Answer this properly please. In a particular Caucasian population 1 in 3,000 peo

Question

Answer this properly please.

In a particular Caucasian population 1 in 3,000 people have the autosomal recessive disorder Cystic Fibrosis. Assuming the population is in Hardy-Weinberg equilibrium, (i) What are the allele frequencies for the mutant (M) and normal (N) alleles? (ii) What is the carrier frequency in the population? (iii) Name three of the theoretical conditions that must be met for the Hardy-Weinberg equation to be applied. (B) In a second, distinct population the following genotypes are observed: NN-608, NM -384, MM - 8 What are the observed frequencies of the M and N alleles in this population?

Explanation / Answer

1 in every 3000 Caucasians gets cystic fibrosis. It is an autosomal recessive disorder. So, 1 in every 3000 has recessive genotype (ff).

According to HWE,

p2 +2pq+q2 =1.

Here p2 is frequency of FF genotype

2pq is frequency of Ff genotype. These are cystic fibrosis allele carriers.

q2frequency of ff genotype

Frequency of ff genotype = q2 = 1/3000 = 0.00033333333

Frequency of f allele = q = 0.01825741858

Frequency of F allele + frequency of f allele = 1

Frequency of F allele (p) = 1-0.01825741858= 0.98174258141.

According to HWE,

p2 +2pq+q2 =1.

p2=0.981742581412 = 0.96381849615

2pq = 2 x 0.98174258141x 0.01825741858 = 0.03584817049

q2= 0.01825741858 x 0.01825741858 = 0.00033333333

A)

i)

Mutant allele frequency = 0.01825741858

Normal allele frequency = 0.98174258141

ii)

Carrier frequency is 0.03584817049

iii)

random mating, no natural selection, no mutation, no migration, no genetic drift

B)

NN genotype = 608.

There are 2 x 608 = 1216 N alleles in a total of 608 NN homozygotes.

NM genotype = 384

There are 384 N alleles and 384 M alleles in 384 MN heterozygotes.

MM genotype = 8

There are 2 x 8 = 16 M alleles in a total of 8 MM homozygotes.

Altogether, there are 1216+384+384+16 = 2000 alleles

Out of 2000, there are 1216+384 = 1600 N alleles

and

there are 384+16 = 400 M alleles.

N allele frequency is 1600/2000= 0.8

M allele frequency is 400/2000 = 0.2

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