Question

In the human male germ line, there is on average one crossover per chromosome in every meiosis. Humans have 23 chromosome pairs. Suppose a male individual had a mutation that completely prevented crossing-over during meiosis. What fraction of this individual's sperm would contain chromosomes he inherited from his mother?

a) 1/23
b) 23/23
c) 0/23
d) 22/23

Answer 1

The fraction of this individual's sperm that would contain chromosomes inherited from his mother is 0/23.

Option C is correct

In normal meiosis, each sperm cell receives half of the father's chromosomes and half of the mother's chromosomes. This is because during meiosis, homologous chromosomes (chromosomes from each parent) pair up and then separate randomly. This process ensures that each sperm cell receives a random assortment of chromosomes from the father and the mother.

In the case ,where a male individual had a mutation that completely prevented crossing-over during meiosis, then each sperm cell would receive either all of the father's chromosomes or all of the mother's chromosomes. We can attribute this to the fact that without crossing-over, the homologous chromosomes would not be able to exchange genetic material, and they would simply separate as intact pairs.