Tay-Sachs Disease (TSD) is a neurological disease that is autosomal recessive. If a mother and father are both unaffected carrie
rs for this gene, what will be true of their offspring?
A all will be homozygous for the disease.
B) All will be heterozygous for the disease.
C) There is a 75% chance that each child would have the disease.
D) There is a 25% chance that each child would have the disease.
A all will be homozygous for the disease.
B) All will be heterozygous for the disease.
C) There is a 75% chance that each child would have the disease.
D) There is a 25% chance that each child would have the disease.
2 answers:
Answer:
The correct answer would be option D.
As TSD is an utosomal recessive disease, thus, a person must be homozygous recessive in order to produce a phenotype.
Both parents are unaffected carrier of the disease that means they bot are heterozygous in genotype.
Thus, the genotype of both the parents would be Tt.
Therefore, both would produce two types of gametes: T and t.
The cross would produce offspring with three types of genotypes: TT, Tt, and tt in the ratio 1:2:1.
Thus, only one out of four offspring has a chance of having the disease.
So, it can be concluded that only 25% chances are there that a child would have a disease.
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