Kaplan Nursing Entrance Practice Exam

What is the main event that occurs during metaphase of mitosis?

1. Chromosomes align in the center of the cell

2. Chromosomes are separated and pulled to opposite sides

3. Cells physically divide into two

4. Nuclear membrane reforms around each set of chromosomes

The correct answer is: Chromosomes align in the center of the cell

During metaphase of mitosis, the primary event is the alignment of chromosomes along the metaphase plate, which is an imaginary line in the center of the cell. This alignment is crucial because it ensures that when the next phase, anaphase, begins, each daughter cell will receive an identical set of chromosomes. The chromosomes, which have already been replicated and condensed, attach to spindle fibers that have grown from the centrosomes at opposite poles of the cell. The precise alignment of chromosomes helps to prevent any errors during cell division, thereby minimizing the risk of genetic abnormalities in the resulting daughter cells. This well-organized placement is critical for maintaining genetic integrity as the cell prepares to divide. In contrast, other answer choices refer to events occurring in different phases of mitosis. For instance, separating chromosomes and pulling them to opposite sides occurs in anaphase, while the physical division of the cell itself happens in cytokinesis, which follows mitosis. The reformation of the nuclear membrane takes place during telophase, which is after metaphase.