A fleshy (false) fruit, formed from an inferior ovary, in which the receptacle or hypanthium has enlarged to enclose the true fruit.

6002. pond
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

A body of standing water which is smaller than a lake, often artifically formed.

6003. ponded
Author:
Definition:

A condition in which free water covers the soil surface, for example, in a closed depression; the water is removed only by percolation, evaporation or transpiration.

6004. ponding
Author:
Definition:

An increase in water surface elevation upstream of a blockage or an obstruction.

6005. pons (Bridge of Varolius)
Definition:

The section of the brain between the mesencephalon and the medulla oblongata.

6006. pool
Author:
Definition:

Portion of a stream with reduced current velocity, often with deeper water than surrounding areas and with a smooth surface.

6007. pool feature
Author:
Definition:

The condition or object that characterizes a pool’s formation. These include: logs, trees, roots, stumps, brush, debris, channel meanders, sediment, culverts, bridges, or other man-made objects, beaver dams, or tunnels.

6008. pool-riffle ratio
Author:
Definition:

Ratio of the surface area or length of pools to the surface area or length of riffles in a given stream reach, frequently expressed as the relative percentage of each category.

6009. poorly drained soil
Author:
Definition:

A condition in which water is removed form the soil so slowly that the soil is saturated periodically during the growing season or remains wet for long periods greater than 7 days.

6010. population
Definition:

A group of organisms of the same species occupying a particular geographic region.

6011. porate
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Of a pollen grain, with rounded apertures only. Compare colporate.

6012. porcine
Definition:

Relating to, affecting, resembling or derived from a pig.

6013. porcine somatotropin (porcine growth hormone, pST)
Definition:

A growth hormone found in pigs; injections of or implants containing this hormone cause pigs over 100 pounds to gain more muscle and less fat. In past years, the hormone was very expensive because it could only be taken from the pituitary glands of slaughtered pigs, but in the early '90s researchers learned how to genetically engineered the bacterium E. coli to produce it. The FDA has not yet approved this hormone for use. See also bovine somatotrophin.

6014. porin
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A protein channel in the lipopolysaccharide layer of gram-negative bacteria.

6015. porphin
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A cyclic tetrapyrrole in which the four pyrrole groups are linked by their alpha-carbon atoms via methene (-CH=) bridges; porphin is the partial compund of porphyrins.

6016. porphyrin
Definition:

A complex nitrogen-containing compound that contains four pyrrhole rings connected by methane bridges in a cyclic configuration.

6017. portal vein
Definition:

A large vein that carries blood from the stomach and intestines to the liver.

6018. porter
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A membrane protein that functions to transport substances into and out of the cell.

6019. Positron Emission Tomography Scan (PET Scan)
Author: Guo Li
Definition:

This measures blood flow and metabolic rates. In the case of study on the myocardium, it can accurately distinguish between dyskinetic myocardium due to ischemia and due to infarction. In the case of study on the brain, it measures cerebral blood flow and cerebral oxygen and glucose metabolism. Cerebral metabolic rate is much lower in permanently unconscious patients.

6020. post cibum (p.c.)
Definition:

This Latin term, which is frequently used in medicine and pharmacy, means "after eating".

6021. posterior
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

1. The rear end of something.
2. Of floral parts, on the side of the flower nearest to the main stem. Compare anterior.

6022. posterior fontanelle
Author: Guo Li
Definition:

This membranous interval is found at the junction of the occipital bone and the two parietal bones of an infant's skull; it closes by the end of the first year.

6023. postictual state
Author: Guo Li
Definition:

This is the patient's condition after an epileptic seizure: e.g. headache, sore muscles, unresponsiveness.

6024. postmyocardial infarction syndrome
Author: Guo Li
Definition:

Postmyocardial infarction syndrome refers to the complications of myocardial infarction (heart attack) such as fever, chest pain, and pericarditis (inflammation of the sac surrounding the heart).

6025. postoperative ileus
Author: Guo Li
Definition:

Postoperative ileus is obstruction of the small bowel after an operation because normal peristalsis is lost for 3 to 5 days after surgery.

6026. postprandial
Definition:

After meals.

6027. posttranscriptional processing
Definition:

The enzymatic processing of the primary RNA transcript, which produces messenger RNA and transfer RNA.

6028. posttranslational modification
Definition:

The enzymatic processing of a polypeptide chain after it's been translated from messenger RNA.

6029. posttraumatic syndrome (post-traumatic syndrome)
Author: Guo Li
Definition:

Post-traumatic syndrome is a collection of non-specific complaints after head injury, such as headache, dizziness, becoming easily tired, and poor memory.

6030. potable
Definition:

Drinkable (e.g., potable water)

6031. potamology
Author:
Definition:

The hydrology of streams.

6032. potentiation
Author: Biological Sciences at Heriot-Watt University
Definition:

Potentiation is the ability of one chemical to enhance the activity of another chemical to an extent greater than the simple summation of the two expected activities.

6033. pothole
Author:
Definition:

A depressional wetland commonly found in Upper Midwest (North and South Dakota and western Minnesota) and similar wetlands found elsewhere.

6034. pothole
Author:
Definition:

Bowl-like excavation in a streambed caused by erosion from an eddy.

6035. powers of attorney for health care
Author: Guo Li
Definition:

This is an authorization for a substitute decision maker with respect to health care.

6036. pp65 protein
Definition:

A protein made by a cytomegalovirus which prevents the cell that the virus has infected from displaying fragments of viral proteins, called antigens, on the cell's surface. In this way the cytomegalovirus is able to evade the body's immune system, more or less permanently.

6037. practical certainty
Author: Biological Sciences at Heriot-Watt University
Definition:

The concept of practical certainty involves the determination of a numerically specified low risk or socially acceptable risk which may be used in decision making where absolute certainty is not possible.

6038. Prader-Willi syndrome
Author: Guo Li
Definition:

Prader-Willi syndrome is characterized by short stature, mental retardation, severe obesity, and lack of muscular tone. It is associated with a deletion or maternal uniparental disomy of chromosome 15.

6039. praemorse
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Appearing bitten off at the end.

6040. pre-embryo
Author: Fertilitext
Definition:

A fertilized egg in the early stage of development prior to cell division.

6041. preactivation
Author: K.S. Gulliya
Definition:

The process of activating a photoactive compound by first by illuminating it with appropriate source of light under controlled conditions. This process results in the formation of new chemotherapeutic agents that function independent of light.

6042. precipitate
Definition:

1. To cause a solid to settle out of a solution.
2. The solid that settles out of a solution.
3. To be deposited out of a solution.

6043. precipitation
Definition:

1. The process of a solid settling out of a solution, or the sum of the settled particles.
2. Rain, snow, hail, etc.
3. In immunology, a reaction between a soluble antibody and a solid antigen, which forms a material that precipitates out of the antibody-antigen solution.

6044. precipitation
Author:
Definition:

Discharge of atmospheric moisture as rain, snow or hail, measured in depth of fall or in terms of intensity of fall in unit time.

6045. precursor
Definition:

1. A molecule which exists as an ingredient, reactant, or intermediate in an anabolic pathway that synthesizes a particular product. The molecule is described as the "precursor" of that product. For example, procollagen is the precursor molecule for collagen because collagen is made from it.
2. A condition or set of conditions which precedes something and/or is necessary for something to occur.

6046. predation
Definition:

A type of organism-organism interaction where one species feeds on another species (or rarely, on a member of the same species). In general, the predator species that does the feeding benefits from this relationship, while the prey species which gets eaten is harmed by the relationship.

6047. predicted environmental concentration
Author: Biological Sciences at Heriot-Watt University
Definition:

This is the estimated concentration of a chemical in an environmental compartment calculated from available information on its properties, its use and discharge patterns, and the quantities involved.

6048. prednisone (deltacortisone)
Image: View the chemical structure
Definition:

A synthetic derivative of glucocortoid cortisone that is given orally for inflammation.

6049. preeclampsia
Author: PharmInfoNet
Definition:

Development of hypertension (high blood pressure), accompanied by edema, or proteinuria, or both, due to pregnancy. This can be a very dangerous condition.

6050. preexcitation syndrome (pre-excitation syndrome)
Author: Guo Li
Definition:

Pre-excitation syndrome refers to the condition when an individual has an accessory pathway of conduction between the sinus node of the heart and the atrioventricular (a-v) node, thus predisposing them to supraventricular tachycardia (abnormally fast heartbeat).

6051. pregnancy (adj.: pregnant)
Author: Guo Li
Definition:

This is the condition of having an embryo or fetus developing in the uterus.

6052. preinfarction syndrome
Author: Guo Li
Definition:

Preinfarction syndrome is the onset of unstable angina (chest pain that leads to a heart attack).

6053. prematurity (premature birth)
Author: Guo Li
Definition:

This is the birth of a fetus of 28 to 36 weeks gestational age; the normal gestational term of 38 weeks has not been completed.

6054. premenstrual syndrome (PMS)
Author: Guo Li
Definition:

Premenstrual syndrome is characterized by recurrent and signs and symptoms that develop during the 7 to 14 days before the onset of menstruation and subsides when menstruation occurs. These signs and symptoms can be variable and diverse, such as water retention, food craving, tiredness, excitability, sore/tender breasts, abdominal pain, mood swings, etc.

6055. preprandial
Definition:

Before meals.

6056. presbycusis
Author: Guo Li
Definition:

This is the progressive sensorineural hearing loss starting after 20 years of age in the highest frequencies and, by the age of 60 or so, affecting all speech frequencies. This condition affects men more than women at a ratio of 5 to 1.

6057. presbyopia
Author: Guo Li
Definition:

This is a form of vision impairment in which distant objects are seen more clearly than closer objects. It is a problem of the accommodation of the eye's lens (the eye is less able to flex to focus) and is often associated with old age.

6058. prescribed burn
Author:
Definition:

The process of burning an area of land in order to kill certain plant species and to favor the growth of others.

6059. preserve
Author:
Definition:

(Noun.) An area in which organisms are protected (i.e., a nature preserve or an agricultural preserve).

6060. prevalence
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

The proportion of individuals in a population having a disease.

6061. prevalence index
Author:
Definition:

A weighted average measure of the sum of the frequency of occurrences of all species along a single transect or as calculated for a plant community by averaging the prevalence index of all sample transects through the community.

6062. Pribnow box
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

The consensus sequence TATAAT located approximately 10 base pairs upstream from the transcriptional start site.

6063. prickle
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A hard, pointed outgrowth from the surface of a plant, involving several layers of cells but not containing a vein.

6064. primary antibody response
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

Antibodies made upon first exposure to an antigen; mostly of the class IgM.

6065. primary cell
Author: Susan A.Hagedorn
Definition:

A cell or cell line taken directly from a living organism, which is not immortalized.

6066. primary host
Definition:

The species (or group of species) that a parasite infects during its adult stage, when it is capable of reproducing. Many parasites live in different host species during different parts of their life cycles. Generally, the parasite is most harmful to its primary host. Compare intermediate host.

6067. primary metabolite
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A metabolite excreted during the growth phase.

6068. primary nystagmus
Author: Guo Li
Definition:

A form of nystagmus in which near vision is good or about normal

6069. primary oocyte
Definition:

An oocyte which was originally formed while the female was an embryo and which is suspended in prophase I of the first meiotic division until the female reaches sexual maturity. Then, it grows and divides into the secondary oocyte and a polar body, ending the first meiotic division. The primary oocyte is a diploid cell.

6070. primary producer
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

An organism that uses light to synthesize new organic material from carbon dioxide.

6071. primary production
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

The quantity of new organic matter created by photosynthesis.

6072. primary production
Author:
Definition:

Production of organic substances by photosynthesis; the quantity of material so produced per unit time.

6073. primary structure
Definition:

The covalent backbone of a macromolecule. The order of subunits in a biological polymer, such as amino acids in a polypeptide or nucleotides in a molecule of DNA or RNA.

6074. primary transcript
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

An unprocessed RNA molecule which is the direct product of transcription.

6075. primase
Definition:

An enzyme that catalyzes the construction of the short RNA nucleotide polymers used as primers by DNA polymerases.

6076. primatologist
Definition:

A primatologist is a scientist who studies primates (apes and monkeys).

6077. primatology
Definition:

Primatology is the scientific study of primates (monkeys and apes).

6078. primer
Definition:

Short pre-existing polynucleotide chain to which new deoxyribonucleotides can be added by DNA polymerase.

6079. primidone (Mysoline)
Definition:

This prescription drug is used to treat convulsions and seizures.

6080. pro re nata (p.r.n.)
Definition:

This Latin term, which is frequently used in medicine and pharmacy, means "occasionally" or "according to circumstances".

6081. probe (hybridization probe)
Definition:

A single-stranded nucleic acid molecule with a known nucleotide sequence which is labeled in some way (for example, radioactively, fluorescently, or immunologically) and used to find and mark certain DNA or RNA sequences of interest to a researcher by hybridizing to it.

6082. probiotic
Definition:

General term for a substance that promotes the growth of microorganisms.

6083. problem area wetland
Author:
Definition:

A wetland that is difficult to identify because it may lack indicators of wetland hydrology and/or hydric soils, or its dominant plant species are more common of nonwetlands.

6084. probract
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Small, leaf-like structure at the base of an inflorescence in members of the cucumber family (Curcurbitaceae), usually arising opposite a tendril.

6085. prochlorophyte
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A prokaryotic oxygenic phototroph that contains chlorophylls a and b but which lack phycobilins.

6086. procollagen
Definition:

This precursor molecule for collagen is synthesized by fibroblasts, osteoblasts and the like. Enzymes cleave it to form collagen outside the cells.

6087. procumbent
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Trailing or spreading along the ground but not rooting at the nodes.

6088. productivity
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

Amount of production over a given period of time. Expressed as a rate such as g/m2 per day, kg/ha per year, etc.

6089. profile
Author:
Definition:

Vertical section of the soil through all its horizons and extending into the parent material.

6090. progesterone
Image: View the chemical structure
Definition:

A steroid hormone which is secreted by the corpus luteum of the ovary and is produced by the placenta during pregnancy; it regulates changes in the lining of the uterus (the endometrium).

6091. progestin (progestogen)
Definition:

Any of several steroid hormones that prepare the uterus for egg implantation and pregnancy.

6092. progonoma
Definition:

A tumor caused by tissue developing in the wrong place in the body.

6093. proinsulin
Author: PharmInfoNet
Definition:

The substance made first in the pancreas that is then made into insulin. When insulin is purified from the pancreas of pork or beef, all the proinsulin is not fully removed. When some people use these insulins, the proinsulin can cause the body to react with a rash, to resist the insulin, or even to make dents or lumps in the skin at the place where the insulin is injected. The purified insulins have less proinsulin and other impurities than the other types of insulins.

6094. prokaryote (procaryote, prokaryotic cell, procaryotic cell)
Definition:

Cell or organism lacking a membrane- bound, structurally discrete nucleus and other subcellular compartments. Bacteria are prokaryotes. Compare eukaryote. See chromosomes.

6095. prolactin (lactogenic hormone)
Definition:

A hormone produced in the pituitary gland which stimulates milk production in the mammary glands and which stimulates the corpus luteum of the ovary to produce progesterone and estrogen.

6096. prolactinoma
Definition:

A pituitary gland tumor which secretes prolactin and can thus cause false symptoms of pregnancy.

6097. prolamin
Definition:

A simple protein found in plants which cannot be dissolved in anything except strong alcohol solutions. It is an important component of gluten.

6098. proliferative retinopathy
Author: PharmInfoNet
Definition:

A disease of the small blood vessels of the retina of the eye. See also: diabetic retinopathy.

6099. proliferous
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Having erect or spreading, elongating stems which are capable of rooting at the nodes but rarely do so.

6100. proline
Image: View the chemical structure
Author: Courtesy of MacMolecule
Definition:

One of the twenty naturally occurring amino acids. Has the following chemical characteristics:


pKa1   pKa2       pI      Water Solubility (30deg C)
1.99   10.60    6.10               63

6101. promoter
Definition:

A site on DNA to which RNA polymerase will bind and initiate transcription.

6102. pronucleus (pl. pronuclei)
Author: Susan A.Hagedorn
Definition:

Either of the two haploid gamete nuclei just prior to their fusion in the fertilized ovum.

6103. propagate
Author:
Definition:

To produce seedlings for revegetation work by germinating seeds, growing cuttings, or using some other method to encourage plant reproduction and growth.

6104. propagule
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A structure with the capacity to give rise to a new plant, e.g. a seed, a spore, or a part of the vegetative body capable of independent growth if detached from the parent.

6105. prophage
Definition:

A bacteriophage that is in a dormant state; its genome is either integrated into that of the host, or is replicated autonomously.

6106. prophase
Definition:

The first stage of mitosis. The individual chromosomes of the cell become clearly visible within the nucleus with a light microscope as they condense from long, thin, wispy structures to thick structures, and they appear as a tangled jumble of paired, identical chromatids. By late prophase, the nuclear membrane disappears and all of the chromosomes are fully condensed.

6107. prophase I
Definition:

The first stage in the first meiotic division of meiosis. The individual chromosomes of the cell become clearly visible within the nucleus with a light microscope as they condense from long, thin, wispy structures to thick structures, and they appear as a tangled jumble of paired, identical chromatids. Prophase ends with the disappearance of the nuclear membrane. This is identical to the prophase stage of mitosis.

6108. prophase II
Definition:

The first stage in the second meiotic division of meiosis, following telophase I. In each of the two cells which were produced by the first meiotic division, the chromosomes migrate towards the cell's center. The stage ends when the chromosomes are aligned along a single plane in the center of each cell.

6109. prophylactic
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

Treatment, usually immunologic or chemotherapeutic, designed to protect an individual from a future attack by a pathogen.

6110. prophyll
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A leaf formed at the base of a shoot, usually smaller than those formed subsequently.

6111. propranolol (Inderal)
Definition:

This drug is a non-selective beta-adrenergic receptor blocking agent (a beta blocker), and it is used to treat high blood pressure, chest pain, and heart arrhythmia.

6112. prospective, randomized, double-blind clinical trial
Author: PharmInfoNet
Definition:

A clinical trial in which the method for analyzing data has been specified in the protocol before the study has begun (prospective), the patients have been randomly assigned to receive either the study drug or alternative treatment, and in which neither the patient nor the physician(s) conducting the study know which treatment is being given to the patient.

6113. prostaglandin
Image: View the chemical structure
Definition:

Any of a class of hormone-like, lipid-soluble regulatory molecules constructed from polyunsaturated fatty acids such as arachidonate. These molecules participate in diverse body functions such as smooth muscle contraction and relaxation, vasodilation, and kidney regulation.

6114. prostaglandins in the semen
Author: Guo Li
Definition:

These hormone-like chemicals are secreted by the seminal vesicles, not by the prostate.

6115. prostate gland
Author: Fertilitext
Definition:

The male gland encircling the urethra that produces one third of the fluid in the ejaculate.

6116. prostate specific antigen (PSA)
Author: Guo Li
Definition:

This is a glycoprotein found in the cytoplasm of epithelial cells of prostate (a gland in the base of the penis). Its level in the blood may be elevated in men who have a benign or a malignant growth in the prostate. For this reason, the PSA test does not always distinguish between benign prostate conditions (which are very common in older men) and cancer. However, its level is useful as a screening test for early detection and to monitor the effectiveness of prostate cancer treatment over time.

Normal range: less than 4 ng/mL

6117. prostatic acid phosphatase (PAP)
Author: Guo Li
Definition:

Blood levels of this enzyme are elevated in the blood of some patients with prostate cancer. Elevated PAP levels also are associated with other types of cancer, including multiple myeloma, osteogenic (bone) sarcoma, and cancers that have spread to the bone. Therefore, this chemical can be used as a tumor marker for these cancers.

6118. prostatic hypertrophy
Author: Guo Li
Definition:

This enlargement of the prostate gland due to glandular hypertrophy and overgrowth of smooth muscle or fibrous tissue; it often causes urinary obstruction.

6119. prostatitis
Definition:

Prostatitis is an infection or inflammation of the prostate.

6120. prosthecae
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A cytoplasmic extrusion often forming a distinct appendage, bounded by the cell wall such as a bud, hypha, or stalk.

6121. prosthetic group
Definition:

An organic compound (other than an amino acid) or a metal ion that is covalently bound to a protein and serves an essential function in its activity.

6122. prostrate
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Lying flat on the ground.

6123. protandrous
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Having the male sex organs maturing before the female; of a flower, shedding the pollen before the stigma is receptive. Compare protogynous.

6124. protease
Author: Susan A.Hagedorn
Definition:

An enzyme that cleaves peptide bonds that link amino acids in protein molecules.

6125. protein
Definition:

A large molecule composed of one or more chains of amino acids in a specific order; the order is determined by the base sequence of nucleotides in the gene coding for the protein. Proteins are required for the structure, function, and regulation of the bodys cells, tissues, and organs, and each protein has unique functions. Examples are hormones, enzymes, and antibodies.

6126. protein binding
Author: Biological Sciences at Heriot-Watt University
Definition:

This is the property of having a physicochemical affinity for proteins.

6127. protein engineering
Definition:

A technique for isolating and studying proteins and creating tailor-made ones by altering the genes that code for them.

6128. protein kinase
Definition:

Any of several enzymes that phosphorylate amino acid residues in specific proteins.

6129. protein targeting
Definition:

The process through which newly-made proteins are sorted and carried to different parts of a cell.

6130. proteinaceous infectious particle (prion)
Author: Susan A.Hagedorn
Definition:

A proposed pathogen composed only of protein with no detectable nucleic acid and which is responsible for Creutzfeldt-Jakob disease and kuru in humans and scrapie in sheep.

6131. proteinuria
Author: PharmInfoNet
Definition:

Too much protein in the urine. This may be a sign of kidney damage.

6132. proteoglycan
Definition:

A macromolecule which is made up of a heteropolysaccharide linked with a smaller polypeptide.

6133. proteolysis (adj.: proteolytic)
Definition:

Proteolysis is the breaking down of proteins by enzymes called proteases.

6134. proteolytic
Author: Susan A.Hagedorn
Definition:

Having the ability to break down protein molecules.

6135. proteosome (proteasome)
Definition:

A complex molecule made up of multiple proteins which is a part of a major catabolic pathway that degrades intracellular proteins after they have outlived their usefulness. An intracellular protein slated for degradation is first marked by the protein ubiquitin, which attaches itself via covalent bonds to the lysine residues of the intracellular protein in a reaction requiring ATP. The proteasome then hydrolyzes the ubiquitinated protein into many small peptides (which also requires ATP) and releases the ubiquitin. Other protease enzymes then hydrolyze the small peptides into individual amino acid molecules. The pathway occurs both in the nucleus and in the cytoplasm of the cell.

6136. prothallus
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A gametophyte body, especially in ferns and related plants.

6137. prothrombin time (PT)
Author: Guo Li
Definition:

This is a measurement of the clotting ability of clotting by the extrinsic pathway. Significant deficiency in factors I (fibrinogen) II(prothrombin), V, VII, and X or anticoagulants will result in prolonged PT.

Normal range: 11 to 15 seconds

6138. protist
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A member of the phylum Protista.

6139. proto-oncogene
Definition:

A gene, usually one that codes for a regulatory protein, that can become an oncogene if it mutates.

6140. protogynous
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Having the female sex organs maturing before the male; of a flower, shedding the pollen after the stigma has ceased to be receptive. Compare protandrous.

6141. protogyny
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

In plants, the development of the female organs before the appearance of the corresponding male products - thus inhibiting self-fertilization.

6142. proton
Definition:

An elementary atomic particle with a positive charge and a mass of about 1 amu.

6143. proton acceptor
Definition:

A base; an anionic substance that accepts a proton during an acid-base reaction.

6144. proton donor
Definition:

An acid; a susbstance that donates protons in an acid-base reduction reaction.

6145. proton motive force (PMF)
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

An energized state of a membrane created by expulsion of protons through action of an electron transport chain. See also chemiosmosis.

6146. protoplasm
Definition:

The entire contents of a live cell.

6147. protoplast
Definition:

A plant or fungal cell that has had the cell wall removed for the purpose of transfection.

6148. prototroph
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

The parent from which an auxotrophic mutant has been derived. Contrast with auxotroph.

6149. protozoan (protozoa)
Definition:

Single-celled, animal-like, eukaryotic organisms of the kingdom Protista. Protozoans can occur wherever moisture exists. There are many parasites and commensals of plants and animals, as well as free-living species. They cause a number of diseases, such as African sleeping sickness, malaria, and dysentery. They are an economically and scientifically important group. It is thought that the organisms of the kingdom Animalia evolved from ancestors which were protozoans.

6150. provenance
Author:
Definition:

For seeding material, the provenance is the harvest location; for plants, it is both the harvest location and the location of the nursery.

6151. provirus
Definition:

A viral genome that has become a part of the chromosomal DNA of a plasmid or host cell.

6152. provitamin
Definition:

A chemical that becomes a vitamin via a natural reaction within an organism, such as when 7-dehydrocholesterol in the skin becomes vitamin D when it's exposed to sunlight.

6153. proximal
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Near to the point of origin or attachment. Compare distal.

6154. Prozac (fluoxetine)
Definition:

A common prescription anti-depressant drug; it is classed as a "selective serotonin reuptake inhibitor," or SSRI, which functionally means that it increases the levels of serotonin in the body. This drug, as is the case with other SSRIs, can be dangerous if they're mixed with other drugs such as other antidepressants, illicit drugs (LSD, cocaine, methamphetamine), some antihistamines (Seldane, Histmanal), some antibiotics, and calcium channel blockers.

Side effects include lethargy, confusion, flushing, sweating and muscle spasms. Overdose can cause damage to red blood cells, breathing problems and kidney damage.

6155. pruinose
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Having a whitish, waxy, powdery bloom on the surface.

6156. pruning
Author:
Definition:

Cutting off of individual plant parts or whole plants for cultivation of the individual plant (growth promotion) in order to obtain a certain form or a certain structure of the community.

6157. pruritus
Author: PharmInfoNet
Definition:

Itching skin.

6158. PSA (prostate specific antigen)
Definition:

A protein which is produced by the prostate gland. A test to determine its levels in the blood is often used to determine whether a man might have prostate cancer or not.

6159. pseudo-
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

False; apparent but not genuine.

6160. pseudocoel
Definition:

An internal fluid-filled body cavity within an organism other than the gut which lies between the gut (derived from the endoderm) and the muscles (derived from the mesoderm) of the outer body wall (derived from the ectoderm). It may contain other organs besides the gut. It is derived from the blastocoel during embryonic development. It is found in triploblastic animals called pseudocoelomates.

6161. pseudocoelomate
Definition:

A triploblastic organism which has an internal, fluid-filled body cavity derived from the blastocoel of the embryo. This cavity surrounds the gut, may contain various other organs, and is called the pseudocoel. It differs from the coeloms of true coelomates because it is not derived from or completely lined with tissue derived from the mesoderm. The term is used to classify multicellular animals by developmental pattern.

6162. pseudolamina
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

The extended apical portion of a phyllode.

6163. pseudomonad
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

Member of the genus Pseudomonas, a large group of Gram-negative, obligately respiratory (never fermentative) bacteria.

6164. pseudopod
Definition:

A membrane-bound cytoplasmic projection from an ameboid cell for digestion and locomotion.

6165. pseudopodium (pl. pseudopodia)
Definition:

The protrusion of an amoeboid cell formed by the extrusion or streaming of the cytoplasm (but still enclosed in the membrane) for the purpose of movement or feeding.

6166. pseudovivipary
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

A condition in which vegetative propagules replace some or all of the normal sexual flowers in the inflorescence.

6167. psoriasis
Definition:

Psoriasis is a chronic, inheritable skin disease that causes red, scaly (or sometimes pustular) patches, usually on the scalp, trunk, knees and elbows. There is no cure, but treatments (usually prescription creams containing certain steroids and/or treatment with ultraviolet light) can often put the disease in remission. The disease is caused by the noncancerous proliferation of skin cells; the skin cells mature much earlier than normal and rapidly divide, creating thick, irregular, inflamed patches of skin that slough off. The disease most often develops in adults in their late twenties, but can afflict people of any age, from infants to the elderly.

6168. psychiatrist
Definition:

A medical doctor who specializes in psychiatry.

6169. psychiatry
Definition:

A branch of medicine concerned with the diagnosis, treatment and prevention of mental illness. Psychiatrists can prescribe medicines, whereas clinical psychologists cannot.

6170. psycho-
Definition:

A prefix that means "mind" or "mental".

6171. psychoimmunology (psychoneuroimmunology)
Definition:

The study of how a person's psychological state affects his or her immune system.

6172. psychology
Definition:

The scientific study of human behavior and the mind's function; compare psychiatry.

6173. psychopharmacology
Definition:

The study of the effect of drugs and medicines on psychological processes.

6174. psychosis (pl. psychoses)
Author: Guo Li
Definition:

Psychosis is a mental disorder characterized by loss of contact with reality (having delusions and hallucinations), and exhibiting regressive behavior and attitudes (diminished control of elementary impulses and desires).

6175. psychro-
Definition:

A prefix that means "cold".

6176. psychrophile
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

An organism able to grow at low temperatures and showing a growth temperature optimum of more than 15 degrees C.

6177. psychrotolerant
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

An organism able to grow at low temperature but having a growth temperature optimum of less than 15 degrees C.

6178. Pteridophyte (Pterophyta, ferns)
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

Ferns. A major division of the plant kingdom, having clear alternation of generations with a dominant vascular sporophyte initially dependent upon the gametophyte which is very reduced.

6179. pterygium (pl. pterygia)
Author: Guo Li
Definition:

This is characterized by atrophy and hyperkeratosis of the epithelium of the conjunctiva of the eye which is caused by repeated exposure to wind and dust. Clinically it is seen as a winglike growth on the nasal half of the conjunctiva, sclera, and cornea.

6180. puberulent
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

Covered with fine, short, and nearly imperceptable down; minutely pubescent, the hairs soft, straight, erect, but scarcely visible to the unaided eye.

6181. puberulous
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Covered with minute, soft, erect hairs.

6182. pubescent
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

1. Covered with short, soft, erect hairs.
2. Relating to someone who has just entered puberty.

6183. public health
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

The health of the human population as a whole.

6184. Pulaski
Author:
Definition:

A heavy digging tool consisting of a handle attached to a metal head with two projecting blunt blades, one an ax, the other a hoe.

6185. pulmonary
Definition:

Relating to the lungs and pleura.

6186. pulmonary alveoli
Author: Biological Sciences at Heriot-Watt University
Definition:

The pulmonary alveoli are minute air-filled sacs in the vertebrate lung, thin walled and surrounded by blood vessels.

6187. pulmonary artery
Definition:

The artery which transports oxygen-poor blood from the heart (the right ventricle in mammals) to the lungs, where the blood picks up oxygen. The pulmonary artery is one of the few in the body which is blue instead of red.

6188. pulmonary edema
Author: Guo Li
Definition:

This is the transudation of fluid from the pulmonary vascular space into the alveolar space. This condition causes hypoxemia.

6189. pulmonary function tests
Author: Guo Li
Definition:

These are a set of tests to evaluate the mechanical properties of the lung by studying lung volumes and capacities. The tests include total lung capacity (TLC), residual volume (RV), tidal volume (Vt), functional residual capacity (FRC), vital capacity (VC), forced vital capacity (FVC), and FEV1.

6190. pulmonary medicine
Definition:

This branch of medicine deals with the causes, diagnosis, prevention and treatment of diseases and disorders affecting the lungs.

6191. pulmonary vein
Definition:

The vein which transports oxygen-rich blood from the lungs to the left atrium of the heart. The pulmonary vein is one of the few in the body which is red instead of blue.

6192. pulvinus
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A swelling at the base of the stalk of a leaf or leaflet, often glandular or responsive to touch.

6193. pulvis (pulv.)
Definition:

This Latin term, which is frequently used in medicine and pharmacy, means "a powder".

6194. punctate
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Marked with dots.

6195. puncticulate
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Minutely dotted.

6196. pungent
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Ending in a stiff, sharp point; having an acrid taste or smell.

6197. Punnett square
Definition:

A method for predicting the ratios of phenotypes in offspring, given the phenotypes and/or genotypes of the parents. Generally, the alleles of two or fewer genetic loci are worked with per square.

Here is an example of a Punnet square:

	X	Y
X°	X°X	X°Y
X	XX	XY

In this example, we see the theoretical offspring of a woman with genotype X°X (X° being an X chromosome carrying an X-linked recessive gene for baldness; this woman is not bald but is a carrier for the gene) crossed with a normal man (genotype XY). By using this square, we find that this pairing has a:

• 25% chance of producing a non-bald, non-carrier daughter
• 25% chance of producing a non-bald, carrier daughter
• 25% chance of producing a bald son
• 25% chance of producing a non-bald son

Now, let's change the square slightly; we'll using the same gene, but with a carrier woman (X°X) crossed with a bald man (X°Y):

	X°	Y
X°	X°X°	X°Y
X	XX°	XY

In this square, we see that this pairing has a:

• 25% chance of producing a bald daughter
• 25% chance of producing a non-bald, carrier daughter
• 25% chance of producing a bald son
• 25% chance of producing a non-bald son

6198. pure culture
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A culture containing a single kind of microorganism.

6199. purine
Image: View the chemical structure
Definition:

A nitrogen-containing, double-ring, basic compound that occurs in nucleic acids. The purines in DNA and RNA are adenine and guanine.

6200. puromycin
Image: View the chemical structure
Definition:

An antibiotic that works by inhibiting protein synthesis in bacteria; puromycin incorporates itself into a growing polypeptide chain and causes its premature termination.

6201. purple sulfur bacteria
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A group of phototrophic prokaryotes containing bacteriochlorophylls a or b and characterized by the ability to oxidize hydrogen sulfide (H2S) and store elemental sulfur inside the cells.

6202. purpura
Definition:

Medical term describing spontaneous hemorrhaging into tissues such as mucous membranes, joints, and skin.

6203. pus
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A viscous, yellowish-white fluid formed in infected tissue, consisting chiefly of leukocytes, cellular debris, and liquified tissue elements.

6204. pustulate
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Covered with small pustule- or blister-like elevations.

6205. pustulate hair
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

Hair with an enlarged base.

6206. pustule
Author: Guo Li
Definition:

This is an elevated lesion on the skin that contains pus.

6207. pycnidium
Definition:

The male producing body of a rust.

6208. pyelonephritis
Author: Basil Vansuch
Definition:

Bacterial infection/inflammation of one or both kidneys involving the renal pelvis and the functional tissue.

6209. pyloric stenosis (hypertrophic pyloric stenosis)
Author: Guo Li
Definition:

Pyloric stenosis is due to the abnormal thickening of the muscle of the pylorus; it causes gastrointestinal obstruction.

6210. pylorus (adj. pyloric)
Definition:

The narrow opening that separates the stomach and the small intestine.

6211. pyoderma gangrenosum
Author: Guo Li
Definition:

This disease is characterized by ulcers on the legs. These ulcers, which have dead (necrotic) tissue around their edges, are often found in patients with inflammatory bowel diseases (such as colitis).

6212. pyogenic
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

Pus-forming; causing abscesses.

6213. pyosalpinx
Definition:

This is a complication of salpingitis in which the fallopian tubes become distended with pus.

6214. pyranose
Definition:

A simple sugar that contains a six-membered pyran ring.

6215. pyrene
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

The 'stone' (endocarp plus seed) of a succulent fruit. Compare berry, drupe.

6216. pyrethrum
Definition:

A natural insecticide that is extracted from chrysanthemums. It is a toxic, nonvolatile hydrocarbon related to kerosene.

6217. pyridoxal phosphate
Image: View the chemical structure
Definition:

A coenzyme that functions in amino group transfer; it contains pyroxidine (Vitamin B6).

6218. pyriform
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

Pear-shaped.

6219. pyrimidine
Image: View the chemical structure
Definition:

A nitrogen-containing, single-ring, basic compound that occurs in nucleic acids. The pyrimidines in DNA are cytosine and thymine; in RNA, cytosine and uracil.

6220. pyrite (fool's gold)
Definition:

A common sulfur-containing iron ore, which often superficicially resembles gold. FeS₂.

6221. pyrogenic
Definition:

Fever-inducing.

6222. pyruvate
Image: View the Chemical Structure
Definition:

Pyruvate is the final product of glycolysis. You get two molecules of pyruvate for every molecule of glucose that goes through glycolysis.

6223. q
Definition:

The symbol representing the long arm of a chromosome.

6224. Q
Author:
Definition:

The symbol used by hydrologists to represent flow. It may also mean the design flow for a particular project. With a subscript number, Q refers to a flow recurrence interval; Q10 is the flow that occurs, on the average, only once in 10 years (also known as the 10% frequency, or recurrence, event), Q25 is the flow which occurs only every 25 years (4% event), and Q100 occurs once in 100 years (1% event). The recurrence interval is a statistical average, not a fixed number of years. Q10, Q25, and Q100 are common design standards for flood control projects.

6225. Q banding
Author: Guo Li
Definition:

Q banding is a method of identifying chromosomes in a karyotype that have abnormalities by staining the chromosomes with quinacrine dye. When the chromosomes are viewed with a fluorescent microscope after this treatment, unique patterns of fluorescent bands are seen with each chromosome.

6226. Q fever
Definition:

A disease caused by the bacterium Coxiella burneti which mainly afflicts sheep and cattle but can be transmitted to humans who have contact with infected animals. Symptoms resemble those of influenza and include fever, headache and lung inflammation.

6227. Q wave
Author: Guo Li
Definition:

A Q wave is a negative deflection at the onset of a QRS complex in an electrocardiogram. An abnormal Q wave is one that spans 0.04 seconds or more in duration and reaches greater than 25% of the amplitude of the adjacent R wave.

6228. Qß phage
Definition:

A single-stranded RNA phage that specifically infects enterobacteria containing the F plasmid. It is widely used to study RNA phage and bacterial cell function.

6229. quadrat
Author:
Definition:

Sample units or plots that vary in size, shape, number and arrangements, depending on the nature of the vegetation, site conditions and purpose of study.

6230. quadriceps
Author: Guo Li
Definition:

Quadriceps is the term usually used when referring to the quadriceps femoris muscles, which are the extensor muscles of the leg covering the front and sides of the femur. It consists of four muscles: rectus femoris, vastus lateralis, medialis, and intermedius.

6231. quadriplegia (adj. quadriplegic)
Author: Guo Li
Definition:

Quadriplegia is the condition of paralysis of all four limbs.

6232. quadrivalent
Definition:

Describes an association of four homologous chromosomes at meiosis.

6233. quality of life
Author: Guo Li
Definition:

Quality of life is a reference to the well-being of a patient, a concept often applied when an assessment of an elderly is made. There are 3 major components of the quality of life:
1. health: diseases and body functions
2. socioeconomic status
3. functional status: physical, social, mental and sexual behavior, daily activities, achievements, and disabilities.

6234. quantal effect (all-or-none effect)
Author: Biological Sciences at Heriot-Watt University
Definition:

A quantal effect is one which either happens or does not happen, e.g. death.

6235. quantify
Definition:

To express as a numerical amount.

6236. quantitative
Author:
Definition:

A precise measurement or determination expressed numerically.

6237. quantum evolution
Definition:

An extremely rapid evolutionary change in a single genetic lineage, thought to result from a sudden and radical change in the species' environment.

6238. quantum speciation (saltational speciation)
Definition:

The rapid evolution of a new species from a small population that is partially or totally isolated from the parent population; the rapid speciation occurs due to genetic drift and founder effect and usually involves a few mutations that have a big impact on the organisms' observable physical traits.

6239. quantum sufficiat (q.s.)
Definition:

This Latin term, which is frequently used in medicine and pharmacy, means "a sufficient quantity".

6240. quarantine
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

The limitation on the freedom of movement of an individual, to prevent spread of a disease to other members of a population.

6241. quarantine
Author: Guo Li
Definition:

A quarantine is a period of isolation of suspected or known disease carriers to prevent the spreading of communicable diseases.

6242. quark
Definition:

An elementary subatomic particle that composes a hadron. There are several "flavors" of quarks:
• Up (found in normal matter)
• Down (also found in normal matter)
• Charm or Charmed
• Bottom or Beauty
• Top or Truth

6243. quarrying
Author:
Definition:

Extraction of non-ore materials such as limestone, sand and gravel from open pits (quarries).

6244. quartan
Definition:

A cyclic fever in which 72 hours elapse between attacks.

6245. quaternary structure
Definition:

The three-dimensional structure of a complex protein; this especially refers to the way the polypeptide subunits fit together.

6246. quellung reaction
Definition:

A technique of making the outer cell wall of a bacterium more visible (darker) by applying a certain antiserum to it.

6247. quickening
Author: Guo Li
Definition:

Quickening is the first perception of fetal movement in pregnancy which often is at about 18 to 20 weeks of gestation for first a pregnancy and at about 14 to 16 weeks of gestation for a subsequent pregnancy.

6248. quinaphthol (chinaphthol)
Definition:

A drug used as an intestinal antiseptic.

6249. quincuncial
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Of the arrangement of corolla lobes in a bud, a variant of imbricate aestivation.

6250. quinestrol
Image: View the chemical structure
Definition:

A synthetic form of estrogen used in oral contraceptives.

6251. quinine
Image: View the chemical structure
Definition:

An alkaloid extract from the bark of the cinchona tree which is used to treat malaria and fever; it is also a minor ingredient in tonic water. Quinine poisoning produces symptoms such as nausea, rash, ringing in the ears, and possibly heart failure.

6252. quinsy
Author: Guo Li
Definition:

Quinsy is a bacterial infection of the tonsil(s) which may include surrounding tissues (peritonsillar cellulitis).

6253. R group
Definition:

A chemical abbreviation that normally denotes an alkyl group, but is occasionally used to refer to other organic groups.

6254. rabies virus (Lyssavirus)
Definition:

A virus in the genus Lyssavirus (family Rhabdoviridae) that causes rabies and is transmitted through contact with the blood or saliva of an infected animal.

Rabies is an acute, normally fatal encephalitis that can infect most mammals but is found particularly in domestic dogs, cats, skunks, raccoons and bats (though bats' reputations for spreading rabies has been highly exaggerated). Rabies is characterized by burning sensations in the skin, agitation, delirium, hallucinations, excessive salivation, fear of/aversion to drinking fluids, convulsions, paralysis, and coma.

6255. raceme (adj. racemose)
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

An indeterminate inflorescence in which a main main stem produces a series of flowers on lateral stalks, the oldest at the base and the youngest at the top.

6256. racemic mixture (racemate)
Definition:

A mixture of equal amounts of the two stereoisomers of an optically active substance.

6257. rachilla (rhachilla)
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

The main stem of a grass spikelet, above the glumes.

6258. rachis (rhachis)
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

The main stem of an inflorescence or a pinnate leaf.

6259. radially
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

Arranged or having parts arranged like rays developing uniformly around a central axis.

6260. radially symmetrical (radial symmetry)
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

Said of an organism or organ which can be cut through the center into equal and similar parts along two or more planes; actinomorphic.

6261. radiation
Definition:

1. In evolution, the process through which a group of species diverge from a single ancestral form.
2. General term referring to the emission of electromagnetic waves (e.g. heat, light. etc.) or particles (e.g. neutrons) from from a material.

6262. radiation oncology
Definition:

The medical study of the use of radiation (x-rays, gamma rays or electrons) to destroy cancers.

6263. radiation therapy
Definition:

The use of x-rays, gamma rays, or electrons to destroy cancerous tissue.

6264. radiation therapy (radiotherapy)
Author: Guo Li
Definition:

Radiation therapy is a form of treatment for cancer or abnormal growth by irradiating the target with radioactive material which can be gamma rays, electrons, alpha particles, and positrons. Common side effects are: patients usually feel very tired during treatment. The radiated tissue looses texture, becomes red (erythematous) , hard and itchy (desquamated) ; towards the end, it can be moist and weepy. Ulceration and necrosis may be seen. Some organs in the field of radiation may be affected, e.g. pulmonary fibrosis from the treatment of breast cancer, radiation enteritis from radiation for intra-abdominal malignancies.

6265. radical (free radical)
Definition:

An atom or or electrically neutral molecule that has one or more unpaired electrons in its outer orbital. Free radicals are unstable and react quickly with other atoms and molecules; because of this, they can cause damage to living tissues.

6266. radical mastectomy
Definition:

The surgical removal of the breast, part of the underlying pectoral muscle and some or all of the lymph nodes under the armpit.

6267. radicle
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

The portion of an embryo that gives rise to the root system of a plant. Compare plumule.

6268. radiculopathy
Definition:

Any disease or degeneration of the roots of nerves in the spine.

6269. radio label (radiolabel)
Definition:

A mildly radioactive molecule that is used to "tag" another molecule (such as a protein) so that it can be identified as it goes through some kind of biochemical process.

6270. radio ligand (radioligand)
Definition:

A small, slightly radioactive molecule that binds to a specific large molecule; the radioactivity is used so the ligand can be tracked through its reactions.

6271. radio waves
Definition:

Electromagnetic radiation with wavelengths of 300 millimeters or longer (even up to several kilometers). Radiation of this type is used to broadcast radio and television signals, and has frequencies up to thousands of megahertz (or one gigahertz).

6272. radioactive isotope
Definition:

An isotope of an element that has an unstable nucleus; it tries to stabilize itself by giving off ionizing radiation.

6273. radiographic anatomy
Author: Guo Li
Definition:

The study of the external and internal features of the body using imaging techniques: x-rays, magnetic resonance, ultrasound, etc.

6274. radioimmunoassay
Definition:

A sensitive method for detecting and measuring trace amounts of a biomolecule based on its ability to displace a radioactive version of itself from combination with its specific antibody.

6275. radioisotope
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

An isotope of an element that undergoes spontaneous decay with the release of radioactive particles.

6276. radiologist
Definition:

A medical doctor who specializes in radiology.

6277. radiology
Definition:

A branch of medicine concerned with the diagnosis and treatment of diseases through the use of x-rays.

6278. radiolucent
Author: Guo Li
Definition:

Radiolucent means a substance offers easy passage of radiation.

6279. radionuclide angiography
Author: Guo Li
Definition:

Radionuclide angiography is an imaging technique by introducing radionuclides into a blood vessel so that the patency of the vessel is examined.

6280. radiosensitizer
Author: Guo Li
Definition:

A radiosensitizer is a substance given to a patient to make the intended target (such as a tumor) more susceptible to the effects of radiotherapy.

6281. radiosurgery
Definition:

A technique for treating inoperable brain cancers; a CT scan is used to locate the tumor, which is then bombarded with a precise, high doses of radiation.

6282. radius
Author: Guo Li
Definition:

The radius is one of the two bones (radius and ulna) in the forearm. It is shorter than ulna. But of the two, only radius articulates with the carpal bones of the wrist.

6283. rainwash
Author:
Definition:

The creep of soil lubricated by rain.

6284. ramet
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

An individual member of a cloned strain.

6285. ramping
Author:
Definition:

1. In logging, the term refers to a short road or ramp which leads down from a haul road or skid road on a steep angle to a bridge, crossing, or streambed.
2. In general engineering, the term refers to construction of a temporary access road (ramp) from a bank above, down into a streambed either by cutting into the solid bank and building the ramp from the soil taken from the cut (cut ramp) or by filling the area between the top of the bank and the streambed with gravel (fill ramp).

6286. randomized, double-blind, placebo-controlled, multicenter clinical trial
Author: PharmInfoNet
Definition:

A clinical trial in which patients have been randomly assigned to receive either the study drug or alternative treatment, in which neither the patient nor the physician(s) conducting the study know which treatment is being given the patient, and in which the alternative to the study drug is a placebo; the study is conducted at several centers.

6287. range
Author:
Definition:

The set of conditions throughout which an organism (e.g., plant species) naturally occurs.

6288. RAPD (Random Amplified Polymorphic DNA)
Author: ForBio Ltd.
Definition:

DNA polymorphisms amplified by arbitrary primers using PCR. Useful as molecular markers.

6289. rape
Author: Guo Li
Definition:

Rape is the nonconsensual penetration of vagina, anus, or mouth by penis, hand, or a foreign object.

6290. raphe
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

The part of the stalk of an anatropous ovule that is fused along the side of the ovule.

6291. raphides
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Needle-like crystals that occur in bundles in the vacuoles of some plant cells.

6292. rapids
Author:
Definition:

1. Swift turbulent flow in a rough, steep reach.
2. Fast and agitated current.
3. Stream section with considerable surface agitation, swift current and drops up to 2 m. Some waves may be present; rocks and boulders may be exposed at all but high flows. (Compare glide; riffle; run.)

6293. rare species
Author:
Definition:

A species of animal or plant listed in: Section 670.2 or 670.5, Title 14, California Administrative Code; or Title 50, Code of Federal Regulations, Section 17.11 or Section 17.2, pursuant to the Federal Endangered Species Act designating species as rare, threatened, or endangered.

6294. RAS oncogenes
Definition:

A family of oncogenes that encode for GTPases (enzymes located at the plasma membrane or in the cytoplasm). They were first identified as the transforming genes in the Harvey sarcoma virus (H- or Ha-ras) and the Kirsten sarcoma virus (K- or Ki-ras).

6295. rate-limiting step
Definition:

The slowest step in a metabolic pathway, or the step in an enzymatic reaction that requires the greatest amount of energy to initiate.

6296. ravine
Author:
Definition:

Watercourse larger than a gully, smaller than a valley, and less bold in relief than a gulch or arroyo.

6297. ray
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

1. A zygomorphic flower in the family Asteraceae; a radial band of cells traversing the conducting elements in woody stems.
2. Of a compound umbel, one of the first (lower) series of branches of the inflorescence main stem.

6298. Raynaud's disease
Author: Guo Li
Definition:

Raynaud's disease affects usually women starting in the late teens with Raynaud's phenomenon type of clinical picture but is bilateral and symmetric.

6299. Raynaud's phenomenon
Author: Guo Li
Definition:

Raynaud's phenomenon is characterized by intermittent blanching and cyanosis of the fingers that is precipitated by cold or emotion. This condition usually involves only a few fingers. The attack can terminate suddenly with throbbing, paresthesia and rubor. Several clinical conditions are associated with Raynaud's phenomenon, among them: collagen vascular diseases, occupational exposure to toxins, thoracic outlet syndrome.

6300. reach
Author:
Definition:

1. Section of stream between two specified points.
2. A length of stream, usually more or less uniform with respect to discharge, depth, area, and slope.
3. A relatively homogeneous section of a stream having a repetitious sequence of physical characteristics and habitat types.
4. A regime of hydraulic units whose overall profile is different from another reach.

6301. reaches
Author:
Definition:

Term used to describe sections of a river. The upper reaches refer to the beginning of a river; the lower reaches to the final stages of a river.

6302. reaction center
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A photosynthetic complex containing chlorophyll (or bacteriochlorophyll) and other components, within which occurs the initial electron transfer reactions of photophosphorylation.

6303. reaction intermediate
Definition:

Any biomolecule which is created and destroyed during the course of of a particular reaction pathway.

6304. reading frame
Definition:

A contiguous, non-overlapping set of triplet codoms in RNA or DNA that begin from a specific nucleotide.

6305. recalcitrant seed
Author: ForBio Ltd.
Definition:

Seed which cannot be stored for long periods under the low temperature, dry conditions used for 'orthodox' species.

6306. receptacle
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

The main stem of a flower (torus); in ferns, a main stem on which sporangia arise.

6307. receptor
Definition:

1. A specialized sensory nerve structure that responds to certain types of stimuli
2. a site on a cell (often on a membrane) that can combine with a specific type of molecule to alter the cell's function.

6308. receptor agonist
Author: The Alzheimer's Association
Definition:

A substance that mimics a specific neurotransmitter, is able to attach to that neurotransmitter's receptor, and thereby produces the same action that the neurotransmitter usually produces. Drugs are often designed as receptor agonists to treat a variety of diseases and disorders when the original chemical substance is missing or depleted.

6309. receptors
Author: Guo Li
Definition:

Receptors are structures which are specific for some molecules such that the adherence of such molecules to the receptors will effect biologic activity. Examples of receptors are: alpha and beta receptors on the blood vessels; the beta-1 receptor of the heart; the histamine receptor on mast cells.

6310. recession
Author:
Definition:

Retreat of shore or bank by progressive erosion.

6311. recessive gene
Definition:

A gene that is expressed only when it is present in two copies or if the other copy is missing.

6312. recessive oncogene (anti-oncogene)
Author: Susan A.Hagedorn
Definition:

A single copy of this gene is sufficient to suppress cell proliferation; the loss of both copies of the gene contributes to cancer formation.

6313. reclamation
Author:
Definition:

1. The engineering of derelict terrain so that it can be used for some purpose.
2. The combined process of land treatment that minimizes water degradation, air pollution, damage to aquatic or wildlife habitat, flooding, erosion, and other adverse effects from surface mining operations, including adverse surface effects incidental to underground mines, so that mined lands are reclaimed to a usable condition which is readily adaptable for alternate land uses and create no danger to public health or safety. The process may extend to affected lands surrounding mined lands, and may require backfilling, grading, resoiling, revegetation, soil compaction, stabilization, or other measures.

6314. recognition sequence (recognition site)
Author: Susan A.Hagedorn
Definition:

A nucleotide sequence -- typically composed of 4, 6, or 8 nucleotides -- that is recognized by a restriction endonuclease. Type II enzymes cut (and their corresponding modification enzymes methylate) within or very near the recognition sequence.

6315. recombinant clones
Definition:

Clones containing recombinant DNA molecules. See recombinant DNA technologies.

6316. recombinant DNA
Definition:

A combination of DNA molecules of different origin that are joined using recombinant DNA technologies.

6317. recombinant DNA
Author: Guo Li
Definition:

Recombinant DNA is a fragment of DNA incorporated artificially into the DNA molecule of a suitable vector so that it can express itself many times. This way a large quantity of the DNA in question can be obtained. The DNA is usually one that contains genes of interest, such as interferon, insulin, or growth hormone. The DNA may also be intended to fix mutated genes causing diseases, such as hemophilia or sickle cell anemia. The vector could be plasmids, bacteriophages, and cosmids (packaged plasmid DNA into a phage particle).

6318. recombinant DNA technologies
Definition:

Procedures used to join together DNA segments in a cell-free system (an environment outside a cell or organism). Under appropriate conditions, a recombinant DNA molecule can enter a cell and replicate there, either autonomously or after it has become integrated into a cellular chromosome.

6319. recombination (genetic recombination)
Definition:

The process by which offspring derive a combination of genes different from that of either parent. In higher organisms, this can occur by crossing over.

6320. recombination frequency
Author: Susan A.Hagedorn
Definition:

The frequency at which crossing over occurs between two chromosomal loci--the probability that two loci will become unlinked during meiosis.

6321. recommended limit
Author: Biological Sciences at Heriot-Watt University
Definition:

This regulatory value is the maximum concentration of a potentially toxic substance which is believed to be safe. Such limits often have no legal backing in which case a control or statutory guide level which should not be exceeded under any circumstances may be set. See control limit.

6322. recruit (recruit fish)
Author:
Definition:

A juvenile fish that has survived long enough to become a part of (i.e., recruited into) a population or an exploitable segment of the population.

6323. recultivation
Author:
Definition:

General expression used for the making of bare areas (raw mineral soils) fertile again through bioengineering and refertilization.

6324. recurrence interval
Author:
Definition:

Expected or observed time intervals between hydrological events of a particular magnitude described by stochastic or probabilistic models (log-log plots).

6325. redd
Author:
Definition:

Nest made in gravel, consisting of a depression dug by a fish for egg deposition (and then filled) and associated gravel mounds.

6326. reducing agent (reductant)
Definition:

A molecule that donates an electron in an oxidation-reduction reaction.

6327. reduction
Definition:

The gain of electrons by a molecule or ion.

6328. reduction mammoplasty
Author: Guo Li
Definition:

Reduction mammoplasty is surgery to decrease the size of the breasts.

6329. reduction potential
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

The inherent tendency of a compound to act as an electron donor or an electron acceptor. Measured in volts.

6330. reductive dechlorination
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

Removal of Cl as Cl- from an organic compound by reducing the carbon atom from C-Cl to C H.

6331. reef
Definition:

1. In general, any solid object that projects from a stream bed or from the floor of any other body of water.
2. Specifically, a porous, often delicate mass of calcium carbonate and some silica made up of the skeletons of marine corals and sponges. Coral reefs serve as an important focus for many shallow-water ocean ecosystems.

6332. reflex sympathetic dystrophy
Author: Guo Li
Definition:

Reflex sympathetic dystrophy is characterized by burning pain and swelling with skin atrophy and increased sweat secretion.

6333. reflexed
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Bent sharply downwards or backwards.

6334. reflux
Author: Guo Li
Definition:

Reflux is the backward flow of fluids; for example, reflux esophagitis (inflammation of the esophagus due to stomach acid), vesicoureteral reflux.

6335. regional index streams
Author:
Definition:

Streams considered typical of a region.

6336. regrade
Author:
Definition:

To intentionally reconfigure the elevations and slopes on a parcel of land by means of surveying technology and construction equipment.

6337. regulation
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

Proceses that control the rates of synthesis of proteins. Induction and repression are examples of regulation.

6338. regulatory enzyme
Definition:

An enzyme that regulates certain functions due to its ability to undergo a change in its catalytic activity through modification of its structure.

6339. regulatory gene
Definition:

A gene that codes for a repressor protein.

6340. regulatory regions or sequences
Definition:

A DNA base sequence that controls gene expression.

6341. regulon
Definition:

A group of genes or operons that are regulated together even though they may be located a good distance from each other in the genome.

6342. rehabilitation (rehabilitate)
Definition:

1. To improve a site ecologically without it becoming completely restored to its virgin state.
2. To help an animal recover from injury so that it is able to be re-introduced into and survive in its natural habitat.
3. To help a person recover from injury or illness so that they are able to maintain a relatively active, healthy lifestyle.

6343. relative basal area
Author:
Definition:

An estimate of basal area for trees, such as produced by the Bitterlich sampling technique.

6344. relative risk
Author: Biological Sciences at Heriot-Watt University
Definition:

This term may have any of the following meanings depending upon context.
1. Ratio of the risk of disease or death among the exposed to the risk among the unexposed: this usage is synonymous with "risk ratio";
2. Alternately, the ratio of the cumulative incidence rate in the exposed to the cumulative incidence rate in the unexposed, i.e. the cumulative incidence ratio;
3. Sometimes used as a synonym for "odds ratio".

6345. relaxed control
Definition:

The ability of certain plasmids to continue to replicate after their bacteria stop dividing; the result is a single bacteria that contains hundreds of plasmids.

6346. relaxed DNA
Definition:

DNA that isn't supercoiled.

6347. relaxed mutant
Definition:

A mutant bacterium that continues to synthesize RNA in a medium that lacks certain nutrients or amino acids which that sort of bacterium normally needs present before it can make RNA.

6348. relaxed plasmid
Author: Susan A.Hagedorn
Definition:

A plasmid that replicates independently of the main bacterial chromosome and is present in 10-500 copies per cell.

6349. relaxing enzyme
Definition:

Any of several enzymes, such as helicase, that unwind DNA prior to its replication.

6350. releasing factors
Definition:

Hormones produced by the hypothalamus which stimulate the release of other hormones in the pituitary gland.

6351. relief
Author:
Definition:

The change in elevation of a land surface between two points; collectively, the configuration of the earth's surface, including such features as hills and valleys.

6352. REM sleep (rapid eye movement sleep)
Author: Guo Li
Definition:

REM sleep is sleep associated with rapid, roving movements of the eyes. The EEG pattern would resemble that of alert animals and humans despite sleep is not interrupted. There is a marked reduction of skeletal muscle tone during REM sleep. REM sleep and dreaming are associated.

6353. remote
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

Separated from one another; separated by intervals or spaces greater than the ordinary.

6354. renal failure (kidney failure)
Author: Guo Li
Definition:

Renal failure is the decrease in kidney function which is often reflected clinically by the elevation of serum urea nitrogen and creatinine concentrations.

Types:

• pre-renal: acute tubular necrosis
• renal: proliferative and crescentic glomerulonephritis, acute pyelonephritis, malignant nephrosclerosis
• post-renal: obstruction of the urinary tract

6355. renature
Author: Susan A.Hagedorn
Definition:

The reannealing (hydrogen bonding) of single-stranded DNA and/or RNA to form a duplex molecule.

6356. Rendu-Osler-Weber syndrome (hereditary hemorrhagic telangiectasia)
Author: Guo Li
Definition:

Rendu-Osler-Weber syndrome is characterized by bleeding tendency and telangiectases of the skin, mucosa of the nose, mouth, and the gastrointestinal tract. It is inherited as an autosomal dominant condition.

6357. reniform
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Kidney-shaped.

6358. rennet
Definition:

The inner lining of the fourth stomach of the calf of a ruminant (such as a cow). It is used to make cheese because it produces the enzyme rennin.

6359. rennin (chymosin)
Definition:

A proteolytic enzyme that is used to curdle milk to make cheese. Rennin is typically used in the form of rennet, a commercial preparation taken from the abomasum of young calves, but because the demand for rennin is so great, the cheese industry is increasingly turning to rennin-producing microbes such Mucor miehei and Mucor pusillus.

6360. Rep protein
Definition:

1. A protein that triggers a plasmid's replication.
2. An acronym for repetitive extragenic palindromic protein; this protein is an enzyme produced by a mutant strain of E. coli that unwinds the DNA helix.

6361. repent
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

Said of a stem that is prostrate and rooting at the nodes.

6362. repetatur (rept.)
Definition:

This Latin term, which is frequently used in medicine and pharmacy, means "let it be repeated".

6363. replacement vector
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A cloning vector, such as a bacteriophage, in which some of the DNA of the vector can be replaced with foreign DNA.

6364. replica plating (replica plate)
Definition:

A lab technique used mainly for identifying and selecting mutant colonies of a microorganism when the mutant can only be selected against. The microorganisms are cultured on a plate of agar, then a replica is made by blotting the colonies with a membrane and blotting the membrane on another plate. This results in all colonies from the first plate being in identical locations on the second plate. The second plate either contains some substance which kills off the mutation of interest, or lacks a substance necessary for the mutant to grow. Later, it is determined which colonies on the first plate failed to grow on the second plate.

6365. replicase (RNA replicase)
Definition:

A type of RNA polymerase which uses RNA molecules as a template for making new RNA molecules (a process which works exactly the same as the replication of DNA molecules).

6366. replication (DNA replication)
Definition:

The process of making an identical copy of a section of duplex (double-stranded) DNA, using existing DNA as a template for the synthesis of new DNA strands. In humans and other eukaryotes, replication occurs in the cell nucleus.

6367. replication fork
Definition:

A Y-shaped region in a chromosome that serves as the growing site for DNA replication.

6368. replicon
Definition:

A plasmid that has the ability to replicate.

6369. replisome
Definition:

A multi-protein complex that promotes the synthesis of DNA at the replication fork.

6370. replum
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A longitudinal partition in an ovary, formed between parietal placentas.

6371. reporter gene
Definition:

A gene that is used to locate or identify another gene.

6372. repose
Author:
Definition:

The stable slope of a bank or embankment, expressed as an angle or the ratio of horizontal to vertical projection.

6373. repressible enzyme
Definition:

In bacteria, an enzyme whose creation is inhibited when its reaction product is plentiful.

6374. repression
Definition:

The inhibition of a gene's expression; this is typically caused by the change in the activity of a regulatory protein.

6375. repressor
Definition:

A type of protein molecule that binds to DNA that shuts up transcription of a gene. See: operon or operator.

6376. reproductive adaptation
Author:
Definition:

A peculiarity of the reproductive mechanism of a species that results in it being better fitted to its environment (e.g., prolonged seed dormancy).

6377. reproductive endocrinologist
Author: Fertilitext
Definition:

An ob-gyn who specializes in the treatment of hormonal disorders that affect reproductive function.

6378. reproductive surgeon
Author: Fertilitext
Definition:

An ob-gyn or urologist who specializes in the surgical correction of anatomical disorders that impair reproductive function.

6379. reproductive toxicology
Author: Biological Sciences at Heriot-Watt University
Definition:

Reproductive toxicology is the study of the effects of chemicals on the adult reproductive and neuroendocrine systems, the embryo, fetus, neonate and prepubertal mammal.

6380. res ipsa loquitur
Author: Guo Li
Definition:

This is a Latin term which means "the thing speaks for itself".

It is a legal term for a method of alleging malpractice against a health care provider. Essentially, the allegation goes like this: "the patient was well before and sustained this condition only after having been cared for by you, therefore something must be wrong with your care". There are three conditions which must be met for res ipsa loquitur to be used:

1. in the ordinary course of affairs, the accident would not have occurred if reasonable care had been used
2. the thing that caused the accident was under the exclusive control of the defendant
3. the plaintiff did not contribute to the occurrence of the accident

6381. resect
Definition:

To remove part or all of an organ or tissue.

6382. resectable
Author: PharmInfoNet
Definition:

Capable of being removed by surgery

6383. reservoir
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

In epidemiology, the organism or environment that normally harbors a pathogen.

6384. reservoir
Author:
Definition:

Man-made body of water created by the damming, or the backing-up, of a river.

6385. resident
Definition:

A physician who has completed medical school and an internship and is in the process of receiving specialized training.

6386. residual volume (RV)
Author: Guo Li
Definition:

The gas remaining in the lung after a maximum expiratory effort.

6387. residue
Definition:

A single unit within a polymer, such as an amino acid within a polypeptide; this term reflects the fact that sugars, nucleotides, and amino acids usually lose a few atoms (usually hydrogens and oxygens) when they're added to a larger molecule.

6388. resistance factor (R Factor)
Definition:

A self-replicating fragment of nucleic acid that confers drug resistance and is transmitted from one bacterium to another via conjugation.

6389. resoiling
Author:
Definition:

The process of artificially building or reconstructing a soil profile.

6390. resolution
Definition:

Degree of molecular detail on a physical map of DNA, ranging from low to high.

6391. respiration
Definition:

A catabolic process that involves the exchange of oxygen and carbon dioxide between the body and the environment, the exchange of those gases within the body, and the oxidation of nutrient molecules for energy production.

6392. respiratory acidosis
Author: Guo Li
Definition:

Respiratory acidosis is the clinical condition in which the patient has acidic pH in his/her blood because of inadequate elimination of carbon dioxide. In a pure respiratory acidosis, the pH decreases by 0.08 for an increase in PCO₂ of 10 mm mercury.

6393. respiratory distress of newborn
Author: Guo Li
Definition:

Respiratory distress of a newborn is observed within 1 to 6 hours of birth and characterized by rapid grunting respiration, cyanosis, and retraction of the intercostal muscles on inspiration. It can be either of pulmonary or extrapulmonary causes. The most common cause is hyaline membrane disease which occurs in preterm infants. Other causes are: aspiration of fluid or meconium, pneumothorax, and pneumonia.

6394. respiratory distress syndrome
Author: Guo Li
Definition:

Respiratory distress syndrome is observed within 1 to 6 hours of birth and characterized by rapid grunting respiration, cyanosis, and retraction of the intercostal muscles upon the infant taking a breath. It can be either of pulmonary or extrapulmonary causes. The most common cause is hyaline membrane disease which occurs in preterm infants. Other causes are: inhalation of clear fluid or meconium, pneumothorax, and pneumonia.

6395. respiratory failure
Author: Guo Li
Definition:

Respiratory failure is either the abnormality of oxygenation or of carbon dioxide elimination. Arterial blood gas analysis of blood taken from an artery confirms the degree of failure. Although the values of PO₂ less than 60 mmHg and PCO₂ higher than 50 are often used as criteria for respiratory failure, the clinical picture of the patient is important to recognize impending failures.

6396. restoration
Author:
Definition:

Measures undertaken to return a degraded ecosystem's functions and values, including its hydrology, plant and animal communities, and/or portions thereof, to a less degraded ecological condition.

6397. restoration measure
Author:
Definition:

A restoration measure consists of one or more features or activities, at a geographic site, that is intended to cause a desirable change in an ecological resource and results in a positive environmental output. Many restoration measures are combinations of several features and activities.

6398. restriction enzyme (restriction endonuclease)
Definition:

A protein that recognizes specific, short nucleotide sequences and cuts DNA at those sites. Bacteria contain over 400 such enzymes that recognize and cut over 100 different DNA sequences.

6399. restriction enzyme cutting site
Definition:

A specific nucleotide sequence of DNA at which a particular restriction enzyme cuts the DNA. Some sites occur frequently in DNA (e.g., every several hundred base pairs), others much less frequently (rare-cutter; e.g., every 10,000 base pairs).

6400. restriction fragment
Definition:

A section of double-stranded DNA which is produced by the action of a restriction endonuclease on the parent DNA.

6401. restriction fragment length polymorphism (RFLP)
Definition:

Variation between individuals in DNA fragment sizes cut by specific restriction enzymes; polymorphic sequences that result in RFLPs are used as markers on both physical maps and genetic linkage maps. RFLPs are usually caused by mutation at a cutting site. See marker.

6402. resupinate
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Twisted through 180°, e.g. as with the ovary of most orchids.

6403. retard
Author:
Definition:

Noun A bank-protection structure designed to check/slow the riparian velocity and induce silting or accretion.

6404. retention basin (retention dam)
Author:
Definition:

A flood control structure that holds back flood water for a short period to take the peak off a downstream flood. The dam on a retention basin is usually provided with an opening too small to allow the full flood flow to pass. This restriction forces water to collect in the basin behind the dam, but as soon as the storm peak passes the basin quickly drains. Most of the time the basin is dry.

6405. retention pond
Author:
Definition:

A retention pond allows water to be held as long as possible and may or may not allow for the controlled release of water. In some cases, the water is allowed to seep into the permeable banks or gravel strata in the foundation.

6406. reticuloendothelial system
Definition:

A system of phagocytes (cellsA which engulf and devour other cells) which can be found all over the body but are mostly concentrated in the liver, spleen, lymph nodes, and bone marrow, and are a part of the body's immune system.

6407. reticuloendothelial system (RES, mononuclear phagocyte system)
Author: Biological Sciences at Heriot-Watt University
Definition:

This is the system of cells which have the ability to take up and retain certain dyes and particles ingested by a living animal.

6408. retina
Definition:

The retina is the innermost layer of the eyeball (the outermost layer being the sclera and the cornea, the middle layer is choroid and the ciliary structures). The retina is the place where the image created by the lens of the eye is focused; the information from this image is turned into nerve impulses, which are then sent to the brain via the optic nerve.

6409. retinaculum
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A hook-like structure to which another structure is tethered; in orchids and members of the family Asclepiadaceae, the structure to which pollen masses are attached; in Acanthaceae, the persistent stalk of an ovule.

6410. retinal detachment
Author: Guo Li
Definition:

This is the separation of the retina from the pigment epithelium. It can be spontaneous or due to trauma to the eye. Immediate medical attention is needed.

6411. retinitis pigmentosa
Definition:

A hereditary eye disease caused by a recessive gene where the retina progressively degenerates. Symptoms include progressive blindness, beginning with night blindness and followed by gradual loss of peripheral vision and pigment migration.

6412. retinoblastoma
Author: Guo Li
Definition:

Retinoblastoma is the most common malignant intraocular neoplasm of infants, about half of all children with retinoblastoma may be inherited as an autosomal dominant trait, in which case, the cancer afflicts both eyes.

6413. retinopathy
Author: PharmInfoNet
Definition:

A disease of the small blood vessels in the retina of the eye.

6414. retinopathy
Definition:

This is a medical term for any disease or disorder of the retina of the eye.

6415. retrofit
Definition:

To modify a device or machine after it's been purchased, either to improve on a design element or to replace a malfunctioning component.

6416. retrorse
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Directed backwards or downwards. Compare antrorse.

6417. retrotransposon
Author: Edward Bollenbach
Definition:

DNA fragments copied from viral RNA with reverse transcriptase that insert in the host chromosomes.

6418. retrovirus
Definition:

Any virus in the family Retroviridae that has RNA as its nucleic acid and uses the enzyme reverse transcriptase to copy its genome into the DNA of the host cell's chromosomes. Many cancers in vertebrates are caused by retroviruses.

6419. return flow
Author:
Definition:

That portion of the water previously diverted from a stream, and subsequently, returned to that stream or to another body of ground or surface water.

6420. retuse
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

With a very blunt and slightly notched apex.

6421. reverse electron transport
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

The energy-dependent movement of electrons against the thermodynamic gradient to form a strong reductant from a weaker electron donor.

6422. reverse transcriptase
Definition:

An enzyme found in retroviruses that enable the virus to make DNA from viral RNA.

6423. reverse transcription
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

The process of copying information found in RNA into DNA.

6424. revetment
Author:
Definition:

Bank protection by armor, that is, by facing the bank or embankment with erosion resistant material.

6425. revetment wall
Author:
Definition:

A wall made of concrete, stone, wood, or other materials which is built against a stream bank or a steep slope to prevent erosion.

6426. Reye's syndrome
Author: Guo Li
Definition:

Reye's syndrome is characterized by encephalopthy (degenerative changes to the brain) and fatty degeneration of the liver, kidney, and brain. It is associated with a viral infection of the upper respiratory tract and the use of salicylates (such as aspirin).

6427. Rezulin (troglitazone)
Definition:

This is a prescription medication used to treat Type II diabetes. It is especially used to treat people who do not respond to other treatments.

6428. Rh factor
Definition:

An antigen that may or may not be present on the surface of human blood cells. If a person's blood has the antigen, their blood type is "positive"; if they do not, it is "negative." The Rh factor is important mainly because if a woman who is Rh- conceives a child who is Rh+, the mixing of their bloods in the placenta may provoke an immune reaction in the mother that can cause a life-threatening agglutination of the fetus' blood cells.

The Rh factor is so named because it was first identified in Rhesus monkeys. See also ABO blood group.

6429. rhabdosarcoma
Definition:

A very dangerous cancer which develops from striated muscle tissue. There are three major forms:
1. alveolar rhabdosarcoma: this cancer, which most often afflicts adolescents, typically develops in the extremities, body or eye cavities.
2. embryonal rhabdosarcoma: this cancer, which strikes infants and young children, develops in the head, neck, extremities or lower genitourinary tract.
3. pleiomorphic rhabdosarcoma: this cancer strikes adults and typically develops in the extremities.

6430. rheumatic fever
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

An inflammatory autoimmune disease triggered by an immune response to infection by Streptococcus pyogenes.

6431. rheumatic heart disease
Author: Guo Li
Definition:

Rheumatic heart disease results from single or repeated attacks of rheumatic fever that produce rigidity and deformity of heart valves such that stenosis or regurgitation results.

6432. rheumatoid arthritis
Author: Guo Li
Definition:

Rheumatoid arthritis is symmetrical (occuring in the same joint on both sides of the body) erosive (joint-destroying) polyarthritis (arthritis in several joints) with positive rheumatoid factor.

6433. rheumatoid factor
Author: Guo Li
Definition:

This is a heterogenous group of autoantibodies directed against human IgG which is elevated with many clinical conditions, among them: rheumatoid arthritis, systemic lupus erythematosus, Sjogren's syndrome, polymyositis, scleroderma, tuberculosis, leprosy, syphilis, and subacute bacterial endocarditis.

6434. rheumatologist
Definition:

A medical doctor who specializes in rheumatology.

6435. rhipidium
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

An inflorescence of cymose units, the lateral branches developed alternately in opposite directions.

6436. rhizobia
Author: Susan A.Hagedorn
Definition:

Bacteria in a symbiotic relationship with leguminous plants that results in nitrogen fixation.

6437. rhizoid
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A thread-like, unicellular absorbing structure, occurring in fern gametophytes and in some non-vascular plants.

6438. rhizome chaff
Author:
Definition:

Mechanically chopped-up pieces of thin rhizomes spread on the ground and covered with soil so they can take root and form new plants.

6439. rhizome cutting
Author:
Definition:

Part of a thick rhizome, which may take root and form a new plant.

6440. rhizophore
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A leafless stem that produces roots.

6441. rhizosphere
Author: Susan A.Hagedorn
Definition:

The region of the soil on and around plant roots.

6442. rhizosphere
Author:
Definition:

The zone of soil in which interactions between living plant roots and micro-organisms are found.

6443. rib wall
Author:
Definition:

Usually a rock, rock gabion, or broken concrete structure constructed across a stream below a dam or weir to raise the water level in a pool below the dam or weir. (This can be used in lieu of a fishway in some cases. Also used to slow down high water velocities.)

6444. ribonuclease
Definition:

A nuclease that catalyzes the breaking of some linkages between nucleotides in RNA.

6445. ribonucleoprotein
Definition:

A conjugated protein (such as telomerase) that contains a ribonucleic acid molecule as a prosthetic group.

6446. ribonucleoside
Definition:

A nucleoside in which purine or pyrimidine base is linked to a ribose molecule.

6447. ribonucleotide
Definition:

A nucleotide in which a purine or pyrimidine base is linked to a ribose molecule.

6448. ribophage
Definition:

A bacteriophage that has an RNA-based genetic structure.

6449. ribophorin
Definition:

Any of several glycoproteins in the endoplasmic reticulum that aid ribosomes during the cotranslational insertion of certain proteins.

6450. riboprine
Definition:

An anti-cancer drug.

6451. ribose
Image: View the chemical structure
Definition:

A five-carbon sugar that is a structural component of ribonucleic acid, riboflavin and other nucleotides and nucleosides.

6452. riboside
Definition:

A glycoside that has ribose as its sugar component.

6453. ribosomal RNA (rRNA)
Definition:

A class of RNA found in the ribosomes of cells.

6454. ribosome binding site
Author: Susan A.Hagedorn
Definition:

The region of a messenger RNA molecule that binds the ribosome to initiate translation.

6455. ribosomes
Definition:

Small cellular components composed of specialized ribosomal RNA and protein; site of protein synthesis. Found in three places in eukaryotic cells:

1. free in the cytoplasm,
2. attached to the endoplasmic reticulum,
3. and in mitochondria

See ribonucleic acid (RNA).

6456. ribovirus
Definition:

A virus that has RNA as its genetic material.

6457. ribozyme (RNA enzyme)
Definition:

A molecule of ribonucleic acid that has catalytic activity.

6458. rickettsias
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

Obligate intracellular parasites which cause a variety of disease, including typhus and Rocky Mountain spotted fever.

6459. ridgeline
Author:
Definition:

A line connecting the highest points along a ridge and separating drainage basins or small-scale drainage systems from one another.

6460. Riedel's thyroiditis
Author: Guo Li
Definition:

This is swelling/inflammation of thyroid gland in which the gland is of a woody consistency and adheres to the neck structures; the normal microscopic cellular pattern of the organ is totally lost.

6461. riffle
Author:
Definition:

1. Shallow section of a stream or river with rapid current and a surface broken by gravel, rubble or boulders. (Compare glide; rapids; run.)
2. A reach of stream in which the water flow is rapid and usually more shallow than the reaches above and below. Natural streams often consist of a succession of pools and riffles. (Sometimes incorrectly referred to as a "ripple.")

6462. rill
Author:
Definition:

1. One of the first and smallest channels formed by surface runoff.
2. A small erosional channel, usually in parallel where surface waters run on steep unprotected soils.
3. A very small brook or trickling stream of water.

6463. rilling (rill erosion)
Author:
Definition:

Development of numerous small, closely spaced channels resulting from the uneven erosion of soil by running water.

6464. riparian
Author:
Definition:

1. On, or pertaining to, the banks of a stream. (As in riparian vegetation or riparian woodland.)
2. Pertaining to the banks and other adjacent, terrestrial (as opposed to aquatic) environs of freshwater bodies, watercourses, and surface-emergent aquifers (e.g., springs, seeps, oases), whose imported waters provide soil moisture significantly in excess of that otherwise available through local precipitation - soil moisture to potentially support a mesic vegetation distinguishable from that of the adjacent more xeric upland.

Source: Warner and Hendrix. Riparian Resources of the Central Valley and California Desert. 1985. California Department of Fish and Game.

6465. riparian area
Author:
Definition:

The area between a stream or other body of water and the adjacent upland identified by soil characteristics and distinctive vegetation. It includes wetlands and those portions of floodplains and valley bottoms that support riparian vegetation.

6466. riparian land
Author:
Definition:

Land situated along the bank of a stream or other body of water.

Source: "Resource Conservation Glossary." Third Edition.

6467. riparian vegetation
Author:
Definition:

1. Vegetation which occurs in and/or adjacent to a watercourse. For the purpose of administering Fish and Game Code Section 1600, et seq., this should be expanded to include vegetation adjacent to lakes as well.
2. Vegetation growing on or near the banks of a stream or other body of water on soils that exhibit some wetness characteristics during some portion of the growing season.
3. Vegetation which occurs along watercourses, and is structurally or floristically distinct from nearby, non-streamside vegetation.
4. Riparian vegetation is terrestrial vegetation that grows beside rivers, streams, and other freshwater bodies and that depends on these water sources for soil moisture greater than would otherwise be available from local precipitation.

Source: Warner, R.E. and Hendrix, K.M., eds. 1984. California Riparian Systems, Ecology, Conservation, and Productive Management. California Riparian Systems Conference, U.C. Davis. September 1981. University of California Press. Berkeley, California.

6468. riparian wetland
Author:
Definition:

Riparian vegetation composed primarily of woody hydrophytes (e.g., such as willows, alders, cottonwoods, sycamores, box elders, aspens, etc.).

6469. riparian woodland (riparian forest)
Author:
Definition:

1. The broad-leaved and winter deciduous, phreatophytic tree formation that lines watercourses.
   Source: Ornduff, R. "An Introduction to California Plant Life." 1974.
2. Streamside forest composed of either wetland species (e.g., willow, cottonwood, etc.) or non-wetland species (e.g., oak, walnut, California bay).

6470. riprap
Author:
Definition:

1. Layer of large, durable materials (usually rocks; sometimes car bodies, broken concrete, etc.) used to protect a stream bank or lake shore from erosion; may also refer to the materials used.
2. A layer of irregularly placed stones or debris positioned on the bank of a stream or beside a levee to resist the eroding action of flowing water.

6471. risk
Author: Biological Sciences at Heriot-Watt University
Definition:

This term must not be confused with the term "hazard". It is most correctly applied to the predicted or actual frequency of occurrence of an adverse effect of a chemical or other hazard.

6472. risk assessment
Author: Biological Sciences at Heriot-Watt University
Definition:

Risk assessment is the identification and quantification of the risk resulting from a specific use or occurrence of a chemical, taking into account the possible harmful effects on individual people or society of using the chemical in the amount and manner proposed and all the possible routes of exposure. Quantification ideally requires the establishment of dose-effect and dose-response relationships in likely target individuals and populations. Compare risk evaluation.

6473. risk evaluation
Author: Biological Sciences at Heriot-Watt University
Definition:

Risk evaluation involves the establishment of a qualitative or quantitative relationship between risks and benefits, involving the complex process of determining the significance of the identified hazards and estimated risks to those organisms or people concerned with or affected by them.

6474. risk factor
Author: PharmInfoNet
Definition:

Anything that raises the chance that a person will get a disease.

6475. risk management
Author: Biological Sciences at Heriot-Watt University
Definition:

Risk management is the decision-making process involving considerations of political, social, economic and engineering factors with relevant risk assessments relating to a potential hazard so as to develop, analyse and compare regulatory options and to select the optimal regulatory response for safety from that hazard. Essentially risk management is the combination of three steps: risk evaluation, emission and exposure control, and risk monitoring.

6476. risperidone (Risperdal)
Definition:

This antipsychotic drug is used to treat schizophrenia.

6477. river continuum
Author:
Definition:

Gradual changes in the biological community of a river as energy sources and physical conditions change from headwaters to lowlands.

6478. river-type fish
Author:
Definition:

Anadromous fish that rear for a year or more in rivers.

6479. RNA (ribonucleic acid)
Definition:

A chemical found in the nucleus and cytoplasm of cells; it plays an important role in protein synthesis and other chemical activities of the cell. The structure of RNA is similar to that of DNA. There are several classes of RNA molecules, including messenger RNA, transfer RNA, ribosomal RNA, and other small RNAs, each serving a different purpose.

6480. RNA life
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A hypothetical life form lacking DNA and protein which may have existed on early earth and in which RNA served both a genetic coding and a catalytic function.

6481. RNA processing
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

The conversion of a precursor RNA into its mature form.

6482. rock
Author:
Definition:

1. Cobble, boulder, or quarry stone used as a construction material.
2. Hard natural mineral, in formation or in piles of talus or detritus.

6483. rock fill dam
Author:
Definition:

A dam composed of large, broken, and loosely placed or pervious rocks with either an impervious core or upstream facing or surface layer.

6484. roiled
Author:
Definition:

Water that has been made turbid by the addition of sediment.

6485. root
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

The water- and mineral-absorbing part of a plant which is usually underground, does not bear leaves, tends to grow downwards and is typically derived from the radicle of the embryo. See adventitious.

6486. root cutting
Author:
Definition:

Part of a root of a woody plant which, under suitable conditions, takes root and forms a new plant.

6487. root nodule
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A tumor-like growth on plant roots that contains symbiotic nitrogen-fixing bacteria.

6488. root pressure
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

Pressure in the roots which, when the shoot is cut off, will cause liquid to ooze from the root stump; the mechanisms and tissues involved in this process are not clearly understood.

6489. root sprout
Author:
Definition:

A living shoot which grows from the root of a plant whose above-ground portion has been cut down.

6490. rootball (root ball)
Author:
Definition:

Nursery transplant with root stock and soil held together by burlap or other wrapping.

6491. rootlet
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

A radicle; a little root or small branch of a root.

6492. rootstock
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A short, erect, swollen structure at the junction of the root and shoot systems of a plant.

6493. roseate
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

Rose-colored or rose-shaped.

6494. rosette
Definition:

A group of organs or other body features, such as leaves or hair, which are clustered and crowned around a common point of attachment.

6495. rostellum
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A beak-like upward extension of the stigma in orchids.

6496. rotate
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

1. Verb: To turn.
2. Adjective: Circular and flattened, e.g. of a corolla with a very short tube and spreading lobes.

6497. rotation
Author:
Definition:

The planned number of years between successive cuttings of a forest; livestock grazing strategy in which cattle are moved from one pasture to another during the grazing season.

6498. rough endoplasmic reticulum
Definition:

A type of endoplasmic reticulum, an organelle found in eukaryotic cells, which has a large number of ribosomes attached all over it. It is important to the making of proteins and in preparing secretions of the cell.

6499. roughness coefficient
Author:
Definition:

Designated by "N" in Manning’s flow equation, the roughness coefficient is an expression of the resistance to flow of a surface such as the bed or bank of a stream.

6500. rubble
Author:
Definition:

1. Rough, irregular, water-worn rock fragments of random size.
2. Stream substrate particles between 64 and 256 mm (2.5 and 10 inches) in diameter.

6501. rubella
Author: Guo Li
Definition:

Rubella is a viral infection by the rubella virus. Rubella infection during pregnancy is associated with fetal malformations, bleeding, and other deleterious effects, so vaccination against this virus for women of childbearing age is suggested and the best time is the immediate postpartum period. The serum rubella antibody is measured and its result is interpreted as follows:

ranges (in IU/mL):

no immunity             < 10.0
equivocal               10.0 - 14.9
immunity                15.0 - 200.0
high immunity           > 200.0

6502. ruderal
Author:
Definition:

Weedy vegetation growing on compacted, plowed, or otherwise distrubed ground and showing a preference for this type of habitat.

6503. rudimentary
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Poorly developed and not functional. Compare vestigial, obsolete.

6504. rugose
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Deeply wrinkled.

6505. rule
Definition:

A statement of conditions, effects, or phenomena typically observed in a given situation or process.

6506. rumen
Definition:

The first four stomach compartments in ruminant animals (such as cattle and deer).

6507. ruminate
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Mottled in appearance, e.g. of bark, or of the food reserves in a seed.

6508. run (fish run)
Author:
Definition:

A group of fish migrating in a river (most often on a spawning migration) that may comprise one or many stocks.

6509. run (stream)
Author:
Definition:

Swiftly flowing stream reach with little surface agitation and no major flow obstructions. Often appears as a flooded riffle. (Compare glide; riffle; rapids.)

6510. run-off (runoff)
Author:
Definition:

1. Water flowing in a river as a result of snow melt or heavy rains.
2. The part of precipitation and snowmelt that reaches streams (and thence the sea) by flowing over the ground.
3. The portion of rain or snow that does not percolate into the ground and is discharged into streams instead.
4. That part of water yield that appears in streams. Expressed in acre feet per year.

6511. runcinate
Definition:

Deeply lobed and with the lobes slanted away from the apex.

6512. runner
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A slender, prostrate or trailing stem which produces roots and sometimes erect shoots at its nodes.

6513. rust
Definition:

A type of club fungus that is a parasite on plants. The most common rust is Puccinia graminis (black stem rust in wheat).

6514. S phase
Definition:

The period during interphase in the cell cycle when DNA is replicated in the cell nucleus. The "S" stands for synthesis.

6515. Sabin vaccine for poliomyelitis
Author: Guo Li
Definition:

This vaccine uses live attenuated virus that is given by mouth, sometimes as liquid drops in a sugar cube.

6516. sac
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A pouch or cavity.

6517. Saccharomyces cerevisiae (baker's yeast, brewer's yeast, budding yeast)
Definition:

A species of yeast which is an important model organism for biological study, particularly for genetics and molecular biology. The entire genome of this species has been base sequenced and it is used to do research on the basic cellular mechanics of replication, recombination, cell division and metabolism.

S. cerevisiae is also economically important in the food industry, where it is used to ferment grain sugars to make beer and as baker's yeast for baking bread or making other food which requires rising by gas bubbles of carbon dioxide. It is also sometimes taken as a vitamin supplement for protein, the B vitamins, and folic acid.

6518. sack concrete wall
Author:
Definition:

A bank stabilization technique where burlap sacks of dry concrete mix are placed from a toe trench in a terraced formation up an embankment, than wetted thoroughly and packed down. While curing, the run-off from sack concrete is highly alkaline (has a high pH); sack concrete walls should not be built in direct contact with the flowing stream.

6519. safe yield
Author:
Definition:

The amount of water that can be withdrawn from a groundwater basin without producing an undesired result such as depletion of groundwater reserves, intrusion of water of undesirable quality, excessive depletion of streamflow by induced infiltration, or land subsidence.

6520. safety
Author: Biological Sciences at Heriot-Watt University
Definition:

Safety is the practical certainty that injury will not result from exposure to a hazard under defined conditions: in other words, the high probability that injury will not result. See practical certainty.

6521. sagittate
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Shaped like an arrow-head.

6522. sakuc horizon
Author:
Definition:

A layer 6 inches or more thick comprised of secondary soluble salts.

6523. saline conditions
Author:
Definition:

Soils or waters that are high in salt content, that is, more than 0.5 parts per thousand (=0.05% salinity). Usually sodium chloride (NaCl) is the predominant salt, but some areas have high concentrations of sulfates, carbonates, and bicarbonates, as well. Habitats are commonly subdivided on the basis of total salt content.

6524. Salk vaccine for poliomyelitis
Author: Guo Li
Definition:

This vaccine uses poliovirus grown in monkey kidney cells and inactivated by formaldehyde and given by intramuscular injection.

6525. Salmonella
Author: Susan A.Hagedorn
Definition:

Salmonella is a genus of rod-shaped, Gram-negative bacteria that are a common cause of food poisoning.

6526. salorthids
Author:
Definition:

Soils of arid regions with salic (salt-bearing) horizon within 30 inches of the surface and saturated within 40 inches for one month or more in most years; common in playas of the Southwest.

6527. salpingectomy
Author: Fertilitext
Definition:

Surgical removal of the fallopian tubes.

6528. salpingitis
Author: Fertilitext
Definition:

Inflamation of one or both fallopian tubes.

6529. salpingitis
Author: Guo Li
Definition:

Salpingitis is the condition characterized by inflammation of the fallopian tube, often caused by infection by bacteria ascending from the vagina.

6530. salpingitis isthmica nodosa
Author: Fertilitext
Definition:

An abnormal condition of the fallopian tube in the place where it attaches to the uterus, characterized by nodules.

6531. salpingoo-oophorectomy
Author: Guo Li
Definition:

Salpingoo-oophorectomy is surgery to remove the fallopian tube (salpingectomy) and the ovary (oophorectomy). This procedure is usually done together with hysterectomy for a variety of reasons such as: ectopic pregnancy, endometrial carcinoma of the uterus, benign tumors of the ovary (cystadenomas and solid tumors) in women approaching menopause or after menopause, and extensive endometriosis.

The procedure: for an uncomplicated procedure, it takes 1 1/2 hours to 2 hours with little chance of blood transfusion. Abdominal approach with phannenstiel (bikini) incisions or midline incisions are often used. Some patients are suitable candidates for laparoscopic approach (with 4 small incisions for the laparoscope and instruments).

Material effects, risks and side effects: Infertility if the procedure is performed for both sides or if the procedure is performed on one side and the remaining side is not functional. Removal of the ovaries results in reduction in the level of circulating female hormones and associated side effects. There are also risks associated with anesthesia.

6532. salpingostomy
Author: Fertilitext
Definition:

An incision in a fallopian tube, such as to remove an ectopic pregnancy.

6533. salpingotomy
Author: Fertilitext
Definition:

An operation to open a blocked fallopian tube.

6534. salt marsh
Author:
Definition:

A community of organisms dominated by plants that are tolerant of wet, saline soils; generally found in low-lying coastal habitats which are periodically wet and unusually saline to hypersaline. The term salt marsh summarizes the saline conditions of the habitat as well as the emergent vegetation which dominates it. Plants which grow in salt marshes are thus tolerant of two conditions: saline and wet.

6535. salt ponds
Author:
Definition:

Perched wetlands that are managed by humans to produce salt.

6536. salt water marsh
Author:
Definition:

Wetland dominated by herbaceous plants under the influence of saline waters. May be coastal (tidal) or perched.

6537. saltation
Author:
Definition:

Bed load transport by leaps or bounds.

6538. saltatory replication
Definition:

A replication process which creates extra copies of segments of DNA along the same strand. An explanation for the existence of satellite DNA, which are highly-repeated, non- transcribed sequences of DNA with no clear function. An alternative explanation to this is crossover fixation.

6539. saltpeter
Definition:

Common name for potassium nitrate; in the context of geologic deposits, it may also be used to refer to other nitrate minerals such as calcium nitrate.

6540. saltwater intrusion
Author:
Definition:

The induced movement of ocean water into coastal aquifers that have been depleted of fresh water generally due to over-drafting (excessive withdrawal from wells) and/or reduction of recharge.

6541. salvage pathway
Definition:

A recycling pathway in which biomolecules such as nucleotides are synthesized from intermediates in the degradative pathway for those biomolecules; compare de novo pathway.

6542. salverform
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

Said of a corolla in which the tube is essentially cylindrical, the lobes abruptly spreading; a gamopetalous corolla.

6543. samara
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A dry, indehiscent fruit with its wall expanded into a wing.

6544. sand
Definition:

Particles in siliciclastic sediment that range in size from 0.0625 millimeters (very fine-grained sand) to 2.0 millimeters (very coarse-grained sand), according to the Udden-Wentworth scale. In field geology, to tell the difference between fine-grained sand and coarse silt, the particle in a rock is "sand" if it can be clearly seen with the naked eye.

6545. sand
Author:
Definition:

1. Substrate particles 0.062 to 2 mm in diameter.
2. Granular soil or detritus coarse than silt and finer than gravel, ranging in diameter from 0.002 to 0.2 inch.

6546. sapling
Author:
Definition:

1. Strong, young tree, the stem of which has normal branch development from the bottom up.
2. Woody vegetation between 0.4 and 5.0 inches in diameter at breast height and greater than or equal to 20 feet in height, exclusive of woody vines.

6547. saponification
Definition:

The alkaline hydrolysis of triacylglycerols to form fatty acids in soaps.

6548. saponin
Definition:

Any of a group of glycosides produced by plants that foam in water; saponins are used as foaming agents in beverages, as emulsifiers, and in detergents.

6549. saprists (mucks)
Author:
Definition:

Organic soils (mucks) in which most of the plant material is decomposed and the original constituents cannot be recognized; less than one-third of the fibers remain visible upon rubbing the material between the fingers.

6550. saprobe
Definition:

An organism that obtains its food directly from decaying organic material.

6551. saprophyte
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A plant which derives its nourishment from dead organic matter and usually lacks chlorophyll. Compare epiphyte, parasite.

6552. sarcoidosis
Author: Guo Li
Definition:

Sarcoidosis is a slow chronic disease in which normal tissue is replaced by islands (granules) of epithelium and lymphoid cells (granulomas). Although over 90% of the cases of sarcoidosis, the lungs are affected, the disease can involve many other organs: skin, eyes, nerves, liver, kidney, or the heart. The cause of sarcoidosis is not known.

6553. sarcoma
Definition:

A general term for a cancerous tumor of soft tissue that is made up of densely packed cells.

6554. sarmentose
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

Producing slender, prostrate branches or runners.

6555. satellite DNA
Definition:

In eukaryotic chromosomes, the function of this highly-repeated, non-translated DNA is not clear; it is most often associated with the centromeric region.

6556. satellite RNA (viroid)
Author: Susan A.Hagedorn
Definition:

A small, self-splicing RNA molecule that accompanies several plant viruses, including tobacco ringspot virus.

6557. saturated
Author:
Definition:

A condition in which all easily drained voids (pores) between soil particles are temporarily or permanently filled with water; significant saturation during the growing season is considered to be usually one week or more.

6558. saturated fat
Definition:

A fat that contains no carbon-carbon double bonds. These fats are solid at room temperature and are most often found in or extracted from animal flesh and milk. Saturated fats include butter, lard, solid vegetable shortening, palm oil, and coconut oil. Some people believe that consuming these fats tends to raise the level of cholesterol in the blood.

6559. saturated genetic map
Author: ForBio Ltd.
Definition:

A linkage map consisting of a large number of genetic markers randomly distributed to completely cover all of the chromosomes.

6560. saturated soil
Author:
Definition:

A condition in which all easily drained voids (pores) between soil particles are temporarily or permanently filled with water; significant saturation during the growing season is considered to be usually one week or more.

6561. saturatus (sat.)
Definition:

This Latin term, which is frequently used in medicine and pharmacy, means "saturated".

6562. savanna (savannah)
Author:
Definition:

A type of woodland characterized by a very open spacing between its trees and by intervening areas of grassland.

6563. scabies
Author: Guo Li
Definition:

Scabies is a skin infection caused by a small mite and its major symptom is itching.

6564. scabridulous
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Slightly rough; diminutive of scabrous.

6565. scalariform
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Having a ladder-like pattern.

6566. scale
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A reduced or rudimentary leaf, e.g. surrounding a dormant bud; a thin flap of tissue, e.g. on the ventral surface of a liverwort thallus and at the base of a stamen in members of the family Simaroubaceae.

6567. scale up
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

Conversion of an industrial process from a small laboratory setup to a large commercial endeavor.

6568. scape
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

The stem-like, flowering stalk of a plant with leaves clustered around the base of its stem.

6569. scapose (scapigerous)
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

Consisting of a scape.

6570. scar
Author: Guo Li
Definition:

A scar is an abnormal condition of the skin after injury. It is characterized by dense fibrotic tissue covered by a thin epidermis.

6571. scarify
Author:
Definition:

1. To abrade, scratch, or modify the surface.
2. To scratch the impervious seed coat of a hard seed.
3. To break the surface of the soil.

6572. scarlet fever
Definition:

Scarlet fever is an acute illness which is caused by a systemic infection with the bacterium Streptococcus pyogenes. It is characterized by a reddish skin rash, sore throat, fever, and vomiting; it may also be accompanied by tonsilitis and a reddening of the tongue (called "strawberry tongue").

6573. scavenger
Definition:

An animal (such as a vulture or coyote) that eats carcasses abandoned by predators, digs through trash cans for food, etc.; true scavengers seldom kill their own prey (but many animals are not exclusively scavengers).

6574. Scheie’s Syndrome (mucopolysaccharidosis type 1 S, MPS-IS, MPS disorder I S)
Definition:

A hereditary metabolic disorder caused by a recessive gene which results in a deficiency of the enzyme alpha-L-iduronidase, which breaks down dermatan sulphate and heparan sulphate, two types of mucopolysaccharides (complex carbohydrates). Consequently, the mucopolysaccharides accumulate in the cells of the body and cause damage. Symptoms include skeletal deformities, mental retardation, coronary artery disease, deafness, and stiff joints, among other things. There are mild and severe forms of the syndrome; the severe form is called Hurler Syndrome, the mild form is called Scheie Syndrome, and children with an intermediate form have Hurler-Scheie Syndrome. Patients with the mild form generally suffer little to no mental retardation and survive to adulthood. There is presently no cure. Scheie’s Syndrome is one of a number of related rare genetic mucopolysaccharide disorders, the most common being Hunter’s Syndrome.

For more information, visit MPS II - Hurler's Syndrome.

6575. schizocarp
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A dry fruit formed from more than one carpel but breaking apart into 1-carpel units when ripe. Compare mericarp.

6576. schizophrenia (adj.: schizophrenic)
Author: Guo Li
Definition:

Schizophrenia is the name for any of a group of mental disorders characterized by abnormal thought, mood and behavior. For example:
• thought: misinterpretation of reality, frequently inclined towards self-protection from perceived harm
• mood: inappropriate emotional response, lack of empathy with others
• behavior: withdrawn, regressive, and bizarre
The cause of schizophrenia is not known. More than 90% of schizophrenic conditions begin before the age of 50.

6577. Schizosaccharomyces pombe (fission yeast)
Definition:

S. pombe is a species of yeast, also called fission yeast, which is used as a model organism for biological and medical study. They are useful because most of the time they are haploid so that both recessive and dominant mutations in the genome will result in a mutant phenotype (since each individual yeast cell has only one copy of each gene, unlike in diploid organisms where a normal copy of a gene can make up for recessive mutations, resulting in mutant phenotypes only for dominant mutations).

6578. sciatica
Author: Guo Li
Definition:

Sciatica is low back pain radiating down the buttock and below the knee.

6579. science
Definition:

1. The study of the material universe or physical reality in order to understand it. This is done by making observations and collecting data about natural events and conditions, then organizing and explaining them with hypotheses, theories, models, laws, and principles.
2. The organized body of knowledge about the material universe which can be verified or tested.
3. A particular branch of either the process of study or the body of knowledge, such as astronomy, biology, chemistry, geology, and physics.

6580. scientific method
Definition:

The universally-accepted, organized approach to the study of science, which consists of the following steps:
1. Observation - collecting data;
2. Hypothesis - forming a preliminary possible explanation of the data;
3. Testing - test the hypothesis by collecting more data;
4. Results - interpreting the results of the test and deciding if the hypothesis should be rejected. The hypothesis is rejected if the results contradict it, showing that it is wrong; and
5. Conclusion - stating a conclusion that can be evaluated independently by others.

6581. scientism
Definition:

1. The methods, activities, and principles which are typical to science.
2. The concept that other areas besides science can and should be studied in a scientific manner, for example the humanities.

6582. scleral icterus
Author: Guo Li
Definition:

This is a yellowish pigment on the sclera, associated with hyperbilirubinemia.

6583. sclerenchyma
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Hard plant tissue with heavily thickened cell walls.

6584. sclerite
Definition:

A hard plate or spicule which may be composed of chitin or calcium carbonate; often refers to the rigid parts of the arthropod (insects, crustaceans, etc.) exoskeleton.

6585. scleroderma
Author: Guo Li
Definition:

Scleroderma is a disorder in which the dermis layer of the affected skin is replaced by collagen, resulting in an extreme hardening of the skin. In some patients this process involves the gastrointestinal tract, heart, lungs, and kidneys leading to impairment of functions of the respective organs. The cause of scleroderma is not known.

6586. scleromorph
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A plant whose leaves (or stems, if leafless) are hard in texture, usually having thick cuticle and containing many fibers. Compare xeromorph.

6587. sclerophyllous
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

With leaves stiffened by sclerenchyma.

6588. scoliosis
Author: Guo Li
Definition:

Scoliosis is a combined abnormality of the vertebrae and vertebral muscles and nerves such that the spine bends laterally.

6589. scorpioid
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Of a cymose inflorescence, branching alternately on one side and then the other. Compare helicoid.

6590. scour
Author:
Definition:

1. Local removal of material from streambeds by flowing water. (Compare fill.)
2. The erosion action of flowing water in streams that removes and carries away material from the bed and banks.

6591. scour pool
Author:
Definition:

A pool formed by scour when flowing water impinges against and is diverted by a stream bank or channel obstruction (e.g., rootwad, woody debris, boulder, bedrock, etc.)

6592. scoured areas
Author:
Definition:

Local zones within a stream where material is removed from the streambed by flowing water. (Compare depositional areas.)

6593. scout film
Author: Guo Li
Definition:

This is an initial x-ray of a part of the patient before more extensive methods of diagnostic imaging are used.

6594. screening tests
Author: Guo Li
Definition:

Screening tests are laboratory tests for disorders which are sensitive easy to administer and cost little. However, they may not be very specific (i.e. some other clinical conditions may produce similar results). Therefore screening tests may detect the presence of disease but more specific tests are required to confirm the diagnosis.

6595. scrotum
Author: Fertilitext
Definition:

The sac that hangs behind the penis and which contains the testicles, epididymis, and vas deferens.

6596. seborrheic keratoses (singular: seborrheic keratosis)
Author: Guo Li
Definition:

Seborrheic keratoses are beige, brown or black elevated benign plaques loosely attached to the lower layer of the skin; they are commonly found in the elderly, especially on the trunk.

6597. Secci disk
Author:
Definition:

A black-and-white disk lowered into the water to measure water transparency; an average is taken of the depth at which the disk disappears when lowered and reappears when raised.

6598. second law of thermodynamics
Definition:

1. All of the chemical and physical processes in a closed system tend to drive that system toward maximum entropy.
2. Clausius statement: No device can operate in a cycle and allow heat to transfer from a colder body to a hotter body unless other compensating activities are taking place.
3. Kelvin-Planck statement: no device can operate in a constant-temperature cycle and convert the heat it receives into work, unless other other compensating activities are taking place.

6599. second meiotic division
Definition:

The second of two consecutive divisions of the nucleus of an eukaryotic cell during the process of meiosis. It includes the following stages of meiosis: prophase II, metaphase II, anaphase II, and telophase II.

6600. second messenger
Definition:

An effector molecule which is synthesized in a cell in response to a signaling first messenger such as a hormone.

6601. second-foot
Author:
Definition:

Unit of discharge, equal to one cubic foot of liquid per second.

6602. second-order kinetics (second-order reaction)
Definition:

A term describing the reaction rate of a chemical reaction in which the rate is proportional to the product of the concentrations (in moles) of two of the reactants (also called "bimolecular kinetics"), or to the square of the molar concentration of the reactant if there is only one. Such a reaction might have an equation like "rate = k[A][B]" or "rate = k[A]²," where k is the reaction rate constant, [A] is the concentration of reactant A, and [B] is the concentration of reactant B.

6603. secondary antibody response
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

An antibody made upon second (subsequent) exposure to an antigen; mostly of the class IgG.

6604. secondary metabolism
Definition:

Pathways producing specialized metabolic products that aren't found in every cell.

6605. secondary metabolite
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A product excreted by a microorganism near the end of the growth phase or during stationary phase.

6606. secondary nystagmus
Author: Guo Li
Definition:

A form of nystagmus that may be caused by problems with the eye movement control center.

6607. secondary oocyte
Definition:

An oocyte which arises from the primary oocyte (which was diploid) after it completes the first meiotic division after the body has become sexually mature. The secondary oocyte eventually divides into the mature egg or ovum (which is haploid) and a polar body (which degenerates), thus ending the second meiotic division.

6608. secondary structure
Definition:

The folded, coiled or twisted shape a polypeptide or polynucleotide chain takes on when hydrogen bonds form between adjacent parts of the molecule.

6609. secrete
Definition:

To discharge a secretion; to release some sort of liquid substance (or substance in liquid). This can be done by the cell, by glands or other organs, or by tissues. Examples of things that are secreted are hormones, saliva, mucus, bile, and sweat.

6610. secrete
Author: PharmInfoNet
Definition:

To make and give off such as when the beta cells make insulin and then release it into the blood so that the other cells in the body can use it to turn glucose (sugar) into energy.

6611. secretion
Definition:

A substance, usually in liquid form, which is exported by a cell or released from a tissue, gland, or other organ. Examples are sweat, bile, mucus, saliva, and hormones.

6612. secretion vector
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A DNA vector in which the protein product is both expressed and secreted (excreted) from the cell.

6613. secund
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

With all the parts grouped on one side or turned to one side (applied especially to inflorescences).

6614. secundum artem (s.a.)
Definition:

This Latin term, which is frequently used in medicine and pharmacy, means "according to art".

6615. secundum legem
Definition:

This Latin term, which is frequently used in medicine and pharmacy, means "according to law".

6616. sedges
Definition:

These are plants that look a bit like grasses, but they belong to a different plant family, the Cyperaceae. Most grasses have stems that are round in cross section, while the stems of sedges are triangular in cross-section, thus you can remember the difference with the rhyme "sedges have edges."

6617. sediment
Author:
Definition:

1. Material carried and deposited by water.
2. Fragments of rock, soil and organic material transported and deposited in beds by wind, water or other natural phenomena. The term can refer to any size of particles but is often used to indicate only fragments smaller than 6 mm.

6618. sediment discharge
Author:
Definition:

The mass or volume of sediment (usually mass) passing a stream transect in a unit of time. The term may be qualified, for example, as suspended-sediment discharge, bedload discharge, or total-sediment discharge, usually expressed as tons per day.

6619. sediment load
Author:
Definition:

The portion of the total sediment load that moves in suspension, free from contact with the streambed, and is made up of particles having such density or grain size as to permit movement disassociated from the streambed. Density and grain size vary according to the amount of turbulence.

6620. sediment loading
Author:
Definition:

The total sediment in a stream system, whether in suspension (suspended load) or on the bottom (bed load).

6621. sediment wedge
Author:
Definition:

Thick, wedge-shaped deposit of mixed soil, rock and organic debris injected into a stream channel by debris avalanches and debris flows from adjacent hill slopes.

6622. sedimentation
Definition:

1. The process where particles suspended in solution settle out of the solution and to the bottom of the container. This can occur by gravity alone, or by centrifugation (high-speed spinning).
2. A sedimentological (geological) term for the settling of particles suspended in moving water into layers over time in the same location to form sedimentary deposits.

6623. sedimentation
Author:
Definition:

1. Gravitational deposit of transported material in flowing or standing water.
2. Deposition of material suspended in a stream system, whether in suspension (suspended load) or on the bottom (bed load).

6624. sedimentation dam
Author:
Definition:

A dam which is designed to collect sediment from the water flowing over or through it, thereby filling in a portion of a streambed or gully.

6625. seed
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A propagating organ formed in the sexual reproductive cycle of gymnosperms and angiosperms, consisting of a protective coat enclosing an embryo and food reserves.

6626. seedling
Author:
Definition:

1. A young tree that is generally less than 3 feet high.
2. Any recently-sprouted plant.

6627. seep
Author:
Definition:

An area of minor groundwater outflow onto the land surface or into a stream channel. These flows are too small to be springs.

6628. seepage
Author:
Definition:

Percolation of underground water through the banks and into a stream or other body of water.

6629. segment
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A part or sub-division of a divided organ; one of a group of similar organs named collectively, e.g. one petal = a segment of a corolla.

6630. segmentation, segments
Definition:

A development pattern of the embryo of the fruit fly Drosophila where the embryo looks like a stack of discs. Each disc is a segment, and each segment consists of two compartments (an anterior and posterior). Various parts of the adult fruit fly (wings, legs, eyes, etc.) arise from specific segments.

6631. segregation
Author: ForBio Ltd.
Definition:

Separation of parental chromosomes at meiosis and of alleles, leading to new gene combinations.

6632. seiche
Author:
Definition:

Resonant oscillation of a large body of water due to transient variation of atmospheric pressure.

6633. selectable marker
Author: Susan A.Hagedorn
Definition:

A gene whose expression allows one to identify cells that have been transforrned or transfected with a vector containing the marker gene.

6634. selection
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

Placing organisms under conditions where the growth of those with a particular genotype will be favored.

6635. selective medium
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A medium which allows the growth of certain types of microorganisms in preference to others. For example, an antibiotic-containing medium allows the growth of only those microorganisms which are resistant to this antibiotic.

6636. selenium (Se)
Definition:

A nonmetallic element that resembles sulfur. Metabolically, it is believed to work closely with vitamin E and is an important part of the enzyme glutathione peroxidase. Large amounts of selenium are toxic, however, and selenium poisoning (characterized by emaciation, hair loss, anemia, and bone and liver damage) is often seen in livestock that eat plants which grow in high-selenium soil.

6637. self-pollination
Author: Susan A.Hagedorn
Definition:

Pollen of one plant is transferred to the female part of the same plant or another plant with the same genetic makeup.

6638. selfing
Definition:

A situation in which an organism (usually a plant) fertilizes or is made to fertilize itself.

6639. selfish DNA
Author: Jayant Raval, Rutgers Univ.
Definition:

DNA that seemingly exists only for the sake of existing and is never expressed in the phenotype.

6640. semen
Author: Fertilitext
Definition:

The fluid containing sperm and secretions from the testicles, prostate, and seminal vesicles that is expelled during ejaculation.

6641. semen analysis
Author: Fertilitext
Definition:

Laboratory examination of semen to check the quality and quantity of sperm.

6642. semen analysis
Author: Guo Li
Definition:

This is a test for male infertility via examination of the semen.

Normal Semen Ranges:

pH: 7.12 to 8.00
sperm count: 50-200 million/mL
sperm motility 60-80% actively motile
sperm morphology 70-80% normally shaped

6643. semiconservative replication
Author: Susan A.Hagedorn
Definition:

During DNA duplication, each strand of a parent DNA molecule is a template for the synthesis of its new complementary strand. Thus, one half of a preexisting DNA molecule is conserved during each round of replication.

6644. seminal vesicles
Author: Fertilitext
Definition:

The paired glands at the base of the bladder that produce seminal fluid and fructose.

6645. seminiferous tubules
Author: Fertilitext
Definition:

In the testicles, the network of tubes where sperm cells are formed.

6646. seminoma
Definition:

A cancerous neoplasm, or abnormal growth, of the testicle which is thought to arise from primordial germ line cells while the individual is still an embryo and the testicle has not yet been sexually differentiated from the generic gonad.

6647. semis (ss.)
Definition:

This Latin term, which is frequently used in medicine and pharmacy, means "one-half".

6648. Sendai virus
Definition:

A paramyxovirus (A type of virus) used to cause cell fusion between somatic cells (any cell that is not a gamete) as a means of studying genetics.

6649. senescence
Definition:

The state of being in old age; the process of aging. The biological study of aging and its effects on the body.

6650. senile dementia
Author: Guo Li
Definition:

Senile dementia is the mental deterioration (loss of intellectual ability) that is associated with old age. Two major types of senile dementia are identified: those due to generalized atrophy (Alzheimer type) and those due to vascular problems (mainly strokes).

6651. senile kyphosis
Author: Guo Li
Definition:

This is the backward curving of the cervical, thoracic and lumbar vertebrae due to aged related degeneration of the intervertebral discs.

6652. sense strand (coding strand, template strand)
Definition:

The strand of DNA which is used during transcription to make mRNA. The mRNA made thus has the sequence of the antisense strand of DNA, and it codes for a sense strand of polypeptide (which eventually becomes a protein or part of a protein) during translation.

6653. sensitive species
Author:
Definition:

1. Species that can only survive within a narrow range of environmental conditions and whose disappearance from an area is an index of pollution or other environmental change.
2. Those species which rely on specific habitat conditions that are limited in abundance, restricted in distribution, or are particularly sensitive to development.
3. Plant or animal species which are:
   1. Federal listed or proposed threatened or endangered species, or candidate species;
   2. bird species protected under the Migratory Bird Treaty Act;
   3. species protected under State endangered species laws and regulations, plant protection laws and regulations, Fish and Game codes, or species of special concern listings and policies; or
   4. species recognized by national, state, or local environmental organizations (e.g., the California Native Plant Society).

6654. sensitization
Author: Biological Sciences at Heriot-Watt University
Definition:

This is the term applied to the exposure to a substance (allergen) which provokes a response in the immune system such that disease symptoms will ensue on subsequent encounters with the same substance.

6655. sepal
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A member of the (usually green) outer whorl of non-fertile parts surrounding the fertile organs of a flower.

6656. sepaloid
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Looking like sepals, e.g. of bracts, usually green and arranged in a ring beneath a flower.

6657. sepsis
Author: Guo Li
Definition:

Sepsis is the clinical condition in which infective agents (bacteria, pathogenic fungi) or products of infection (bacterial toxins) enter the blood circulation and profoundly affects the patient's blood pressure, heart rate, and body temperature.

6658. septate
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Divided internally by partitions.

6659. septicemia
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

Infection of the bloodstream by microorganisms.

6660. septicidal
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Of the dehiscence of a fruit, along lines coinciding with the partitions between loculi. Compare loculicidal.

6661. septifragal
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Of the dehiscence of a fruit, when the valves or backs of the carpels break away leaving the septa intact.

6662. septum (pl. septa)
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A partition.

6663. sequence
Definition:

1. The noun: the order in which subunits appear in a chain, such as amino acids in a polypeptide or nucleotide bases in a DNA or RNA molecule.
2. The verb: To find out in what order the subunits appear in the chain.

6664. sequence hypothesis
Author: Susan A.Hagedorn
Definition:

Francis Crick's seminal concept that genetic information exists as a linear DNA code; DNA and protein sequence are colinear.

6665. sequence tagged site (STS)
Definition:

Short (200 to 500 base pairs) DNA sequence that has a single occurrence in the human genome and whose location and base sequence are known. Detectable by PCR, STSs are useful for localizing and orienting the mapping and sequence data reported from many different laboratories and serve as landmarks on the developing physical map of the human genome. Expressed sequence tags (ESTs) are STSs derived from cDNAs.

6666. sequencing (protein sequencing, DNA sequencing, RNA sequencing)
Definition:

Determination of the order of nucleotides (base sequences) in a DNA or RNA molecule or the order of amino acids in a protein.

6667. sequential hermaphrodite
Definition:

A type of hermaphrodite which starts out life as one sex and will either turn into a member of the other sex at a later point in life or will be capable of doing so if an appropriate condition arises (for example, the removal of all of the males in a population triggers the most dominant female to become a male).

6668. seriate
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

In rows or whorls.

6669. sericin
Definition:

A silk protein that binds the two strands of the raw fiber.

6670. serine
Image: View the chemical structure
Author: Courtesy of MacMolecule
Definition:

One of the twenty naturally occurring amino acids. Has the following chemical characteristics:


pKa1   pKa2     pI      Water Solubility (30deg C)
2.21   9.15    5.68            32

6671. serine proteases (serine proteinases)
Definition:

A group of enzymes that break down proteins and have a serine and a histidine involved at the active site of the catalysis. This group includes enzymes active in digestion, blood clotting, immune reactios, and fertilization of the ovum.

6672. serology
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

The study of antigen-antibody reactions in vitro.

6673. serotonergic system
Author: The Alzheimer's Association
Definition:

The system of nerve cells that uses serotonin as their neurotransmitter.

6674. serotonin
Definition:

A hormone, also called 5-hydroxytryptamine, which has the chemical formula C₁₀H₁₂N_2O. It is produced in the pineal gland and found in blood platelets, the digestive tract, and the brain. It is both a neurotransmitter (a substance that transmits nerve signals from neuron to neuron) and a vasoconstrictor (a substance that causes the blood vessels to narrow).

6675. serrate
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Toothed, with asymmetrical teeth pointing forward.

6676. Sertoli cells
Author: Fertilitext
Definition:

The cells in the testicles that provide nourshment to the early sperm cells.

6677. serum
Definition:

The liquid portion of blood left over after all of the cells have been removed.

6678. serum antiHAV
Author: Guo Li
Definition:

This is an IgG which peaks after 1 month of hepatitis A infection and may persist for years. Its presence indicates previous infection, noninfectivity, and immunity to recurring HAV infection.

6679. serum AntiHBc
Author: Guo Li
Definition:

This is the antibody against the core protein of the hepatitis B virus. it is the most reliable indictor that infection with hepatitis B has taken place in the past.

6680. serum antiHBe
Author: Guo Li
Definition:

This is the antibody against a viral product during the incubation period and therefore its presence indicates infection has occurred. But this antibody is detected only when infection is decreasing.

6681. serum antiHBs
Author: Guo Li
Definition:

This is an antibody against the surface antigen of the hepatitis B virus. Its presences alone only indicates infectivity. Its presences together with the disappearance of HBsAg signifies recovery from an infection and immune protection from recurrent hepatitis infection.

6682. serum antiHCV
Author: Guo Li
Definition:

This is a test for the presence of antibodies to the Hepatitis C which is responsible for over 90% of hepatitis from blood transfusion. However, most cases of Hepatitis C (96%) is transmitted from intravenous drug use. Recombinant immunoblot assay (RIBA) detects antibodies to four HCV antigens.

6683. serum antiHEV
Author: Guo Li
Definition:

This is an antibody against hepatitis E, formerly known as non-A non-B hepatitis.

6684. sessile
Author: 1st def. mirrored from Jim Croft's Flora of Australia
Definition:

1. In botany terminology, refers to a plant part without a stalk (when applied to a stigma, indicates that the style is absent, the stigma being 'sessile' on the ovary).
2. Describes an animal which is unable to move, or does not move very much. Examples include coral, sponges, barnacles, and sea squirts.

6685. seston
Author:
Definition:

Particulate matter suspended in water.

6686. settling basin
Author:
Definition:

Retention basin whose primary purpose it is to provide extremely low flow velocities to allow water-borne silt to settle out.

6687. sex chromosomes
Definition:

The chromosomes which determine the gender of the organism (for organisms whose gender is determined by genes rather than by environment). In humans, fruit flies, and other animals where the male is the heterogametic sex, they are the X chromosomes and Y chromosomes. In birds, moths, and other animals where the female is the heterogametic sex, they are the W chromosomes and Z chromosomes. For humans, the sex chromosomes are the 23rd pair of all chromosomes. The sex chromosomes of most plants (when they exist) are also known as X and Y chromosomes; Ginkgo trees have a different system of sex chromosomes. Compare autosome.

6688. sexual reproduction
Author: Susan A.Hagedorn
Definition:

The process where two cells (gametes) fuse to form one hybrid, fertilized cell; results in a new genome that is different than that of either parent.

6689. sexually transmitted disease (STD)
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A disease, such as genital herpes, gonorrhea, or chlamydia, whose usual means of transmission is by sexual contact.

6690. sexually transmitted disease (STD, sexually transmitted infection, venereal disease)
Definition:

A disease that is transmitted during sexual intercourse (anal, oral, or vaginal). Such diseases include:
• AIDS (HIV)
• chlamydia
• genital herpes
• genital warts (HPV)
• gonorrhea
• hepatitis B
• crab lice
• syphilis
• trichomoniasis

6691. sheath
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

1. A secreted, tubular structure formed around a chain of cells or around a bundle of filaments; cells within a sheath may or may not subsequently separate from the sheath.
2. A layer of outer membrane covering the bacterial flagella.

6692. sheath
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

1. A protective covering.
2. The lower part of leaf enveloping stem or culm.

6693. Sheehan's syndrome
Author: Guo Li
Definition:

Sheehan's syndrome is hypopituitary function because of poor perfusion secondary to hypotension from severe blood loss in the peripartum period.

6694. sheet erosion
Author:
Definition:

1. Initial surface erosion by water running off as sheets, as distinct from channelized erosion in rills and gullies.
2. The uniform washing or eroding of surface soils on a large denuded surface area or a steep embankment or slope.

6695. shifting cultivation (shifting agriculture, extensive cultivation)
Definition:

A farming method where land is extensively used to cultivate crops for a few years, then allowed to lie fallow for several years, then used again.

6696. Shine-Dalgarno sequence
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A short stretch of nucleotides on a prokaryotic mRNA molecule upstream of the translational start site, that serves to bind to ribosomal RNA and thereby bring the ribosome to the initiation codon on the mRNA.

6697. shingle
Author:
Definition:

Beach or streambed cover of flat pebbles or small cobbles in a thin and fairly uniform layer.

6698. shoal
Author:
Definition:

A shallow region in flowing or standing water, especially if made shallow by deposition.

6699. shock
Author: Guo Li
Definition:

Shock is the medical condition in which the circulation of blood is so low that it cannot supply the metabolic needs of the tissue. It can be caused by:
• low blood volumes, e.g. due to dehydration or bleeding (hemorrhagic shock)
• heart cannot pump effectively (cardiogenic shock), e.g. after a heart attack
• obstruction to blood flow, e.g. occlusion of the blood vessels by amniotic fluid (amniotic fluid embolism)

6700. shoot
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

A young branch which sprouts from the main stock.

6701. short term exposure limit (STEL)
Author: Biological Sciences at Heriot-Watt University
Definition:

According to American Conference of Governmental Hygienists, this is the time weighted average (TWA) airborne concentration to which workers may be exposed for periods up to 15 minutes, with no more than 4 such excursions per day and at least 60 minutes between them. See time weighted average.

6702. short-day plant
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

A plant requiring less than 12 hours of daylight in order for flowering to occur.

6703. shotgun culvert
Author:
Definition:

A culvert which discharges directly onto an unprotected slope. Typically these will have a large eroded gully below the culvert discharge, and often there will have been substantial erosion of culverts supporting material, leaving the downstream end projecting well out from the bank.

6704. shotgun method
Definition:

Cloning of DNA fragments randomly generated from a genome. See genomic library.

6705. shoulder
Author: Guo Li
Definition:

The shoulder is the juncture connecting the arm and the trunk, part of the upper limb.

6706. shoulder dystocia
Author: Guo Li
Definition:

Shoulder dystocia is the arrest of spontaneous delivery of the fetus because of impaction of the anterior shoulder behind the pubic symphysis, because of a disproportion between fetal and maternal size (in other words, the baby is too big to fit through the birth canal and his/her shoulder gets wedged behind the mother's pubic bone).

6707. shoulder-hand syndrome
Author: Guo Li
Definition:

Shoulder-hand syndrome is characterized by burning pain and swelling of the fingers and hand with skin atrophy and increased sweat secretion in association with a painful, stiff shoulder. The range of motion of the shoulder on the affected arm is decreased. The pathogenesis of this condition is still uncertain.

6708. shrub
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A woody plant less than 5 meters (approx. 15 feet) high, either without a distinct main main stem, or with branches persisting on the main main stem almost to its base.

6709. shrub vegetation (bush, scrub)
Author:
Definition:

A community of shrubs.

6710. shuttle vector
Definition:

A recombinant DNA vector that can be replicated into several different host species.

6711. si opus sit
Definition:

This Latin term, which is frequently used in medicine and pharmacy, means "if it is needed".

6712. sick sinus syndrome
Author: Guo Li
Definition:

Sick sinus syndrome is characterized by heart sinus arrest, sinus exit block, or persistent sinus bradycardia. Tachy-brady syndrome is part of the sick sinus syndrome.

6713. sickle-cell anemia
Definition:

A disease found almost exclusively in people of African ethnic descent which is characterized by the presence of defective hemoglobin molecules that cause red blood cells to be malformed, often taking on a sickle shape. The protein defect is caused by a homozygous allele that codes for the Beta chain of hemoglobin (the genetic defect causes a valine to be inserted at position 6 instead of a glutamine; in low oxygen conditions, the malformed hemoglobins link into polymers that damage the cell's membrane and cause it to take on the sickle shape). The malformed cells can't carry oxygen properly, and can tend to clog capillaries and small veins. Symptoms include joint pain, acute abdominal pain, and ulcerations of the lower extremities.

6714. sickle-cell trait
Definition:

This condition occurs in people who have one of two possible genes (i.e., they are heterozygous for the allele) that code for the defective hemoglobin responsible for sickle-cell anemia. The codition is diagnosed by exposing an individual's red blood cells to a low oxygen environment; if the trait is present, the cells will turn to a sickle shape. People with this trait may suffer milder symptoms of sickle-cell anemia, or may have no symptoms. Some scientists believe the trait actually provides an evolutionary advantage in tropical environments because the slightly altered shape of the blood cells causes a person to be more resistant to malaria.

6715. side effect
Author: The Alzheimer's Association
Definition:

An undesired effect of drug treatment that may range in severity from barely noticeable, to uncorfortable, to dangerous. Side effects are usually predictable.

6716. side-cast
Author:
Definition:

Noun: Road construction material that is not used for fill and is pushed to or placed on the down-slope side of the road. Such material may travel long distances down slope before coming to rest.

Verb: To move such material.

6717. signa (Sig.)
Definition:

This Latin term, which is frequently used in medicine and pharmacy, means "label" or "let it be imprinted".

6718. signal peptide
Definition:

A sequence of amino acids that determine whether a protein will be formed on the rough endoplasmic reticulum or on free ribosomes. Note: all protein synthesis begins on free ribosomes.

6719. signal transduction
Author: Susan A.Hagedorn
Definition:

The biochemical events that conduct the signal of a hormone or growth factor from the cell exterior, through the cell membrane, and into the cytoplasm. This involves a number of molecules, including receptors, proteins, and messengers.

6720. signature sequence
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

Short oligonucleotides of unique sequence found in 16S ribosomal RNA of a particular group of prokaryotes.

6721. silent mutation
Definition:

A mutation that causes no moticeable change in the biological activity of the proteins the gene codes for.

6722. silicone
Definition:

Any of many polymers made up of alternating oxygen and silicon atoms combined with other organic groups. Silicone can be an oil, grease, gel or plastic, but all forms are resistant to heat, water and will not conduct electricity. It is used for a huge number of uses in industry (lubricants, paints, adhesives, coolants, etc.) Silicone is used in medicine to replace body parts, and its use in breast implants has come under fire because there is evidence that these appliances may leak, and further evidence that leaked silicone may cause autoimmune disorders.

6723. silicosis
Definition:

This is a lung disease that causes inflammation and fibrosis of the lung; it is caused by inhaling silica dust.

6724. silicula
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A short siliqua, not more than twice as long as its width.

6725. siliqua
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A dry, dehiscent fruit formed from a superior ovary of two carpels, with two parietal placentas and divided into two loculi by a false septum between the placentas.

6726. silique
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

The long, narrow pod of plants of the mustard family, Cruciferae, with valves which fall away from a frame bearing the seeds.

6727. silt
Definition:

Particles in siliciclastic sediment that range in size from 0.0039 millimeters (very fine silt) to 0.0625 millimeters (coarse silt), according to the Udden-Wentworth scale. In field geology, a mudrock has silt in it if it feels smooth to the fingers but tastes gritty between the teeth. Silt and clay are collectively classified as mud.

6728. silt
Author:
Definition:

1. Earthy sediment of fine particles of rock and soil suspended in and carried by water.
2. Substrate particles 0.004-0.062 mm in diameter.

6729. siltation
Author:
Definition:

1. The accumulating deposition of eroded material.
2. The gradual filling in of streams and other bodies of water with sand, silt, and clay.

6730. silviculture
Author:
Definition:

The tending, harvesting and replacement of forests, resulting in forests of distinctive form.

6731. simple
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Undivided; of a leaf, not divided into leaflets; of a hair or an inflorescence, not branched.

6732. simple fracture
Author: Guo Li
Definition:

A clean bone break with little damage to the surrounding tissues.

6733. simulated annealing
Definition:

In the biosciences, this refers to using computers to model how complementary strands of DNA or RNA will link via hydrogen bonds to form a double-stranded molecule, or how a protein sequence will fold up and make hydrogen bonds with itself to form a more convoluted molecule.

For more information, visit Molecular Origami.

6734. simultaneous hermaphrodite
Definition:

A type of hermaphrodite which has both male and female organs at the same time and is able to produce both sperm and eggs at the same time. Such an organism is also able to fertilize its eggs with its own sperm (self-fertilization).

6735. sine
Definition:

This Latin term, which is frequently used in medicine and pharmacy, means "without".

6736. single gene disorder
Definition:

Hereditary disorder caused by a mutant allele of a single gene (e.g., Duchenne muscular dystrophy, retinoblastoma, sickle cell disease). Compare polygenic disorders.

6737. single stranded binding protein (SSB)
Definition:

SSB's are proteins responsible for holding the replication fork of DNA open while polymerases read the templates.

6738. single-cell protein
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

Protein derived from microbial cells for use as food or a food supplement.

6739. sinuate
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

With deep, wave-like depressions along the margin. Compare undulate.

6740. sinuosity
Author:
Definition:

1. The ratio of channel length between two points on a channel to the straight line distance between the same two points.
2. The ratio of channel length to down valley length.

6741. sinus
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A notch, depression or cavity on the surface of an organ.

6742. sister chromatid exchange
Author: Biological Sciences at Heriot-Watt University
Definition:

This is the process producing reciprocal exchange of DNA between the two DNA molecules of a replicating chromosome.

6743. site
Author:
Definition:

The spatial confines of a particular project.

6744. site-directed mutagenesis
Definition:

Any of several methods used to create specific alterations in a gene.

6745. site-specific recombination
Definition:

A type of genetic recombination that takes place only in specific sequences.

6746. Sjõgren's syndrome
Author: Guo Li
Definition:

Sjõgren's syndrome is characterized by dryness of mucous membranes, often the mouth and the conjunctiva and is frequently associated with rheumatoid arthritis and Raynaud's phenomenon.

6747. skeleton (skeletal system)
Definition:

A solid or fluid system which allows muscles to relax after contracting (in general, because there is an opposing muscle which pulls the skeletal part in the opposite direction when it contracts). The skeletal system may also be a support structure or a form of protection. Types of skeletons include hydroskeletons and exoskeletons.

6748. skin
Author: Guo Li
Definition:

The external covering of the body; the outermost layer is called epidermis, the next layer is called the dermis, and the lowest layer is the subcutaneous tissue.

6749. slack water
Author:
Definition:

A quiet part of, or a still body of water in, a stream (e.g., on the inside of a bend, where the current is slight).

6750. sleep apnea syndrome
Author: Guo Li
Definition:

Sleep apnea syndrome is characterized by sleep-disordered breathing with daytime sleepiness. It affects about 4 percent of men and 2 percent of women in their middle age. The prevalence of this condition increacese with age and become a major cause of reported sleep disturbance and of people feeling excessively tired/sleepy during the day.

6751. slime layer
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A diffused layer of polysaccharide exterior to the bacterial cell wall. Compare with capsule and glycocalyx.

6752. slime mold
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

A nonphototrophic eukaryotic microorganism lacking cell walls, which aggregate to form fruiting structures (cellular slime molds) or simply masses of protoplasm (acellular slime molds).

6753. slipout
Author:
Definition:

Gravitational movement of unstable mass of highway embankment or streambank.

6754. slope
Author:
Definition:

1. Land gradient described as the vertical rise divided by the horizontal run and expressed in percent.
2. For engineering purposes, slope is expressed as horizontal distance over vertical distance (e.g., a slope of "3 to 1" (3/1) is one with 1 vertical unit for every 3 horizontal units). A slope of "6 to 1" (6/1) is much flatter than a slope of "2 to 1" (2/1).

6755. slough
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

A wet place of deep mud or mire; a sluggish channel; a swamp, bog, or marsh, especially one that is part of an inlet or backwater.

6756. slough (sluf)
Author:
Definition:

Slide or slipout of a thin mantle of earth, especially in a series of small movements.

6757. slow virus (prion)
Author: Guo Li
Definition:

The so-called "slow viruses" are a group of infective agents of which very little information is known. In fact, one is not sure if these agent has compositions resembling that of the viruses: all one knows is that they are communicable, with slow replication and long latent intervals in the host. Another name given to these agents is "prions" : proteinaceous and infectious. An example is scrapie, which is a disease of sheep; its incubation period is longer than 4 months, and the prion can withstand boiling, x-ray irradiation, and treatment with formalin. In 1996, bovine spongiform encephalopathy (BSE) was linked to the ingestion of beef infected with prions (the mad-cow disease). It was speculated that the prions induced changes in the conformation of certain proteins of brain cells.

6758. slump
Author:
Definition:

A landslide in which a whole mass of earth subsides as a unit, sometimes rolling slightly as well as moving downwards.

6759. small nuclear RNA (snRNA)
Author: Susan A.Hagedorn
Definition:

Short RNA transcripts of 100-300 base pairs that associate with proteins to form small nuclear ribonucleoprotein particles (snRNPs), which participate in RNA processing.

6760. smolt
Author:
Definition:

Juvenile salmonid one or more years old that has undergone physiological changes to cope with a marine environment; the seaward migration stage of an anadromous salmonid.

6761. smoltification
Author:
Definition:

Suite of physiological, morphological, biochemical and behavioral changes, including development of the silvery color of adults and a tolerance for seawater, that take place in salmonid parr as they prepare to migrate downstream and enter the sea.

6762. smooth endoplasmic reticulum
Definition:

A type of endoplasmic reticulum, an organelle found in eukaryotic cells, which plays an important role in the making of steroid hormones.

6763. snag
Author:
Definition:

A standing dead tree. Sometimes a submerged fallen tree in large streams. The top of the tree is exposed or only slightly submerged.

6764. sodium (Na)
Definition:

Sodium is a soft, silvery, highly reactive alkali metal which has an atomic number of 11 and an atomic weight of 22.990. It is most commonly found in the form of salt, sodium chloride (NaCl). It was first identified as an element by the English scientist Sir Humphrey Davy in 1807.

Sodium chloride is a critical nutrient in humans (it plays an important role in nerve function), but too much of it can cause health problems such as aggravating high blood pressure. Pure metallic sodium is a fire hazard, and it can explode if it comes into contact with water.

Other commonly used sodium compounds include soda ash (sodium carbonate, Na₂CO₃), baking soda (sodium bicarbonate, NaHCO₃) and caustic soda (sodium hydroxide, NaOH).

6765. sodium chloride
Definition:

Table salt; NaCL.

6766. sodium erythorbate
Definition:

This compound is used in the food industry to keep processed meat, such as hot dogs and beef sticks, from turning strange colors. It is chemically similar to vitamin C, which was used for the same purpose before this compound, but only gives the body 1/20th of the vitamin C one would get from taking regular vitamin C. It is made from sugar, commonly beet and cane sugar.

6767. soft palate
Author: Guo Li
Definition:

The soft palate is the posterior one-third of the palate; it is fibromuscular.

6768. soil
Author:
Definition:

Unconsolidated material on the earth's surface that supports or is capable of supporting plants out-of-doors.

6769. soil horizon (A horizon, B horizon, C horizon)
Author:
Definition:

A distinct layer of soil, more or less parallel with the soil surface, having similar properties such as color, texture and permeability; the soil profile is subdivided into the following major horizons:
1. A-horizon, characterized by an accumulation of organic material;
2. B-horizon, characterized by relative accumulation of clay iron, organic matter or aluminum;
3. C-horizon, the undisturbed and unaltered parent material.
(Some soils have an E-horizon, characterized by leaching of organic and other material.)

6770. soil hue
Author:
Definition:

A characteristic of color related to one of the main spectral colors (red, yellow, green, blue or purple), or various combinations of these principle colors; one of the three variables of color; each color chart in the Munsell Soil Color Charts (Kollmorgen Corporation 1975) represents a specific hue.

6771. soil matrix
Author:
Definition:

The portion of a given soil having the dominant color; in most cases, the matrix will be the portion of the soil having more than 50 percent of the same color.

6772. soil permeability
Author:
Definition:

The ease with which gases, liquids or plant roots penetrate or pass through a layer of soil.

6773. soil phase
Author:
Definition:

A subdivision of a series based on features such as slope, surface texture, stoniness and thickness.

6774. soil phase
Author:
Definition:

A subdivision of a soil series having features (e.g., slope, surface texture and stoniness) that affect the use and management of the soil, but which do not vary sufficiently to differentiate it as a separate series.

6775. soil pore
Author:
Definition:

An area within soil occupied by either air or water, resulting from the arrangement of individual soil particles.

6776. soil profile
Author:
Definition:

A vertical section of the soil through all its horizons and extending into the parent material.

6777. soil series
Author:
Definition:

A group of soils having horizons similar in differentiating characteristics and arrangements in the soil profile, except for texture of the surface layer.

6778. soil structure
Author:
Definition:

The combination or arrangement of primary soil particles into secondary particles, units or peds.

6779. soil suborder
Author:
Definition:

Second highest taxonomic level of the current U.S. soil classification system.

6780. soil surface
Author:
Definition:

The upper limits of the soil profile; for mineral soils, the upper limits of the highest mineral horizon (A-horizon); for organic soils, the upper limit of undecomposed organic matter.

6781. soil texture
Author:
Definition:

The relative proportions of the various sizes of particles (silt, sand and clay) in a soil.

6782. soil value (soil color)
Author:
Definition:

The relative lightness or intensity of color; approximately a function of the square root of the total amount of light; one of the three variables of color.

6783. solitary
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Of flowers, borne singly, not grouped in an inflorescence.

6784. solute
Definition:

A substance that is dissolved in a solvent. One of the two parts (along with solvent) which make up a solution.

6785. solutio (sol.)
Definition:

This Latin term, which is frequently used in medicine and pharmacy, means "solution".

6786. solution
Definition:

A liquid or gas which consists of two parts: a solvent and a solute. The solute is any substance which is dissolved in the solvent.

6787. solvate
Definition:

The compound formed by the interaction of a solvent and a solute.

6788. solve (solv.)
Definition:

This Latin term, which is frequently used in medicine and pharmacy, means "dissolve".

6789. solvent
Definition:

A liquid or gas that will dissolve another substance; the continuous phase of a solution (which is made up of the solvent and the solute together). Water is the most common liquid solvent.

6790. somatic cell
Definition:

Any cell in the body except gametes and their precursors.

6791. somatic cell gene therapy
Author: Susan A.Hagedorn
Definition:

The repair or replacement of a defective gene within somatic tissue.

6792. somatomedin
Definition:

Any of a group of polypeptide growth factors produced in the liver in response to growth hormones. Somatomedins promote growth by being nutritious to a wide variety of cells in the body, including liver cells (hepatocytes), lymphocytes, fat cells (adipocytes), and cartilage cells (chondrocytes).

6793. somewhat poorly drained soil
Author:
Definition:

A condition in which water is removed slowly enough that the soil is wet for significant periods during the growing season.

6794. sorus (pl. sori)
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

In ferns, a discrete group of sporangia.

6795. Southern blot (Southern hybridization, Southern blotting)
Definition:

A technique used for searching for a specific DNA fragment. The process is as follows:
1. Separate DNA fragments by gel electrophoresis
2. change pH of gel to basic, thus allowing disruption of H-bonds
3. blot gel with nitrocellulose paper
4. heat paper so as to fix DNA fragments
5. probe with labeled messenger RNA or cDNA
6. wash
7. complementary mRNA/cDNA fragments will have hybridized.

6796. spacer DNA
Author: Jayant Raval, Rutgers Univ.
Definition:

In sequencing, DNA that is left after all the recognizable units have been identified.

6797. spadix
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A spikelike inflorescence with a stout, often succulent main stem.

6798. spathaceous
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Like a spathe; with a spathe.

6799. spathaceous
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

Having a spathe, or having the nature of a spathe.

6800. spathe
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A large bract ensheathing an inflorescence.

6801. spathella
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

A closed membranous sac which envelopes the immature flower in some members of the family Podostemaceae, rupturing irregularly as the pedicel elongates at anthesis.

6802. spathulate (spatulate)
Author: Mirrored from Jim Croft's Flora of Australia
Definition:

Spoon-shaped; broad at the tip and narrowed towards the base.

6803. spawner-recruit model
Author:
Definition:

Biological model that relates the number of recruits or mature spawners in one generation to the number of spawners in the previous generation.

6804. special aquatic sites
Author:
Definition:

Those sites identified in 40 CRF 230, Subpart E (i.e., sanctuaries and refuges, wetlands, mud flats, vegetated shallows, coral reefs, and riffle and pool complexes). They are geographic areas, large or small, possessing special ecological characteristics of productivity, habitat, wildlife protection, or other important and easily disrupted ecological values. These areas are generally recognized as significantly influencing or positively contributing to the general overall environmental health or vitality of the entire ecosystem of a region.

Source: Environmental Protection Agency, 40 CFR § 230.3(q-1).

6805. speciation
Definition:

The formation of two or more new species from a single old species.

6806. species
Definition:

Groups of populations (which are groups of individuals living together that are separated from other such groups) which can potentially interbreed or are actually interbreeding, that can successfully produce viable, fertile offspring (without the help of human technology). [Ernst Mayr, 1969] The species is the most fundamental unit of evolution and is the most specific taxonomic level.

6807. species area curve
Author:
Definition:

The curve on a graph produced when plotting the cumulative number of plant species found in a series of quadrats against the cumulative number or area of those quadrats; it is used to determine the number of quadrats sufficient to adequately survey the herbaceous understory.

6808. species selection
Definition:

A type of natural selection which acts upon species within higher taxonomic groups. Species selection occurs when speciation and extinction rates are affected by whether the species has a particular characteristic, such that the number of species within a higher taxon which have the characteristic might change depending on how beneficial or harmful it is to a species.

6809. species-specific
Author:
Definition:

Applying only to a particular species; said of effects that vary depending on the species in question.

6810. specific activity
Definition:

A measure of enzyme purity; it refers to the number of micromoles of a substrate an enzyme can transform per minute per milligram of protein at 25 degrees C.

6811. specific epithet
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

The label (or designation) of a particular species in the binomial nomenclature system. For example, "coli" is the specific epithet of Escherichia coli.

6812. specific heat
Definition:

The amount of energy (measured in calories or joules) needed to raise the temperature of one gram of a pure substance by one degree C.

6813. specificity
Author: Mirrored from Tsute Chen's Glossary of Microbiology
Definition:

The ability of the immune response to interact with individual antigens.

6814. spectinomycin
Image: View the chemical structure
Definition:

An antibiotic originally obtained from the funguslike bacterium Streptomyces spectabilis; it is now mainly produced synthetically. It is especially useful for treating penicillin-resistant strains of gonorrhea.

6815. spectrophotometer
Definition:

A machine used to measure how much light of a given wavelength is absorbed by a liquid sample, or to measure how intense (bright) the spectral lines and bands produced by the sample are, relative to each other.

6816. spectroscopy (spectroscope)
Definition:

Spectroscopy is the science of measuring the emission and absorption of different wavelengths (spectra) of visible and non-visible light; this can be done via a spectroscope, which consists of a slit, prism, collimator lens, object lens, and a grating.

6817. sperm (spermatozoan)
Definition:

A reproductive cell produced by the male of an animal species which, when united with an egg (of the same species), results in conception and the development of an embryo.

6818. sperm bank
Author: Fertilitext
Definition:

A facility where sperm are kept frozen in liquid nitrogen for later use in artificial insemination.

6819. sperm count
Author: Fertilitext
Definition:

The number of sperm in the ejaculate (when given as the number of sperm per millileter it is more accurately known as the sperm concentration or sperm density).

6820. spermatid
Definition:

An immature sperm cell. It has a haploid number of chromosomes, but does not yet have a distinct head or tail.

6821. Spermatophyta
Author: Mirrored from Dave Sutton's Aquatic Plant Glossary
Definition:

A major division of the plant kingdom, characterized by reprodution by seed and subdivided into the Gymnospermae (gymnosperms) and Angiospermae (angiosperms).

6822. spermicide
Definition: