Question

The lack of pigmentation, called albinism, in man is the result of a recessive allele (a) and normal

pigmentation is the result of its dominant (A). Two normal parents have an albino child. What
is the genotype and phénotype of each parent? Show all work to prove your answer.

Answer 1

The genotype of each parent is Aa, and their phenotype is normal pigmentation.

Step-by-step explanation:

To determine the genotype and phenotype of each parent, we can use a Punnett square. Since albinism is a recessive trait, the albino child must have two copies of the recessive allele. Let's use the following notation: A represents the dominant allele for normal pigmentation, and a represents the recessive allele for albinism.

Let's assume that the genotype of the albino child is aa, as both parents must have at least one copy of the recessive allele. Since both parents are normal, their genotypes must be heterozygous, Aa. Using a Punnett square, if we cross Aa with Aa, we get:

• AA - Normal pigmentation
• Aa - Normal pigmentation
• Aa - Normal pigmentation
• aa - Albinism

Therefore, the genotype of each parent is Aa, and their phenotype is normal pigmentation.