Question

In mitosis, what chromatid combination(s) will be present during metaphase? What combination(s) will be present at each pole at the completion of anaphase?

Short answer

Answer: After the completion of anaphase, each pole will have the same chromatid combinations as the parent cell had, which would be X at one pole and Y at the other pole.

Step-by-step solution

Understanding Mitosis

Mitosis is a process in which a cell divides to form two identical cells. This process occurs in stages: prophase, metaphase, anaphase, and telophase. In this exercise, we will focus on metaphase and anaphase.

Metaphase

During metaphase, the chromosomes line up along the cell's equator (middle of the cell), attached to spindle fibers at their centromeres. The spindle fibers keep the sister chromatids (identical copies of chromosomes after replication) connected to each other. In this stage, there are 2^n possible combinations of chromatids, where "n" is the number of chromosome pairs.

Chromatid Combinations in Metaphase

The chromatid combinations present during metaphase depend on the number of chromosome pairs. For these combinations, allow X and Y to represent a pair of chromosomes. For a single pair of chromosomes, there are 2^1 = 2 possible combinations: XX and YY. With more pairs of chromosomes, the combination possibilities will increase exponentially (2^n).

Anaphase

During anaphase, the sister chromatids are separated by the action of spindle fibers, which shorten and pull the chromatids toward opposite poles of the cell. The separated chromatids are now called daughter chromosomes.

Chromatid Combinations after Anaphase

At the completion of anaphase, each pole will have a complete set of chromosomes, identical to the original parent cell. Therefore, the combinations present at each pole will be the same as the starting combinations of chromatids in the parent cell. Following our chromatid examples during metaphase, let's say for example, if the parent cell had combinations of XX and YY, each pole will also have the corresponding combinations of X and Y, respectively. To recap, during metaphase, there are 2^n possible chromatid combinations, with n being the number of chromosome pairs. At the completion of anaphase, each pole will have the same chromatid combinations as the parent cell had.