovascular accidents (CVA), tumor,
hematoma, AV malformations, and aneurysms.
1242.
brain stem (brainstem)
Definition:
The lowest part of the brain, which merges with the spinal cord. It
consists of the medulla
oblongata, midbrain and
pons.
Movement of the
branch point in a branched
DNA
sequence formed from two parent DNA molecules with practically identical
sequences. See Holliday
intermediate.
A genus of plants belonging to the mustard family Brassicaceae. The whole family includes a total of 376 different genera and 3,200 different
species. The family is also known as "Cruciferae" because the four petaled flowers of these plants look like crosses. The plants are distributed worldwide and have annual (living one year), biennial (living two years) and perennial (living many years) members.
Member species of genus Brassica include Brassica napus which produces rapeseed or canola oil; Brassica nigra which produces yellow mustard; Brassica oleracea whose subspecies and strains include kale and collard greens (B. oleracea acephala), broccoli (B. oleracea botrytis), cauliflower (B. oleracea cauliflora), head cabbage (B. oleracea capitata), brussel sprouts (B. oleracea gemmifera), and kohlrabi (B. oleracea gongycoides); and Brassica rapa, whose subspecies include pak choi (B. rapa chinensis), Chinese cabbage (B. rapa pekinensis), and turnip (B. rapa rapifera). Also, one subspecies of B. rapa is used as a model organism to study genetics, molecular biology, plant breeding, cell biology, and physiology; it is called the "rapid cycling" Brassica or RCBr or the Wisconsin Fast PlantTM, and was developed specifically for scientific study. Additionally, the radish Raphanus sativus is a member of the Brassicaceae family. The full taxonomic classification is kingdom Plantae,
division Tracheophyta, subdivision Spermatophyta,
class Angiospermae, subclass Dicotyledeonae, order Papaverales, family Brassicaceae.
1246.
BRCA1
Definition:
BRCA1 is a tumor-supressing gene; if even one copy of it is damaged, cancer can develop. Certain mutations confer a high probability (85% lifetime risk) of developing breast cancer, and other types cause ovarian cancer. Familial mutations of this gene are particularly common among people in the Ashkenazi Jewish ethnic group.
1247.
breeder reactor
Definition:
This is a nuclear reactor which produces nuclear fuel as it produces energy for electricity.
This is the procedure in which an instrument is introduced through the mouth or
the nostril to examine the upper airway: nasal pharynx, oral pharynx,
larynx, trachea and the bronchi. Biopsy and cell samples (sputum or
bronchial washings) could be obtained and foreign body could be retrieved.
In rigid bronchoscopy a metal tube is used. In fiberoptic bronchoscopy a
flexible fiberoptic instrument is used. Laser excision of bronchial tumors
is also performed through a bronchoscope.
Material effects, risks and side effects: bleeding after biopsy; coughing;
laryngospasm; aspiration; collapse of small airways; hypoxemia.
A genetic disease in which the body takes in too
much iron from food; this causes excess iron to be deposited in the liver
and heart and other organs, eventually leading to organ failure and death. This illness is called
"bronze diabetes" because the kidneys often fail, leading to symptoms similar to those found with
diabetes mellitus, and because the
deposition of iron into the skin makes the person look like he or she has an all-over tan.
It used to be believed that this disease was rare and mainly affected people of Caucasian descent, but
in recent years scientists have realized it is more common and affects a wide range of ethnic groups. Some believe
that this genetic defect actually helps people (especially women) survive in areas where malnutrition is
widespread and iron is scarce in food.
Regular bloodletting (or blood donation) may help people suffering from this disease.
In botany terminology, describes a plant which has many branches parallel or almost so and usually erect.
1257.
broth
Definition:
In the food industry, a thin liquid which is made by boiling meat or vegetables or bones and is used in preparing other foods. It can be found in powder form in most grocery stores.
A liquid medium containing a variety of nutrients which is used to grow cultures of bacteria and other microorganisms.
ipsilateral motor disturbance and impairment of proprioception
contralateral loss of pain and temperature appreciation below the
lesion
1259.
browse protection
Author: Definition:
Mechanical or chemical protection of shrubs and trees against damage caused by game and grazing animals.
1260.
browsed
Author: Definition:
Any tree with several centimeters of one or more limb tips, including but not restricted to, the tallest limb, bitten off by deer or other wildlife.
1261.
brush habitat
Author: Definition:
Includes a wide variety of plant and animal life dominated by and associated with coastal scrub and chaparral.
1262.
brush layering
Author: Definition:
Placing horizontal layers of tree branches or twigs in a gully or along a slope and then partially covering the branches with soil; the branches act to hold the soil in place and to absorb momentum from water flowing over the area.
1263.
bryophyte
Definition:
Any primitive plant in the division Bryophyta; includes liverworts, mosses, and hornworts.
1264.
bubbler irrigation
Author: Definition:
An irrigation system which injects a slow trickle of water into the ground next to plant roots.
A hollow, spherical molecule consisting of 60 carbon atoms arranged in a soccer ball pattern of hexagons and pentagons. The molecule can superconduct, lubricate, and absorb light. The molecule is a type of fullerene, was the first one to be discovered and studied, and is named after the architect R. Buckminster Fuller.
A small swelling or projection on a plant, from which a shoot, cluster of leaves, or flowers develops; a rudimentary, undeveloped shoot, leaf, or flower.
1267.
Budd-Chiari syndrome (Chiari's syndrome, Chiari-Budd syndrome)
Author:Guo Li Definition:
Budd-Chiari syndrome is characterized by a enlarged, tender liver with intractable ascites. This syndrome is often caused by the thrombosis or obstruction of the hepatic vein. Pathological finding may reveal thickening of the intima of the hepatic veins.
A chemical used to maintain the pH of a solution by absorbing hydrogen
ions (which would make it more acidic) or hydroxyl ions (which
would make it more basic).
1270.
buffer capacity
Definition:
The ability of a buffer solution to absorb added alkali or acid while maintaining the solution's pH.
Strip of vegetation left intact along a stream or lake during and after logging.
1272.
buffer zone
Author: Definition:
An area of land separating two distinct land uses that acts to soften or mitigate the effects of one land use on the other.
1273.
bulb
Definition:
A modified underground stem which has one or more buds enclosed in fleshy
modified leaves or scales which supply energy to the bud(s) when they
start to grow; onions and tulips have bulbs.
Marker analysis applied to two bulked DNA samples prepared from individuals selected, in a segregating population, to be contrasting with respect to a trait of interest.
1277.
bunch grass
Author: Definition:
Any of a number of perennial grasses (family Gramineae) which grow in tight clumps and regenerate each year from deep roots.
1278.
Bunsen burner
Definition:
A small, widely-used piece of laboratory equipment which produces an adjustable gas flame for the purposes of heating chemical reactions and the short-term sterilization of other small pieces of laboratory equipment.
1279.
Bunyaviridae
Definition:
A large family of viruses
containing single-stranded RNA
that infect a
wide range of vertebrate hosts; some are responsible for hemorrhagic fever.
1280.
buried soils
Author: Definition:
Soil covered by an alluvial, loessal, or other deposit (including manmade).
A type of cancer associated with the Epstein-Barr virus (EBV),
though it
is not known if EBV actually causes the tumor or not. This lymphoma of the B lymphocytes is
rare in developed countries but is relatively common among people
living in New Guinea and East Africa.
Damage to skin or other tissues caused by agents such as fire, radiation, or corrosive chemicals. The severity of burns:
first degree: skin is red in appearance, no blisters and sensation is intact (e.g., sunburn).
second degree: partial thickness burn (thickness refers to the layers of the
skin), blisters common, sensation is intact.
third degree: full thickness burn, the skin is without sensation (anesthetic to touch), and dry with a leather-like or charred texture.
The area of the body burned is usually expressed in percentages of the
total body surface area that has sustained second and third degree burn. The
following method can give a rough estimate of the area burn:
adult: head 9%; anterior trunk 18%; posterior trunk 18%; each arm 9%;
each leg 18%; genitals 1%
child: the proportion of body areas changes with age, it is difficult
to find a simple method to estimate the percentage of burned area
A rough or prickly propagule consisting of a seed or fruit and associated floral parts or bracts.
1284.
Bursa of Fabricius
Definition:
A saclike organ found in the cloaca (excretory and reproductive opening) of birds which produces B lymphocytes.
1285.
burst number
Definition:
The number of viral particles
that emerge from a cell after a viral
infection has burst it open.
1286.
buspirone (BuSpar)
Definition:
This is a psychotropic drug with anxiolytic properties which belongs chemically to the class of compounds known as the azaspirodecanediones. It is used to treat anxiety.
A substance that the pancreas releases into the bloodstream
in equal amounts to
insulin. A test of C-peptide levels will
show how much insulin the body is making.
1293.
C-reactive protein (CRP)
Definition:
A protein which is not normally found in blood, but when it is present, it indicates inflammation. In vitro it will precipitate when exposed to somatic C-polysaccharide (a complex sugar molecule) from the bacteriaPneumococcus.
1294.
C3 cycle (Calvin cycle)
Definition:
The part of the photosynthesis process where carbon dioxide is converted into three-carbon compounds, which can then be turned into six-carbon sugars.
1295.
C4 cycle (Hatch-Slack pathway)
Definition:
An alternative, very efficient pathway used by plants living in areas with low levels of carbon dioxide, to convert carbon dioxide into a form usable by the plants during photosynthesis.
A protein which can be found in the blood; it is useful for detecting
and evaluating ovarian cancer.
1298.
CA-125 tumor marker
Author:Guo Li Definition:
This is a protein measured in blood samples. It is produced by a variety of cells, but particularly by ovarian cancer cells. It is used as a tuomor marker to confirm the suspicion
of ovarian cancer and to follow the presence of residual or recurrence of
ovarian cancer after surgery. Its blood levels may be elevated in pregnant women and patients
with breast and colorectal cancers, endometriosis, ovarian cysts,
fibroids, cirrhosis, hepatitis, or pancreatitis.
Cachexia is the appearance of widespread of wasting of the body, pale color, dry
wrinkled skin and mental depression; a clinical sign of serious chronic disease,
especially cancer.
This protein fragment is found
in the urine of patients
who suffer from debilitation and wasting from cancer, particularly cancers of the lung,
breast, ovary and pancreas. It is believed to cause the wasting by
degrading muscle proteins and inhibiting the creation of new proteins.
1302.
Caenorhabiditis elegans
Definition:
This is a free-living (non parasitic)
species of
nematode which makes a good model organism for biological study because it has a small
genome of only six
chromosomes. It also has a short generation time of about three days (at room temperature), and is easy to grow at high densities (up to 10,000 worms on one Petri dish).
C. elegans has been thoroughly studied by
geneticists,
developmental biologists and neurologists. The worms can be used to study
genetic manipulation,
gene therapy, and the molecular basis of differentiation during development. Much of the world's knowledge about aging, inheritance, and the factors which control gene expression during development comes from studying this and other nematodes. The full
taxonomic classification of C. elegans is: kingdom Animalia,
phylum Nematoda,
class Secernentea, subclass Rhabditia, order Rhabditida, family Rhabditidae.
1305.
calcemia (hypercalcemia) (adj.: calcemic, hypercalcemic)
Author:Guo Li Definition:
Calcemia is the condition in which the blood level of calcium is abnormally high; more often known as hypercalcemia. People affected with hypercalcemia do not have appetite, feels nausea and vomiting and weak. The normal levels of serum calcium is 2.1 to 2.6 mmol/L and adjusted according to the levels of albumin.
Calcification is the process of deposition of calcium salts. In the formation of bone this is a normal condition. In other organs, this could be an abnormal condition. Calcification of the aortic valve causes narrowing of the passage (aortic stenosis). Calcification of breast tissues should be investigated as there is a high potential of cancerous growth.
1307.
calcination
Definition:
The process of heating a solid below its melting point to break it down into another compound (for instance, heating calcium carbonate to send off carbon dioxide gas and create calcium oxide).
Calcinosis is the abnormal deposit of calcium in tissues.
1309.
calcitonin
Definition:
A hormone which is released by the thyroid and parathyroid glands when the levels of calcium compounds in the blood are too high. The hormone acts to reduce the levels of calcium and phosphate.
Calcitonin is a hormone secreted by a type of cells in the thyroid gland. (Calcitonin is different from the thyroid hormone thyroxine ). Calcitonin is a small peptide of 32 amino acids. It functions to lower the circulating calcium and phosphate levels. Its secretion is controlled via feedback inhibition by calcium levels.
1311.
calcium (Ca)
Definition:
Calcium is a hard, silvery metallic element which has an atomic number of 20 and an atomic weight of 40.078. It is classified as an alkaline earth element and burns with a yellow-red flame. It is highly reactive (pure calcium reacts explosively with water) and is therefore not found in its pure form in nature. Instead, it is typically found in minerals such as gypsum and fluorite, in limestone (as calcium carbonate) and stalactites/stalagmites, and in the bones, teeth and shells of animals.
Calcium is essential in the human diet (people normally consume 600 1400 milligrams per day). The body needs it for a
variety of functions, such as blood clotting, the transmission of nerve signals, muscle contraction,
and proper heart function. Calcium imbalances can cause many health
problems, and some chemical imbalances can cause the mineral to build up in nerve cells, poisoning and ultimately killing them.
1312.
calcium ATPase
Definition:
A type of ATPase, which is an enzyme that removes a phosphate from an ATP molecule, turning it into ADP in the process. The calcium ATPase enzyme needs to have calcium.
1313.
calcium carbimide (Temposil)
Definition:
This drug is used to treat alcoholism; if a person takes this drug and then drinks any alcohol at all, they will get sick (headache, nausea, vertigo, etc.)
The calcium channel is the channel via which calcium cations pass through the cell membrane. In
excitable cells the action potential results from the transmembrane fluxes
of Na+, Ca2+ and K+.
A drug that blocks the entry of calcium into
cells, thereby preventing cell dealth and loss of function caused by excess
calcium. Calcium channel blockers are used primarily to lower blood pressure and to treat certain heart conditions and stroke, but are being studied as potential
treatments for Alzheimer's disease.
1316.
calcium channel blocker
Author:Guo Li Definition:
A calcium channel blocker is a drug that interferes with the generation of an action potential in cells dependent on the calcium current for their activation; verapamil, nifedipine, and diltiazem belong to this class. By reducing the flux of calcium, these drugs slow down the heart rate, and lower blood pressure thereby reducing oxygen demand of the heart. These drugs are used to treat angina, and hypertension.
1317.
calcium metabolism
Definition:
A set of biochemical processes which act to keep the level of calcium in the blood at a constant level, with enough around to build bones and teeth.
A chemical compound with the formula CaO which is a whitish, odorless solid that does not dissolve well in water. It will, however, react with water (H20) to form calcium hydroxide (CaOH, a base). It has a melting point of 2614 degrees Celsius and a boiling point of 2850 degrees Celsius. It can be made by heating calcium carbonate (CaCO3, limestone) until carbon dioxide (CO2) is released. It has a great many industrial uses.
1319.
calcivirus
Definition:
The one genus of viruses in the family Calciviridae. Includes a variety of feline calcivirus strains, the San Miguel sea lion virus, the vesicular exanthema of swine virus, and (possibly) the Norwalk virus.
1320.
calculus (pl. calculi)
Author:Guo Li Definition:
A calculus is a mineral deposit resembling a stone at abnormal body locations. Plural:
calculi. A kidney stone is called a renal calculus; stones in the salivary glands are called calculi of the salivary glands.
The clinical condition of having calculi, however, is described by (medical name of
organ)-lithiasis. For example:
A small area of skin, usually on the foot, that has become
thick and hard from rubbing or pressure. Calluses may lead to
other problems such as serious infection. Shoes that fit well
can keep calluses from forming.
A unit of measurement defined as 4.184 absolute joules, or the amount of
energy it takes to raise
the temperature of one gram of water from 15 to 16 degrees Celsius (or
1/100th the amount of energy needed to raise the temperature of one gram
of water at one atmosphere pressure from 0 degrees C to 100 degrees C);
food calories are actually equal to 1,000 calories (1 food calorie = 1
kilocalorie).
One calorie (note lower-case c) is a unit of heat equal to the amount of heat the raise the temperature of one gram of water from 14.5° C to 15.5° C. The clinical unit of Calorie (note the upper-case C) is equal to 1000 calories (Kilocalories).
1328.
Calvin cycle (dark reactions)
Definition:
In plants, a cyclical series of carbon-fixing, sugar-producing reactions in the chloroplasts. Some of the sugars (triose phosphates) are recycled, others are stored as carbohydrates. Light is not needed for these reactions; they use the carbon dioxide and energy produced in the light reactions of photosynthesis.
In mosses, a cap-like structure covering or partly covering the capsule and derived from the neck of the archegonium; in a flower, a cap covering the stamens and carpels in the bud and formed by fusion or cohesion of perianth parts.
This alkaloid was originally
isolated from a Chinese tree, Camptotheca acuminata but has also
been found in the nothapodytes tree (Nothapodytes foetida). It is
the first known naturally-produced DNA topoisomerase I
inhibitor, and as such is being heavilly researched as a
treatment for a wide variety of cancers.
Cancellous bone is the central trabeculated part of the bone. This part of bone is composed of lamellar bone in which the collagen bundles are arranged either in parallel sheets or in concentric laminae around a central vessel.
1341.
cancer
Definition:
A type of disease caused by cells that divide and grow uncontrollably,
invading and disrupting other tissues and spreading to other areas of the
body (metastasis).
1342.
cancer (malignant tumor)
Author:Guo Li Definition:
Cancer is an abnormal uncontrolled growth of tissue that has potential to spread to distant sites of the body. Cancer exerts its deleterious effect on the body
by:
destroying the surrounding adjacent tissues: e.g. compressing nerves, eroding blood vessels, or causing perforation of organs
replacing normal functioning cells in distant sites: e.g. replacing blood forming cells in the bone marrow, replacing bones leading to increased calcium levels in the blood, or in the heart muscles so that the heart fails.
1343.
Candida albicans
Definition:
C. albicans is a species of
yeast which is commonly found in the mouth, intestines, and vagina as a part of the human body's normal flora and which normally does not cause problems. However, it can cause candidiasis of the mucous membranes in the mouth (also called thrush) and of the vagina (called vaginitis or simply a yeast infection). It can also cause more serious diseases in people with AIDS and in
chemotherapy patients.
1344.
candidate species
Author: Definition:
Any species or subspecies of bird, mammal, fish, amphibian, reptile, or plant that is being considered for listing as endangered or threatened but is not yet the subject of a proposed rule.
1345.
cannula
Definition:
A small tube which a surgeon or doctor inserts into a body cavity, duct or vessel for therapeutic purposes.
The overhead branches and leaves of stream-side vegetation.
1349.
canopy cover
Author: Definition:
Vegetation projecting over a stream, including crown cover (generally more than 1 m above the water surface) and overhang cover (less than 1 m above the water).
1350.
canopy density
Author: Definition:
The percentage of the stream covered by the canopy of plants, sometimes expressed by species.
The smallest of the body's blood vessels. Capillaries have
walls so thin that oxygen and glucose can pass through them
and enter the cells, and waste products such as carbon
dioxide can pass back into the blood to be carried away and
taken out of the body. Sometimes people who have had
diabetes
for a long time find that their capillaries become weak,
especially those in the kidney and the retina of the eye.
1355.
capillary action
Definition:
The phenomenon of a liquid such as water spontaneously creeping up thin tubes and fibers; this is caused by adhesive and cohesive forces and surface tension.
1356.
capillary electrophoresis
Definition:
A technique for separating compounds; a sample of a compound to be
separated is placed in a capillary tube, which is then subjected to a
high voltage current that separates its chemical components.
1357.
capillary fringe
Author: Definition:
A zone immediately above the water table in which water is drawn upward from the water table by capillary action.
A methylated (has a -CH3 attached) guanosine nucleotide attached to the 5'-end (the beginning) of an eukaryoticmRNA, thought to give the mRNA stability.
1363.
capping of mRNA
Definition:
The process of adding a guanosinenucleotide to the 5'-end (the beginning) of an eukaryoticmRNA, then methylating (adding a -CH3 to) the guanosine.
1364.
caprine
Definition:
Relating to, affecting, resembling or derived from a goat.
1365.
capsid
Definition:
The protein covering, or outer coat, of a virus particle.
1366.
capsomere
Definition:
A group of identical protein molecules which form the outer coat of a virus (called the capsid).
1367.
capsula (caps.)
Definition:
This Latin term, which is frequently used in medicine, means "capsule".
A dry fruit formed from two or more united carpels and dropping at maturity to release the seeds.
1369.
capsule
Definition:
A coat of carbohydrates or other slimy substance around microorganisms which enable them to avoid phagocytosis (being engulfed by other microorganisms, or by the defense cells of a host's immune system).
This tricyclic prescription drug is used to treat convulsions, epilepsy and manic episodes.
1371.
carbocation (carbonium ion)
Definition:
A positively charged carbon atom.
1372.
carbohydrate
Definition:
A compound or molecule that is composed of carbon, oxygen and hydrogen in
the ratio of 2H:1C:1O.
Carbohydrates can be simple sugars
such as sucrose and fructose or
complex polysaccharidepolymers
such as chitin.
1373.
carbohydrate antigen 15-3
Author:Guo Li Definition:
This protein is found in elevated amounts in the blood of patients with breast cancer; however, as of 1997 it was not yet suitable to be used clinically as a tumor marker.
1374.
carbohydrate antigen 19-4
Author:Guo Li Definition:
This protein is found in elevated amounts in the blood of patients colorectal cancer; however, as of 1997 it was not yet suitable to be used clinically as a tumor marker.
1375.
carbon dioxide cycle
Definition:
First, an organism which can photosynthesize (such as a plant or some bacteria) will absorb carbon dioxide (CO2) from the air and incorporate it into its body or turn it into organic matter. Then, other organisms which cannot photosynthesize will eat the organic matter, or the photosynthesizing organism, and release CO2 gas as a waste product back into the air.
1376.
carbon fixation
Definition:
The process by which photosynthetic
organisms such as plants
turn inorganic carbon (usually carbon dioxide) into organic compounds (us.
carbohydrates).
1377.
carbon source
Definition:
Any carbon-containing organic molecule (carbohydrate, amino
acid) that an organism can use to produce energy in the form of ATP.
1378.
carbonyl group
Definition:
A group in which an oxygen atom is double-bonded to a carbon atom: O=C. The carbon atom then has two additional bonds to attach to the rest of the molecule. Organic molecules containing a carbonyl group are a very important, major group of compounds studied in the field of organic chemistry.
An injected chemotherapy
drug which is typically used to treat advanced
ovarian cancer (carcinoma).
Side effects include lowered blood cell
counts (all types), nausea and diarrhea, hair loss, pain and other
neurologic problems.
This is a blood test in which the percentage of carbon monoxide bound hemoglobin
is measured. Carbon monoxide's affinity to bind to hemoglobin is 200
times more than that of oxygen. Carboxyhemoglobin level is elevated in smoke
inhalation (such as fire in an enclosed space), car exhaust inhalation, and
smoking.
Reference range: non smokers less than 3% and smokers greater than 12%
1381.
carboxyl group
Definition:
-COOH group. One of the oxygens is double-bonded to the carbon atom, making it a carbonyl group, and the other oxygen is single bonded to the carbon on one side, and single bonded to the hydrogen on the other. The remaining bond on the carbon atom is attached to the rest of the molecule. Organic molecules containing carboxyl groups are an important, major group of compounds studied in the field of organic chemistry.
The end of a polypeptide chain with the unattached carboxyl group (a -COOH group). Each amino acid in the middle of the chain has an amino group (a -NH2 group) on one side (which is attached to the carboxyl group of the previous amino acid) and a carboxyl group on the other side (which is attached to the amino group of the next amino acid). The other end of the polypeptide chain is called the amino terminal.
1383.
carboxyl-terminal residue
Definition:
This amino acidresidue defines the carboxyl
terminus of
the polypeptide; it's the
only residue with a free alpha-carboxyl group.
1384.
carboxylic acid
Definition:
An organic acid containing the functional group -COOH.Structurally, the group looks like:
Debilitation and emaciation caused by advanced-stage cancer.
1389.
carcinoembryonic antigen (CEA)
Author:Guo Li Definition:
This is an antigen in blood which is elevated in certain cancers of epithelial origin, notably colon, breast, lung and stomach. CEA is a molecule expressed on surfaces of epithelial cells during embryogenesis but is later confined to only the apical surface. Its function is related to cell adhesions. Tumor formation is accompanied with elevated expression of CEA. Blood CEA levels is a tumor marker to detect the recurrence of cancer or residual activity of cancer after surgery. However, CEA is a non-specific marker of cancer, and may be elevated in noncancerous conditions such as cigarette smoking, ulcerative colitis, liver disease, and lung infection. Therefore, CEA is not useful as a screening test.
Normal levels of serum carcinoembryonic antigen are 0 to 2.5 ug/L.
1390.
carcinogen
Definition:
A chemical or physical agent that tends to cause cancers or tumors.
1391.
carcinogenesis
Definition:
The process of a normal cell becoming cancerous.
1392.
carcinogenic
Definition:
This adjective describes anything that can cause cancer.
This is an agent which increases tumor production by another substance when applied to susceptible organisms after their exposure to the first substance.
1394.
carcinoid syndrome
Definition:
The group of symptoms caused by a carcinoidtumor if it produces secretions. Symptoms can include diarrhea, wheezing, heart murmurs, enlarged liver, and a dusky appearance to the skin.
1395.
carcinoid syndrome
Author:Guo Li Definition:
Carcinoid syndrome consists of facial flushing, head and neck edema, abdominal cramps and diarrhea, bronchospasm, pulmonic and tricuspid valves lesions and increased urinary excretion of 5-HIAA (5-hydroxyindoleacetic acid). It is caused by the proliferation of carcinoid tumors (serotonin-producing neuroendocrine tumors that occur mainly in the small intestine and liver).
Yellow, canceroustumors of hormone-making cells in the gastrointestinal tract (specifically, they are classed as neuroendocrine or amine precursor uptake and decarboxylation tumors). They produce excess endocrines such as kallikrein (an activator of bradykinin release) and serotonin. These tumors can be found in the intestine, stomach, or sometimes on the liver. In later stages, this type of cancer causes symptoms such as diarrhea, wheezing, heart murmurs, enlarged liver, and a dusky appearance to the skin. Carcinoids can be diagnosed with a urine test or with a CAT scan.
A tumor that develops from epithelial
cells, such as the inside of the
cheek or the lining of the intestine.
1399.
carcinoma in situ
Definition:
An epithelial cancer,
typically in the uterus, that has not yet spread to
underlying tissues.
1400.
carcinoma of pancreas (pancreatic cancer)
Author:Guo Li Definition:
This cancer of the pancreas mainly occurs in the cells of the ducts; 2/3 of the tumors occur at the head of pancreas and obstruction of the pancreatic ducts is the first symptom.
1401.
carcinosis (carcinomatosis)
Definition:
The extensive spread of cancer throughout the body.
1402.
cardiac catheterization
Author:Guo Li Definition:
This is a procedure involving the introduction of a catheter into the
right side or the left side of the heart to study the pressures in the central
vein, across the valves of the arteries and the chambers of the heart. The
volumes in the cardiac chamber during the cardiac cycle and the patency
of the coronary artery are also measured by observing the flow pattern of
radiographic dye injected through the catheter.
Right heart catheterization measures the right atrial, right ventricular,
pulmonary artery and pulmonlary capillary wedge pressures, oxygen saturation,
and cardiac output. The catheter is inserted through the femoral vein or
subclavian vein.
Left heart catheterization measures the aortic and mitral valve stenosis
and regurgitations, global and regional left ventricular functions and coronary
ateriography.The catheter is inserted through the femoral artery or the
brachial artery.
Alternative courses of action include: ultrasound, thallium scan, which
can give an accurate idea of ventricular function, but neither can demonstrate
the degree and location of obstruction of the coronary artery.
Material effects, risks and side effects include: allergy to the radiography
dye, bleeding, pneumothorax, arrhythmias, air emboli, pulmonary emboli,
pulmonary artery rupture and infarction, cerebrovascular accident, myocardial
infarction, perforation of the myocardium, infections, sepsis, vasovagal
reactions.
Local vascular complications at the site of puncture: arterial thrombosis,
arterial laceration or dissection, pseudoaneurysm, hematoma, a-v fistula.
Also known as cardiac ultrasound; this is used to diagnose in real time, the
movement of valves and the walls of the heart during a cardiac cycle.
Vavular stenosis and regurgitation, septal defects between the chambers,
ventricular dyskinesia and growth of myxoma (a type of cancer) can be diagnosed.
1404.
cardiac muscle
Definition:
A muscle of the heart (which is basically a giant muscle), responsible for pumping blood throughout the body. As an involuntary muscle, its contractions are controlled by the autonomic nervous system rather than the individual.
These are tests in which radioactive molecules are injected intravenously to
demonstrate damages and evaluate the function of the heart. As the injected
radionuclide circulates to the heart, the presence of radioactivity in the
ventricles of the heart or the myocardium is measured.
Thallium scan: Thallium is taken up by normal cells, in which case the scan
shows an evenly distributed pattern of radioactivity. Ischemic areas or
infarcted areas take up less thallium and appear as cold spots on the scan.
Technetium-99m pyrophosphate scintigraphy: This is used to diagnose acute
myocardial infarction at least 18 hours postinfarction. Areas of damaged
myocardium contain calcium which complexes with the Technetium-99m.
Therefore infarcted areas appear as hot spots.
Thallium Stress Testing: Evaluates heart function. This is the observation of thallium distribution in the
myocardium during exercise. Ischemic areas induced by stress will appear as
cold spots.
Persantine Thallium Scan: Evaluates heart function. For patients who cannot exercise, the
persantine-thallium scan can be used to reveal ischemic areas. Persantine is
the trademark for the drug dipyridamole which is a coronary vasodilator.
Persantine dilates normal coronary vessels more than the occluded vessels.
Blood would preferentially flow to the normal vessels; a sort of "steal"
phenomenon. A thallium scan can then reveal the ischemic areas by
demonstrating reduced perfusion.
A cardiac tamponade is an accumulation of fluids in the pericardium which can cause inadequate ventricular filling so that cardiac output is decreased. The fluid in the pericardium could be the result of trauma, infections, or cancers (often breast cancers) that have metastasized to the pericardium.
Cardiomyopathy is a group of chronic disorders affecting the muscle of the heart resulting in impairment of the pumping function of the heart. This could be secondary to viral infection, malnutrition, alcoholism, amyloidosis, chemotherapy with doxorubicin, and metastasis to the heart. However, the cause of cardiomyopathy is usually not known.
1410.
cardiopulpnary resuscitation (CPR, cardio-pulmonary resuscitation)
Author:Guo Li Definition:
CPR is the artifical method involving external measures to assist a
patient to maintain some form of blood flow and exchange of oxygen and
carbon dioxide when his/her cardio-pulmonary systems fail.
1411.
cardiotoxin
Definition:
A toxin (poisonous substance) which primarily affects the heart or other parts of the cardiovascular system.
Relating to the heart and blood vessels (arteries, veins, and
capillaries); the circulatory system.
1413.
cardiovascular system
Definition:
A type of circulatory system which includes blood, vessels, and at least one
heart. The blood, which is pumped by the heart, transports materials through the vessels to every
cell in the body.
1414.
carinate
Definition:
Shaped like a ridge, or having a structure so shaped.
A molecule normally found within the muscle tissue of vertebrates. Carnosine is composed of two amino acids,
Beta-alanine and
histidine, joined together with a
peptide bond (a dipeptide).
One of a group of red, orange, purple or yellow pigments typically found
as accessory pigments in
plants and some fungi. They are
fat-soluble and are called lipochromes when
they are found concentrated in animal fat.
Carotenoids are widely used as food colorings, and one pigment, ß
carotene, is used as a source of Vitamin A.
Compare anthocyanin
A nerve disorder affecting the hand that may occur in people
who do a lot of repetitive hand motions, such as typing or doing assembly-line work; caused by a pinched nerve.
1420.
carpal tunnel syndrome
Author:Guo Li Definition:
Carpal tunnel syndrome is caused by the compression of the median
nerve by the carpal ligament in the wrist. Classic symptoms include pain and numbness in the wrist and hand (the area innervated by the nerve); wasting or paralysis of the
abductor pollicis brevis muscle.
An organ (generally believed to be a modified foliar unit) at the centre of a flower, bearing one or more ovules and having its margins fused together or with other carpels to enclose the ovule(s) in an ovary, and consisting also of a stigma and usually a style.
In ferns, the stalk of a sporocarp; in a fruit, the stalk of a mericarp.
1423.
carrageenan
Definition:
A gel-forming polysaccharide
goo found in the red algaeChondrus
crispus and Gigartina mammillosa which is used as an
emulsifier in foods, cosmetics and pharmaceuticals.
1424.
carrier
Definition:
An individual who does not display the symptoms of a disease, but harbors the pathogen which causes it, or has the gene(or genes) for it, and can transmit the disease to others either through interacting with other individuals, or by passing the disease-causing gene (or genes) to offspring.
A substance which transports things.
1425.
carrier protein
Definition:
A protein which transports specific substances through the cell membrane in which it is embedded and into the cell. Different carrier proteins are required to transport different substances, as each one is designed to recognize only one substance, or group of similar substances.
1426.
carrying capacity
Author: Definition:
The maximum average number or biomass of organisms or of a given species that can be sustained on a long-term basis under a given flow regime by a steam or stream reach.
1427.
carrying capacity
Author: Definition:
Maximum average number or biomass of organisms that can be sustained in a habitat over the long term. Usually refers to a particular species, but can be applied to more than one.
A series of reactions in a metabolic pathway that break down complex compounds into simpler ones, usually releasing energy in the process. This is the opposite of an anabolic pathway.
1438.
catabolism
Definition:
The breaking down of complex substances into simple substances; in
biochemistry, it specifically refers to the energy-producing breakdown of
nutrient molecules.
1439.
catabolite
Definition:
A substance which can be broken down into simpler components by the process of catabolism (a metabolic process), so that energy is released and can be used by the body.
1440.
catabolite gene activator protein (CAP)
Definition:
A positive repression process in cellular transcription, in which
RNApolymerase binds poorly to
the operon'spromoter. The
binding of CRP
and cAMP to the promoter causes RNA polymerase to bind more
effectively and initiate transcription. Active
constituents of this process are cAMP
and CRP.
1442.
catagenesis (katagenesis)
Definition:
Evolutionary change toward simpler, more general forms, and away from complex forms which are highly-specialized for a particular set of environmental conditions.
1443.
catalase
Definition:
A type of peroxidaseenzyme which removes hydrogen peroxide (H2O2) from the cell by turning it into water and oxygen. Catalase is mostly found in small organelles called peroxisomes, found in the cytoplasm of the cell.
1444.
catalyst
Definition:
A substance which speeds up a chemical or biochemical reaction which, without the catalyst, would have occurred anyway but at a much slower rate. The catalyst is never used up in the reaction, so that there is always the same amount at the start and the end of the reaction. Enzymes are biological catalysts.
1445.
catalytic site
Definition:
The site on an enzyme where the substrate or substrates (the reactants of a chemical or biochemical reaction) attach in order to convert to the product or products of the reaction, at a much higher speed than the substrate(s) would need to convert to the product(s) alone.
Any hormones (e.g. epinephrine)
that affects the sympathetic nervous system and is a derivative of the
steroid catechol, which is
derived from the amino acidtyrosine.
1450.
catenation
Definition:
The spontaneous linking of certain chemical elements to each other, such as carbon to make rings or chains.
The linking of multiple copies of a macromolecule to each other.
This protein is found in elevated amounts in the blood of patients with breast cancer; however, as of 1997 it was not yet suitable to be used clinically as a tumor marker.
1452.
cathodic protection
Definition:
The attachment of an active metal to a system to protect the system from corrosion. The active metal serves as the anode, making the metal in the system a cathode.
A spike in which the flowers are unisexual and without conspicuous perianth.
1456.
cauda equina syndrome
Author:Guo Li Definition:
Cauda equina syndrome results from the compression of many lumbosacral nerve roots in the cauda equina (caudal to L2-3 level, below the conus medullaris). Clinical presentation includes intense leg pain, numbness and weakness or paralysis of legs, buttocks or genitalia. Bowel and urinary dysfunction may be
present.
Causalgia is a type of reflex sympathetic dystrophy. It is characterized by a painful and burning sensation along the distribution of the nerves. There are trophic changes of the skin and nails in the same area supplied by the nerves. Causalgia begins in the first week after partial injuries of the affected nerves. Brachial plexus, median, or sciatic nerves are often the case.
1461.
caving
Author: Definition:
The collapse of a streambank by undercutting due to wearing away of the toe or an erodible soil layer above the toe.
1462.
cavitation
Author: Definition:
Erosion by suction, especially in the partial vacuum of a diverging jet.
1463.
CC-CKR-5 gene
Definition:
A gene which encodes a protein (also called CC-CKR-5) embedded in the surface of immune cells. The HIVvirus (the virus which causes AIDS) uses the protein to invade the immune cells. People who have one mutated and one working copy of this gene take longer to develop AIDS after infection with HIV than people who have two working copies of the gene. People who have mutations in both copies of this gene are resistant to HIV infection.
1466.
cDNA library (copy DNA library)
Author:Susan A.Hagedorn Definition:
A library composed of
complementary copies of cellular messenger RNAs.
1467.
CEA
Definition:
A protein that can be found in the blood and is useful in detecting
and evaluating colon cancer.
1468.
cecum
Definition:
The sac-like front end of the large bowel which
contains the entry of the appendix and the end of the small intestine.
1469.
ceiling value (CV)
Definition:
The ceiling value is the maximum safe airborne concentration of a potentially toxic substance and is a concentration that should never be exceeded in an area where people are breathing.
1470.
celerity
Author: Definition:
Velocity of a moving wave, as distinguished from velocity of particles oscillating in the wave.
Celiac disease is caused by an intolerance to gluten, a protein found in grains such as wheat, rye and oats (but not in rice or buckwheat). It is characterized by damage to the mucosa of the proximal small intestine, which results in poor absorption of most nutrients. It can also cause a wide range of maladies such as diarrhea, gas, and may contribute to mental depression in some people. Some forms of this disease are recessively inherited. The condition can be confirmed via a biopsy of the small intestine.
1472.
cell
Definition:
The smallest membrane-bound biological unit capable of replication.
Cells can function cooperatively as a part of a tissue or organ or can
function independently as free-living microorganisms.
1473.
cell biology
Definition:
The study of the cell and its components (organelles and other structures) and processes (growth, functions, behaviors, reproduction, etc).
In nerve cells, this is the central portion containing the cell
nucleus, from which axons and
dendrites sprout. The cell body is primarily
concerned with carrying out the life-sustaining functions of a cell.
1475.
cell culture
Definition:
A population of cells grown on a medium such as agar for research purposes.
1476.
cell cycle
Definition:
The normal sequence of development and division in the cell. It can be divided into two general phases, mitosis (when the cell's nucleus divides as a part of its reproduction) and interphase (the rest of the time, when the cell does everything else besides mitosis).
1477.
cell fractionation
Definition:
A lab technique which uses a centrifuge to separate the contents of a cell into fractions, after the cell has been turned into a cell-free extract (the contents of the cell after the cell wall and/or outer cell membranes have been removed).
1478.
cell fusion
Definition:
The process in which two different cells fuse into one single cell. The resulting cell has all of the contents from the original cells and has one nucleus containing the genetic material from both of the original cells. This occurs naturally during sexual reproduction, when gametes (eggs and sperm) fuse to produce the zygote, and can also occur under laboratory conditions between somatic cells (any cell other than a gamete).
1479.
cell line
Definition:
A culture of a particular type of cell that can be reproduced
indefinitely, thus making the cell line "immortal."
1480.
cell lineage
Definition:
The ancestry of a particular cell type, including ancestral cells and all of the subsequent cell divisions which occurred to produce the cell type.
1481.
cell plate (phragmoplast)
Definition:
A boundary between two plant nuclei which have just formed via mitosis, which begins to form just before the cell divides into two daughter cells. It consists of cell wall material and cell membrane material that grows and eventually connects with the existing cell walls and cell membranes.
1482.
cell potential
Definition:
The voltage of an electrochemical cell; the larger the cell potential, the greater the extent of reaction when equilibrium is reached.
1483.
cell sorter
Definition:
A device used to separate different kinds of cells from a mixed, or heterogeneous, population.
1484.
cell synchronization
Definition:
Synchronization of the growth and division phases of cells in a population, so that all cells divide at the same time.
1485.
cell theory
Definition:
The theory that all cells come from previously existing cells, and that cells are the most fundamental structural units of all living things.
1486.
cell wall
Definition:
A structure that forms the outer surface of plant cells, fungi cells, and certain bacterial cells (the gram-positive species) and is on the outside of the cell membrane. The cell wall is a rigid structure which helps the cell keep its shape and gives the cell strength.
1487.
cell-division-cycle (cdc) genes
Definition:
Genes which control the yeastcell cycle. There are around 50 different genes which do this.
A yeastcell which has cell-division-cycle genes that have mutated to become sensitive to temperature; at certain temperatures (usually high ones), various parts of the normal yeast cell cycle become abnormal, and in some strains the yeast cell does not survive at all.
1489.
cell-free extract
Definition:
A liquid that is a mixture of the contents of a particular type of cell;
sometimes the organelles are
also filtered out of the liquid.
A type of immune response mediated by killer T cells which the body uses to destroy cells with foreign antigens (like tumor cells, cells that have become infected with a virus, organs or tissues donated by a non-matching individual, etc.)
A new discipline emerging at the interface between cell biology and microbiology. One major focus of this new field is on the interference of pathogenic bacteria with many eukaryotic cell functions, such as maturation of intracellular compartments, internal cellular communication, or even cell division and differentiation. The study of cellular mcirobiology in this respect, is providing a sophisticaled tool kit for mammalian cell biologists. (Ref: Science 271:315, 1996).
A normal gene that, when it's mutated
or improperly expressed, can cause cancer to develop.
1494.
cellular respiration
Definition:
The conversion within the cell of nutrients (such as sugar molecules) into chemical energy in the form of ATP, by reacting the food with oxygen (O2) until the food has completely been degraded into CO2 and H2O.
1495.
cellulase
Definition:
An enzyme that breaks down cellulose to cellobiose, a
sugar composed of two glucose units.
Cellulitis is a spreading infection of connective tissues, usually caused by streptococci bacteria.
1497.
cellulose
Definition:
A polysaccharide that
serves as a structural molecule in plants; only
certain types of microbes can break down cellulose, and thus herbivores
frequently harbor cellulose-digesting bacteria in their digestive
systems. Cellulose is the main component of paper and can be used to
synthesize alcohol.
An organelle (essentially an organ within a cell) which breaks down cellulose (a structural carbohydrate found in plants) and is found in certain bacteria (specifically the ones which can digest cellulose).
1500.
Celsius
Definition:
The temperature scale defined by the values 0 °C for the freezing point of water and 100 °C for the boiling point of water; a °C is the same size as a Kelvin.
This is a scale for measuring temperature, usually abbreviated as C. The freezing point of water is 0° C, and boiling point of water is 100° C. The normal oral temperature is 36.3° to 37.1° C. The rectal temperature is about 0.5° C higher than the oral temperature. To convert Celsius to Fahrenheit which is another commonly used scale of temperature, one can use this formula: multiply degrees in C by 9/5 and add 32.
Usually the location in the world where the oldest cultivation of a
particular crop has been identified.
1503.
centimorgan (cM)
Definition:
A unit of measure of recombination
frequency. One centimorgan is equal to a 1% chance that a marker at one
genetic locus will be separated
from a marker at a second locus due to crossing over in a single
generation. In human beings, 1 centimorgan is equivalent, on average, to 1
million base pairs.
The apparent force which seems to pull an object outward when the object is spun around in a circle. In reality, it is the centripetal force which keeps the object rotating around in the circle when the object's inertia makes the object inclined to move in a straight tangential line away from the circle. The centrifugal force does not really exist and, in a strictly physical sense, the term is a misnomer. However, the term is useful to biologists and chemists who are using centrifuges.
Separating molecules by size or density using centrifugal forces generated by a spinning rotor. G-forces of several hundred thousand times gravity are generated in ultracentrifugation.
1509.
centrifuge
Definition:
A laboratory apparatus that separates mixed samples into homogenous
component layers by spinning them at high speed.
1510.
centriole
Definition:
A cylinder-shaped organelle composed of microtubules and found in the nucleus of a cell. During nuclear division it forms the spindle, which ensures that the duplicated chromosomes are equally divided between the daughter cells. Resembles a basal body in structure. Centrioles are not found in plant cells.
The part of the brain that
serves
to coordinate muscle movement; it is
located behind and below the cerebrum
and is made up of two side lobes and a middle lobe.
1517.
cerebral cortex
Definition:
The wrinkled gray covering of the cerebrum.
It is made up of layers of nerve cells and their
connecting pathways, and it is the place where thought
processes occur.
Cerebral palsy is a catch-all term for a collection of neonatal motor and neurologic
disorders that is nonprogressive and nonhereditary. Intrauterine hypoxia and
perinatal asphyxia is believed to be the major cause.
A sugar-lipid complex, the lipid portion being a sphingolipid and the sugar most commonly galactose, which is found in nerve and brain tissue.
1520.
cerebrospinal fluid
Definition:
A fluid within the skull which surrounds the brain and the top of the spinal cord that helps cushion these organs from blows and other trauma.
1521.
cerebrospinal fluid (CSF)
Author:Guo Li Definition:
Cerebrospinal fluid is the clear fluid that fills the cerebral ventricles and subarachnoid space (the areas that surround the brain and the spinal cord). It is produced by the choroid plexuses.
Relating to or involving the blood vessels in the cerebrum.
1523.
cerebrovascular accident (CVA)
Author:Guo Li Definition:
A cerebrovascular accident produces a clinical picture of what is commonly referred to as a "stroke": hemiplegia, blindness, speech problems, or confusion.
Damage to the blood vessels in the brain, resulting in a
stroke. The blood vessels become blocked because of fat
deposits or they become thick and hard, blocking the flow of
blood to the brain. Sometimes, the blood vessels may burst,
resulting in a hemorrhagic stroke. People with
diabetes are
at higher risk of cerebrovascular disease. See also:
macrovascular disease; stroke.
1525.
cerebrum
Definition:
The part of the brain that receives and processes conscious sensation,
generates thought and controls conscious activity. It is the uppermost
and largest part of the brain, and is divided into left and right
hemispheres, which are joined by and communicate through the corpus callosum.
The lower portion of the
uterus that opens into the vagina.
1530.
cesium
Definition:
A radioactive alkaline (basic)
metal element that becomes liquid at slightly
above room
temperature; it reacts violently with both water and oxygen, as well as
with other substances.
A type of density gradient centrifugation, a lab technique used to separate or purify nucleic acids. It involves putting cesium chloride and the nucleic acids into a centrifuge to be spun for hours or days. The cesium chloride forms a density gradient (highly dense at the bottom, thinnest at the top), and the different nucleic acids separate along the gradient according to their buoyancies in different densities.
A waxy alcohol [CH3-(CH2)14CH2OH] that is used as an emulsifier and softener in cosmetics; has been used in ointments to treat skin irritations. It is insoluble in water, soluble in other alcohols and ethers.
1534.
cetyl lactate
Definition:
A waxy solid (C19H38O3) that is used as an emollient to improve the texture and feel of ointments and cosmetics.
1535.
CH3 choline
Definition:
An alcohol [formula: HO-CH2-CH2-N(CH3)2] which is a part of acetylcholine, a chemical that transmits information between nerve cells.
Thin, membranous scales or bracts; thin, dry unfertilised ovules among the fully developed seeds of a fruit.
1537.
chain isomer (skeletal isomer)
Definition:
One of two or more compounds having the same chemical composition but differing in the arrangement of the atoms (usually carbon atoms) forming the backbone of the structure of the compounds.
1538.
chain reaction
Definition:
A reaction in which a product reacts and thus continues the reaction.
In botany terminology, the part of an ovule to which the end of the stalk (funicle) is attached.
1540.
chalcogen
Definition:
One of the elements in the same column of the periodic table as oxygen.
1541.
chalcone
Author:
Michael Allen
Definition:
An organic molecule prepared by aldol condensation of acetophenone and
benzaldehyde.
1542.
channel
Author: Definition:
The space above the bed and between banks occupied by a stream.
Natural or artificial waterway of perceptible extent that periodically or continuously contains moving water. It has a definite bed and banks that serve to confine water. (River, stream, creek, run, branch, anabranch, and tributary are some of the terms used to describe natural channels. Canal, ditch, and floodway are some of the terms used to describe artificial channels.)
1543.
channel protein
Definition:
A protein embedded in the cell membrane which is part of a structure that determines what particle sizes and/or charges are allowed to diffuse into the cell.
1544.
channel stability
Author: Definition:
Measure of the resistance of a stream to erosion that determines how well a stream will adjust to and recover from changes in flow or sediment transport.
1545.
channel width
Author: Definition:
The horizontal distance along a transect line from bank to bank at the high water marks, measured at right angles to the direction of flow. Multiple channel widths are summed to represent total channel width.
The direct transfer of a reaction product from one enzyme'sactive site
to that of another, thus catalyzing
the next step in a sequential pathway.
1548.
channelization
Author: Definition:
The straightening and/or deepening of a watercourse for purposes of storm-run-off control or ease of navigation. Channelization often includes lining of stream banks with a retaining material such as concrete or rock.
1549.
chaparral
Author: Definition:
A plant community of drought-adapted shrubs, usually found in rocky and rapidly drained shallow soils.
A chelator is an organic chemical that bonds with and removes free metal ions from solutions. Chelating agents are sometimes used to treat people suffering from metal poisoning.
A process in which one or more substances are changed into one or more different substances.
1562.
chemical equation
Definition:
A representation of a chemical reaction in which chemical symbols represent reactants on the left side and products on the right side.
1563.
chemical equilibrium
Definition:
A state in a reversible chemical reaction at which the reactants are turning into products at the same rate as the products are turning back into the reactants, so that the amounts of each reactant and product remains constant.
1564.
chemical formula
Definition:
A represention of the elemental composition of a species; subscripts are used to indicate the relative numbers of atoms of each kind of element present.
1565.
chemical reaction
Definition:
A process in which one or more substances are changed chemically into one or more different substances. reactant + reactant(s) --any catalyst(s)--> product(s)
1566.
chemical sequencing
Definition:
A lab technique used to determine the sequence of nucleotides in a DNA molecule. The DNA molecule is labeled with radioactive phosphorous (chemical element P), cut into fragments, and analyzed through electrophoresis.
1567.
chemical synergism (chemical synergy)
Author: Definition:
Interaction of chemicals in a mixture to produce a greater toxic effect than would be expected from the sum of the toxicities of the individual chemicals.
1568.
Chemiclave
Definition:
A machine that sterilizes surgical instruments with high-pressure, high-temperature water vapor, alcohol vapor, and formaldehyde vapor.
1569.
chemiluminescent labeling
Definition:
A technique of labeling DNA strands; two different DNA probes emit light when they come together in the same region of a gene.
The linking of
ATP synthesis to electron
transfer by way of an electrochemical hydrogen cation gradient across a
membrane.
1572.
chemiosmotic theory (chemiosmotic hypothesis, chemiosmosis)
Definition:
The theory that the synthesis of ATP (an energy source made and used by the organism) within mitochondria and chloroplasts occurs by way of a proton gradient which forms when electrons are passed through their inner membranes. When protons are then passed through the inner membrane in the opposite direction, energy is released and used to make ATP.
1573.
chemistry
Definition:
The scientific study of the composition, structure, properties, and
interactions of chemicals.
A microorganism which can make its own food using chemicals like ammonia or sulfur compounds rather than solar energy as in photosynthesis. It derives its energy by oxidizing the chemical bonds. A type of autotroph.
1575.
chemokine
Definition:
A chemokine is a type of cytokine (a soluble molecule that a cell produces to control reactions between other cells) that specifically alters the behavior of leukocytes (white blood cells). Examples include interleukin 8, platelet factor 4, melanoma growth stimulatory protein, etc.
1576.
chemokinesis
Definition:
Any response of a unicellular organism or other motile cell to a chemical
that causes the cell to make some kind of change in it's movement,
either by speeding up or slowing down or changing direction. See also chemotaxis,
klinokinesis, and
orthokinesis
A molecular structure on the surface of a cell that is
sensitive to chemical substances, such as
epinephrine
released by the adrenal glands.
1580.
chemoresistance
Definition:
Resistance of cells to the actions of specific chemicals.
1581.
chemosensitizers
Definition:
Drugs or chemicals that enhance the therapeutic effects of chemotherapy drugs and therefore improve their effectiveness.
1582.
chemosis
Definition:
In medicine, this is the term given to any swelling around the eye (specifically, edema of the conjunctiva) which is caused by exposure to a chemical.
1583.
chemostat
Definition:
A machine that maintains a microbial culture at a particular growth
rate by controlling the culture's nutrients and environment.
1584.
chemosterilant
Definition:
A chemical for controlling insect populations which prevents them from reproducing without killing them or changing their mating behaviors. Compare pesticide.
1585.
chemosynthesis
Definition:
The use of inorganic substances such as carbon dioxide to make
carbohydrates from the energy released by chemical reactions. Compare
photosynthesis.
1586.
chemotactic
Definition:
Having to do with the movement of microorganisms, cells, or viruses toward or away from a chemical substance ( chemotaxis).
1587.
chemotherapy
Definition:
Loosely, the use of chemicals to treat cancer; more specifically, the treatment of cancer with drugs designed to selectively kill faster-growing tumorcells.
1588.
chemotroph
Definition:
An organism that gets its energy by metabolizing organic
material taken from other organisms.
This is the examination of the chest and its contents by x-ray. Several views may
be taken to examine for bony structures of the ribs and vertebrae, soft
tissue of the chest wall, the airways, the lungs, the heart and vessels, the
esophagus and stomach, and the pleural spaces and the diaphragm.
1590.
chestnut blight
Definition:
A disease of chestnut trees caused by the fungusEnqothia parasitica. The major symptom is swollen, cracked cankers that form on the outside of the tree, spread into the tree and kills it. This disease is the primary reason why there are almost no American chestnut trees alive today. The population was decimated when the disease was introduced to America with Japanese chestnut trees.
1591.
Cheyne-Stokes respiration
Author:Guo Li Definition:
This is the breathing pattern in which the rate decreases until there is a very long pause, then suddenly changes to a very fast rate and the cycle repeats; it is a clinical sign of problems affecting the respiratory center of the brain
Short, active sequences of DNA which strongly encourages crossing over of chromosomes to occur at that site. These sites become chiasmata more often than other sites.
1594.
chi structure
Definition:
The name for the X-shaped structure which forms during the recombination process between two plasmids, or circular pieces, of DNA. The Greek letter chi resembles this structure.
Chickenpox is an infection caused by varicella virus. The incubation period is 10 to 20 days. It starts with 1 to 3 days of symptoms resembling that of common cold: fever and sore throat. A rash appears afterwards, mainly on the trunk, face, and scalp. There is intense itching associated with the rashes. Seven days after the initial event, eruption of rashes stops. Once crusting begins, the patient is not contagious. Treatment is supportive: rehydration, and control of fever and itching. Recovery from an infection confers immunity in nearly all patients from future chickenpox infections. But, in about 10% of these patients, the varicella virus stays in sensory ganglia and reappears as
herpes zoster.
1603.
Chinese restaurant syndrome
Author:Guo Li Definition:
Chinese restaurant syndrome is the sensation of facial pressure, burning, and chest discomfort due to the ingestion of foods containing monosodium glutamate (MSG).
1604.
chiral
Definition:
A term used to describe a molecule which, in a given configuration, cannot be superimposed on its mirror image. This is in contrast to achiral molecules which can be superimposed on their mirror images. The two mirror image versions of the molecule are known as "levo" (left-handed), abbreviated "L," or "dextro" (right handed), abbreviated "D," depending on which way they rotate polarized light.
1605.
chiral compound
Definition:
A molecule that has an asymmetric center and can be found in two
non-superimposable mirror-image forms (enantiomers).
1606.
chiropractics
Definition:
The medical study of diagnosing and treating back
disorders through manual manipulation of the spine.
A polysaccharide that
serves as a structural molecule in the shells of
insects and crustaceans and in the flesh of fungi.
1608.
chitinase
Definition:
An enzyme which breaks down chitin, which is a polysaccharide that forms the hard outer shell of arthropods (insects, spiders, crustaceans, etc.), and the cell walls of fungi, and some algae.
1609.
chitinolytic
Definition:
Having to do with an enzyme which converts chitin, a polysaccharide that forms the hard, outer shell of arthropods (insects, spiders, crustaceas, etc.) and the cell walls of fungi and some algae, into chitobiose, which is a disaccharide secreted by such things as spiders and some plants.
1610.
chitobiose
Definition:
A disaccharide of two molecules of N-acetyl-D-glucosamine. The substance is secreted by organisms such as spiders and some plants.
1611.
chlamydia
Definition:
A genus of gram-negativebacteria which is a parasite living within the cells of humans and other animals, causing a wide variety of diseases. In humans, they cause inclusion conjunctivitis and the venereal (sexually-transmitted) disease by the same name. This STD causes symptoms such as abnormal genital discharge and pelvic pain (in women), but often it produces no symptoms at all. If left untreated, it can cause pelvic inflammatory disease in women (which can lead to sterility and other problems) and, if transmitted during birth, can cause eye infections and pneumonia in newborns. It can be cured with antibiotics.
1612.
chlamydial infections
Author:Guo Li Definition:
Chlamydiae are small, obligatory intracellular parasites (bacteria) which cause a major
proportion of sexually transmitted diseases. Infections can often produce no symptoms, but left untreated can cause pelvic inflammatory disease (PID) in women, which can lead to sterility.
1613.
Chlamydomonas
Definition:
A genus of green
algae consisting of more than 600 species worldwide, living in marine, freshwater, soil, and even snow environments. They are single
celledeukaryotic organisms ranging from 5 to 100 micrometers long which can be roughly spherical, egg shaped, or elliptical. Most species have two flagella (coming out the same side) for swimming. Most of the time they are haploid and reproduce by dividing into two (binary fission); when they are stressed they can form gametes which fuse to form diploidcysts which later divide into four haploid cells. Taxonomically they have been classified under plants, animals, and
protists. Several species from this genus are important model organisms for the study of cell biology, molecular biology, genetics, plant
physiology, and
biotechnology. The species most commonly used in scientific experiments is Chlamydomonas reinhardtii (also known as C. reinhardi or C. reinhardii).
A broad-spectrum antibiotic
that inhibits bacterialprotein synthesis; it
was first isolated from the funguslike bacterium
Streptomyces venezuelae but is now produced
synthetically.
A lab technique used to determine whether a given fragment of DNA has a promoter on it to encourage transcription to occur, by attaching the gene (called the CAT gene) which codes for the CAT enzyme to it, and observing whether the CAT enzyme is produced.
1617.
chlordane (CD-68, Velsicol, Toxichlor, Niran, Octachlor,Ortho-Chlor, Synchlor, Corodane, Belt)
Image:View the chemical structure Definition:
A toxic, viscous, colorless chlorinated organic chemical that is used as
an insecticide and as a
fumigant. The EPA has restricted use of this
chemical except for subsurface termite control and on non-food plants.
Symptoms of poisoning include convulsions and depression. Chronic
exposure can cause liver damage and possibly cancer.
This prescription drug has sedative, hypnotic, antianxiety, and muscle relaxant properties, and is mainly used to treat tension and anxiety. It may cause drug dependence, and withdrawal symptoms are similar to those seen with barbiturates.
This is a serum electrolyte; normal value is 95 - 107 mmol/L.
Sweat chloride is measured for the diagnosis of cystic fibrosis; normal
value of sweat chloride is 4 - 60 mmol/L. Elevated sweat chloride coupled
with clinical picture is diagnostic of this condition.
1620.
chlorinated hydrocarbons
Definition:
Molecules which are almost entirely carbon and hydrogen, but have had at least one chlorine atom introduced to them that has replaced one of their hydrogen atoms.
1621.
chlorinated organics
Definition:
Any organic chemical which includes chlorine atoms. A class of water pollutants. Chlorinated organic compounds, along with other halogenated organics, are believed to cause health risks such as cancer, endocrine system disruption, birth defects, compromised immune systems, and reduced fertility. Examples of chlorinated organics include trichloroethylene, ethylene dichloride, vinyl chloride, PCBs, chlorobenzene, and many chlorinated solvents and
biocides.
A green, light-absorbing pigment found in plants and other photosynthetic
organisms. A magnesium-porphyrin complex, it is an essential electron
donor in photosynthesis.
An oral hypoglycemic agent (a prescription drug that people take to lower the level of
glucose in the blood). The pills work for some people
whose pancreas still makes some
insulin. They can help the
body in several ways, such as by causing the cells in the
pancreas to release more insulin.
A cigar-shaped structure bounded by a nonunit membrane and containing the light harvesting bacteriochlorophyll in green sulfur bacteria and in Chloroflexus.
1629.
chlorpromazine (Thorazine)
Definition:
This prescription drug is used to treat psychosis (possibly by blocking the action of dopamine) and mania; it is sometimes used to treat nausea and vomiting. This drug can have dangerous interactions with a wide range of other medications, and it can cause a wide range of side effects. It can cause withdrawal symptoms if the patient suddenly stops taking the drug.
This is surgery to remove the gallbladder. Cholecystectomy is indicated for patients with gallstones that cause severe symptoms. If the stones are less than 1 cm in diameter and contain no calcium, dissolution therapy with ursodeoxycholic acid is successful in 50% of the cases at six months of therapy. Shock-wave treatment (extracorporeal shock-wave lithotripsy) is applicable in only about 7% of the patients (with less than 3 stones, total stone diameter less than 20 mm and stone volume less than 15 mL). Only 50% of patients receiving shock-wave therapy have relief of their symptoms.
For patients with medical problems severe enough to contraindicate immediate cholecystectomy, percutaneous catheter cholecystostomy may be preferable. For these patients, cholecystecomy can be performed after their general medical condition improves.
The operative death rate 0.1% in patient under age 50 and 0.5% in patients over 50. Most deaths occur in patients who have other preoperative medical problems.
Delaying cholecystectomy when indicated increases the chance of cholangitis, acute pancreatitis (inflammation of the pancreas), empyema and perforation of the gallbladder, gallstone ileus and common bile duct obstruction.
Cholecystitis is inflammation of the gallbladder, often caused by infection or the presence of stones.
1634.
cholecystokinin (pancreozymin)
Definition:
A hormone released by the duodenum (the first part of the small intestine) in response to the excessive presence of fatty acids in the small intestine. The hormone is only 33 amino acids long, and when released, it causes the release of enzymes from the pancreas and the gall bladder to contract.
1635.
choleglobin
Definition:
A protein which is formed from the breakdown of hemoglobin (a protein that carries oxygen in the blood) and is a precursor to the bile pigment biliverdin.
An epidemic disease caused by the bacteriaVibrio cholerae which involves severe diarrhea, resulting in severe dehydration, eventually resulting in shock, kidney failure, and death. It is spread by food and water contaminated with feces from individuals who have the disease.
Cholesteatoma is a complication of chronic otitis media which creates negative pressure of the middle ear such that a mass consisting of keratin and epidermis is drawn into the middle ear through a perforated eardrum. Cholesteatoma typically erodes the mastoid bone and damages the ossicles.
A lipid which higher
organisms use in the construction of cell membranes and as a precursor
molecule in steroid synthesis. If a person produces too much cholesterol, the excess often gets laid down on the interior of blood vessels as plaque, causing heart disease, hardening of the arteries, and often heart attacks or strokes.
Cholesterol is carried through the bloodstream in molecules called lipoproteins. There are two major types: low density lipoproteins (LDLs, also known as "bad" cholesterol) and high density lipoproteins (HDLs, aka "good" cholesterol).
When your doctor measures your cholesterol, he takes readings of the different types of cholesterol in your blood:
Total Cholesterol
Desirable: less than 200 mg/dl
Borderline High: 200-239 mg/dl
High: more than 240 mg/dl
LDL Cholesterol
Desirable: less than 130 mg/dl
Borderline High: 130-159 mg/dl
High: more than 160 mg/dl
HDL Cholesterol
Desirable: more than 35 mg/dl
Risk Level: less than 35 mg/dl
Those with high cholesterol are generally advised to engage in aerobic exercise, lose weight (if they are overweight), avoid eating foods high in saturated fats and cholesterol, and quit smoking (smoking raises the amount of LDL in the blood).
Having elevated amounts of triglycerides in your blood may also increase the risk of heart disease (a normal reading is less than 200 mg/dl). You can generally lower the amount of triglyceride in your blood by exercising, eating a low-fat diet, and losing weight.
Cholesterol is absorbed from the instestine and contained in chylomicron which brings the cholestrol to the liver. Some cholesterol is synthesized by the liver. Cholesterol is the precursor of steroid hormones and constituent of cell membranes. Some cholesterol is excreted in the bile. The rest of cholesterol is carried in blood by lipoproteins.
Lipoproteins in serum are classified according to their density.
High-density lipoproteins (HDL), low-density lipoproteins (LDL), and very low density lipoproteins (VLDL). Each fraction contains cholesterol. It is the proportion of cholesterol in these fractions of lipoprotein that is associated with the risk of atherosclerotic heart disease (ASHD): the higher the level of LDL cholesterol, the greater the risk of ASHD, and the higher the level of HDL cholesterol, the lower the risk of ASHD.
Lowering the serum cholesterol level in patients without cardiac disease do not reduce mortality rate. Lowering the cholesterol level in cardiac patients clearly reduces mortality. This reduction of risk is proportional to the reduction in LDL cholesterol and the increase in HDL cholesterol.
Normal ranges for serum cholesterol are 1.2 - 6.5 mmol/L
A
thick, alkaline, water-and-alcohol soluble
liquid in the vitamin B
complex. It acts mainly to inhibit lipid decomposition in the liver and
to lower blood pressure. It is found in vegetables, seeds, beans, organ
meats, and egg yolk.
Affecting or in reference to nerve endings or other physiological parts or
processes that are influenced in some way by the
neurotransmitteracetylcholine.
The system of nerve cells that uses
acetylcholine as
its neurotransmitter; nerve cells in the cholinergic system are damaged in
the brains of Alzheimer's patients.
1648.
cholinesterase (choline esterase II, pseudocholinesterase, serumcholinesterase)
Definition:
1649.
cholinesterase and pseudocholinesterase inhibitors
Definition:
These are substances which inhibit the enzymecholinesterase and thus enhance and subsequently prevent transmission of nerve impulses from one nerve cell to another or to a muscle.
1650.
chondroitin sulfate
Definition:
A sugar acid often found among other chemicals in the cell coat, which is a layer of collagen and other sugars found on the outside of the cell membranes of some animal cells.
Chorea is an involuntary, uncoordinated, rapid, jerky type of movement of brief duration. Such movement, although variable, is continual. The best known
chorea is the Hungtington's chorea, an autosomal dominantinherited disease.
1652.
chorion
Definition:
The chorion is the outermost membrane enclosing the fetus. It is formed from tissues on the outside of the
embryo such as the
trophoblast, and the part of it attached to the uterus wall eventually develops into the
placenta.
Referring to the chorion or membrane enclosing the
fetus.
1654.
chorionic villus sampling
Author:Guo Li Definition:
This is a technique of prenatal genetic screening by obtaining samples from the
chorionic villi. It can be done at 8 to 10 weeks of gestation (earlier than
amniocentesis) but complication rates are higher than with amniocentesis.
Polypetalous; having unconnected or separate petals.
1657.
chroma
Author: Definition:
The relative purity or saturation of a color; intensity of distinctive hue as related to grayness; one of the three variables of color.
1658.
chromatid
Definition:
One of two daughter chromosomes after duplication but before separation from the other daughter chromosome (they can also be called "sister chromatids"). The pair of chromatids are joined together with a centromere, and can be seen during the earlier stages of mitosis and meiosis before the pair is separated and pulled to opposite ends of the nucleus.
An analytical technique used to separate molecules based on how they tend
to cling to or dissolve in various solids, liquids and gases:
column chromatography is used most often to separate proteins
based on their binding to a column lined with a ligand specific to a certain
protein.
gel filtration chromatography is used most often to separate
proteins by running the solution containing the proteins through a column
filled with porous carbohydrate
gel beads which will trap or slow down
small molecules but will allow larger molecules to slide past.
paper chromatography separates molecules by taking advantage
of their differing solubilities in a mix of solvents. The material to
be separated is applied to a special piece of paper, and the edge of
the paper is put in the solvent mix, which travels through the paper by
capillary action and carries the different molecules at different rates
with it.
Producing color; a chromogenic colony is a pigmented colony.
1662.
chromogenic label
Definition:
A molecule which can be used as a label to a biological probe molecule because it forms a colored compound when the probe molecule is attached to its target.
1663.
chromomeres
Definition:
Beadlike structures seen on the chromosomes of amphibian eggs during meiosis.
A series of bands of condensed chromatin along an eukaryotic chromosome which stains darkly.
1664.
chromosomal aberration
Definition:
Any abnormality of a chromosome's number or structure.
1665.
chromosomal mutation
Definition:
Can refer to any of a number of DNAmutations which results in a change in the protein encoded by the mutated gene, such as point mutations, insertion or deletion mutations (frameshift mutations), or nonsense mutations. More often this refers to mutations involving chromosomes, such as the inversion of part of one chromosome such that the inverted part no longer matches with its homologous pair, a translocation of one part of a chromosome to a different chromosome, deletions of parts of chromosomes, or accidents which happen during the division of the nucleus like the unequal portioning of chromosomes between the daughter cells.
1666.
chromosome mapping
Definition:
The mapping of the relative locations of genes on a chromosome by analyzing linkage frequencies (how often different genes are inherited together) and crossover frequencies (how often different combinations of three or more genes are inherited) or recombination frequencies.
1667.
chromosome rosette
Author:
John Jordan
Definition:
Right before metaphase,
human
chromosomes briefly form
this single ring structure.
A technique in which, working from a flankingDNAmarker, overlapping clones
are successively identified that span a chromosomal region of interest.
1669.
chromosomes
Definition:
The self-replicating genetic structures of cells containing the cellular DNA that bears in its nucleotide sequence the linear array of genes. In prokaryotes, chromosomal DNA is circular, and the entire genome is carried on one chromosome. Eukaryoticgenomes consist of a number of chromosomes whose DNA is associated with different kinds of proteins.
1670.
chronic toxicity
Definition:
Illness caused by repeated or long-term exposure to low doses of a toxic
substance; compare acute
toxicity.
Adverse effects occurring as a result of repeated dosing with a
chemical on a daily basis, or exposure to the chemical, for a large part of an organism's lifespan (usually more than 50%). With experimental animals, this usually means a period of exposure of more than 3 months. Chronic exposure studies over 2 years using rats or mice are used to assess the carcinogenic potential of chemicals. See carcinogenicity.
1672.
chronospecies
Definition:
A chronospecies is a species which changes physically, morphologically,
genetically, and/or behaviorally over time on an evolutionary scale (experiences a phyletic shift) such that the species from the early point in time and the species it becomes at the later point in time could not be classified as the same species had they existed at the same point in time. Throughout the change, there is only one species at any point in time and diversity does not increase.
1673.
chronotropic effect
Author:Guo Li Definition:
Chronotropic effect is the effect of increasing the heart rate.
This is the contraction of the facial muscles caused by a light tap on the facial nerve of that side; it is a clinical sign associated with low serum calcium or magnesium.
Microtubular, hairlike structures that some single-celled organisms use for locomotion through liquids. They also cover the cells of certain tissues, such as the epithelium lining the lungs, and help those cells sweep away fluids or particles. Cilia are smaller than flagella.
1678.
Cimetidine
Definition:
A prescription drug which inhibits acid secretion in the stomach.
Opening splitting by a transverse fissure around the circumference, leaving an upper and lower half; said of certain seed pods or capsules.
1684.
cirrhosis
Definition:
A disease characterized by the formation of nodules and dense scar tissue in the liver, which may severely impair its function. Cirrhosis may be caused by excessive, long-term consumption of alcohol or by diseases such as hepatitis.
Cirrhosis is the condition in which there is destruction of the liver parenchyma and its replacement by fibrous tissue. As such, liver function is impaired. However, patients are not symptomatic until extensive damage is done. In most cases, cirrhosis is an end-stage finding. Alcoholism is commonly linked to cirrhosis.
1686.
cis acting
Definition:
Having to do with a genetic element (such as a promoter or other regulatory locus) having an effect (like promotion or suppression) on two unrelated targets (such as genes) on the same chromosome as a result of their relative positions on the chromosome.
1687.
cis configuration
Definition:
The configuration of an organic molecule containing a double bond between two carbon atoms, where the largest, most complex R groups are on the same side:
H H
\ /
C=C
/ \
H3C CH3
-OR-
The configuration of an organic molecule containing a ring, where the largest, most complex R groups are on the same side:
Two mutations in different genes coding for the same phenotype which are on the same chromosome (as opposed to the trans configuration where each homologue has one of the mutations).
1689.
cis-trans test (complementation test)
Definition:
A lab test which is used to determine whether two mutations of different genes which affect the same phenotype are on the same functional unit (indicating a cis configuration of the mutated genes) or on different functional units (indicating a trans configuration of the mutated genes). (A functional unit can be a chromosome.) The test is done by mating an individual that has one of the mutations to an individual that has the other one, and observing whether their offspring have the mutant phenotype. If the offspring do not have the mutant phenotype, then the genes are known to be trans, because the offspring have normal copies of each mutant gene on the different functional units which are able to genetically complement each other. If the offspring do have the mutant phenotype, then the genes are known to be cis, because the offspring will always inherit at least one of the mutant genes on the one functional unit, resulting in the mutant phenotype.
An important intermediate in the citric acid cycle which breaks down glucose into water and carbon dioxide when oxygen is present. The acid contains three carboxyl groups, has the chemical formula of C6H8O7, and is found in citrus fruits (oranges, grapefruit, lemons, etc.). It is used as an antioxidant and as artificial flavoring in commercially-processed foods.
A biological class that is composed of all the birds (e.g., penguins, pigeons, eagles, canaries, vultures, etc.)
1697.
Class Bacillariophyceaea (diatoms)
Definition:
There are about 10,000 species of diatoms; these organisms make
up a major portion of ocean plankton and are also a major source
of food for many small marine animals. Unlike other members of
the division, diatoms sometimes reproduce sexually via a process
called syngamy. Diatoms are encased in double shells which are
made of silicon and fit together like two halves of a pillbox;
some of these microscopic boxes are quite beautiful. These
organisms are sometimes able to move around on their own by
secreting cilia-like fibrils along a special groove called the
raphe.
Diatom shells are used as abrasives in silver polish and
toothpaste, as filters, and in highway reflectors.
1698.
Class Chrysophyceae (golden-brown algae)
Definition:
There are about 1500 species of golden-brown algae. This class
of organisms is quite diverse; some species have flagella, others
move like amoebas, others don't move on their own at all. They
reproduce via cell division, create food via photosynthesis, and
are characterized by having the accessory pigmentfucoxanthin.
1699.
Class Dinophyceae (dinoflagellates)
Definition:
The members of this class of fire algae (Division Pyrrophyta) are
a major component of marine algae. Dinoflagellates, many of
which have a very strange appearance, usually move via two
flagella that beat in grooves along their bodies. These organisms, which are often red in color, can produce strong
toxins; they are responsible for the deadly red tides that can kill many fish and other marine organisms. One dinoflagellate,
Gessnerium catenellum, often causes red tides on the Pacific coast and Gulf of Mexico. Filter-feeding mollusks such as clams and oysters sometimes become toxic to humans and
other animals due to their eating dinoflagellates.
Many species of dinoflagellates are bioluminescent; they produce a faint light
when they are disturbed, thus sometimes causing nighttime waves breaking against the shore to be faintly luminous.
The arrangement of organisms into groups based on mutual similarity or evolutionary relatedness.
1701.
clastogen
Definition:
A clastogen is any substance which causes chromosomal breaks.
1702.
clastogenesis
Definition:
Any process resulting in the breakage of chromosomes or the loss or rearrangement of pieces of chromosomes.
1703.
clastogenic
Definition:
This adjective describes any substance or process which causes breaks in chromosomes.
1704.
clathrate
Definition:
A type of solid in which water molecules form cages that trap a gas, formed by very slowly warming a mixture of the gas and tiny grains of ice.
1705.
clathrin
Definition:
A large, fibrous protein which forms a basketlike network around vesicles (bubbles within a cell that have formed by pinching off from the cell membrane) in order to transport food particles into or waste particles out of an eukaryotic cell.
Claudication is the medical term for limping. However, intermittent claudication is pain of the leg muscles on exercise. The usual cause of intermittent claudication is decreased circulation of the femoral artery because of atherosclerotic changes.
Smoking aggravates this condition.
A narrow, stalk-like basal portion of a petal, sepal or bract.
1710.
clay
Definition:
Particles in siliciclastic sediment that are smaller than 0.0039 millimeters in size, according to the
Udden-Wentworth scale. Clay and
silt are collectively classified as
mud.
A collective term for a large group of minerals that are found in great abundance in extremely fine-grained sediments or sedimentary rocks (i.e. shales).
1711.
clay
Author: Definition:
Substrate (soil) particles generally smaller than 0.004 mm in diameter.
A furrow which forms on an animal
cell, indicating imminent cell division into two daughter cells, especially during the first few cellular divisions of a newly-fertilized animal zygote.
This birth defect is a gap in the midline of the palate. It is due to an
incomplete fusion of the palatal processes of the maxilla (the upper jaw) during embryonic development. The most common form is x-linked.
The condition of having flowers which never open and self-pollination occurs, and the flowers are often small and inconspicuous.
1717.
clinical chemistry
Definition:
This is the use of laboratory chemistry techniques to aid in the diagnosis or treatment of diseases and disorders. Clinical chemistry techniques can involve such things as testing blood or urine for the presence of certain biomolecules or metabolites, therapeutic drug monitoring, etc. See also immunology, hematology, toxicology, nutrition, and endocrinology.
1718.
clinical trials
Definition:
The experimental administration of new drugs or medical therapies to human patients in tightly controlled settings, to find out if there are any unexpected harmful side effects, before making the new drug or therapy available to the general population.
This tricyclic prescription drug is used to treat depression and obsessive disorders. It works by inhibiting norepinephrine and serotonin uptake into central nerve terminals. It can cause seizures, heart arrhythmias, and other side effects.
1721.
clonal deletion
Definition:
The removal of B cell and T cell varieties which recognize parts of the organism's body as targets of the immune system. This process naturally occurs early in the organism's development so that the organism will not be autoimmune (having an immune reaction against one's own body tissues) later in life.
The process of asexually producing a group of cells (clones), all genetically identical, from a single ancestor. In recombinant DNA technology, the use of DNA manipulation procedures to produce multiple copies of a single gene or segment of DNA is referred to as cloning DNA.
1728.
cloning vector
Definition:
A DNA molecule originating from a
virus, a
plasmid, or the cell of a higher organism into
which another DNA
fragment of appropriate size can be integrated without loss of the
vectors capacity for self-replication; vectors introduce foreign DNA
into host cells, where it can be reproduced in large quantities.
Examples are plasmids, cosmids, and yeast artificial
chromosomes; vectors are often recombinant
molecules containing DNA sequences from several sources.
1729.
closed vascular system (closed circulatory system)
Definition:
A type of system for the circulation of blood in which the blood
is restricted to
blood vessels.
1730.
Clostridium
Definition:
Clostridium is a genus of anaerobicbacteria that produce strong
toxins and
are responsible for diseases such as tetanus, botulism and gas gangrene.
1731.
clozapine (Clozaril)
Definition:
This antipsychotic drug is used to treat schizophrenia; it works by binding to dopamine receptors.
Organic material having at least a dimension ranging from 1 mm to 10 cm. Technically includes both living and dead material, but often used more specifically to detritus.
1737.
coarse sediment
Author: Definition:
Sediment with particle sizes greater than 2.0 mm, including gravel, cobbles and boulders.
A vesicle, or bubble found within a cell which was formed by pinching off the cell membrane, which is coated with the proteinclathrin and contains nutrient particles, is transporting a regulatory molecule from outside the cell to its destination within the cell, or is transporting newly-made proteins to other organelles or to the outside of the cell. Coated vesicles arise from coated pits.
1741.
cobble (rubble)
Author: Definition:
Rock smaller than boulder and larger than gravel; arbitrarily 1 to 50 pounds or 2 to 8 inches in diameter.
Substrate particles 64 to 256 mm (2.5 to 10 inches) in diameter. Often subclassified as small (64 to 128 mm) and large cobble (128 to 256 mm).
This Latin term, which is frequently used in medicine, means "a tablespoonful" or "a big spoonful".
1747.
cochleare medium (coch. med.)
Definition:
This Latin term, which is frequently used in medicine, means "a dessertspoonful" or "a medium spoonful".
1748.
cochleare parvum (coch. parv.)
Definition:
This Latin term, which is frequently used in medicine, means "a teaspoonful" or "a small spoonful".
1749.
codominance (codominant genes)
Definition:
Two alleles of a gene which result in distinctly different phenotypes, but when they are both inherited together in an individual (one from the mother and one from the father - called heterozygosity), the individual has both of the phenotypes. For example, if one allele is for red hair and the other allele is for blue hair, then the individual will have patches of blue hair and patches of red hair. (This is in contrast to incomplete dominance, where the individual would inherit a blend of the two alleles and have purple hair).
1750.
codon
Definition:
The basic unit of the genetic code, comprising three-nucleotide sequences of
messenger ribonucleic acid (mRNA),
each of which is translated into one amino acid in protein synthesis.
1751.
coelom
Definition:
An internal fluid-filled body cavity (other than the gut) within an organism; it lies between the gut (derived from the endoderm) and the outer body wall (derived from the ectoderm) and is lined entirely with tissue derived from the
mesoderm. It is formed from the mesoderm during embryonic development. It is found in triploblastic animals called
coelomates.
1752.
coelomate
Definition:
A triploblastic organism which has an internal, fluid-filled body cavity which originated from the
mesoderm during
embryonic development. This cavity surrounds the gut, may contain various other organs, and is called a
coelom. It differs from the pseudocoels of the
pseudocoelomates because it is not derived from the blastocoel. The term is used to classify multicellular animals by developmental pattern.
1753.
coenzyme
Definition:
An organic, nonprotein molecule that binds with an apoenzyme (a protein
molecule) to form an active enzyme.
Coenzymes are often derived from
vitamins.
A coenzyme derived from
cobalamine which is
involved in carbon skeletal rearrangements. It is the only biomolecule
known that has a carbon-metal bond.
1756.
cofactor
Definition:
A coenzyme or inorganic ion
that is needed for catalytic activity by enzymes.
1757.
cognate
Definition:
In biochemistry, this term refers to two biomolecules that typically
interact (e.g., a receptor
and its ligand).
1758.
Cohen, Stanley
Definition:
Born 1922. A molecular biologist who was the first to do experiments in the molecular cloning of genes from one strain of bacteria into another. In particular, he cloned the gene for resistance to tetracycline (an antibiotic), found in Staphylococcus aureus, into Escherichia coli, which did not have resistance to tetracycline before. By doing this, he demonstrated that it is possible to take genes from one organism, put them into a different organism, and have the gene survive intact and able to make functioning proteins in the new organism.
The sticking together of floral parts of the same whorl without organic fusion.
1760.
cohesive force
Definition:
An intermolecular force between like molecules, important in the phenomenon of surface tension.
1761.
cohort
Definition:
A cohort is a group of animals of the same species, identified by a common characteristic, which are studied over a period of time as part of a scientific or medical investigation.
The name for the intermediate structure which forms during the process of transposition, where a small piece of DNA (called a transposon) at one site in a genome or a plasmid makes a copy of itself at a random other site, sometimes removing itself from the first site and sometimes not. The structure is composed of the first site and the new site attached together while the transposon is copying.
1765.
Col E1
Definition:
A plasmid which naturally occurs in some strains of the bacteriaEscherichia coli. It codes for an E. coli-produced antibiotic called a colicin and immunity to its self-produced colicin (so that it doesn't unintentionally destroy itself). It is one of a number of such plasmids, each of which code for a different type of colicin. The plasmid is useful for making cloning vectors for making recombinant DNA molecules.
1766.
colcemid
Definition:
A chemical substance which blocks the formation of microtubules, thus interfering with processes and structures where microtubules are essential to function. Microtubules are important to such things as mitosis and meiosis ( spindle formation and thus proper chromosome division), cilia and flagella.
A group of antibiotics naturally produced by the bacteriaEscherichia coli which kills other bacteria by a variety of methods (depending on the type), such as blocking protein synthesis and degrading DNA. Colicins are encoded by a group of naturally occurring E. coliplasmids, like Col E1.
Gram-negative, nonsporing, facultative rod-shaped bacteria that fermentlactose with gas formation within 48 hours at 35 degrees C. Examples of coliform bacteria are members in the genera Escherichia ( e.g. E. coli), Klebsiella (e.g. K. pneumoniae), Enterobacter (e.g. E. cloacai), and Citrobacter (e.g. C. freundii).
1770.
coliforms
Definition:
A group of bacteria which live within the bowels of larger organisms and ferment a sugar called lactose, producing gas within 48 hours of growth. They are generally small, gram-negative, bacilliform (shaped like rods), facultative anaerobes and they include strains such as Escherichia, Kelbsiella, Enterobacter, and Citrobacter. They are useful for measuring the amount of water pollution by feces.
1771.
colinear
Definition:
A linear molecule having a sequence of units which corresponds to the sequence of units in another linear molecule. For example, the sequence of amino acids in a polypeptide corresponds to the sequence of nucleotide bases of the mRNA which was translated to make it. In bacteria the sequence of nucleotide bases in an mRNA molecule is colinear with the sequence of nucleotide bases in a DNA segment which was transcribed to make it (though this is not the case for eukaryotes, which have introns).
1772.
coliphage
Definition:
A bacteriophage (a virus which infects bacteria) that specializes in colliforms (a type of bacteria which inhabits the bowels of larger organisms).
1773.
collagen
Definition:
A fibrous protein that makes
up a major part of connective tissue.
Living, supportive tissue with chloroplasts generally just beneath the surface consisting or more or less elongated cells usually thickened unevenly in a manner somewhat variable in different groups of plants.
Properties (such as freezing-point depression) of solutions that vary according to how much solute is in the solution.
1776.
collision frequency
Definition:
The rate at which chemical species collide; used in theories of chemical kinetics. Also, the frequency with which gaseous molecules collide.
1777.
collision theory
Definition:
A mathematical description of the number of collisions between molecules in a sample of matter per unit time; useful for predicting rates of reaction.
1778.
colloid
Definition:
Microscopic particles suspended in some sort of liquid medium. The particles are between one nanometer and one micrometer in size and can be macromolecules.
1779.
colloidal dispersion
Definition:
A mixture containing particles larger than those found in a solution but small enough to remain suspended for a very long time.
1780.
colluvium
Author: Definition:
A general term for loose deposits of soil and rock moved by gravity (e.g., talus).
This is a procedure involving the insertion of a fiberoptic endoscope of about 1 cm diameter into the anus and advanced through the sigmoid colon, descending colon and the transverse colon up to the caecum. The appearance of the mucosa is observed for inflammation and growths. Samples are often taken for microscopic study. It is a procedure with significant discomfort and sometimes pain. The patient usually receives sedation by intravenous injection.
Material effects, risks and side effects: over-sedation causing respiratory depression; biopsied site may bleed; mucosal damage may lead to infections, perforation of the bowel results in intra-peritoneal air and may necessitate emergency laparotomy.
A clone of bacterial cells on a solid medium that is visible to the naked eye.
1786.
colony counter
Definition:
A device which counts the number of colonies on an agar plate (a solid growth medium).
1787.
colony hybridization
Definition:
A genetics lab technique used to identify which colonies of bacteria on an agar plate contain a particular sequence of DNA or a particular gene. The technique involves pressing a nylon or nitrocellulose membrane onto the plate so that each colony contributes a small smudge of itself to the membrane, then treating the membrane with chemicals and heat, then washing the membrane with a labeled probe to find the specific DNA sequence. The smudges which are indicated by the probe are then compared back to the colonies on the agar plate. This technique is often used in conjunction with experiments involving the making of genomic libraries.
1788.
colony-forming unit (CFU)
Definition:
An individual cell which is able to clone itself into an entire colony of identical cells.
Any entity (usually a single living cell) which can form a colony on an agar plate.
1790.
colorimeter
Definition:
A device used to find out the concentration of particles suspended in a solution or a liquid medium by beaming light through it and measuring the amount of light that makes it out the other side. (The process is a part of the study of spectroscopy.) The device can be used to measure turbidity, or the amount of bacterial cells in a medium. The method of colorimetry is based on the Beer-Lambert Law.
1791.
colostomy
Definition:
Surgery to create an artificial opening from the colon (large intestine) to the outside of the body; this is often done when sections of the lower bowel must be removed due to disease.
This is a direct examination of the vagina and the cervix with an instrument
fitted with a binocular low power microscope (from 13.5 to 60 x). Candidates
for this procedure include those with abnormal Pap smear test and
those exposed to diethystilbestrol in utero. Biopsy may be taken under the
guidance of colposcopy.
The lower part of an awn in grasses, when distinctly different in form from the upper part; a structure (a.k.a. a gynostemium ) in orchids which extends above the ovary of a flower and incorporates stigma, style and stamens.
The heat-producing reaction of a material with oxygen gas or other oxidant, often producing a flame.
1802.
combustion analysis
Definition:
A method for determining the chemical composition of a compound by burning the compound under controlled conditions. Often used to determine the relative amounts of carbon and hydrogen in a compound.
The metabolic transformation of a substance while a second substance serves as primary energy or carbon source.
1804.
commensalism (commensal)
Definition:
A type of symbiosis where two (or more) organisms from different species live in close proximity to one another, in which one member is unaffected by the relationship and the other benefits from it.
1805.
comminution
Definition:
The process of grinding or crushing a solid into fine particles.
An epidemic resulting from infection of a large number of people from a single contaminated source.
1812.
community
Author: Definition:
An association of living organisms having mutual relationships among themselves and to their environment and thus functioning, at least to some degree, as an ecological unit.
1813.
compartment syndrome
Author:Guo Li Definition:
Compartment syndrome is the increase of tissue pressure in a closed fascial space because of trauma to the tissue. This increase in tissue pressure constricts circulation and results in ischemia and further tissue injury. The vicious cycle repeats itself and in serveral hours, leads to muscle and nerve death. The most common causes are infections and electrical burns.
1814.
compatibility group
Definition:
A group of plasmids (rings of DNA) which is able to coexist in the same cell with another plasmid from a different group.
An ephemeral state, induced by treatment with cold cations, during which
bacterial cells are capable
of uptaking foreign DNA.
1818.
competition
Definition:
A type of organism-organism interaction which can be either between members of the same species or members of different species. The relationship occurs when commodities (like food, mates, shelters, etc.) are scarce and there are not enough to go around for all members which need them. In general, all involved members of the relationship are harmed by this interaction.
1819.
competition hybridization
Definition:
A lab technique used to determine how similar two strands of single-stranded nucleic acids are to each other by putting them with a third strand (called a standard) and observing how well they can bond with each other to become double-stranded (how well they hybridize).
1820.
competitive inhibition
Definition:
The prevention of an enzyme from binding to its intended substrate as a result of the presence of another molecule which can also attach to the enzyme's active site. The other molecule competes with the substrate for the active site, and the more of the other molecule there is, the slower the enzyme is at carrying out its intended purpose. This type of enzyme inhibition is reversible by increasing the amount of the enzyme's intended substrate. Compare noncompetitive inhibition.
The term can also be generalized to apply to any other set of molecules which compete with and inhibit one another for the same site.
A biochemical substance (e.g. protein, vitamin, mineral, etc.) that
is added to a food to improve its nutritional quality or to correct a
deficiency created in cooking or processing.
1825.
complementary DNA cloning (cDNA cloning)
Definition:
A lab technique where a double-stranded cDNA molecule (or dscDNA) is inserted into a cloning vector (another DNA molecule which will continue to be capable of replication after insertion of foreign material), so that the gene encoded by the cDNA can be expressed (transcribed and used) or so many copies of the gene can be made.
1826.
complementary DNA library (cDNA library)
Definition:
A collection of all of the mRNA molecules present in a cell or organism, all turned into cDNA molecules with the enzymereverse transcriptase, then inserted into vectors (other DNA molecules which can continue to replicate after addition of foreign DNA). The library can then be probed for the specific cDNA (and thus mRNA) of interest.
The ability of two unrelated single strands of DNA or RNA to pair with each other and become double stranded, due to the coincidental matching of an adequate number of nucleotide base pairs between the single strands.
1829.
complementation-fixation test (CF test)
Definition:
A test for the presence of antibodies in a serum, based on whether an antigen and complement, when put together with some red blood cells, are able to destroy them. If the red blood cells are destroyed, then antibodies were not present to prevent it. If the red blood cells are not destroyed, then antibodies were present to combine with the antigen and bind the complement, making them unable to attack the red blood cells.
1830.
complete medium
Definition:
A growth medium which supplies all of the nutrients and organic compounds necessary for a microorganism to grow, without forcing the microorganism to synthesize anything it needs on its own.
1831.
complex ion
Definition:
An ion formed by the combination of a central metal ion and ligands.
Of leaves, the lamina (or part of the lamina) folded upon itself.
1835.
composite transposon
Definition:
A segment of DNA which contains the insertion elements at either end but can contain just about anything in the middle (genes, markers, etc.). These types of transposons tend to be very large, and many of them came about when the inner two insertion elements of two smaller transposons stopped working and only the two at the far ends continue to work, so that when the transposon moves, it takes everything in between the two original transposons with it. Some composite transposons are used in genetics experiments; Tn5 and Tn10 are two such composite transposons which have genes that encode resistance to certain antibiotics.
1836.
compositus (comp.)
Definition:
This Latin term, which is frequently used in medicine, means "compound".
1837.
compost
Definition:
A mix of different types of organic matter, all of it decaying, such as fallen leaves, bananna peels and/or manure; a mulch. It is used as a fertilizer or to rejuvenate soil. The word can be a noun or verb.
A type of wetland determination that is based on the strongest possible evidence, requiring the collection of quantitative data for all three wetland identification criteria.
This is a method of creating cross-sectional images of the human body through the use of x-ray images compiled together into computer graphics.
1845.
concanavalin A (con A)
Definition:
A protein found in the jack beans plant Canavalin ensiformis which sticks various cell types and glycoproteins (proteins with sugars attached) to one another by crosslinking them. It can also function much like platelets in blood do for animals. Also, it encourages mitosis and cell division in dormant lymphocytes. It is used in the lab technique of affinity chromatography to purify glycoproteins.
A DNA segment composed of repeated
sequences linked end to end.
1848.
concentration cell
Definition:
An electrochemical cell in which the two compartments contain the same solutions, but at different concentrations.
1849.
concentration-effect curve
Definition:
This is a graph produced to show the relationship between the exposure concentration of a drug or other foreign chemical and the magnitude of the graded effect that it produces.
1850.
concentration-response curve
Definition:
This is a graph produced to show the relation between the exposure concentration of a drug (or other chemical) and the degree of response it produces, as measured by the percentage of the exposed population showing a defined, often quantal, effect.
A localized concentration of chemical compounds, (e.g., calcium carbonate and iron oxide) in the form of a grain or nodule of varying size, shape, hardness and color; concretions of significance in hydric soils are usually iron oxides and manganese oxides occurring at or near the soil surface, which have developed under conditions of fluctuating water tables.
1853.
condensation
Definition:
The process whereby a gas becomes a liquid or a solid.
A chemical reaction between two organic compounds which produces (among other things) water, ammonia, or a simple alcohol.
A chemical reaction between two molecules which links them together and expels a molecule of water. For example, the joining of two amino acids by a peptide bond during the formation of a polypeptide.
1854.
condensation polymer
Definition:
The kind of polymer that is formed by the combination of monomers and the release of a small molecules at the point where monomers are joined.
1855.
condensing vacuole
Definition:
A vacuole bound by plasma membrane which originates from the Golgi apparatus and is condensing, by progressively losing water, into a small granule which will transport secretions to the outside of the cell.
1856.
conditional mutation
Definition:
A mutation which makes itself apparent only under certain conditions, such as low or high temperatures.
This method of birth control is easy-to-use and relatively inexpensive. Condoms are especially effective when they are used in conjunction with spermicides (creams or jellies that contain chemicals that kill sperm and some disease-causing microorganisms). When properly used, condoms provide a high rate of protection (96% effectiveness) against pregnancy. Heat (such as from storing a condom in a glove compartment on a hot day) and oil-based lubricants can weaken the rubber in condoms and cause them to break.
While the vast majority of condoms are latex, some are made from animal membranes; membrane condoms are not effective in preventing the transmission of diseases because viruses and bacteria can pass through microscopic pores in the membrane.
In gymnosperms and club mosses, a group of sporophylls arranged compactly on a central axis; in the angiosperm family Casuarina, a woody multiple fruit incorporating the bracts and bracteoles associated with the flowers.
1860.
configuration
Definition:
The three-dimensional arrangement of an organic molecule that is caused by:
double bonds that prevent free rotation, or
chiral centers that have
side groups arranged around them in a particular order.
A configurational isomer can't be turned into
another configuration without breaking covalent bonds.
A compound inflorescence consisting of two or more unit inflorescences.
1862.
confluence
Author: Definition:
The convergence of two streams of comparable size into a single channel.
1863.
conformation
Definition:
The three-dimensional arrangement of side groups on a molecule which can
freely rotate into different positions without breaking any bonds.
1864.
congenital
Definition:
Describes something which was acquired while the individual was still developing in the uterus. For example a congenital defect is a defect that is not found in the individual's genes but developed for some other reason while the individual was a fetus.
Heart failure caused by loss of pumping power by the heart,
resulting in fluids collecting in the body. Congestive heart
failure often develops gradually over several years, although
it also can happen suddenly. It can be treated by drugs and,
in some cases, by surgery.
1866.
congestive heart failure (CHF, cardiac failure)
Author:Guo Li Definition:
Congestive heart failure is the disorder in which the output of the heart (cardiac output) cannot meet the circulatory and metabolic needs of the body. It can be caused by atherosclerotic heart disease (myocardialischemia or infarction), congenital heart disease, cardiomyopathy, myocarditis, systemic hypertension and valvular heart diseases. The three cardinal signs of congestive heart failure are:
cardiomegaly (enlarged heart)
tachypnea (rapid breathing; occurs in the case of left side failure)
hepatomegaly (enlarged liver; occurs in the case of right side failure)
1867.
conidiophore
Definition:
A structure found at the tips of hyphae in fungi which will bud the conidia, or fungal spores.
Surgical removal of a cone-shaped portion of the
cervix, usually as a
treatment for a precancerous condition.
1872.
conjugase
Definition:
An enzyme which removes glutamate molecules from the macromolecule polypteroylglutamic acid.
1873.
conjugate
Definition:
Paired together.
In chemistry, this refers to an acid and a base which can convert to each other by the gain or loss of a proton (a hydrogen nucleus), which together are called a "conjugate acid-base pair." It can also refer to two liquids in equilibrium with each other.
The nuclear division of both haploidnuclei in a dikaryon at the same time (in a dikaryon which has two nuclei). The term is relevant to the biology of fungus.
A protein which is embedded in the cell membrane that forms gap junctions with connexins embedded in other cells, for the purpose of passing through inorganic ions and most small organic molecules (like simple sugars and individual amino acids).
1882.
connexon (hemichannel)
Definition:
The structure which includes a gap junction and its connexins (a type of transmembrane proteins) from two opposing cell membranes where small organic molecules and inorganic ions can pass through.
A genetic map developed by merging the results from different mapping programs.
1884.
consensus sequence
Definition:
A sequence of nucleotide bases which are extremely similar among many different genes of different systems. In eukaryotes, this sequence is known as the "TATA box" or the "Hogness box," and it has the general sequence of TATAAAA. In the bacteriaEscherichia coli it is known as the "Pribnow box" and has the general sequence of TATAATG. The sequence is most often found in promoters and does important things like binding important proteins (including RNA polymerase) to initiate transcription.
1885.
conservative replication
Definition:
Replication of DNA in such a way that the original parent strands of the DNA molecule end up back with each other. The entire preexisting double-stranded DNA molecule is conserved during each round of replication. Compare semiconservative replication.
A two- (or more) membered bacterial culture (or natural assemblage) in which each organism benefits from the other.
1888.
constant region (C region)
Definition:
The stem and forking part of the Y-shaped antibodyprotein, consisting of amino acid chains, that is exactly the same in all antibody molecules within the same individual. (The ends of the Y-shaped molecule will vary widely between different antibodies).
Any of many enzymes that a cell
must have at all times to stay alive.
1891.
constitutive gene
Definition:
A gene which is continuously expressed without any regulation (transcription can be neither suppressed nor encouraged). These genes generally encode housekeeping functions and are expressed at low levels in all cells.
1892.
constitutive heterochromatin
Definition:
Regions on chromosomes which are permanently condensed and genetically inactive in every cell in the body. The condensed portions are always in the same position on both homologous chromosomes. An example is the centromeres.
An organism with a mutation in a regulatory gene, so that the genes which its flawed regulatory product are supposed to suppress become constitutive genes, or impossible to turn off. Thus, the products of the uncontrolled genes are produced to excess.
An artificially assembled DNA segment to be transferred into the target tissue. Typically, the construct will include the gene of a particular interest, a marker gene and appropriate control sequences.
An engineered gene unit, usually involving a gene of interest that has been fused to a promoter.
1895.
consumptive water use
Author: Definition:
Water made unavailable for recapture and reuse as a result of direct surface evaporation or being taken up by plants.
1896.
consumptive wildlife use
Author: Definition:
Activities that involve harvest of wildlife, such as hunting and fishing.
1897.
contact dermatitis
Definition:
Skin irriration (generally a rash) due to direct contact with an irritating substance, such as copper or soap.
1898.
contact inhibition
Definition:
The inhibition of continued growth and division of a cell or colony due to physical contact with other cells or colonies. The stopping of continued growth when a certain density of cells has been reached.
The momentary stopping of all movement when a mobile cell runs into another cell.
1899.
contamination
Definition:
The introduction of unwanted microorganisms or chemicals in a laboratory culture.
1900.
contig map (contiguous map)
Definition:
A map depicting the relative order of a linked library of small overlapping clones representing a complete chromosomal segment.
1901.
contigs
Definition:
Groups of clones representing
overlapping regions of a genome.
1902.
continuous culture
Definition:
A culture of microorganisms in a liquid medium which is maintained under constant conditions with a constant nutrient supply so that it can grow steadily for an extended period of time. Continuous culture is the opposite of batch culture.
1903.
continuous stream
Author: Definition:
A stream that does not have interruptions in space (i.e., dry sections).
1904.
contractile ring
Definition:
A ringlike structure consisting of actin and myosin (most commonly found in muscle tissue) found around dividing animal cells which contracts to separate the two daughter cells.
A regulatory value applied to the airborne concentration in the workplace of a potentially poisonous substance which is judged to be "reasonably practicable" for the whole spectrum of work activities and which must not normally be exceeded.
A bruise or other blunt-force injury that does not involve the cutting or
piercing of tissues.
1910.
convergent evolution
Definition:
The process where two unrelated structures in unrelated organisms evolve to perform similar functions. (The structures are called "analogous structures.") For example, the wings of bats, birds, and insects evolved separately from each other but all are used to perform the function of flying. For another example, the complex eyes of vertebrates, cephalopods (squid and octopus), cubozoan jellyfish, and arthropods (insects, spiders, crustaceans) evolved separately, but all perform the function of vision.
An immunological lab test to detect antibodies which attack the red blood cells of its own body (called autoantibodies). The test is important to the diagnosis of certain blood disorders. The test first reacts red blood cells with serum from the test individual, then with antibodies to the autoantibodies. If the autoantibodies exist, they will bind to the red blood cells. When the antibodies to the autoantibodies are added, they will bind the autoantibodies (still attached to the red blood cells) and cause the red blood cells to clump together. Large clumps of red blood cells indicate that the autoantibodies exist; absence of the clumps indicates that they don't.
The regulatory mechanism where an entire group of different enzymes, all of which play a part in the same metabolic process, is synthesized at the same time. This comes about because the chemical signal to begin synthesis of each enzyme is the same for all of them.
A synthetic nucleic acid chain composed of only two nucleotide bases, arranged either in random order (if chain is DNA) or in alternating order (if chain is RNA).
A polymer that was made by simultaneously polymerizing two or more different monomers.
1917.
coprophile (coprophilous)
Definition:
An organism which is attracted to or lives or grows in fecal matter.
A genetic recombination mechanism where the new DNA molecule comes about by replicating selected parts of each parental DNA molecule and by alternating between the two (maternal and paternal).
1919.
copy number
Definition:
The number of copies of a particular sequence of DNA, a particular gene, or a particular set of genes, in the haploidgenome of an organism.
The number of plasmids per bacterium. Plasmids which are replicated easily and often are called "high-copy-number plasmids"; plasmids which are more strictly controlled in their replication are called "low-copy-number plasmids." The different types have different uses to a geneticist.
With a sinus and rounded lobes at the base, the overall outline usually ovate; often restricted to the base rather than to the outline of the entire organ; heart-shaped.
The group of eight histones ( protein molecules which act like spools for DNA to wrap around so that it can be compacted to fit within the nucleus) in the middle of a nucleosome (which is the histone core particle plus the small segment of DNA wrapped around it).
1925.
corepressor
Definition:
An "effector" molecule which can bind to a repressor molecule, so that together the effector repressor complex can stop transcription of a gene.
The cornea is the clear, round tissue at the front of the eye; it covers the eye's pupil, iris, and lens.
1929.
cornybacteria
Definition:
A group of small, Gram-positivebacteria which come in a number of shapes from straight and curved rods to club shapes. One member of the group, cornybacterium diphtheriae, causes the disease diphtheria.
Damage to the heart. Not enough blood flows through the
vessels because they are blocked with fat or have become
thick and hard; this harms the muscles of the heart. People
with
diabetes are at a higher risk of coronary disease.
1933.
Coronavirus
Definition:
A genus of pleomorphicviruses which look like coronas or halos when viewed with a microscope. It is the single genus of the family Coronaviridae. Members of Coronavirus cause hepatitis (inflammation of the liver) in mice, gastroenteritis (inflammation of the digestive system) in pigs, and respiratory infections in birds and people.
1934.
corpus callosum
Definition:
A band of white neural tissue that joins the left and right hemispheres of
the
cerebrum.
1935.
corpus luteum (yellow body)
Definition:
A temporary endocrine gland which forms from the remains of the ovarian follicle after an ovum (egg) has been released, rupturing the follicle in the process. The gland can secrete both progesterone and estrogen, two female hormones which play a role during pregnancy. The gland disappears if pregnancy does not occur.
Corrigan's sign is the rapid rise and fall of pulse of the carotid artery on inspection which is consistent with the wide pulse pressure of aortic regurgitation.
1937.
corrosion of tissue
Definition:
This is the destruction of tissue by a substance (such as a strong acid or base) on direct contact.
1938.
corrosive
Definition:
Refers to any substance that oxidizes metal or flesh; in a
chemical labeling context, it
specificially refers to a highly reactive substance that causes obvious
damage to living tissue.
1939.
corrosive of tissue
Definition:
This describes any substance (such as a strong acid or base) which destroys tissues on direct contact.
1940.
cortex
Author:
various
Definition:
The region of a stem or root surrounding the vascular cylinder but inside the epidermis (def. courtesy Jim Croft)
The region inside the spore coat of an endospore, around the core. (def. courtesy Tsute Chen)
1941.
cortical reaction
Definition:
The reaction of an egg cell to fertilization which changes its surface cell membrane and prevents additional sperm cells from entering (among other things).
A vesicle, or membrane-bound bubble, in an animal egg cell that releases proteases and other enzymes immediately after fertilization, chiefly to change the egg's surface cell membrane so that no more sperm cells can enter.
A racemoseinflorescence in which the pedicels of the lower flowers are longer than those of the flowers above, bringing all flowers to about the same level.
1946.
cos cells
Definition:
Cells from a monkey which have had genes from the virus SV40 added to it. The genes are used by the virus to replicate its DNA. The cells are used by scientists as host cells in cloning experiments to make lots of gene clones of eukaryotic DNA molecules of interest, along with cloning vectors made from more parts of the SV40 genome and in which the eukaryotic DNA of interest is inserted.
1947.
cos site
Definition:
A 12-nucleotide bases-long segment of single stranded DNA that exists at both ends of the bacteriophage lambda's double-stranded genome. The two cos sites at the ends of the genome are complementary to one another so that the genome can become circular once the virus has infected a host bacterium. The circular genome can then be duplicated continuously until there are many repeats of it strung together; the cos sites show the virus where to cut them apart right before they are packaged into individual capsids as new progeny viruses ready to infect more host cells.
1948.
cosmid
Definition:
Artificially constructed cloning
vector containing the cos gene of phage lambda.
Cosmids can be packaged in lambda phage particles for infection into
E. coli; this permits cloning of larger DNA fragments (up to 45 kb) that can be introduced into bacterial hosts in plasmid vectors.
A cough is the often involuntary action of taking a deep breath, and letting out a strong flow of air from inside the lungs in an attempt to clear some irritation in the upper airways.
1953.
Coulter counter
Definition:
A device which counts cells as they float in a liquid by passing them through a small slit. The device does this by measuring the change in electrical conductivity at the slit when a cell passes through it.
1954.
coupled reaction
Definition:
Two chemical reactions that share a common intermediate (e.g., the product
of the first reaction is a reactant in the second) and therefore have
some kind of energy exchange between them.
1955.
coupled transport (cotransport)
Definition:
The linked, simultaneous transport of two substances across a cell membrane (or another intracellular membrane). If the two substances are moving in the same direction (both into the cell or both out of the cell) it is called symport. If the two substances are moving in opposite directions (one moves into the cell while the other moves out) it is called antiport.
1956.
covalent bond
Definition:
A bond between two or more atoms that is provided by electrons that
travel between the atoms' nuclei, holding them together but keeping them
a stable distance apart.
1957.
covalently closed circular DNA (cccDNA)
Definition:
A circular molecule of double-stranded DNA which is supercoiled, or coiled up on itself due to internal tensions, because there are no breaks in the phosphate backbone (upon which the nucleotide bases are mounted) to relieve the tensions and allow it to form an open circle.
1958.
cover
Definition:
Anything that provides protection from predators or ameliorates adverse conditions of streamflow and/or seasonal changes in metabolic costs. May be instream cover, turbulence, and/or overhead cover, and may be for the purpose of escape, feeding, hiding, or resting.
1959.
cover class
Author: Definition:
A category into which plant species would fit based upon their percent areal cover; the cover classes used (midpoints in parentheses) are T = < 1% cover (0), 1 = 1-5% (3.0), 2 = 6-15% (10.5), 7 = 51-75% (63.0), 6 = 76-95% (85.5), 7 = 96-100% (98.0).
1960.
coxsackie viruses
Definition:
A group of viruses which live in the intestines and spread in fecal matter, any of which can cause a disease resembling polio (but without the paralysis) that tends to occur in children during warm weather.
A fissure or fracture. Caused by the effects of stress on weak or weakened parts of a material.
To break a large, complex compound into simpler compounds.
To open something slightly.
A narcotic drug illegal in most countries which is a cheaper, more addictive, smokeable version of cocaine (another illegal narcotic) with more adverse effects on the user than cocaine.
1963.
creatine
Definition:
A compound which is made by the body and is used to store energy in the form of phosphate molecules. When phosphate molecules are attached to it, it is called creatine phosphate and is capable of donating phosphate to ADP in order to make ATP. (ATP is the molecule which is converted into ADP with a release of energy that the body then uses.)
A high-energy compound found in muscle cells which is used to convert ADP into ATP by donating phosphate molecules to the ADP. (ATP is the molecule which is converted into ADP with a release of energy that the body then uses.)
1966.
creatine phosphokinase (CPK, CK)
Author:Guo Li Definition:
This is an enzyme from the muscles of the heart, skeletal muscles and the brain. It is released to blood after damage, after which serum level rises in 6 hours, peaks in 18 hours, returns to normal in 2 to 3 days. It is often measured to confirm the clinical diagnosis of myocardial infarction. The isoenzymes can be fractionated by electrophoresis as CPK1 also known as CPK-BB from the brain; CPK 2 also known as CPK-MB originated from myocardial (heart muscle) damage; and CPK3 also known as CPK-MM from the skeletal muscles. CPK is elevated in:
myocardial damage from infarction, defibrillation (cardioversion), and myocarditis
skeletal muscle damage including convulsion, intramuscular injection, malignant hyperthermia, and radomyolysis
brain trauma, cardiovascular accidents, electroconvulsive therapy, and tumors
Normal range of CPK is 30 - 300 IU/ml with an MB fraction less than 4%
1967.
creatinine
Definition:
The end product after the compound creatine has been metabolized. It can be found in muscle cells, blood, and urine.
This is an indicator of renal function. Blood creatinine level is dependent on the breakdown of muscle and not to dietary intake, furthermore, its excretion is entirely by glomerular filtration, it is a more sensitive indicator than BUN. In renal failure, serum creatinine level rises within hours, in the absence of renal function, at a rate of 80 - 125 umol/L per day (1 - 1.5 mg/dL per day).
It should be noted that when the rise of creatinine level reaches a plateau, renal function is actually recovered, despite creatinine level is still above normal (in equilibrium, production is equal to excretion).
Normal range: 50 - 120 umol/L
1969.
creatinine clearance test
Author:PharmInfoNet Definition:
A test
of the amount of creatinine in blood or in blood and urine
shows if the kidneys are working right or if one or both are diseased.
1970.
creatinuria
Definition:
The condition of having an unusually large amount of the compound creatine in the urine.
1971.
creek
Author: Definition:
A small stream, usually active.
A naturally occurring swale or depression, which carries water either seasonally or year-round, and which appears as an above-ground creek on the Geological Survey Map.
The condition of a red blood cell which has abnormally shrunk, in general due to osmotic changes in its surrounding medium (blood plasma, usually) -- that is, the amount of solutes in the medium becomes much greater than the contents of the red blood cell so the water plumping up the red blood cell flows out of it and into the medium, causing it to shrink.
A reddish-brown powder which can be dissolved in water or alcohol that has the chemical formula of C21H18O5S. The dissolved compound has different colors depending on the pH; when the pH is 7.2 it is yellow, when the pH is 8.8 it is red, and when the pH is 2-3 it is orangish. As a result, it is used as an acid-base indicator. It is also used as a stain in the study of histology.
CREST syndrome occurs to some patients with scleroderma. It includes: Calcinosis cutis (calcium deposits in the skin), Raynaud's phenomenon, Esophageal involvement, Sclerodactyly (fingers are swollen, firm with tight skin) , and Telangiectasia. Scleroderma patients with CREST syndrome have better prognosis than those not associated with CREST.
A rare neuro-degenerative disease, a contagious form of spongiform encephalitis, thought to be caused by a slow virus which is usually fatal and has no cure. The main symptom is progressive dementia (deterioration of brain function), and other symptoms which can also occur include wasting away of the muscles, tremors, and a variety of different neurological conditions. Recent research has linked this disease with bovine spongiform enchephalitis (BSE), more popularly known as "Mad Cow Disease," which is thought to be caused by a prion (an abnormally-configured protein).
1978.
cri-du-chat syndrome
Author:Guo Li Definition:
Cri-du-chat syndrome is characterized by mental retardation, cat-like cry, abnormally small head, round face, hypertelorism, micrognathia and hypotonia. This syndrome is associated with deletion of the short arm of chromosome 5.
A congenital human syndrome caused by the loss of part of the
short arm of Chromosome 5. The syndrome gets its name from the
peculiar cry of afflicted infants, which sounds like the mewing of a
cat. The syndrome causes severe retardation and various congenital
malformations.
1980.
Crick, Francis
Definition:
An English biologist born in 1916 who was one of three people to win the Nobel Prize in 1962 for the category of physiology or medicine. He and James Watson, an American biochemist and alumnus of Indiana University, discovered the double-stranded helix structure of the DNA molecule and built the Watson-Crick model of this structure. Their work was heavily based on the work of Maurice Wilkins (who also won the Nobel Prize in physiology or medicine in 1962) and Rosalind Franklin (who died before the 1962 Nobel Prize winners were selected). The model they postulated is the accepted model used today.
1981.
cricopharyngeus muscle
Definition:
This is the horizontal muscle located at the top of the esophagus.
1982.
crippled strain
Definition:
A strain of bacteria,
typically highly pathogenic,
that has been
genetically engineered so that
it can't survive on anything but a very
specialized medium of nutrients; this is done so that geneticists can
experiment on certain pathogens without the risk that they will escape from
the lab.
1983.
crisis period
Definition:
A situation in which most of the secondary cells in a culture die off,
even though conditions exist which should normally be favorable for
their growth.
The minimum concentration of oxygen in the water needed for the growth of a culture which has been submerged, where oxygen is the limiting factor to the growth of the culture.
1987.
critical flow
Author: Definition:
Very high velocity water flow at which point fish migration can be severely hampered or impeded.
Minimum flows required to prevent death of a specified species of fish in a stream during periods of extremely low flows.
1988.
critical gradient
Author: Definition:
The maximum stable inclination of an unsupported slope under the most adverse conditions that it will likely experience, as determined by current engineering technology.
1989.
critical habitat
Author: Definition:
Specific areas within the geographic area occupied by a species at the time it is listed in accordance with the Endangered Species Act.
Specific areas outside the geographical area occupied by a species at the time it is listed if there is a determination that such areas are essential for conservation of the species.
1990.
critical mass
Definition:
The minimum amount of mass of a combination of radioactive substances needed for the substances to generate and lose an exactly balanced number of neutrons to make a chain reaction which will keep going by itself.
1991.
critical velocity
Author: Definition:
The maximum speed a device or organism can sustain over a specified distance or length of time, or the maximum velocity against which device or organism can sustain a position over a specified length of time.
Velocity through which a fish will not swim, creating a velocity barrier.
1992.
cro protein
Definition:
A protein made by the lambda bacteriophage which causes the virus to go for a lytic cycle (quickly reproduce, destroy the bacterium, and infect other bacteria) rather than a lysogenic cycle (become dormant) once the virus has infected a bacterium. It does this by getting in the way of the synthesis of C repressor, another protein which causes the virus to go for a lysogenic cycle.
A gastrointestinal disease characterized by pain and inflammation in the large intestine and sometimes of the stomach and esophagus as well. The cause is unknown, but bacteria or a virus may be the culprit.
1994.
cross linking (crosslinking)
Definition:
The linking of the chains of a polymer to one another so that the polymer, as a network, becomes stronger and more resistant to being dissolved.
The abnormal linking of two strands of DNA by covalent bonds (as opposed to the normal hydrogen bonds between base pairs), which can occur by exposure to X-rays. Such linking is a type of damage to the DNA molecule and must be repaired before the DNA can replicate and function properly again.
Fertilization of a plant from a plant with a different genetic makeup.
1997.
cross-reactive antibodies
Definition:
Antibodies which don't respond to any one specific antigen, but will respond to a number of them. These antibodies can be responsible for false positive results in antigen-antibody tests.
1998.
cross-sectional area
Author: Definition:
The area of a stream, channel, or waterway opening, usually taken perpendicular to the stream centerline.
1999.
crossing over
Definition:
The breaking during meiosis of one maternal and one paternal chromosome, the exchange of corresponding sections of DNA, and the rejoining of the chromosomes. This process can result in an exchange of alleles between chromosomes. Compare recombination.
