Genetics Exam Iii: Hardy Weinberg Equilibrium

Front 1

Allele frequences for the Hardy Weinberg Equilibrium Principle

Back 1

p = freq of A (dominant)
q = freq of a (recessive)
p + q = 1

Front 2

What is the frequency for heterozygotes?

Back 2

2pq

Front 3

What is the frequency for the dominant trait?

Back 3

p2 + 2pq

Front 4

Why is the H-W an equilibrium?

Back 4

The equilibrium of the alleles stays the same throughout the population

Front 5

Assumption of the H-W equilibrium

Back 5

1. 2 alleles
2. Random mating
3. Large population
4. No migration, new mutations, natural selection

Front 6

X-linked genes

Back 6

Males have 1/3 of all x alleles and females have 2/3 of all x alleles

For affected males, phenotype frequency equals q.

Front 7

Non-random mating

Back 7

pple do not generally mate randomly.
1. Pple mate w/ those of the same ethnicity
2. pple do not mate w/ pple far away
3. Assortive mating-pple choose a mate based on some commonality.
4. Consanguinity

Front 8

mating between pple with increased relatedness increases the chances of retention of recessive traits in a population.

Back 8

Consanguinity

Front 9

Traits that kill individuals before mating occurs and prevents alleles from being passed on.

Homozygous traits

Back 9

Negative selection

Front 10

Heterozygous advantage

Back 10

-Maintains alleles
Some autosomal recessive traits are negative but confer advantage to the heterozygote.
-ie: Sickle cell trait, resistant to malaria
-Heterozygotes keep the trait at a higher frequency than expected.

Front 11

new mutation

Back 11

New alleles in a population do occur

Front 12

Genetic Drift & Founder Effect

Back 12

If the pop. splits, there may be more mutants in oen pop. than other

Front 13

Drift down

Back 13

If there are more mutations

Front 14

Drift up

Back 14

If some mutations disappear

Front 15

Founder effect (a special case of drift)

Back 15

Population bottleneck (small group splits off)

Front 16

Migration

Back 16

This is not necessarily physical movement of an entire population

This can occur into a population or out of a population

Front 17

Bias of ascertainment

Back 17

Did we really count accurately

-Some do not represent phenotypically, dec. penetrance, phenocopies, and inaccurate reporting

Front 18

List the factors that affect the HW equilibrium?

Back 18

1. Nonrandom mating
2. Selection Pressure
Negative selection
Heterozygous advantage
3. New mutations
4. Genetic Drift & Founder effect
5. Migration
6. Bias of ascertainment