Consider 2 genes each with 2 alleles B and b H and h If a po

Consider 2 genes each with 2 alleles: B and b, H and h If a population is in genetic equilibrium and if 30% of sperm and eggs carry the allele B and 60% of eggs and sperm carry the allele H, what are the predicted frequencies of these offspring genotypes? SHOW YOUR WORK.

Solution

We use the Hardy-Weinberg principle to solve this problem.

If 30% of sperms and eggs are B then 70% of sperms and eggs are b

Therefore p= 0.3 and q= 0.7

Probability of B sperm meeting B egg= 0.3 X 0.3 = 0.09

Probability of B sperm meeting b egg= 0.3 X 0.7 = 0.21

Probability of b sperm meeting B egg= 0.3 X 0.7 = 0.21

Probability of b sperm meeting b egg= 0.7 X 0.7 = 0.49

Therefore the following generation, will have the following proportion of genotypes:

If 60% of sperms and eggs are H then 40% of sperms and eggs are h

Therefore p= 0.6 and q= 0.4

Probability of H sperm meeting H egg= 0.6 X 0.6 = 0.36

Probability of H sperm meeting h egg= 0.6 X 0.4 = 0.24

Probability of h sperm meeting H egg=  0.6 X 0.4 = 0.24

Probability of h sperm meeting h egg= 0.4 X 0.4 = 0.16

Therefore the following generation, will have the following proportion of genotypes:

So, if the frequencies of alleles are p and q, then according to Hardy-Weinberg Equation

p² + 2pq + q²

The frequency of BB and HH individual will be p².

The frequency of Bb and Hh individuals will be 2pq.

The frequency of bb and hh individuals will be q².