genetics chapter 18

gene pool

the collection of all alleles in the members of the population

population genetics

the study of the genetics of a population and how the alleles vary with time

gene flow

alleles can move between populations when individuals migrate and mate

f(AA)=

# of AA individuals/# of total individuals

f(Aa)=

# of Aa individuals/# of total individuals

f(aa)=

# of aa individuals/# of total individuals

f(AA)=

nAA/N

f(Aa)=

nAa/N

f(aa)=

naa/N

genotypic frequencies

the frequency of each type of homozygote and heterozygoe in the population

frequency of an allele=

# of particular allele/total # of alleles in the population

what can allelic frequencies be calculated from?

genotype frequencies

how do you find allelic frequencies?

p=f(A)=(2nAA +nAa)/2N diploid
q=f(a)=(2naa+nAa)/2N

how many times do you have to count chromosomes in allelic frequencies?

twice

how do you find allelic frequencies from genotype frequencies?

p=f(A)=f(AA)+1/2f(Aa)
q=f(a)=f(aa)+1/2f(aa)

hardy-weinberg law

describes the effect of reproduction on genotypic and allelic frequencies

Assumptions of Hardy-Weinberg

1. large population
2. random mating
3. no mutation
4. no migration
5. no natural selection

what happens when the assumptions of hardy-weinberg are met?

reproduction alone does not alter allelic or genotypic frequencies

which of the following is an assumption of the hardyt-weinberg law?

the population randomly mates

What is Hardy-Weinberg equilibrium?

a condition in which allele frequencies remain constant

How is the Hardy-Weinberg principle expressed mathematically?

p+q=1

f(A)=

p

f(a)=

q

f(AA)=

p^2

f(Aa)=

2pq

f(aa)=

q^2

what conclusion can be drawn from hardy-weinberg equillibrium?

random mating will produce genothyps of the next generation in proportions p^2(AA), 2pq(Aa), q^2(aa)

you want to know the allele frequencies for alleles B and b. The frequency of allele B you caluclate as 0.55. What is the allele frequency of b?

0.45