Question

Mitotic anaphase differs from metaphase in possessing

• A. same number of chromosomes and same number of chromatids
• B. half number of chromosomes and half number of chromatids
• C. half number of chromosomes and same number of chromatids
• D. same number of chromosomes and half number of chromatids.

Answer 1

The Correct Option is D

The question requires us to distinguish the differences between mitotic anaphase and metaphase concerning the number of chromosomes and chromatids. Let's explore these phases step-by-step to understand the differences:

1. Metaphase:
   • During metaphase, chromosomes align at the cell's equator, known as the metaphase plate.
   • Each chromosome, at this point, consists of two sister chromatids held together at the centromere.
   • The number of chromosomes is equal to the number of chromosome pairs.
   • Therefore, if a cell has n chromosomes during metaphase, it has 2n chromatids.
2. Anaphase:
   • In anaphase, the centromeres split, and the sister chromatids are pulled to opposite poles of the cell by the spindle fibers.
   • Once the sister chromatids are separated, they are considered individual chromosomes.
   • Thus, the cell still has the same number of chromosomes as metaphase (formerly chromatids), but each chromosome now consists of only one chromatid.
   • Therefore, if the metaphase had n chromosomes (with 2n chromatids), anaphase will have n chromosomes each with one chromatid, effectively reducing the number of chromatids to n.

From this analysis, during anaphase, the number of chromosomes remains the same as in metaphase, but the number of chromatids is halved. Therefore, the correct answer is:

Same number of chromosomes and half number of chromatids.