AP Biology Review

Part 2

Reproductive BarriersLeading to Speciation

• Prezygotic Barriers

• Postzygotic Barriers

1. Habitat Isolation

2. Temporal Isolation

3. Behavioral Isolation

Mating

4. Mechanical Isolation

5. Gametic Isolation

Fertilization

6. Reduced Hybrid viability

7. Reduced Hybrid fertility

8. Hybrid breakdown

Lab 8Population Genetics and Evolution

• You used the class as a sample group to look at the relationship between violating a Hardy-Weinberg condition and the changes in allele frequency.

• Evolution here is defined as change in allelic frequency. • Hardy and Weinberg independently suggested a way to view

evolution as changes in frequency of alleles in a population.• If certain conditions are met the allele and genotype frequencies will

remain constant from generation to generation. They are:• Hardy-Weinberg Conditions

– Large Population– Random Mating– No Mutation– No immigration or emigration– No selection

Hardy Weinbergp2 + 2pq + q2 = 1

• Total of all alleles p + q = 1

• p = A allele, q= a allele

• p2 = AA homozygote (dominant)

• pq = Aa heterozygote

• q2 = aa homozygote ( recessive)

4% of a sheep population has black wool, 96% white. If black wool is recessive what % of the

population is heterozygous?

• q2=.04

• q = √.04= .2

• 1-q = p

• 1-.2= .8

• So q= .2 p=.8

• Substitute in 2pq

• 2 (.8) (.2) = .32 or 32%

4% of a sheep population has black wool, 96% white. If black wool is recessive what % of the

population is heterozygous?

• What % of the population is homozygous for white wool?

• Substitute in for p2

• .82= .64 = 64%

A Few Genetics Terms• Autosomal traits- on non-sex chromosomes.• Sex-linked-genes on sex chromosome• sex-influenced- trait that appears differently in different sexes. On

autosomes.• Sex-limited- characteristic appearing exclusively in one sex but

whose gene is usually on an autosome.• Allele- form a trait can take.• Test cross-cross between an unknown genotype with a pure

recessive for the trait (you always know the genotype from the phenotype).

• Linked genes- on same chromosome. Won’t show classic mendelian ratio.

• Crossing over- exchange between homologous chromosomes.

A Few more genetics termsInteraction between alleles:

1. Complete dominance- one allele appears phenotypically if present.2. Incomplete dominance- The phenotype is intermediate between the

dominant and recessive form, often due to ½ the product of the gene being produced.

3. Codominance- both alleles are fully expressed.4. Multiple alleles- more than two alleles for a gene are found within the

population (not within an individual).5. Epistasis- one gene alters the effect on another gene.6. Polygenic inheritance- many genes contribute to a phenotype.7. Pleiotrophy- one gene can effect several phenotypic traits.8. Environmental Influence- where the genotype and environment

interact to determine the final phenotype.

Lab 7 Genetics of drosophila

• You collected data from a fruit fly cross and analyzed results,• Drosophila have 4 pairs of chromosomes.• They show complete metamorphosis-egg, larvae, pupa, adults.

• We looked at three types of crosses:1. monohybrid-single contrasting pair of characteristics.2. Dihybrids-two pairs of contrasting traits are considered

simultaneously.3. Sex-linked-mutant characteristic associated with the X

chromosome. (white eyes).

P=generation-pure parentsF1= offspring of the P generationF2= offspring of the F1 generation

Lab 7 Genetics of drosophila-analysis

• You counted e.g.: 67 red eyed flies33 sepia flies

• You would expect 3:1 ratio– 100 x ¾ = 75 (100 is the total number of flies)– 100 x ¼ = 25

• Chi- square- statistic used to see if your results are close enough to the expected results to be acceptable (significant)

• X2 = ∑ (o-e)2 o= observede e= expected

Lab 7 Genetics of drosophila-analysis

• X2= (67-75)2 + (33-25)2 = 3.41

75 25

Determine degrees of freedom

Categories – 1 So 2-1 =1

If probability from the Chi-Square table is greater than your value you may accept your null hypothesis-

“There is no statistically significant difference between your observed and expected data.”

Genetics question• A male fruit fly with red eyes and long wings was

mated with a female with purple eyes and vestigial wings. All of the offspring in the F1generation had red eyes and long wings.

• These F1 flies were test crossed with purple- eyed vestigial winged flies. Their offspring, the F2 generation, appeared as indicated below:

• 125 red eyed, long winged• 124 purple eyed, vestigial winged• 18 purple eyed, long winged• 16 red eyed, vestigial winged

Genetics question• Knowns: Purple and vestigial are recessive- The

F1 generation in a dihybrid cross shows the dominant trait because all of the organisms are hybrid. This was a special cross, it was a test cross in the F1 generation.

• P cross was : p+p+v+v+ x ppvv• F1 generation was: p+pv+v (all red & long)• F1 test cross was p+pv+v x ppvv

• p= purple v= vestigial• P+ = wild red v+ = wild long

Genetics question

• F2 p+v+ p+v pv+ pv

pv p+pv+v p+p+vv ppv+v ppvv

Red, Long

Red, Vestig.

Purple

Long

PurpleVestig.

This cross does not show a typical 9:3:3:1 ratio of a dihybrid cross. Nor does it show the 1:1:1:1 ratio predicted from the Punnett Square (see above). The number of parental types seen in the F2 is large and indicates there is linkage of the two traits. They are on the same chromosome. Crossing over is responsible for the few recombinants.

Lab 4Plant Pigment and Photosynthesis

• Part I: You separated plant pigments using chromatography.• Part II: You measured the rate of photosynthesis is isolated

chloroplasts.• We used a blue dye, DPIP. When it is reduced (OIL RIG) it goes

from blue to clear.• Electrons usually reduce NADP but reduce reduce DPIP instead in

this setup.• You measured % transmittance of light using the cholorimeter.• You compared rate of

– Unboiled in the dark (no light to excite the electrons)– Unboiled in the light – Boiled in the light ( chloroplast membranes were disrupted)– No Chloroplasts (Control)

Plants• Meristems-generate cells throughout the plants life.

– Apical- extend roots and shoots (Primary Growth)– Lateral- add girth (secondary growth)

• Transport tissues– Xylem-water and minerals– Phloem- carry sugar

• Xylem is made of: – Tracheids- long thin– Vessel elements- wider, shorter– Both are dead at functional maturity

• Movement of water from roots to leaves occurs by– Bulk-Flow- the movement of fluid driven by a pressure difference at

opposite ends of a conduit.– The pressure difference is generated at the leaf end by transpirational

pull ( lower pressure) at the leaf end.– Water pulled tight against the cell walls in the air spaces of the leaf

cause the negative pressure which draws water up xylem.

PlantsAlternation of Generations

Sporophyte Generation (2n)

Gametophyte Generation (n)

Sporophyte

Gametophyte

Spore

Zygote

Fertilization

Meiosis

Gametes

♀ ♂

Major Branches of the Animal Kingdom

Animals

“Porifera”Sponges

SubkingdomEumetazoa

Radiata-”Cnidarians”Radial Symmetry

Bilateria(bilateral symmetry)Cephalization3 germ layers

Coelomate

Have a true coelom- a body cavity lined with tissue of mesodermal origin

Protostomes

Mollusks, Annelids and Arthropods

-Spiral Cleavage (cell divisions are along a diagonal line)

-Determinate (cell fate is established early)

Mouth forms from blastopore

Schizocoelus (solid masses of mesoderm form coelom)

Deuterostomes

Echinoderms and Chordates

-Radial Cleavage (cell divisions line up with the original cell divisions).

-Indeterminate (allows for identical twins!)

-anus forms from blastophore

-Enterocoelous (outpockets of the archenteron form the coelom)

Acoelomate

No cavity between the gut and the body wall.

Flatworm “Platyhelminthes”

Pseudocoelomatea

Rotifer-Coelom not completely lined by mesoderm

Germ Layers and Their Derivatives

There are three germ layers

Ectoderm

Endoderm

Mesoderm

Germ Layers and Their Derivatives

• Ectoderm– Epidermis and associated parts hair and nails– Lens and retina of the eye– Enamel of teeth– Nerve Cells– Medulla of the adrenal gland– Inner Ear

Germ Layers and Their Derivatives

Endoderm• Inner lining of

– Alimentary Canal– Lungs– Middle ear and eustachian tube– Gallbladder– Lung tubes– Urethra– Urinary Bladder

• Bulk of– Thyroid– Parathyroids– Thymus (where immune cells mature)– Pancreas– Liver– Prostate Gland

Germ Layers and Their Derivatives

• Mesoderm– Dermis of skin– Connective tissue– Cartilage– Bone– Lymphoid Tissue– Blood– Blood Vessels– Heart– Skeletal Muscles– Smooth Muscles– Kidneys– Testes– Ovary– Cortex of the Adrenal Gland

A partial list for all germ layers.

Operons

• In Prokaryotes• Region of a chromosome where a set of genes

are transcribed at one time.• Allows all of the enzymes needed for a pathway

to be present at once.• Two Types

– Inducible are usually off but can be turned on. Like the lac operon.

– Repressible are usually on but can be turned off. Like the trp operon.

Muscle Contraction

• Sliding Filament Theory of Contraction– Thick (myosin) and thin (actin) myofilaments slide past one

another shortening the muscle.– Control- Ca++ from the sarcoplasmic reticulum floods the

muscle fiber when depolarized by a nervous impulse. The Ca++ moves the regulatory protein (tropomyosin) out of the way, by binding to troponin, allowing the cross bridges to form.

• Functional unit: Sarcomere• Muscle fibers can be slow-twitch (slow to fatigue) or fast

twitch ( quick source of power)• Cardiac muscle-interconnected• Smooth muscle-lack myofilament organization, but still

use sliding filament theory.

Circulatory System

• Open or closed (kept in vessels, all vertebrates).– No separate blood and lymph in the open system (like insects).

Fluid is not called blood. It is hemolymph.• Blood vessels carry blood

– Plasma-carries ions, proteins, hormones and metabolites.– Formed elements of the blood are erythrocytes (red blood cells)-

carry O2

– Leukocytes (white blood cells)-fight infection.– Platelets-cell fragment function in blood clotting.

• Blood Vessels– Arteries carry blood away from the heart, Veins to,

• Lymphatic System returns interstitial fluid to the bloodstream. Moves through lymph nodes where many cells of the immune system search for antigens

Evolution of the Heart

• Fish-– Single loop- to the gills, body, gills– Two chambered heart

• Amphibians and reptiles– Double loop– Three chambered heart

• Mammals and birds– Double loop– Four chambered heart– Better for active animals-keep oxygenated and

deoxygenated blood separate,

Lab 11aAnimal Behavior

• You looked at the response of organisms to environmental variables.

• Ethology is animal behavior• Behavior may be

– Learned– Innate (inherited)

• Orientation Behaviors- help animal find the most favored environment.– Taxis-toward or away from a stimulus– Kinesis- random movement-not orienting toward a stimulus.

• Agonistic behavior– Animal response that is aggressive or submissive.

• Mating behavior– Complex behaviors that promote continuing the species.

Lab 11BReproductive Behavior in Fruit Flies

• Mating follows a distinct behavioral pattern, a courtship pattern.– 1. Orientation– 2. Male Song (wing vibration)– 3. Licking of the female genitalia– 4. Attempted copulation– 5. Copulation– 6. Rejection (extrusion of ovipositor)

Blood Clotting

• Vessel damaged, muscle cause constriction.• Platelets adhere, form a plug

– Platelets pinch off from large cells in the bone marrow called megakaryocytes

• Enzymatic reactions below are triggered by the platelets adhering.

• Prothrombin is converted to thrombin• Fibrinogen is converted to fibrin which reinforces

the clot the platelets are forming.