ssume that Migaloos albinism is caused by a rare recessive g

ssume that Migaloo\'s albinism is caused by a rare recessive gene In a mating of two heterozygous, normally pigmented whales, what is the probability that the first three offsprings will all have normal pigmentation? What is the probability that the first female offspring is normally pigmented? What is the probability that the first offspring is a normally pigmented female?

Solution

Assume that the dominant allele is A and the recessive allele is a. Cross between two heterozygotes, Aa and Aa will have the progeny with the following genotypes:

Aa* Aa --à A_ (3/4, dominant), aa (1/4, recessive)

The probability of all three offspring to be normal is = (3/4)^3 = 27/64

The probability of first female offspring to be normally pigmented is = probability of being normally pigmented = 3/4

The probability for the 1^st offspring to be normally pigmented = probability of being female* probability of being normally pigmented = ½* 3/4 = 3/8