Question

Question 3 When an embryo is only 2 cells large, one of the 2 cells divides and acquires a cancer promoting mutation in one allele of the gene p53. As the embryo develops, one of the tissues that the mutated cell gives rise to are all the cells that create sperm. When the person grows up, he also acquires a cancer promoting mutation in one allele of the gene KRAS in his colon. He then fathers a biological child. After he has children, he acquires more mutations and develops colon cancer. A. What is the probability that the child inherited his mutation in p53? Explain in three sentences or fewer B. What is the probability that the child inherited his mutation in KRAS? Explain in three sentences or fewer.

Answer 1

A. The chances of receiving the p53 mutation from father to son are 1/2. As there is a mutation in one allele so though it's in sperm cells the chances of getting it carried to the next generation is 1/2. The normal allele of p53 would also share the same chances.

B. The chances of inheriting the mutation in the KRAS gene are 0. As this mutation is in somatic cells not in germ cells. The mutations in germ cells are carried forward to the next generation through male or female gametes i.e. sperms and eggs.