Biology Ch. 5 and 6 Flashcards
Capacitation
Final maturation step of sperm once inside female reproductive tract.
Enzymes in the uterus and fallopian tubes remove the glycoprotein coat of sperm, revealing the acrosome and making the sperm hyperactive.
Fertilization Process
Sperm pushes through corona radiata.
ZP receptors determine if it is same species.
ZP3 triggers acrosome reaction, which releases acrosin to break through the zona pellucida.
Sperm head enters perivitelline space and fuses with the plasma membrane.
Fast and Slow Blocks to Polyspermy
Fast: Na channels open immediately after fusion, which causes depolarization of the egg membrane and prevents entry of more sperm for short period of time.
Slow: aka cortical reaction. Depolarization causes Ca2+ release from ER, which triggers exocytosis of cortical granules. This causes swelling of the perivitelline space and inactivates ZP receptors.
After the slow block, a second meiotic division of the egg is completed.
Phases of Arrest in Oogenesis
Primary oocytes begin meiosis and are arrested at prophase 1 during development.
During puberty, hormones cause one primary oocyte at a time to continue meiosis and become a secondary oocyte.
The secondary oocyte is arrested in metaphase 2.
If the secondary oocyte is fertilized, it will continue the rest of meiosis.
Cleavage
Rapid cell division without growth (making slices in a pizza).
Cleaved cells are called blastomeres.
Types of cleavage in Protostomes and Deuterostomes
P: determinant, spiral.
D: indeterminant, radial.
Morula
Blastula
Gastrula
M: 16-32 blastomeres; becomes blastula thru blastulation.
B: hollow ball of cells; becomes gastrula through gastrulation.
G: invagination called blastopore begins to form; will either become mouth or anus.
Archenteron
Space caused by the blastopore in gastrula
Gray Crescent
In amphibians.
After fertilization, cytoplasm rotates 30 degrees to form gray crescent.
Cells in the grey crescent are vital in development and can develop into an entire organism.
Neurulation
Notochord stimulates overlying ectoderm to thicken, forming the neural plate.
The neural plate folds inward and pinches off to form the neural tube, which becomes the brain and spinal cord.
Ectoderm Derivatives
Epidermis
Adrenal Medulla
Jaw and teeth
Sensory system
Nervous system
Skull bones, muscles, and connective tissue.
Endoderm Derivatives
Epithelial lining of GI, respiratory, excretory, and reproductive tracts.
Thyroid
Parathyroid
Thymus
Liver
Pancreas
Mesoderm Derivatives
Bones, cartilage, muscles, connective tissue.
Adrenal cortex
urogenital organs, kidneys, spleen
heart, circulatory, lymphatic systems
Notochord
Simple vs. Complex Reflexes
S: 2 nerves, controlled at spinal cord.
C: 3 nerves (interneuron) controlled at brain stem/cerebrum.
Imprinting
Specific type of irreversible learning in young animals if the appropriate stimulus is experienced during critical/sensitive period.
Ex: baby geese recognizing something that moves as their mother.
Fixed Action Patterns
Sequence of instinctive behavior initiated by sign stimuli.
The action will usually be completed even if original stimulus is removed.
Insight
Behavior with positive outcome performed in response to novel situation never encountered before.
Operant Conditioning
Connection of own behavior to reward or punishment.
Positive: giving
Negative: taking away
Habituation vs. Sensitization
H: Decrease in response to stimulus after repeated exposure without consequences.
S: increased response to stimulus; opposite of habituation.
Mating Systems:
Semelparity
Iteroparity
S: one reproductive event during life; lots of offspring with low survival rate.
I: repeated reproduction; few but large offspring with high survival rate.
Survivorship Curves
Type I: most survive to middle age and die quicker after that; K selected (humans).
Type II: length of survivorship is random (birds).
Type III: most die young, and few survive to reproductive age and beyond; R selected(plants).
Biomagnification
as one organism eats another, toxins become more concentrated at higher trophic levels.
Eutrophication
Process where water becomes enriched with excess nutrients and biomass increases.
Leads to water being depleted of oxygen and death of aquatic organisms.
Primary vs. Secondary Succession
1: occurs on substrates that never previously supported living things.
2: occurs where communities were entirely/partially destroyed by a damaging event.
Fundamental Niche vs. Realized Niche
F: niche that an organism occupies where there are no competing species present.
R: smaller subset of the niche that species occupy when competition is present.
Fitness
Ability of an offspring to survive and produce fertile offspring.
Stabilizing Selection
Directional Selection
Disruptive Selection
S: bell curve favors an intermediate.
Dir: favoring of traits at one extreme, while traits at the other extreme are selected against.
Dis: traits at either extreme are favored while moderate/common traits are selected against.
Founder Effect vs. Bottleneck Effect
F: small group of individuals migrate to a new location; small gene pool; after several generations, the genetic makeup will be different than original population.
B: population undergoes dramatic decrease in size due to natural catastrophes; gene pool is smaller and subject to genetic drift.
Gene Flow vs. Genetic Drift
GF: introduction and removal of alleles from the population when individuals leave or enter the population.
GD: random increase and decrease of an allele by chance; larger effect on small populations.
Requirements for Hardy-Weinberg Equilibrium
- No mutations
- No natural selection
- No gene flow
- Large population
- Random mating
Hardy-Weinberg Equation
p^2 + 2pq + q^2 = 1
p^2: frequency of homozygous dominant
2pq: frequency of heterozygous
q^2: frequency of homozygous recessive
p + q = 1
p: freq of domininat
q: freq of recessive.
Sources of Genetic Variation
Mutation
Sexual Reproduction
Balanced polymorphism
Diploidy
Homologous vs. Analogous Structures
H: body parts that resemble one another between different species descended from a common ancestor.
A: body parts that resemble one another between different species that evolved independently. ( bat and bee wings).
Divergent Evolution
formation of two or more species that descend from a common ancestry and become increasingly different over time (results of speciation).
Convergent Evolution
Two unrelated species independently evolving similar traits as a result of having to adapt to similar environments (analogous traits)
Parallel Evolution vs. Coevolution
P: two related species develop similar adaptations or traits after their divergence from a common ancestor.
C: two or more species having a close ecological relationship evolve together in response to new adaptations that appear in another species (predator/prey).
Allopatric vs. Sympatric Speciation
A: population is divided by a geographic barrier.
S: occurs without the presence of a geographic barrier (polyploidy).
Prezygotic vs. Postzygotic Reproductive Isolation
Pre: happens before zygote is formed.
Post: happens after zygote is formed.
Mullerian vs. Batesian Mimicry
M: two or more harmful species that are not closely related but share common predators mimic each other’s warning signals.
B: harmless species has evolved to imitate the warning signals of harmful species directed at a common predator.
