Hardy Weinberg

Question 1

what is hardy weinberg

Answer 1

mathematical representation of the relationship between genotype and allele frequencies in an ideal population

Covers an autosomal locus with two alleles:

Makes several key assumptions about the population

To deliver 2 key predictions about genotype and allele frequencies

Question 2

the 5 assumptions

Answer 2

The population is infinitely large

Random mating occurs within the population

The population is free from the effects of migration

There is no natural selection

No mutations occur

Question 3

predictions

Answer 3

When the assumptions are met:

• The genotype and allele frequencies are constant
• In the proportions p2, 2pq, q2 where p is the frequency of allele A and q is the frequency of allele a

Question 4

after one generation of random mating

Answer 4

Given any set of initial genotype frequencies after one generation of random mating the genotype frequencies in the progeny are in the proportions:
-	p2, 2pq, q2
•	Where 
-	f(AA) = pxp = p2 
f(Aa) = pxq + pxq = 2pq 
f(aa) = qxq = q2 

These are the expected frequencies of genotypes under HWE giving the relationship
- p2 + 2pq + q2 = 1

They will stay in these proportions generation after generation given random mating and the absence of factors that change allelic or genotype frequencies

Question 5

when a population obeys HW law it is said to be in what

Answer 5

Hardy Weinberg Equilibrium

Question 6

when a population is in HWE

Answer 6

genotypes frequencies can be predicted from allele frequencies

Question 7

when is HW law true

Answer 7

in populations where all the assumptions are met

It may also be true/ approximately true in some populations where assumptions are not met

Question 8

what does linkage describe

Answer 8

when alleles are not passed independently to the next generation

Question 9

what does linkage violate

Answer 9

the law of independent assortment

Question 10

when does linkage usually occur

Answer 10

with alleles that are physically close on the same chromosome

Question 11

what does HWE describe

Answer 11

a state of independence between alleles at one locus

Question 12

what does linkage equilibrium describe

Answer 12

a state of independence between alleles at different loci

Question 13

what is linkage disequilibrium

Answer 13

the non-random association of alleles at different loci

Question 14

linkage equilibrium/linkage disequilibrium

Answer 14

If there is no linkage disequilibrium between alleles at different loci they are said to be in linkage equilibrium

Question 15

how is linkage disequilibrium caused

Answer 15

by linkage or by other population genetic effects such as population subdivision

Question 16

p and q meanings

Answer 16

p + q = 1

p2 + 2pq + q2 = 1

p = frequency of the dominant allele in the population
q = frequency of the recessive allele in the population

p2 = percentage of homozygous dominant individuals
q2 = percentage of homozygous recessive individuals
2pq = percentage of heterozygous individuals

Question 17

what happens if a population is not in equilibrium

Answer 17

one generation of random mating will return the population to equilibrium.

Question 18

see powerpoint for

Answer 18

example questions