Calculate the composition of an ideal population if 1 out of 400 individuals has aa genotype

1) g2 = 1/400 (frequency of the homozygous genotype for the recessive allele);
2) the frequency of the recessive allele a will be equal to:
g =, i.e. 1 part (one allele) out of 20;
3) the frequency of the dominant allele will be: 20 – 1 = 19;
4) the composition of the population: (p + g) 2 = p2 + 2pg + g2.
(19 + 1) 2 = 192 AA + 2 x 19 Aa + 12 aa = 361 AA + 38 Aa + 1 aa.
Answer: 361 AA: 38 Aa: 1 aa.