Lecture 22C Flashcards
what does population genetics focus on
allele and genotype frequencies and how they change overtime
how do we keep track of evolution?
Allele frequency(phenotype)
what are the 5 evolutionary processes
genetic flow
genetic drift
natural selection
mutation
sexual selection
HWE
stable allele frequency
hwe explains
The gene pool remains stable, and there are no new mutations introducing new alleles
hwe conditions
no mutation
Random mating (no sexual selection or inbreeding)
No natural selection
No gene flow
no genetic drift
Large population size
when considering w single cross, )/3 gametes produced by
parents
when considering a population use gametes produced by
all members of population
p and q are the frequencies of the
A and a alleles of the population
who was the hwe derived by
george hardy and wilhelm weinberg
what year did hwe come about
1908
The hardy Weinberg principle states that, after one generation of random mating, genotype frequencies for two alleles at one gene will be
p^2, 2pq, and q^2
what does q equal in hwe
frequency
p^2 is
frequency
2pq is
heterozygous genotype
q^2 is
homozygous recessive genotype
p^2+2pq+q^2=?
1
where does the 2 come from in 2pq
there are 2 ways to make the heterozygous genotype
what frequencies remain constant in succeeding generations if specific conditions are met
allele and genotype
a gene in hwe
is not evolving
instead of A and a in Hwe we use
A1 and A2
Consider a population with a frequency of allele A1 = 0.2
and allele A2 = 0.8. If this population is in Hardy-Weinberg equilibrium (HWE), what is the EXPECTED frequency of each genotype (A1A1, A1A2, and A2A2)
A1A1:(.2)^2= .04
A1A2=2(.2)(.8)=2(.16)= .32
A2A2= (.8)^2 =.64
The Amish population of Pennsylvania has a high incidence of polydactyly (extra fingers or toes). This is caused by a single dominant allele. In one population, 36 percent of children are born with polydactyly.
Assuming Hardy-Weinberg Equilibrium, the frequency of the dominant allele in the population is
100-36= 64
sqrt64= .8
p=1-q
1-.8=(.2)!!!
HW focuses on one
gene at w time
