Kaplan Nursing Entrance Practice Exam

During which phase do two chromosomes align in mitosis?

1. Prophase

2. Metaphase

3. Anaphase

4. Telophase

The correct answer is: Metaphase

During mitosis, the alignment of chromosomes is a critical step for ensuring that each daughter cell receives an identical set of chromosomes. This alignment occurs during metaphase. In this phase, the chromosomes, which have already been duplicated and consist of two sister chromatids, are arranged along the metaphase plate or equatorial plane of the cell. The spindle fibers, which have formed from the microtubules, attach to the centromeres of the chromosomes. This precise alignment is essential for the subsequent separation of the sister chromatids, which takes place in anaphase. The orderly arrangement during metaphase helps to mitigate errors in chromosome distribution, thereby maintaining genetic stability in the daughter cells. In contrast, during prophase, the chromosomes condense and become visible, but they are not yet aligned. Anaphase is characterized by the separation of the chromatids as they are pulled toward opposite poles, and telophase involves the reformation of the nuclear envelope around the separated chromosomes, completing the cell division process. Thus, the alignment of the chromosomes specifically takes place during metaphase.