Question

In a population $N_{AA}$ and $N_{aa}$ are the numbers of homozygous individuals of allele ‘$A$’ and ‘$a$’, respectively and $N_{Aa}$ is the number of heterozygous individuals. Which one of the following options is the allele frequency of '$A$' and '$a$’ in a population with $N_{AA}=90,N_{Aa}=40$ and $N_{aa}=70$?

• A. A = 0.55 and a = 0.45
• B. A = 0.40 and a = 0.60
• C. A = 0.35 and a = 0.65
• D. A = 0.25 and a = 0.75

Answer 1

Answer: (A)

Allele A frequency
$=\frac{2N_{AA}+A_a}{2N}$
Total number of individuals in population $=N$
$N=90+40+70=200$
$N=200$
$A=\frac{2\times 90+40}{2\times 200}$
$=\frac{180+40}{400}$
$=\frac{220}{400}=0.55$
Allel 'a' frequency $=\frac{2N_{aa}+A_a}{2N}$
$a=\frac{2\times 70+40}{2\times 200}$
$=\frac{140+40}{400}$
$=\frac{180}{400}=0.45$
So,$A=0.55$
$a=0.45$