What is a short sentence including the word chromosome
2 answers:
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Answer:
E. 27/64
Explanation:
Knowing that the couple is heterozygous (Aa) for Niemann-Pick disease, they can have children with the following pairs of alleles:
A x A = AA (Dominant homozygous - Unaffected)
A x a = Aa (Heterozygous - Unaffected)
a x A = Aa (Heterozygous - Unaffected)
a x a = aa (Recessive homozygous - Affected)
So each allele pair has a probability of:
AA = 1/4
Aa = 1/4
Aa = 1/4
aa = 1/4
As the disease only affects recessive homozygous individuals (aa), the probability of an unaffected child being born is 3/4.
Since the couple expects to have three children, the probability of neither being born with the disease is obtained by multiplying the probability of each, as follows:
Thus, it is concluded that the probability of none of the children having Niemann-Pick syndrome is 27/64.