Population Genetics

Question 1

Hardy Weinberg Equilibrium (what is it and what equations are used?)

Answer 1

-Connection between allele frequency and genotype frequency in population

Allele Freq: p + q=1

Genotype Freq: p^2 + 2pq + q^2 = 1

Question 2

How to decide if a population is in HWE?

Answer 2

1- Calc OBSERVED genotype frequency (based on phenotype data)
2- Convert to OBSERVED allele frequency
3- Calc predicted genotype freq if in HWE (using observed allele frequencies)

**If observed and predicted genotypes are the same then population is in HWE

Question 3

5 Factors That Disrupt HWE

Answer 3

1- Non-random mating (inbreeding or assortative mating)
2- Small population size (genetic drift, founder effect)
3- Migration
4- Mutation
5- Selection

**All must be happening in CURRENT generation

Question 4

Why is Inbreeding so Bad?

Answer 4

-Increases homozygosity in all loci across genome

Question 5

Assortative Mating

Answer 5

Preferential mating w/ same phenotype (height, deafness, intelligence, socioeconomic status)

-Less dangerous than inbreeding because only genes involved in these preferences are not in HWE

Question 6

Genetic Drift

Answer 6

-If population is really small then allele frequency will change from one generation to the next simply due to CHANCE

Question 7

Founder Effect

Answer 7

New population will have diff gene frequencies than parent population (where founders came from)

Question 8

Mutation-Selection Balance

Answer 8

• Mutation = introduce new disease-causing variation
• Selection = removes disease causing variation b/c person w/ disease does not reproduce
• Dom diseases almost always caused by new mutation b/c mutation introduced and selected against all b/f mutation can be passed to next generation
• Rec alleles more common b/c carriers are not selected against

Question 9

Heterozygote Advantage

Answer 9

-When disease-causing allele is more common than you would predict –> selection favors heterozygotes over both homosygotes (hetero must provide some sort of protective function)

ex- sickle cell carriers and malaria