Cycle 6 (Workshop + Study Session) Flashcards
Define:
Allele
Slight variation of the same gene (gives different genotype/phenotype)
Define:
Locus
Location of gene on a chromosome
Define:
Gene pool
Collection of all possible alleles for a particular gene
What the are the key points of Mendelian Inheritance?
Use Punnett squares
Predicts offspring genotype/phenotype
What assumptions are made in Mendelian Inheritance?
Population “in equilibrium”
Random crosses
No selection for/against anything
True or False:
Mendelian Inheritance is accurate in real populations
False, Mendelian Inheritance is not applicable to all populations
Define:
Genotype frequency
How common is that genotype in the entire population
Define:
Allele frequency
How common is that allele in the entire population
Calculate:
In a population of 2000, if we have 400 P alleles, what frequency does the P allele occur?
0.2
What do we call the conditions where the population isn’t undergoing any changes, thus Mendel’s principles are able to be applied?
Hardy-Weinberg Equilibrium
If the ________ frequencies that come out of your cross _______ the ________ frequencies you calculated with the original data, that population is in ___
Genotype
Matches
Genotype
HWE
What will disrupt HWE?
Selection
Mutation
Migration
Genetic Drift
Non-random mating
How does selection disrupt HWE?
Perhaps for or against a phenotype
How does mutation affect HWE?
New alleles are made
How does migration affect HWE?
New alleles may enter the population, old ones may leave, or something similar
How does genetic drift affect HWE?
A sudden, massive change to the allele frequencies
How does non-random mating affect HWE?
For example, inbreeding causes certain members of a population preferentially mate instead of completely randomly
State the Hardy-Weinberg Principle
p^2 + 2pq + q^2
What does the p^2 stand for? 2pq? q^2
Frequency of homozygous dominant genotype
Frequency of heterozygous genotype
Frequency of homozygous recessive genotype
True or False:
p + q must equal 1 in Hardy-Weinberg Principle
True
Define:
Absolute fitness (W)
Number of surviving offspring (that reproduces) for each genotype
True or False:
Absolute fitness is not a measurable quantity
False, absolute fitness is a measurable quantity
Define:
Relative fitness
Absolute fitness divided by absolute fitness of the most fit genotype
Give an example of an absolute fitness
Number of eggs
The most fit genotype has w = _
1
All other genotypes besides the most fit genotype has w < _ (_ / _____)
1
W / Wmax
Determine type of selection by comparing relative fitness:
w(YY) < w(Yy) > w(yy)
Heterozygote advantage
Determine type of selection by comparing relative fitness:
w(YY) = w(yy) > w(Yy)
Heterozygote disadvantage
Determine type of selection by comparing relative fitness:
w(YY) = w(Yy) > w(yy)
Dominant advantage
Determine type of selection by comparing relative fitness:
w(YY) = w(Yy) < w(yy)
Recessive advantage
Determine type of selection by comparing relative fitness:
w(YY) = w(Yy) = w(yy)
No selection
Does the dominance status of an allele that is not related to fitness affect its frequency over time?
No it does not
Define:
Dominance status
Dominant or recessive favoured
Determine relative fitness of selection against dominant allele and its effects
w(AA) = w(Aa) < w(aa)
Overtime, dominant allele will be removed from the population
No presence of homozygous/heterozygous dominant phenotype, only homozygous recessive phenotype
Determine relative fitness of selection against a recessive allele and its effects
w(AA) = w(Aa) > w(aa)
Overtime, frequency of recessive allele decreases but never disappears completely
Frequency of recessive phenotype will occur occasionally, but will be removed quickly due to selection
Determine relative fitness of heterozygote advantage and its effects
w(AA) < w(Aa) > w(aa)
Allele frequencies will stabilizes near 0.5
Once stabilized, selection is still occurring but evolution is not
Genetic variation maintained (balancing selection)
In Heterozygote advantage, allele frequencies will stabilize near ___. Once frequencies stabilize, _________ is occurring, but _________ is not
0.5
Selection
Evolution
True or False:
In heterozygote advantage, genetic variation is not maintained
False, in heterozygote advantage, genetic variation is maintained
What is maintained genetic variation called?
Balancing selection
Determine relative fitness of heterozygote disadvantage and its effects
w(AA) = w(aa) > w(Aa)
More common allele frequency increases to 1, less common allele vanishes
Rare allele disappears not because it’s harmful, but they are most likely to be found in heterozygotes
Genetic variation decreases
In heterozygote disadvantage, the more common allele frequency __________ to _, less common allele _________
Increases
1
Decreases
In heterozygote disadvantage, rare allele disappears. Why?
They are most likely to be found in heterozygotes
Genetic variation decreases in:
Heterozygote disadvantage
True or False:
Most phenotype are quantitative phenotypes
True
What are quantitative phenotypes?
Quantitative means expressed with a distribution in population
What are qualitative phenotypes?
Can be described a category
What are types of quantitative selection?
Directional selection
Stabilizing selection
Disruptive selection
Balancing selection
True or False:
Selection doesn’t always mean evolution
True
Evolution is occurring, if _______ ___________ are changing
Allele frequencies
How can selection occur without changing the overall frequencies?
One example could be heterozygote advantage
What is assortative mating also known as?
Inbreeding
What is dissociative mating known as?
Inbreeding avoidance
Define:
Inbreeding
Organisms that mate with similar phenotypes
What effect does assortative mating have?
Increases homozygosity (the amount of homozygotes, could result in inbreeding
True or False:
Inbreeding changes allele frequencies
False, inbreeding changes genotype frequencies
Inbreeding causes ____ __ ______________, but allele frequencies are the ____
Loss of heterozygosity
Same
True or False:
Associative/inbreeding decreases variability
True
Dissociative/inbreeding avoidance increases ___________ or _____________
Variability
Heterozygosity
List the consequences of assortative mating
Increase in homozygosity
Increases probability of harmful recessive alleles to be expressed
List the consequences of disassortative mating
Increase in heterozygosity
Can work with selection to select for advantageous phenotypes
What is the “increase probability of harmful recessive alleles to be expressed” also known as?
Inbreeding depression
Describe stabilizing selection
Culls extreme variations
Narrows width of distribution
Describe:
Directional selection
Favours one extreme
Shifts distribution left/right
Describe:
Disruptive selection
Favours both extremes
Creates bimodal distribution
Define:
Random sampling error
An error that occurs in small populations
In genetic drift, allele frequencies change due to ______
Chance
Give examples of genetic drift
Population bottlenecks
Founder effect
True or False:
In genetic drift, over many generations, one allele may completely disappear or completely take over
True
Define:
Bottleneck
Catastrophic reduction in population, small number survive
Define:
Founder effect
Only small number will move to a different environment, start new pop there