Question

1. In humans, normal pigmentation is due to a dominant gene (A), albinism to its recessive

allele (a). A normally pigmented man marries an albino woman and their first child is an
albino. What are the genotypes of these three persons? If they have several other children,
what are the probabilities that they will be: albino, normal pigmentation, carriers for
albinism?

Answer 1

The mother has a genotype of aa, the father has a genotype of Aa and the child has a genotype of aa.

Explanation: If the couple decides to have more children the children would have a 50% 50% chance of being albino. Every child they have will be a carrier of the recessive gene gained from their mother. The children would either have a genotype of Aa or aa. Also, the father has a heterozygous genotype. He also is a carrier of the recessive gene since their first child was albino. You cannot be made albino unless both alleles from your parents are recessive and even though the father is not albino (because he had the dominant allele A), he had an albino child therefore making him a carrier of the allele a. Please let me know if you require further explanation!