AP Biology Review
Part 2
Reproductive Barriers
Leading 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 8
Population 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
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Large Population
Random Mating
No Mutation
No immigration or emigration
No selection
Hardy Weinberg
p2 + 2pq + q2 = 1
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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?
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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 terms
Interaction 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
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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.
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1.
2.
We looked at three types of crosses:
monohybrid-single contrasting pair of characteristics.
Dihybrids-two pairs of contrasting traits are considered
simultaneously.
Sex-linked-mutant characteristic associated with the X
chromosome. (white eyes).
3.
P=generation-pure parents
F1= offspring of the P generation
F2= offspring of the F1 generation
Lab 7
Genetics of drosophila-analysis
• You counted e.g.:
67 red eyed flies
33 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= observed
e
e= expected
Lab 7
Genetics of drosophila-analysis
• X2= (67-75)2
75
+
(33-25)2 = 3.41
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 purpleeyed 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
• P+ = wild red
v= vestigial
v+ = wild long
Genetics question
• F2
p+v+
pv
p+v
pv+
pv
p+pv+v p+p+vv ppv+v
ppvv
Red,
Long
Purple
Vestig.
Red,
Purple
Vestig. Long
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 4
Plant 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
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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.
Plants
Alternation of Generations
Sporophyte
Meiosis
Zygote
Sporophyte Generation (2n)
Gametophyte Generation (n)
♀
♂
Fertilization
Gametes
Gametophyte
Spore
Major Branches of the Animal Kingdom
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
“Porifera”
Sponges
Animals
Bilateria
(bilateral symmetry)
Cephalization
3 germ layers
Pseudocoelomatea
Subkingdom
Eumetazoa
Rotifer-Coelom not
completely lined by
mesoderm
Radiata-”Cnidarians”
Radial Symmetry
Acoelomate
No cavity between the gut and the
body wall.
Flatworm “Platyhelminthes”
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)
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
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Alimentary Canal
Lungs
Middle ear and eustachian tube
Gallbladder
Lung tubes
Urethra
Urinary Bladder
• Bulk of
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Thyroid
Parathyroids
Thymus (where immune cells mature)
Pancreas
Liver
Prostate Gland
Germ Layers and Their Derivatives
• Mesoderm
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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 11a
Animal 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 11B
Reproductive 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.