Population Genetics and Hardy- Weinberg Equilibrium

Population genetics

• the study of the genetic composition of populations

• how and why allele frequencies change over time within and between populations.

The genotype frequency of aa is:
a. 0.2
b. 0.3
c. 0.5
d. 0.75

c. 0.5

The allele frequency of “a” is:
a. 0.2
b. 0.3
c. 0.5
d. 0.65

d. 0.65

gene pool

is the set of all genes (alleles) in a population.

Dominant alleles will increase in frequency over time.
a. TRUE
b. FALSE

b. FALSE

Hardy-Weinberg Equation assumes

• No selection (each allele has equal “fitness”)

• Random mating

• No migration in or out of the population

• No mutation (no new alleles)

• Large population size

• organisms are diploid

Evolution

Changes in allele frequency of a population over (generational) time

Consider a population with 2 alleles at a particular locus:
Freq (Allele 1) = 0.6
Freq (Allele 2) = 0.4
If this allele was under HWE, what is the expected frequency of A1A2 heterozygotes?
a. 0.62
b. 0.42
c. 0.6 0.4
d. 2 0.6 * 0.4
e. not possible to determine without genotype information

d. 2 0.6 * 0.4

How many of the 8088 white Bing students are expected to be carriers for CF the CFR1 alleles are at HWE?

Let’s assume that: 1/3000 white students have CF

283.08

*Both heterozygotes and homozygotes are symptomatic, where homozygotes typically have the more severe symptoms. What type of relationship do the wildtype and rs671 alleles have? a) WT is dominant to rs671
b) rs671 is dominant to WT
c) Incomplete dominance
d) Codominance

c) Incomplete dominance

In a sample population, you find 75% of individuals have at least 1 allele of rs671.
What is the allele frequency of rs671 in this population (assuming HWE)?
a. 𝟏 − 厂𝟏/𝟏𝟔 = 0.75
b. 𝟏 − 厂𝟏/𝟐 = 0.707
c. 厂𝟏/𝟏𝟔 = 0.25
d. 𝟏 − 厂𝟏/𝟒 = 0.5
e.Cannot be determined without knowing the population size

d. 𝟏 − 厂𝟏/𝟒 = 0.5

Consider a population with 3 alleles at a particular locus:
Freq (Allele 1) = 0.5
Freq (Allele 2) = 0.3
Freq (Allele 3) = ?
What is the frequency of allele 3?
a. 0.2
b. 0.3
c. 0.4
d. not possible to determine without genotype information

a. 0.2