Normal hearing in humans is caused by the dominant S gene, and hereditary deafness is determined by the recessive s gene. From the marriage of a deaf woman to a normal man, a deaf child was born. Identify the genotypes of the parents.
S – normal hearing, s – hereditary deafness.
The child showed a recessive trait, which means his ss genotype. In the child’s genotype, one allele came from the mother’s body, and the second from the father’s. The mother conditionally showed a recessive sign. Therefore, its genotype is ss. His father has normal hearing, which means that one allele is dominant and the other is recessive, which he passed on to the child. If the father was homozygous for this feature, the child was born with normal hearing, but heterozygous (carrier of the deafness gene).
Answer: parental genotypes of ss and ss.
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