Lecture 1                                                                                                                      January 28

 

Science:  Knowledge about the natural world attained through study.

Biology:  Science of life.

 

Scientific Method:  1.  observation (form question).

                   2.  hypothesis - a tentative explanation.

       3.  experiment - testing.

       4.  decision - evaluation of results.

A few general comments:

*Hypothesis has to be testable and at least potentially falsifiable.

*Hypothesis can be supported or falsified (refuted), but it can never be proven (in theory).

*Hypotheses become theories: theories become laws (principles).

*Hypotheses, experiments and conclusions become part of the public record.

 

Simple Example:

1.  OBSERVATION:  lemming population undergo "cycles" in abundance every 3.5 - 4 years.

2.  HYPOTHESIS:  peek populations destroy food resources & this leads to starvation & a                     decline in numbers.

3.  EXPERIMENT:  supply extra food.  experiment w/control and experimental groups.

4.  DECISION:  do the data from the experiment support or refute our hypothesis?

 

Five Characteristics if Living Things:

1.  Living things are organized.

non-living things tend to be homogeneous (simple).  living things are heterogeneous (complex).

     biological systems are organized in hierarchal fashion.

Levels of Biological Organization:

A.  the cell is the basic unit of life.

B.  different cells form tissues.

C.  tissues form organs.

D.  organs form organ systems.

E.  organ systems are organized into organisms.

F.  organisms of the same kind form a population.

G.  populations at a specific place form a community.

H.  a community and it's physical environment form an ecosystem.

I.   all ecosystems on earth together make up the biosphere.

 

2.  Living things respond.

living things must  maintain a constant internal state (homeostasis).

     signals if environmental change are called stimuli.

 

3.  Living things metabolize.

metabolism - chemical conversion of nutrient molecules (food) into useable energy and building              materials.

 

4.  Living things reproduce.

offspring have same general characteristics as their parents.

     reproduction insures that the genetic message carried in molecules of DNA is passed from one generation to the next.

 

5.  Living things are adapted.

living things possess traits called adaptations that help them to survive.

     Adaptations are the result of evolutionary processes.

 

 

Lecture 2                                                                                                                      January 30

 

Chemical Foundations for Cells

The atom is the basic chemical unit.

1.  nucleus:  protons (+) and neurons (0).

2.  electrons (-) rotate around the nucleus.

Ions: atoms that have lost or gained electrons.(Na often loses 1 electron to form Na+ sodium ion)

 

92 naturally occurring atoms (elements).

 

95% of living material is made up of:

     1.  20% carbon (C)

     2.  62% oxygen (O)

     3.  10% hydrogen (H)

     4.  3% nitrogen (N)

Remaining 5% made up of 30 different elements.

 

- Atoms combine to form molecules. (O atoms combine to form O2.)

- Different atoms combine to form compounds. (H2O, NH3, CO2)

- Atoms with filled outer shells are inert. (He helium doesn't react with anything.)

- Other atoms are held together by chemical bonds.

 

Ionic bonding:  losing or gaining electrons. (weaker bond)

Covalent bonding:  sharing of electrons. (very strong, hard to break.)

Polar covalent bond:  unequal sharing of electrons.

Nonpolar covalent bond:  equal sharing of electrons.

Hydrogen bonding:  bonding between polar molecules.

 

Acids and Bases

 

Acids:  compounds that release H+ ions (hydrogen).  ie: HCl stomach acid, H2SO4 in car

            how much H+ released determines how strong or mild

Bases:  compounds that release OH- ions (hydroxide).  ie: NaOH, KOH

pH scale:  measures strengths of acids and bases (like an index).

see chart 2.12 p. 26

1.  Ranges from (strong acid) 0 to 14 (bases).

2.  Measures concentrations of H+ and OH- ions.

3.  Pure water is neutral and has pH = 7.0.

4.  Acids have pHs less than 7; bases have pHs greater than 7.

Organisms must regulate their pH. (like back to homeostasis) ie: pH of blood is 7.4.

 

Buffers:  compounds that pickup or release H+ or OH- ions and thus regulate pH.

 

Four major groups of biologically important molecules:

1.  Carbohydrates

2.  Lipids (fats)

3.  Proteins

4.  Nucleic acids

 

I.  Carbohydrates:  C, H and O

Monosaccharides: (simple sugars) consist of 3 - 6 carbon atoms, 6 - 12 hydrogen atoms, and 3 - 6                          oxygen atoms (1C:2H:1O).  ie: glucose

Disaccharides: (double sugars) 2 monosaccharides linked together by a chemical bond.  ie:                   glucose + glucose = maltose (malted sugar for brewing beer).

Polysaccharides: (many sugars) macromolecules consisting of many monosaccharides linked                        together.

 

Macromolecules made up of small subunits are called polymers.  Small subunits are called monomers.

monomer             polymer

      monosaccharides            polysaccharides

          amino acids                      proteins

          nucleotides                nucleic acid

 

Polysaccharides are the storage forms of monosaccharides.  (plants: starch; humans: glycogen)

 

II.  Lipids.

Fats:  glycerol and 3 fatty acids.

 

Two other important kinds of lipids:

1.  phospholipids: cell membranes (allow things to enter/exit).

2.  steroids:  metabolism and regulation (hormones). Important for growth and reproduction.

 

III.  Proteins:  most diverse group of biological molecules.

Functions of proteins:

1.  enzymes

2.  structural/support materials  ie: hair, claws, nails, feathers, etc.

3.  transport  ie:  hemoglobin in red cells transports oxygen.

4.  energy  (body prefers to use carbohydrates first and then fats, but use proteins in starvation.)

 

Proteins are macromolecules: polymers of smaller monomers called amino acids.

Amino acids contain C, H, O and Nitrogen.

 

COOH

 |

       NH2____   C  ____ H

 |

R

1.  amino group:  -NH2

2.  carboxyl group: -COOH

3. residue: - R (varies)

 

20 different amino acids in living material.  Different ones have different R groups.

ie:  R = -CH3 for alanine;  R = -CH2-SH for cystine.

 

peptide bond:  two amino acids linked together by a condensation reaction to form a peptide.

 

Many amino acids linked together by peptide bonds are called polypeptides.

 

proteins:  one or more polypeptides.

denaturation:  changing of protein structure.  can be caused by changes in pH, temperature (eg.               heat), radiation or chemical agents.

 

Our body makes about 10,000 different proteins.  Bacteria makes about 700 different proteins.

 

Proteins are very important and diverse molecules.

 

IV.  Nucleic acids:  long polymers of smaller subunits called nucleotides.

Control structure and function of cell.

Two important nucleic acids:

1.  deoxyribonucleic acid (DNA):  makes up the hereditary factors called genes.

2.  ribonucleic acid (RNA):  works with DNA to control the construction of proteins (protein                                         synthesis).

 

carbohydrates - energy

storage (polysaccharides)

lipids - fats

           phospholipids - cell membrane

           steroids (hormones)

proteins - energy

   support/structural

   enzymes - regulate chemical rxn in cells

   transport

nucleic acids - polymers

          subunit:  nucleotides

nucleotides: a 5 carbon sugar (ie: ribose), a phosphate group and a nitrogenous base.

 

O      nitrogenous base

 |                |

O  ___  P ___ 5 - C sugar

| |

O

nucleotides form chains called nucleic acids.  Single chain = RNA.  Double chain = DNA.

 

P            P            P

         /      \     /     \      /

P            P            P                             S         S         S

          /     \      /     \     /                                |          |            |

                     S        S           S                                NB     NB        NB

         |        |             |                                   NB     NB        NB

       NB    NB        NB                           |          |             |

       S         S           S

   RNA                                    \     /     \      /     \

P            P            P

P = Phosphate

S = Sugar                                                                            DNA

NB = Nitrogenous Base

 

 

Lecture 3                                                                                                                      February 4

 

Cell Structure and Function

Cells:  The basic unit of life.

 

Cells have three major components:

1.  plasma membrane:  envelope - holds cell together.

2.  DNA.

3.  cytoplasm:  contains organelles.

 

Plasma Membrane:  "fluid mosaic model"

1.  double layer of phospholipids.  With polar (hydrophilic) head (*);  and nonpolar  U                                                         (hydrophobic) head (U)                                     *        

2.  proteins embedded in the lipid bilayer.

 

Proteins have at least two important functions:

1.  transport of molecules.

2.  receptors of chemical messages.

 

Plasma membrane is selectively permeable.

 

Materials move in and out of cell through the plasma membrane via:

1.  Diffusion - movement of molecules from a region of high concentration to a region of low                concentration.  ie: deodorizers and colognes, O2, CO2

2.  Osmosis - diffusion of water across a cell membrane - osmotic pressure.

 

osmotic pressure - difference in concentration of water inside and around the cell.

 

Note:  Diffusion and osmosis take place without the cell expending any energy.  (Just happens.)

 

3.  Active transport - movement of molecules against the concentration gradient.  Cell must                         expend energy (ATP).            [revolving door]

4.  Endocytosis and exocytosis - for big stuff

             into cell                  out of cell

 

Two general types of cells:

 

          before -  nucleus

1.  Prokaryotes:  the bacteria.

     a.  DNA not enclosed in a nucleus.

     b.  a semi-rigid cell wall (polysaccharide) outside plasma membrane.

     c.  cytoplasm contains only ribosomes (where protein synthesis occurs).

 

2.  Eukaryotes:  cells having nuclei.

     a.  DNA enclosed in a nuclear envelope.

     b.  cytoplasm contains ribosomes and other organelles.

 

     prokaryotes

<  eukaryotes    ___  plants

\ 

   animals

 

Eukaryotic cells:  plant or animal.

 

Characteristics Common to Plants and Animals:

 

nucleus = membrane bound control center that contains cell's genetic material.

1.  nuclear envelope (contains pore).

2.  chromosomes - DNA and protein.

3.  nucleolus - little nucleus that makes ribosomes.

 

other cellular organelles:

1.  ribosomes - site of protein synthesis.

2.  endoplasmic reticulum (ER) - passage ways

     a.  rough ER - studded with ribosomes, produces proteins to be sent out of cell.

     b.  smooth ER - site of hormone synthesis.

3.  golgi bodies (pancakes) - packaging plant make vesicle(membrane bound lipids)  for storage.

[See figure 3.14 in book for illustration]

4.  lysosomes - made by golgi bodies; makes digestive enzymes; can self destruct by releasing                      these digestive ezymes into cell.

5. mitochondrion - power house of cell; membrane bound; site of cellular respiration ( where                   food is converted into energy).

6.  cytoskeleton - microtubules (thread-like) made up of protein called tubulin.  To anchor                cellular organelles.

 

Flagella and cilia are unique to animal cells.  Plants have all others # 1 - 6.

 

Structures Unique to Plant Cells:    [figure 3.12]

 

1.  plastids - chloroplasts (site of photosynthesis) and chlorophyll (pigmentation).

2.  central vacuole - storage compartment: starch, amino acids, proteins; makes up 80% of cell.

3.  cell wall - layer of cellulose.

 

 

Lecture 4                                                                                                                      February 6

 

Energy Pathways

 

Metabolism:  ability of cell to acquire energy and to use this energy to build, store, break apart            and eliminate substances in a controlled fashion.

Energy:  "heat or anything that can be transformed into heat"  - measured in calories.

 

Chemical bonds contain energy.

 

Metabolic pathways:  orderly sequences of chemical reactions.

1.  biosynthetic pathways:  small molecules assembled into larger molecules.

2.  degradative pathways:  large molecules broken down into smaller molecules.

 

Characteristics of enzymes:

1.  they are protein molecules.

2.  they speed up chemical reactions.

3.  they are not used up.

4.  they are very selective.

Cells must have energy in a biologically useable form = adenosine triphosphate (ATP).

 

ATP consists of a 5 carbon sugar (ribose), a nitrogenous base (adenine) and 3 phosphate groups.

O            O            O            adenine  (NB)

 |           |          |                 |

O  ___  P    *    P    *    P  ____  ribose  (5 carbon sugar)

| |          | |            | |

O            O            O

[phophate group]                          * high energy Phosphate Bond

PO3

ATP  <--------  energy + ADP        "high energy phosphate bond" readily broken to release energy

 

[See also ATP Cycle in notes (top half is cellular respiration) P.16]

 

How organisms obtain energy:

1.  autotrophs:  organisms that are able to make their own food(green, photosynthetic                         plants, some bacteria).

2.  heterotrophs:  organisms that must obtain food by eating other organisms (living or dead).

 

Autotrophs obtain energy via photosynthesis.

 

Photosynthesis:  energy in sunlight converted to carbohydrate (glucose).

takes place in the chloroplast of the plant cell.

6 H2O + 6 CO2 + energy (sunlight)  ------->  6 O2 + C6H12O6

 water    carbondioxide                                      oxygen        glucose

 

Two separate sets of reactions:

1.  the light reactions:  sunlight energy is used to make ATP = photophosphorylation.

2.  the dark reactions:  Co2 and energy (ATP) used to make glucose.

 

Light reactions.

1.  photolysis:  splitting of H2O from light energy into H+H+, O (released)

2.  posphorylation:  released energy from 1st electron transport system forms ATP.

3.  NADP converted to NADPH.  2nd transport system adds H+H+ to NADP

 

Dark reactions (Calvin-Benson Cycle):  refer to textbook.

 

Miscellaneous points about photosynthesis:

1.  30% efficiency rate.

2.  18 ATPs and 12 NADPHs used to produce 1 glucose molecule.

 

Cellular Respiration:  carbohydrates are oxidized and energy is released in the form of ATP.

 

Respiration is the reverse of photosynthesis:

C6H12O6 + 6 O2  -------->  6 H2O + 6 CO2 + energy (ATP)

 

Two types of cellular respiration:

1.  aerobic respiration - eukaryotes (contain mitochondria) do this when oxygen is available.

2.  anaerobic respiration - when oxygen is not available.  Does not produce as much energy.

 

Aerobic respiration:  1 glucose produces 38 ATPs.

1.  glycolysis.

2.  Krebs cycle.

3.  oxidative phosphorylation.

[See notes P.19 - 21 for Gly., K.C., Ox.Phos., Alc.Ferm. and Lac.Ferm. Illust.]

 

Glycolysis:

1.  stepwise breakdown of glucose (C6) into 2 molecules of pyruvic acid (C3).

2.  occurs in the cytoplasm of the cell.

 

Krebs Cycle:

1. cyclic reactions.

2. occurs in the mitochondria.

4   ATP  k.c., glycol

1 molecule of glucose==>      + 34 ATP  ox. phos.

38 ATP/glucose

Oxidative Phosphorylation:

1.  generates 34/38 ATP molecules.

2.  electron transport system in mitochondria.

3.  NADPH2 makes 3 ATP, FADPH2 makes 2 ATP.

4.  H+ bonds with O2 to form "metabolic H2O".

 

Anaerobic respiration:  respiration in the absence of oxygen.

1.  much less efficient.  2 ATP/glucose.

2.  a means to continue glycolysis.

 

Two different kinds of anaerobic respiration:

1.  alcohol fermentation (yeast).

2.  lactic acid fermentation (we do).

     a.  same as alcohol fermentation, but no alcohol produced--pyruvic acid is simply rearranged.

     b.  muscle fatigue symptoms due to lactic acid build up in muscle tissue.  You develop                "oxygen debt" which is why we breath heavily after a workout.

 

 

Lecture 5                                                                                                                      February 11

 

Mitosis and Meiosis

 

Reproduction:  production of new organisms or cells from pre-existing ones.

 

Two types of reproduction:

1.  asexual reproduction:  offspring are "clones" of the parent.

2.  sexual reproduction:  offspring are genetically "diverse".

 

Chromosomes:  carry genetic info

1.  contain DNA and protein (in eukaryotes).

2.  are found in the cell nucleus.

 

Species have a diploid number (2N) of chromosomes.  ie:  humans  = 46, dog = 78, fruitfly = 14

 

 

Chromosomes occur in homologous pairs.

each pair has 1 maternal + 1 paternal and have identical info as its partner.

 

Before reproduction, chromosomes must undergo replication - consists of two "sister" chromatids held together by a centromere.

 

Mitosis consists of two events:   (simultaneous)

1.  replication of parent chromosomes and distribution of chromosomes to "daughter" nuclei.

2.  division of the cytoplasm (cytokinesis).

 

mitosis - nucleus

 cytokinesis

 

Nondividing cells are in interphase (most of lives).  Chromosomes appear as chromatin

Replication of chromosomes occurs at end of interphase.

 

Stages of Mitosis:                        IPMAT

1.  Prophase

     a.  chromatin condenses.

     b.  centrioles begin to move to poles.

     c.  spindle fibers (microtubules) begin to appear.

     d.  nuclear envelope disappears.

2.  Metaphase

     a.  chromosomes align along equator.

     b.  spindle fibers attach to centromeres.

3.  Anaphase

     a.  centromeres of each chromosome divide.

     b.  spindle fibers begin pulling sister chromatids toward opposite poles.

     c.  sister chromotids are now chromosomes.

4.  Telophase

     a.  nuclear envelope reappears (around two new nuclei).

     b.  chromosomes revert to chromatin.

     c.  cytokinesis - division of cytoplasm into two separate cells.

1.  furrowing and splitting cells.

2.  cell plate formation.

 

Importance of mitosis:

1.  daughter cell is identical to mother cell.

2.  daughter cells are identical to each other.

 

Mitosis serves two major functions:

1.  growth and repair.

2.  asexual reproduction.

     a.  binary fission - amoeba

two    split

     b.  budding - yeast

     c.  vegetative reproduction - strawberry plants, bermuda grass, ferns

 

Miscellaneous points about meiosis:

sexual reproduction

1.  new life begins life as zygote. 

2.  fusion of gametes (sex cells) form the zygote.

3.  two parents each contribute one gamete to the zygote.

4.  gametes are haploid (1N).

5.  gametes produce germ tissue (gonads) (ie:  ovaries & testes)

6.  gametes produced by meiosis.

 

Meiosis

1.  two nuclear divisions (meiosis I and II)

reduction of chrom.   mitosis

2.  results in 4 haploid daughter cells.

3.  DNA replication occurs just before meiosis.

 

Meiosis:

1.  Prophase I

     a.  homologeous chromosomes form tetrads.

     b.  crossing-over occurs.

2.  Metaphase I

     a.  tetrads line up along equator of nucleus.

3.  Anaphase I

     a.  tetrads separate and go to opposite poles.

     b.  chromosome number has been reduced.

4.  Telophase I

     a.  chromosomes regress into chromatin.

 

~ Interphase ~

 

Meiosis II

1.  Prophase II

     a.  reappearance of chromosomes.

2.  Metaphase II

     a.  chromosomes line up along equator.

3.  Anaphase II

     a.  centromeres divide.

     b.  chromatids are now daughter chromosomes.

     c.  chromosomes begin moving to poles.

4.  Telophase II

     a.  nuclear envelope reappears (4).

     b.  cytokinesis produces 4 daughter cells.

 

In our species:

1.  spermatogenesis

2.  oogenesis

O

          /      \

     ooo       O     ovum

                   polar bodies- nonfunctional gametes that eventually disintegrate

 

Importance of meiosis:

1.  keeps diploid number constant.  Without haploid gametes, diploid # would always double.

2.  source of genetic variation because of  1.) independent assortment and  2.) crossing-over.

 

 

Lecture 6                                                                                                                      February 18

 

Patterns of Inheritance

 

Genetics:  study of the inheritance of biological traits.

 

Theory of blending inheritance.  (fluids)

 

Gregor Mendel

1.  Austrian monk.

2.  experimented with pea plants.

3.  "father of modern genetics."

 

Mendel's first experiment:  Law of Segregation.

1.  used traits with two alternate expressions.  ie:  seed color (yellow/green).

2.  true breeding parent lines (P1).

3.  crossed P1 lines to get an F1 generation.

4.  F1 displayed only one of the parent types.  ie:  all plants with yellow seed.

5.  then "selfed" to get an F2 generation.

     a.  missing characteristic reappeared in F2 generation (green seeds).

     b.  ratio 3:1   3y : 1g  in F2.

6.  repeated experiment with other traits.

 

Important points:

1.  dominance - recessiveness   ( always present but d or r).

2.  Mendel's Law of Segregation:  "an organism contains two discrete hereditary factors for each        trait and these factors segregate during gamete formation so that each gamete contains only           one factor from each pair of factors."

 

Particular Inheritance.

Modern terminology for Mendel's experiment:

1.  traits controlled by a single gene.

     gene - segments of DNA molecules containing instructions for one protein.

2.  alternate forms of a gene are called alleles.  Green alleles and yellow alleles.

3.  genotype:  an individual's allelic make up.

     a.  homozygous (ie: YY, yy)  yellow, green.

     b.  heterozygous (ie:  Yy)  yellow/green.

4.  phenotype:  physical expression of the genotype - what you see  ie:  yellow or green.

5.  meiosis results in a gamete receiving only one (not two) allele.

 

Return to Mendel's experiment:

1.  P1 parental lines are YY and yy

2.  Each parental type produces one kind of gamete.

3.  F1 all heterozygous individuals (Yy).

4.  F2 obtained by a monohybrid cross (selfing F1).

 

Yy

     _____Y_______y___            Yellow is dominant (Y).

Yy            Y  |            YY       |    Yy    |            3 yellow : 1 green.

y   |____Yy____|     yy    |

 

5.  F1 parents (Yy) produce 2 types of gametes.

6.  F2 produced by fertilization of 2 kinds of eggs (1/2 Y, 1/2 y) by 2 kinds of pollen (1/2Y, 1/2y).

 

Notice:  ratio of dominant to recessive phenotypes is 3:1 (1/4 and 1/4).

 

Test cross - dominant phenotype crossed with a homozygous recessive individual.

    - not equal to monohybrid cross.

 

B?  x  bb                    B - black   b - white

     if  BB ----> you get Bb    all offspring will be black (B is dominant).

     if  Bb ----->            .b.

       B|  Bb |            half offspring black

       b |  bb |            half offspring white

 

Mendel's Law of Independent Assortment:

members of each pair of factors segregate independently of all others.  (traits)

 

Mendel's other experiments:  the dihybrid cross

1 pair {Y = yellow            1 pair { S = smooth

          {y = green                  { s = wrinkled

 

1.  P1:  YYSS and yyss.

2.  F1:  YySs all yellow, smooth plants (Y and S are dominant).

3.  F2:  selfed (dihybrid cross) to get an F2.

4.  Phenotypic ratios of the F2:                                                YySs

     a.  yellow, smooth  = 9/16                                     .......YS.......Ys.......yS.......ys.......

     b.  yellow, wrinkled  = 3/16                      YS  |  YYSS   YYSs   YySS   YySs    |

     c.  green, smooth  = 3/16             YySs          Ys  |   YYSs   YYss    YySs    Yyss    |

     d.  green, wrinkled  = 1/16                       yS  |   YySS    YySs    yySS    yySs    |

      ys   |   YySs     Yyss    yySs     yyss     |

Prob. of being green and wrinkled = 1/4 x 1/4.

 

Some miscellaneous points:

1.  Not all traits are controlled by dominant and recessive alleles. 

     a.  incomplete dominance.      ----->  P1:   red  x  white

     b.  codominant alleles.              F1:        pink

2.  Some genes have more than two alleles. 

Example:  the ABO blood group.

 

Blood Group                Genotype                    RBC Antigen                         IA __   codominant

IB      /

A                     IAIA , IAIO                  Type - A                                

B                      IBIB , IBIO                  Type - B                                  IO   -  recessive

AB                   IAIB                              Type - A, Type - B

O                     IOIO                              none

 

 

Lecture 8                                                                                                                      February 25

 

DNA REPLICATION & PROTEIN SYNTHESIS

 

The genetic material:  DNA or protein?

 

Hershey-Chase Experiment (1952)                                                  / \

virus T-2 bacteriophase infects bacteria                                      |    |   <== protein coat

(protein is very rich in sulfur)                                         \   /

(DNA contains phosphorus)                                         | |

1.)  Injected radioactive sulfur in coat and infected bacteria cell.      /    \

[Sulfur did not show up.]

2.)  Injected radioactive phosphorus and infected bacteria cell.

[It did show up.]

Conclusion:  DNA is the genetic material.

 

DNA must be capable of 3 things:

1.  replication

2.  direct protein synthesis

3.  mutation

 

DNA is a nucleic acid -- chain of nucleotides.

 

Characteristics of DNA nucleotides:

1.  always contain sugar deoxyribose.

2.  nitrogenous base:

     a.  purines:  adenine or guanine ( double ring structures).

     b.  pyrimidines:  thymine or cytosine (single ring structures).

 

Watson and Crick:  "the double helix model".

 

Chargaff's rule:  A = T  and  G = C  (the amounts).

 

Watson and Crick's Double Helix Model:     (fig. 11.5)

1.  a twisted double chain of nucleotides.

2.  sugar-phosphate backbone.

3.  chains held together by hydrogen bonding between bases of nucleotides.

4.  bases display complementary base pairing:  A always bonds with T , G always bonds with C.

 

DNA Replication:

-- Each nucleotide chain is the "compliment" of the other.

-- During replication, each chain serves as a template for the construction of its complementary chain.

 

Miscellaneous Points:

1.  DNA polymerase (an enzyme) needed for nucleotide assembly on parent strand [unzippering]

2.  Energy (ATP) required for breaking and forming bonds between nucleotides.

 

|=|

|=|

|=|

 

|=|                     |=|

|=|                     |=|

|=|                     |=|

 

3.  replication process is semiconservative.

4.  mutation results from errors in replication (A - A instead of A - T).

 

Protein Synthesis:

1.  transcription -  copy DNA instructions to send to ribosomes.

2.  translation.

 

The "Genetic Code"                                                              (4 bases)

DNA base triplets:  3 bases specify 1 a.a. (amino acid).    3 nucleotides

The genetic code is degenerate.                                                       3    times

Table:  fig. 12.7 p.187                           bases  4            =    64 a.a.

61 triplets specify 20 a.a.    

 3 triplets are stop signs.

 

A gene:  all the base triplets needed to specify the a.a. sequence of one polypeptide.

 

protein  = 600 a.a.

DNA bases  = 1800

 

Nuts and bolts of protein synthesis.

 

I.  Transcription

     Takes place in the cell nucleus.

     DNA triplets copied into messenger RNA.

     Characteristics of RNA:

     1.  a single chain of nucleotides.

     2.  nucleotides contain sugar ribose.

     3.  bases are G, C, A and U (Uracil).

|-------|                                                 codon

|-------|                                                    v

|-T   A-|                                          U  A  G  C  A

            /-G   C-\                                          |    |    |    |    |  

          /-C G    G-\                                          mRNA

        /-A  U        T-\

-  One strand of DNA serves as a "template" (guide) for formation of mRNA (RNA polymerase - the enzyme used to do this.

-  DNA base triplets converted to mRNA codons.

-  mRNA leaves nucleus and goes to ribosome.

[Illus.. in book 12.? and in notes p.5]

 

II.  Translation

Ribosomes consist of ribosomal RNA that serve as a "work bench" for translation.

transfer RNAs (tRNAs) have an anticodon and bring a specific amino acid to the ribosome.

tRNAs match their anticodon with mRNA codon.

Amino acids linked by peptide bond.

Process proceeds until "stop codon" is reached.

 

Important points:

1.  codon is degenerate  (fig. 12.5 p.166).

2.  compliment of DNA  triplets, codons and anticodons:

 

  DNA      A  T  C  G  T  C        DNA base triplets                 

    ¯ [translation] ¯                                                  

mRNA     U  A  G  C  A  G     codons                         [ON EXAM]

    ¯ [transcription] ¯                                                         

tRNA       A  U  C  G  U  C            anticodons                              

 

DNA    C C G T A A T

tRNA   C C G U A A U

 

3.  the genetic code is universal.  (same in bacteria as in a tree or dog that is also making protein)

 

 

Lecture 9                                                                                                                      February 27

 

RECOMBINANT  DNA & GENETIC ENGINEERING

 

DNA replication and protein synthesis: the "central dogma" of molecular biology.

 

Selective breeding.

 

Recombinant DNA technology: procedures by which DNA from different species can be             isolated, cut and spliced together - new “recombinant” molecules are then multiplied in          quantity in populations of rapidly dividing cells (ie: bacteria, yeasts).

 

[Taking human genes and putting into bacteria to grow more.  Then sell it.]

 

Basis for the technology:

1.  Bacterial plasmids.

2.  Restriction endonuclease (pour it on) cuts DNA molecules at specific places (base triplets)       and makes restriction fragments.

 

Restriction endonucleases: 

     Many different kinds of endonucleases.  Each cuts DNA at specific recognition sites.        Produces fragments with “stick ends.”

Example: EcoRI cuts DNA at sequence GAATTC.

.   ¯                        .

 G A A T T C

  |   |   |   |   |   |

 C T T A A G         

       ­

Restriction fragments with “sticky ends”

 

Let’s make some recombinant DNA.

 

1.  Obtain plasmids from DNA.

2.  Cleave with a restriction endonuclease.

3.  Obtain human DNA and cleave with endonuclease.

4.  Human and plasmid fragments mixed with DNA ligase (ties things together) to produce                 recombinant plasmids.

5.  DNA library amplified to get cloned DNA.

6.  Screen the library.

 

Some Miscellaneous Points:

1.  DNA to be cloned: natural or synthetic.

         ie: somatostatin (14 a.a. 42 nucleotides).

2.  Virus are also used as vectors for cloning (instead of plasmids).

 

Gene Therapy.  To cure genetic disorders-- New.

 

1990 - First approved human gene therapy.

Young girl suffering SCID (severe combined immune deficiency).

protein: A.D.A. (enzyme) for formation of white blood cells.

ADA gene cloned and put into white blood cells.

Symptom-free for nearly 5 years (w/occasional boosters).

 

Practical applications of recombinant DNA technology:

 

1.  Agricultural applications.

- extends life before rotting.

- resist attack by insects.

2.  Environmental applications.

- bacteria to detoxify landfills, sewers, etc.

Forensic applications: “DNA fingerprints”.

 

Problems with old tests:

1.  Need fresh samples in sufficient amounts. 

2.  Only excludes suspects; not evidence of guilt.

 

DNA testing overcomes these difficulties.

[DNA does not decompose easily - very stable, can be ancient]

[tiny amounts needed for pcr]

 

Polymerase Chain Reaction (PCR)

billions of copies of DNA made in a few hours

1.  DNA heated to 94° C in a thermal cycler.  (Boiling)

        (Double helix comes apart into two strands.)

2.  Put in free nucleotides and DNA polymerase (Taq).

        (Allow to cool, nucleotides match with compliments.)

3.  Temperature is lowered and doubled stranded DNA is formed.

4.  Each cycle takes about 5 min. And each cycle doubles the amount of DNA present -- 30       cycles (2.5 hour) will in theory increase the amount of DNA one billion times.

 

RFLP analysis generates DNA fingerprints.

Restriction fragments length Polymorphism.

                                                                                                           

                                                                                                            Restriction fragments

 

                                                                         Migrate in electric field

+ | ---                   |                                              Depending on their size.

    DNA                           | ---                 |                                            

fingerprints                       | ---                 |                                            

-  | ---                 |                                            

 

1.  DNA is cleaved with one or more restriction endonucleases creating restriction fragments.

2.  Fragments are labeled with dye and separate by gel electrophoresis.

3.  Cleaved DNA from different people produce different banding patterns: restriction fragment length polymorphisms (RFLP).

 

Odds of identical fingerprints from different persons is 1 in 100,000 to 1 in a billion.

 

|            |      |     |           |            semen sample DNA

|     |     |    |          |        |          suspect  #1

|           |    |      |      |                 suspect  #2

|            |      |     |           |            suspect  #3

 

 

 

Lecture 10                                                                                                                    March 10

 

HISTORY OF EVOLUTIONARY THOUGHT

 

Evolution is a central unifying concept.

 

Dobzhansky: “Nothing in biology makes sense except in the light of evolution.”

 

Diversity of life: 8 - 30 million species.

 

Question: What process has produced diversity?

Hypothesis: Evolution.

 

Evolution: a misunderstood concept.

 

[speciation = production of new life forms and species.]

 

Two definitions for “evolution:”

Darwin: evolution is descent with modification.

Dobzhansky: genetic changes in populations through time.

 

Important points:

1.  The population is the unit of evolution.

2.  Evolution is a dynamic process (great changes).

3.  Implies new species arise from pre-existing species.

 

An alternative to evolution.

Special Creation: life forms created by a supernatural being.

 

Several important points about creation models:

1.  There are many creation models.

2.  Creation models are beyond the realm of science because they cannot be subjected by       scientific method.

 

Evolution: “it’s only a theory.”

The “law” of evolution?

 

History of Evolutionary Thought.

Let’s go back to the 18th century!

 

Ideas about natural world derived from religious beliefs ie: Book of Genesis.

[6,000 years old - Bishop Usher - October 24, 4004 B.C.]

 

General beliefs of the time:

1.  Young earth.

2.  Catastrophism.

3.  Special creation.

4.  Immutability of species: can’t change because they are created as they are.

 

Challenges to these beliefs:  special creation

1.  Geology and the theory of uniformitarianism.

     questioned earth’s age

2.  Biology

     questioned special creation

 

Jean Baptiste Lamarck (1744 - 1829)

French naturalist one of the 1st to propose a mechanism for evolutionary change.

[An attempt - but completely wrong]

 

Inheritance of acquired characteristics:

Species change through the use or disuse of structures during the organism’s lifetime.

 

Charles Robert Darwin

Born in England on Feb. 12, 1809 (same exact day as Lincoln).

Famous wealthy family

Medical student at the Univ. Of Edinburgh

Theologist student at Cambridge.

The voyage of the H.M.S. Beagle (1831 - 1836) 5 yrs.

(Seasick the whole time.)

 

Things that influenced Darwin on the voyage:

1.  Lyell’s “Principles of Geology”

(large change over time by series of small observable changes.)

2.  The Galapagos Islands:  tortoises and finches

 

Darwin returned to England (1836) and starts his “notebooks”.

   Wrote that “species are mutable” and began using the phrase “descent with modification”.

 

A mechanism for “descent with modification”?

Malthus and the “struggle for existence”.

 

Artificial selection - breed for particular characteristics

natural selection

 

1858:  Chuck gets a letter from Alfred Russel Wallace  -- leads to joint presentation

 

1859: “Origin of Species”

 

6 major points in Darwin’s theory:

1.  Organisms display variation.

2.  Many of these variations are heritable (genetic).

3.  More offspring are produced than survive to reproduce.

4.  Offspring that do survive, do so because they posses variations favored by the environment.               (Adaptations.)

5.  Surviving offspring will leave more offspring that will also be favored by the environment.               (Natural selection: differential reproduction of genetic types.)

6.  These favored characteristics will accumulate over time. 

(Descent with modification.)

 

NOTICE: Evolution is the process and natural selection is the mechanism.

 

Response to “Origin of Species”:

1.  Scientific community - quickly embraced (supported it).

2.  General public - did not!  Especially clergy.

 

Thomas Henry Huxley (“Darwin’s bulldog”)

 

Darwin’s ideas misused by economists:

1.  Herbert Spencer and “social darwinism”.

     “Survival of the fittest”  --  grounds for slavery, racism, sexism, imperialism, etc.

2.  Karl Marx - social progress by revolution resulting from this struggle.

 

The “BIG” criticism of Darwin’s theory.

blending inheritance  => natural selection diluted

 

1860 - Mendel’s publication but ignored until 1900.

 

Darwin dies in 1892   Mendel’s work rediscovered in 1900.

 

The modern synthetic theory of evolution:

1.  Integration of Darwin’s theory and Mendelian genetics.

2.  Natural selection is primary evolutionary mechanism.

3.  Other mechanisms (mutation, gene flow and genetic drift) also cause evolutionary change.

 

 

Lecture 11                                                                                                                    March 6

 

THE EVOLUTIONARY PROCESS

Population genetics.

 

Population:  a group of organisms of the same species at a particular place.

Gene pool:  all the genes and alleles in a population.

 

Populations use two statistics:

1.  Genotype frequencies.

2.  Allele frequencies.

 

EXAMPLE: MN blood group system.

 

�         1 gene

‚         M allele

N allele

ƒ MM   MN    NN            genotypes

 

A small town in Southwest U.S.

Blood collected from 208 individuals.

Genotypes for MN blood group determined.

                                                          

|   MM   |   MN   |   NN   |   TOTAL   |

|   119    |    76     |   13    |      208       |

|   119    |    76     |   13     |      208       |

|   208    |   208    |  208   |      208       |

|  0.57    |  0.37    |  0.06  |      1.00      |

 

Allele frequencies: frequency of M = p and frequency of N = p.

 

Note: If there are 208 diploid individuals, there are 416 alleles in the sample.

 

         (119 ´ 2) + 76

p =  ---------------------  =  0.75

                416

 

          (13 ´ 2 ) + 76

q =  ---------------------  =  0.25

    416

 

Note:  p and q must add to 1.00.

 

Note: If p is known, q = 1 - p   since p + q = 1.

 

Hardy - Weinberg Law:

Under certain conditions, allele and genotype frequencies will remain the same from generation to generation.

 

H - W equilibrium: a nonevolving state.

 

Here’s why the Hardy - Weinberg Law works:

1.  Alleles A and a in frequencies p and q.

Freq. A = p

          a = q                   p + q = 1

2.  Gametes have allele frequencies p and q.

3.  If gametes combine randomly, then genotype frequencies for the next generation will be:

 

     _           _

  (A) p       q                             Freq.  AA =  p ´ p =  p²

(A)  p  |     p²     |   pq    |                                  aa  =  q ´ q =  q²

  __            q  |    pq     |    q²    |                                  Aa =  p ´ q  +  q ´ p =  2pq

 

4.  Allele frequencies in the next generation are still p and q.

5.  Equilibrium will be reached.

 

H - W Law can be expressed as the expansion of the binomial:

p + q = 1

(p + q)² = p² + 2pq + q² = 1

 

Example: In our population, p = 0.75, and q = 0.25.

    Therefore:

 

     (p + q)² = p² + 2pq + q² = 1

 

    Freq. MM = p² = 0.56

 MN  = 2pq = 0.19 + 0.19 = 0.38

 NN  =  q² = 0.06

 

Looks like our population is in H - W equilibrium.

 

Assumptions of Hardy - Weinberg Law:

1.  Random Mating.

Inbreeding.

     - same genotypes a lot more often.

     - increases homozygote frequencies.

Inbreeding depression and “incest taboos”

     Offsprings:  poor health, infertility

[many genetic disorders are recessive alleles.  When two heterozygotes mate they form homzygotes and these alleles become dominant.]

2.  No Gene Flow.

Gene flow: nonrandom movement of genes into or out of a population.

     - a source of genetic variation.

homogenizing effect on gene flow.

p = 1.00     ï            p = 0

q = 0                            p = 1.00

  AA                 ð             aa

 

p = 0.5            ï            p = 0.5

q = 0.5            ð            q = 0.5

Gene flow must be eliminated in order for speciation.

    “      ”    breaks down differences.                              

3.  No Mutation.  (Changes in DNA)                          MM

     Mutation is the source of new alleles.                     ¯  ø mutation

4.  Large Population Size.                                                     M     N

as population grows larger, random chance is less a problem.

Genetic drift: random sampling error of gametes.

- most important in small populations.

- causes populations to lose genetic variation.

5.  No Differential Reproduction of Genotypes.

natural selection: differential reproduction of genotypes.

- proposed by Darwin and Wallace.

- most important force in evolution.

 

Several important points:

1.  Fitness: relative contribution of a genotype to future generations (ability to reproduce).

2.  Adaptations: genetic traits that aid the organism in surviving and reproducing (favored by ns).

3.  Natural selection operates through agents in the environment(ie:predation, disease resistance)

4.  Fitness is environment specific.

 

Forces of Evolutionary Change:

1.  Nonrandom mating.

2.  Gene flow.

3.  Mutation.

4.  Genetic drift.

5.  Natural selection.

 

 

Lecture 12                                                                                                                    March  13

 

SPECIATION AND MACRO EVOLUTION

 

Species: collections of populations containing individuals that can interbreed.

 

Each species has a geographic distribution.

 

Genetic variations among populations.

Populations display genetic differentiation.

 

Factors producing genetic differentiation:

1.  Mutation.

2.  Genetic drift.

3.  Natural selection.

 

Factors that minimize genetic differentiation:

1.  Gene flow.

2.  Natural selection.

 

Several patterns of geographic variation:

1.  Clinal variation - gradual, directional change in a genetic trait in response to an                     environmental gradient.  Ie: Bergmann’s Rule:    N|  /

S| /    

example: Grizzly Bears                                           body size

     Alaska     largest

 |

 |           natural selection favors this characteristic

¯

     Mexico    smallest

2.  Ecological rate formation - abrupt changes in environment causes abrupt changes in       phenotype.  ie: black lava/white sand...black mice/white mice interbreed, brown offspring die.

 

Speciation: formation of new species from pre-existing ones.

 

Typological species (morphospecies) concept.

look different  --  great subjectivity

Cats -- 28 genera or 3 genera

 

Biological species concept: natural group of actually or potentially interbreeding organisms that              are reproductively isolated from other such groups.

- potentially?

- interbreeding excludes asexually reproducing organisms.

- only includes living organisms, not fossils.

 

Allopatric Speciation:

                 ¡   ®   •  

  ì                                               î 

¡  _BARRIER_ _BARRIER_ •

 

              î                                               ì     ¡

                        ¡   ®    ¡

 

 

×If they can still mate - no                      barriers prevent gene flow                                          speciation, but look different.

                                                                                     ×If they can’t - reproductive                                                                                                     isolation - now diff. species.

1.  Barrier fragment the distribution:

     Geographically isolation (no gene flow).

2.  Genetic divergence during isolation.

3.  Genetic differences may become so large that the populations may no longer be able to        interbreed (reproductive isolation).

 

Reproductive Isolation Mechanisms (RIMs):

 

I.  Pre-Zygotic Mechanisms: prevent hybrid zygotes rom being formed (no mating).

    1.  Ecological or habitat isolation.

They’re fund in different places, they don’t come in contact with each other. 

    2.  Seasonal isolation.

Plants - bloom at different times.

    3.  Behavioral isolation.

Mating calls differ, behavioral courtship; birds, frogs, lightening bugs.

    4.  Mechanical isolation.

“Lock and key” isolation - insects.

 

II.  Post-Zygotic Isolating Mechanisms: operate after fertilization.

     A.  Hybrid invariability.

Die before reproductive ability; sheep and goats -- zygotes die.

     B.  Hybrid sterility.

Live but cannot reproduce; horses and mules (not sickly) 99% of mules can’t reprod.

 

 

Lecture 13                                                                                                                    March 13

 

EVIDENCE FOR EVOLUTION

 

Evolution makes two broad predictions:

1.  Species should be capable of change over time (descent with modification).

2.  All the different species on earth have evolved from a common ancestor.

 

Evidence that species can change over time:

1.  Artificial selection.

2.  Evolution in nature.

   Examples of natural selection.

 

Evidence that life forms have all evolved from a common ancestor:

1.  Fossils.

     A.  Simplest fossils found in oldest; more complex forms found in youngest strata.

   Age                Appearance of:

3.5 bya   bacteria

600 mya            invertebrates

440 mya fishes

225 mya            mammals

1.5 mya              “man”

     B.  Fossils in younger strata are more similar to living organisms than fossils in older strata.

     C.  Gradual changes seen in many fossil lineages, intermediate forms have often been found.

2.  Morphological similarities.

     a.  Embryonic development.

All vertebrates including humans have embryos containing gill slits.

     b.  Transitional forms.

ie: Archaeoptyerx; platypus

birds                 reptiles

feathers            teeth, jointed tail

 

 

Lecture 14                                                                                                                    March 20

 

CIRCULATORY SYSTEM

 

Circulatory system:  transport of materials.

 

Single-celled organisms - diffusion and active transport.

 

Two general types of circulatory systems:

1.  open circulatory system

     in insects and crustaceans.

     blood not always contained in blood vessels.

2.  closed circulatory system

     in higher animals.

     blood is always contained in vessels.

 

Vertebrate circulatory system:

1.  heart  - muscular pumping system that propels blood through system.

2.  blood  - transport medium.

3.  vessels  - structures through which blood moves.

a.  arteries  - vessels that carry blood away from heart

           branch into

       1. arterioles  - smaller arteries

                  branch into

     2.  capillaries - single cell layer thick where materials are exchanged

  where the action is!!

  our body has 50,000 miles of capillaries

b.  venules  - going to heart taking waste away from capillaries

c.  veins  - formed by venules

Blood:  medium of circulatory transport

Functions:

1.  transports dissolved molecules to the cells.

2.  carries away cellular and metabolic waste products.

3.  helps stabilize internal pH. (measuerment of acidity.)

blood contains protein molecules called buffers: H+ are picked up or released to regulate              acidity.

4.  helps maintain a constant body temperature.

5.  involved in fighting infections.

 

Components of blood:

1.  plasma   [pH of 7.4]

2.  red blood cells  (eurythro cytes)  

- produced by stem cells in the bone marrow.

- life span:  120 days

- mature rbc's are anucleate(no nucleus) to make room 4 hemoglobin(protein+iron heme)

 

      oxyhemoglobin            vs.            reduced hemoglobin

        O2 is bound               goes back to lungs

       found in lungs

 

3.  white blood cells  (leukocytes)

- larger, less of them

- 5 kinds involved in fighting fighting infection

- produced by stem cells in bone marrow.

4.  platelets  (thrombocytes)

- aren't real cells - they're cell fragments

- produced by stem cells in bone marrow

- life span:  5 - 9 days

- initiates clotting response by releasing thrombokinase (enzyme) which uses dissolved      proteins:  takes them out as threads an forms clots  "scab"

 

Human heart:

cardiac muscle tissue surrounded by the pericardium  (outside protective layer).

Four Chambers:

1.  right atrium   receives blood coming back from cell

     a.  anterior vena cava   -  large vein bringing blood from head, neck, arms & chest.

     b.  posterior vena cava   -  large vein bringing blood from stomach, pelvis & legs.

2.  right ventricle   blood from atrium pumped here into lungs

     a.  pulmonary artery   -  large ventricle leading to lungs.

3.  left atrium  

     b.  pulmonary vein   -  blood going to heart from lungs.

4.  left ventricle   contracts and forces blood out through:

     a.  aorta

 

The Cardiac Cycle:   systole and diastole.  

(series of contractions and relaxations.)

Sinoatriole node:  the pacemaker - bundle of nerves located on the right atrium.   [how to beat]

"Heart sounds":  (lub-dub) created by closing of atriovenricular valve (lub) and semilunar valve                         (dub).  [when atriums (lub) and ventricles (dub) contract.]

 

Rate of cardiac cycle controlled by nervous system:

Medulla oblongata

- monitors O2, CO2 and blood pressure

- sends message to the pacemaker  (sinatriole node).

 

Lymphatic System:

series of vessels and organs.

reclaim fluids forced out of capillaries.

help defend body against infection.

 

Components:

1.  lymph capillaries and vessels.

2.  lymph nodes.

chambers located along lymph vessels--

contain lymphocytes and macrophages.

 

 

Lecture 15                                                                                                                                April 1

 

DIGESTIVE SYSTEM AND NUTRITION

 

Animals are heterotrophic.

1.  herbivores.

2.  carnivores.

3.  omnivores.

 

Digestive System:  system for securing and processing food.

 

Types of digestive systems:

1.  incomplete digestive system.

typical of primitive animals (flat worms).

same opening for food intake and exit.

no specialized parts.

 

2.  complete digestive system.

found in higher animals.

different openings for food intake and exit.

specialization of parts.

 

Mouth.

1.  teeth.  (32)

     a.  incisors -- chisel-shaped for biting.

     b.  canine -- pointed for tearing (eye teeth).

     c.  premolars -- for grinding.

     d.  molars -- for crushing (incl. wisdom).

2.  salivary glands.

     moisten food and secretes salivary amylase (enzyme: breaks down starch - polysaccharides).

 

Esophagus and peristalsis (movement of food through contractions).

 

Stomach.

  secretes gastric juice (HCl and pepsin).

  chyme -- acidic fluidthat leaves stomach.

  pH = 2 -- kills bacteria, promotes activity of pepsin (pepsin breaks down protein), destroys salivary amylase.

 

Small intestine.

  receives secretions from the liver (bile - digest fats) and the pancreas (pancreatic juice - contains sodium carbonate and converts chyme from acidic to basic.)

  [pancreas also secretes insulin which regulates glucose -- contains trypsin, lipase & amylase which breaks down proteins, fats & starch/amylase respectively.]

 

villi.

recovers the good stuff.

 

   amylase  -  starch

pancreatic juice {  trypsin    -  proteins

    lipase     -  fats

 

sodium bicarbonate

 

Liver.

produces bile sent to gall bladder & put into small intestine.

1.  detoxify blood.  (alcohol)

2.  destroy old RBC.  (hemoglobin contains iron + is prim. constituent of Bile)

3.  stores glucose as glycogen.

4.  produces urea.

takes a.a. from proteins and uses nitrogen for energy as urea.

 

Large Intestine:

1.  water reabsorption.  (put  back into the circulatory system.)

2.  ion regulation.  (sodium, potassium and iron.)

 

75 % water  25 % solid is left.

 

study figure 30.5 in text.

 

Nutrition.

4 types of human nutritional requirements:

1.  energy sources. (to make ATP)

2.  organic precursors.  (building blocks)

3.  vitamins.  (metabolism)

4.  minerals.  (usu. iron)

 

Energy sources:  (can be broken down to make ATP).

1.  carbohydrates.  (preferred)

2.  fats.

3.  proteins.

 

Organic precursors:

1.  fats.

turns into phospholipids (in cell membrane) + hormones (estrogen - for ovulation +         menstruation).

2.  protein (amino acids).

 

[There are 20 a.a. our body can only make 12 of them, the rest we get from blood.]

 

8 essential amino acids.

complete and incomplete proteins.

omnivore            herbivore

 

Kwashiorkor (swahili - the 1st child dies when the 2nd child is born.)

 

difficiency of protein -- can't grow, little energy, mental retardation.

 

mother's milk contains these essential proteins/a chunk of cheese a day for 50 lb kid is sufficient.

 

 

3.  Vitamins.

in tiny amounts.

used in metabolic reactions.

13 different vitamins needed by humans (that we do not produce ourselves).

1.  Niacin (B vitamin) - respiration

2.  Riboflavin (b vitamin) - FAD

3.  Vitamin D and rickets. - disorder of absorption/deposits of calcium in bones.

4.  Vitamin C and scurvy - wounds/sores don't heal, gums bleed teeth fall out .[sunshine vitamin]

 

Dangers of "megavitamin therapy."

too nuch vitamin A: hair falls out, sore muscles, loss of hunger.

 

4.  Minerals.

a.  iron  and anemia   (not getting oxygen to the cells).

b.  iodine  and goiter  (pouch under neck thyroid swells -- leads to neurlogical problems).

- thyroxin - hormone produced by thyroid gland in throat.

- iodized salt, seafood

 

Diets.

1/3 of Americans are overweight.

vegetarian diets.

- young children should not participate.

- no milk, cheese, etc.

 

Zen Macrobiotic Diets.

- 7 categories of food bad  ® good (brown rice).

- eventually only eat brown rice.

- leads to kidney damage, anemia, etc.

* Be weary of diets w/overwhelming amounts of one product while avoiding others.

* Always choose a balnced diet.

* Fat mobilizing hormones - non-existing.

- If you depend on fat for energy, too much H+ hydrogen ions lead to acidosis (acidity in             blood).  Stay away from Dr. Atkins.

* Only see a qualified nutritionist or doctor, no grocery store magazine diets.

 

 

Lecture 16                                                                                                                                April 3

 

RESPIRATORY AND EXCRETORY SYSTEM

 

The respiratory system is closely integrated with the circulatory system.

 

Respiratory suface:  site of gas interchange between organism and its environment.

1.  integument  (skin)  - earthworms   ®  diffusion.

2.  tracheal system  (insects)  don't use blood (circ. sys.).

- spiracles, tracheae and tracheoles.

- pumps body not blood.

3.  gills - protected by operculum (plate).

4.  lungs  - internal structure, kept moist.

 

Human Respiratory System.            fig 29.10

1.  mouth + nose.

2.  trachea  (windpipe) from mouth down to chest.

3.  bronchi  - passage ways.

4.  bronchioles  - smaller passage ways.

5.  alueolus  - sac on the end of bronchioles (300million) -wher the action is- site of gas                exchange.   Cilia for filters.

[epiglottis - flap that keeps food from going down trachea - each ahve a capillary attached.]

 

Breathing:

lungs contained in thoracic cavity.

1.  inhalation.

-rib mscles extend out.

- diaphragm bends down.  _

- causes negative pressure gradient.

2.  exhalation.

 

Breathing rate:

- respiratory center in the medulla oblongata.

- chemoreceptors in aorta and carotid arteries concentrations of CO2 & H+.

 

Gas transport and exchange.

· based on diffusion and concentration gradients.

· fluids have low capacities for dissolving gases.

· capacity greatly enhanced b the addition of a respiratory pigment  =  hemoglobin.

· increases capacity of blood to carry dissolved by 70_.

 

Hemoglobin binds with other gas molecules ie: carbonmonoxide  (CO).

 

Carbon dioxide disposal.

1.  some CO2 dissolves into blood plasma.

2.  some CO2 binds with hemoglobin.

3.  most  CO2 transported as bicarbinate ions.

         carbonic     ì hydrogen ions - picked up by buffers

CO2  +  H2O   —­®   H+   +   HCO3

       anhydrase    î  bicarbonate ions

 

 *** Excretory System  -- Three functions:   ***

1.  elimination of nitrogenous wastes.

2.  control ionic concentrations in fluids (sodium, potassium, etc)

3.  osmoregulation -- controls how much water body contains.

 

Nitrogenous wastes.

1.  ammonia - NH3 - produced by marie invertebrates and freshwater fish.

2.  uric acid - insects, birds, + reptiles - insoluble, produced by liver.

3.  urea - marine fishes + mammals - produced form ammonia in liver.

 

Ionic cincentrations  Na+  K+  Mg ++

 

Osmoregulation

 

Human Excretory System:

1.  kidneys

cortex, medulla & rural pelvis.

2.  renal arteries.

3.  renal veins (cleaned blood).

4.  ureter.

5.  urinary bladder.

6.  urethra.

 

Nephron:  functional unit of kidney.

1.  Bowman's capsule.

2.  proximal tube, loop of Henle and distal tubule (convoluted tubule).

4.  collecting duct.

5.  glomerulus.

 

Nephron function:

1.  filtrationand glomerular filtrate.    (blood plasma).

2.  reabsorption

diffusion and active transport.

[water is collected in collecting duct and then put back in the body.]

 

Urine  can be hypnotic (less), isotonic (same) or hypertonic (more) to the blood.

 

Reabsorption of Na+ and water controlled by hormones:

1.  aldosterone.

produced by adrenal glands (on top of kidneys)

regulates Na+ reabsorption in distal tubule.

2.  antidiuretic hormone (ADH)  (in cells lining collecting duct).

produced by pituitary gland (in brain).

regulates H2O absorption in collecting duct.  fear and alcohol can mess up this cycle.

 

urea             aldo            ­            Na+  reabsorp            ­

ADH       ­            H2O   reapsorp                ­

 

Different organisms fce different problems.

1.  freshwater fish,

- gills have active transport for Na+.

- fish do not drink, kidneys reabsorb well.

- urine a lot but w/little salt -- very dilute in terms of sodium content.

2.  marine fish.

- active transport to get rid Na+.

- drink a lot of water but pump Na+ out through gills.

- small amounts of urine -- isotonic.

Salmon - freshwater + saltwater - have reversible pumps in gills.

 

3.  Other marine animals.

seagulls have nasal glands to eliminate extra salt.

4.  Land animals.

we need to conserve water, can produce hypo-, iso- or hypertonic .

 

[Vitamin A & D are not water soluble, they're fat soluble, stored in fat, even up to toxic levels.]

[Vitamin C is water soluble, extra amounts are passed throgh urine.]

 

 

Lecture 17                                                                                                                                April 8

 

NERVOUS AND ENDOCRINE SYSTEMS

 

Homeostasis:  Maintaining a constant interval environment.

Nervous System:  basis of animal behavior.

Neuron (nerve cells):  basic functional units.

1.  dendrites.

2.  cell body.

3.  axon (nerve fiber) - insulated by myelin sheath inside Schwann cells.

 

Two major types of neurons:

1.  motor neuron - transmit impulses from CNS to effectors (muscles organs, glands, etc.).

2.  sensory neuron - carry impulse from sensory receptors to CNS.

 

Human nervous system.

1.  central nervous system - brain & spinal cord.    Incl . 97 % of neurons.

2.  peripheral nervous system

a.  somatic nervous system - nerves to skeletal muscles, skin, joints - both motor and                                                   sensory neurons.

b.  autonomic nervous system - organs and glands - motor neurons only. 

 

Nerve:  a bundle of neurons.

 

Nerve impulse.

- an electrical charge.

- changing polarity of nerve cell membranes.

- action potential  level must be reached before inpulse prod.

- refractory period  axon recharges itself.

1 milisecond - time between nerve impulses.

- not connected b/c it would be weakened.

- signal regenerated at each synapse.

 

Transmission of nerve impulses:  the synapse.

 

Synapse.

1.  presynaptic membrane.

     A.  synaptic vesicles

     B.  neurotransmitters    ie:  acetylcholine.

2.   synaptic cleft - space.

3.  postsynaptic membrane.

 

Effects of drugs and poison.

1.  some stim or block the release of n.t.

ie:  LSD and blotulism toxic.

blocks n.t.   Þ  paralysis

2.  some mimc or stim. n.t.

ie:  amphetamines, caeffine and nicotine      Þ  hyperactivities

 

Nervous disorders are sometimes related to difficulties if n.t.

ie:  Alzheimer's disease    Þ   lack of acetylcholine.

 

Endocrine System

endocrine glands and hormones.

Hormones secreted into the blood stream.

hormones have specific "target cells".

 

Exocrine glands:  not part of endocrine system.

secretes products through ducts.

ie:  sweat glands, mammary glands, tear glands.

 

Hormones and Hormone Action:

Hormones are called "chemical messengers"

Stim particular reactions or synthesis of particular proteins.

Either polypeptide (protein) or steroid (lipid) molecules.

 

Peptide hormones.

Large and cannot enter target cell.

Form hormone - receptor complex.

cAMP - "second messenger."

 

Steroid hormones  - act on protein synthesis turning things on/off.

- synthesized from cholesterol.

- can enter target cell.

- Form hormone-receptor complex in cytoplasm.

- Complex either promotes (gene activation) or retards (gene inhibition) transcription of a             particualr gene.

 

Important endocrine glands:

 

Pituitary gland.

1.  posterior:  secretes ADH and oxytocin.

     A.  ADH = antidiuretic hormone to reabaorb water.

     B.  oxytocin  - tissue to form uterus in pregnacy.

2.  anterior: the "master gland"

     A.  thyroid stimulating hormone (TSH).

     B.  growth hormone  (GH)

     C.  Prolactin  - produces milk - tissue of mammary glands to is target cell.

 

Thyroid gland.

thyroxin - regulates metabolism.  (its a hormone)

 

Adrenal glands.

paired glands on top of kidney.

1.  epinephrine and norepinephrine.  (stress)

"fight or flight"hormone.

some functions slightly different chem. make up.

 

Pancreas.

Islets of Langer hans.   produces hormones.

1.  insulin  take glucose in blood, puts it into storage energy - glycogen.

2.  glucogan glycogen to glucoes.

 

 insulin

blood, glucose _                   glycogen

glucagon

Testes.

Seminiferous tubules produces sperm  (meiosis ® gamete).

Interstitial cell produce testosterone.

testosterone responsible for 2ndary sexual charct.

 

Ovary.

Graafian follicles produces ova  (meiosis prod. haploid gametes.

Produce hormones estrogen and progesterone.

responsible for 2ndary sexual charc., menstrual/ovarian ycle.

 

 

Lecture 18                                                                                                                    April 10

PATTERNS OF REPRODUCTION

 

Reproduction:  biological processesby which existing organism give rise to new organisms.

 

Two modes of Reprodution. 

1.  Asexual.    mitosis --1 parent

2,  Sexual.         2 parents.

 

Asexual reproduction.

1.  budding - hydra, sea anemone.

2.  fragmentation - starfish.

 

Parthenogenesis -developement of new individuals from ova that aren't fertilzed by male gamete.

1.  haplodiplody

ie: honey bees - workers  sexual reprod.  &  drones  asexual repruction.

2.  unisexual reproduction.

ie: some species of fish + reptiles entire species in white.

 

Sexual Reproduction

 

External v. Internal fertilization

 

Timing of reproduction