Question

You have a population of 1000 people, and you are looking at the population genetics of a blood marker that has two alleles. The dominant allele (Y) makes the protein, and the recessive allele (y) does not make the protein. When you test the blood of the population, you find: 490 people have the genotype YY. 420 people have the genotype Yy. 90 people have the genotype yy. What are the allele frequencies (Y and y)?

Answer 1

the allele frequencies (Y and y) = 0.7 and 0.3

Step-by-step explanation:

Total population = 1000

p² = 490 people have the genotype YY

2pq = 420 people have the genotype Yy.

q² = 90 people have the genotype yy.

What are the allele frequencies (Y and y)?

To calculate the allele frequencies , we need to go by Hardy Weinberg's principle;

p + q = 1

p² + 2pq + q² = 1

p is the frequency of the dominant allele.

q is the frequency of the recessive allele.

p² is the frequency of individuals with the homozygous dominant genotype.

2pq is the frequency of individuals with the heterozygous genotype.

q² is the frequency of individuals with the homozygous recessive genotype.

Frequency of the individuals =
`(individuals)/(Total population)`

=
`(490)/(1000)`

p² = 0.49

To find p, we need to look for the square root of p²

p=
`√(0.49)`

p= 0.7

Using the first Hardy-Weinberg equation p + q = 1 to solve for q.

p + q = 1

q = 1 − p

q = 1 − (0.7)

q = 0.3

∴ the allele frequencies (Y and y) = 0.7 and 0.3