Question

Consider a diploid cell that has a total of 16 chromosomes. At the end of meiosis I the cell will contain an ‘X’ number of chromosomes and a ‘Y’ number of sister chromatids. What are ‘X’ and ‘Y’?

• A. X = 8; Y = 16
• B. X = 8; Y = 8
• C. X = 16; Y = 8
• D. X = 16; Y = 16

Answer 1

The correct option is A X = 8; Y = 16

Meiosis is a type of cell division that occurs in the reproductive cells of sexually reproducing organisms. In meiosis, the chromosome number is reduced to half, resulting in the formation of haploid daughter cells.

• Meiosis is preceded by a single cycle of DNA replication without a change in the chromosome number. At this stage each chromosome will have two sister chromatids attached at the centromere. So, a cell with 16 chromosomes will have 32 sister chromatids.
• Following DNA replication, when the cell enters meiosis I, the homologous chromosomes of the parent cell get divided among two daughter cells. Each daughter cell receives only half the number of chromosomes from the parent cell. At this stage, a diploid cell with 16 chromosomes will have 8 chromosomes in the daughter cells. Since each chromosome has two sister chromatids attached at the centromere, there are a total of 16 sister chromatids. Thus, X = 8 and Y = 16.