In an electrophoretic study of enzyme variation in a species of pelican, you find 77 A1A1, 45 A1A2, and 18 A2A2 individuals at a particular locus in a sample of 140. What are the allele frequencies for the A1 and A2 alleles? Calculate the genotype frequencies for this locus.

Respuesta :

Answer:

Frequencies of allele [tex]A_{1}[/tex] and [tex]A_{2}\\[/tex] are [tex]0.74[/tex] and [tex]0.26[/tex] respectively.

Frequencies of Individuals with genotype [tex]A_{1}A_{1}, [tex]A_{2}A_{2} and [tex]A_{1}A_{2} are [tex]0.55, 0.128, 0.32[/tex] respectively.

Explanation:

As per Hardy Weinberg's equation -

[tex]p^{2} +q^{2} +2pq= 1[/tex] ----------Equation (A)

[tex]p+q= 1[/tex]-----------Equation (B)

Where "p" represents the frequency of "[tex]A_{1}[/tex]

"q" represents the frequency of "[tex]A_{2}[/tex]

[tex]p^{2}[/tex] represents frequency of individual  [tex]A_{1}A_{1}[/tex]

[tex]q^{2}[/tex] represents frequency of individual [tex]A_{2}A_{2}[/tex]

[tex]pq[/tex] represents frequency of  individual [tex]A_{1}A_{2}[/tex]

Here genotype frequencies are  -

[tex]A_{1}A_{1} = 77\\p^{2} = \frac{77}{140} \\= 0.55\\[/tex]

[tex]A_{2}A_{2} = 18\\q^{2} = \frac{18}{140} \\= 0.128\\[/tex]

Substituting this values in equation A, we get

[tex]0.55 + 0.128 + 2pq = 1\\2pq = 1-(0.128+ 0.55)pq = 0.321[/tex]

Frequencies of allele [tex]A_{1}[/tex] and [tex]A_{2}\\[/tex] are -

For [tex]A_{1}[/tex][tex]= \sqrt{p^{2} } \\= \sqrt{0.55} \\= 0.74[/tex]

Substituting this value in equation B, we get

[tex]p+q=1\\0.74 + q = 1\\q = 1-0.74\\q = 0.26[/tex]

Frequencies of allele [tex]A_{1}[/tex] and [tex]A_{2}\\[/tex] are [tex]0.74[/tex] and [tex]0.26[/tex] respectively.

Frequencies of Individuals with genotype  [tex]A_{1}A_{1}, A_{2}A_{2}, A_{1}A_{2}[/tex]are [tex]0.55, 0.128, 0.32[/tex] respectively.