Question

Solve the following problem:

A population has the following genotype distribution, where H is a dominant allele and h is a recessive allele:

HH = 160  Hh = 230  hh = 110

What is the size of the population?

Solve the following problem:

A population has the following genotype distribution, where H is a dominant allele and h is a recessive allele:

HH = 160 Hh = 230 hh = 110

What is the frequency of the p allele?

Solve the following problem:

A population has the following genotype distribution, where H is a dominant allele and h is a recessive allele:

HH = 160 Hh = 230 hh = 110

What is the frequency of the p allele?

Solve the following problem:

A population has the following genotype distribution, where H is a dominant allele and h is a recessive allele:

HH = 160 Hh = 230 hh = 110

What is the observed frequency of the dominant phenotype?

Solve the following problem:

A population has the following genotype distribution, where H is a dominant allele and h is a recessive allele:

HH = 160 Hh = 230 hh = 110

What is the expected genotype frequency of the heterozygote?

Solve the following problem:

A population has the following genotype distribution, where H is a dominant allele and h is a recessive allele:

HH = 160 Hh = 230 hh = 110

What is the observed frequency of the homozygous recessive genotype?

Answer 1

1) it is given that there are only two alleles H and h. Hence there are only three combinations are possible- HH, Hh, hh. So inorder to find the total population size , we have to just add all the observed genotype numbers. Given observed number of HH phenotype is 160, that of Hh phenotype is 230 and that of hh is 110.

Hence the total population size= 160+ 230+110 = 500.

2) frequency of p allele=?

Genotype frequency of hh , q^2 = 110/500 = 0.22

Hence gene frequency of q = √0.22 = 0.47

Gene frequency of p = 1- q = 1- 0.47 = 0.53

[ p + q = 1]

3) observed frequency of dominant penotype=?

As H is dominant over h and H masks the expression of h , both HH and Hh genotype individuals will exhibit the dominant phenotype.

Observed number of dominant penotype= 160 + 230 = 390

Total number of population= 500

Observed frequency of dominant phenotype= 390/500 = 0.78

4) expected genotype frequency of heterozygote=?

Heterozygote is the one which have both H and h allele. Usually in F2 cross, we obtain 1 HH: 2Hh: 1hh

Hence Hh genotype will be observed in half of the total progenies we get, so the expected genotype number of heterozygote= 500 * 2/4 = 250

Expected genotype frequency of heterozygote = 250/500 = 0.5

5) frequency of observed homozygous recessive genotype =?

Recessive genotype is the one which have two recessive alleles.

Frequency of Observed homozygous recessive genotype= number of homozygous recessive genotype observed/ total number of individuals in the population

= 110/500= 0.22