Question

Tay-Sachs is an inherited, recessive trait which involves the inability to properly break down certain lipids. A normal couple has a child affected with Tay-Sachs. For each of the following situations, select the most appropriate frequency from the list below. What is the probability that the mother of the Tay-Sachs child is heterozygous dominant.

Answer 1

Answer:

The mother must be heterozygous.

Explanation:

t=Tay-Sachs trait

T=Normal trait

Parent genotype combinations:

Tt x Tt

Possible genotypes:

    |  T    |    t  

T  | TT  |   Tt  

t   | Tt   |    tt  

Since it is a recessive trait there must be 2 of the recessive alleles for the trait to show. This means neither of the parents can be totally normal(TT).

Since both parents are considered normal the both must be heterozygous to be able to produce an child with Tay-Sachs.