Question

Albinism is the inability of a child to produce or deposit the pigment protein melanin in skin cells and other pigment-containing cells of the body. Albinism is not a trait shared by his parents.

How is this possible?

A. Despite having two alleles for skin pigmentation, the child only has one. His albino characteristics are caused by having fewer genes.

B. The child produced the albino protein due to a spontaneous mutation that was not present in either parent. The albino protein takes the place of normal melanin.

C. In the child, the normal DNA from both parents has merged to form a new form of DNA. The albino protein is coded for by this faulty DNA.

D. Each parent carries one normal DNA allele as well as one that codes for albinism. The parents produce enough melanin protein for normal skin colour, but the child does not.

Answer 1

Hint: Recall the basics of genetics and inheritance. Albinism is a recessive genetic disorder, meaning that it requires two copies of the albinism gene to be expressed.

Complete step-by-step Answer: Albinism is a recessive genetic disorder, meaning that both copies of the gene responsible for skin pigmentation must be mutated in order for the disorder to be expressed. If a person has one normal copy of the gene and one mutated copy, they will not have albinism but will be a carrier of the gene.

In this case, the child's parents each have one normal allele for skin pigmentation and one allele for albinism. This means that the parents are carriers of the albinism gene. When the parents had a child, there was a 25% chance that the child would inherit two copies of the albinism gene and have albinism, a 50% chance that the child would inherit one copy of the albinism gene and one copy of the normal gene and be a carrier, and a 25% chance that the child would inherit two copies of the normal gene and not have albinism.

Hence the correct answer is Option D

Note: Albinism is a relatively rare condition, affecting about 1 in 20,000 people worldwide. It can cause a variety of problems, including vision problems, skin sensitivity, and an increased risk of skin cancer. However, with proper care, people with albinism can live healthy and fulfilling lives.