During mitosis, which of the following DOES occur in Prophase?
A. The mitotic spindle begins to grow
B. Centrosomes are duplicated
C. Chromatids separate
The correct answer and explanation is :
The correct answer is A. The mitotic spindle begins to grow.
Explanation:
Mitosis is the process by which a eukaryotic cell divides to form two identical daughter cells. It consists of several phases: prophase, metaphase, anaphase, and telophase. In prophase, several important events occur to prepare the cell for division. Let’s break down the options:
- Option A: The mitotic spindle begins to grow
- This is the correct answer. In prophase, the mitotic spindle, which is a structure made up of microtubules, begins to form and grow. The spindle fibers emanate from the centrosomes (specialized regions of the cell that organize the microtubules). The spindle will eventually play a critical role in separating the sister chromatids during later stages of mitosis, specifically during anaphase.
- Option B: Centrosomes are duplicated
- Centrosomes do indeed play a role in mitosis, but their duplication occurs earlier, during interphase (specifically in the S phase), before the cell enters mitosis. During prophase, the centrosomes are already present and begin migrating to opposite sides of the cell, aiding in the formation of the mitotic spindle.
- Option C: Chromatids separate
- This event does not occur during prophase. Chromatids (which are the two identical halves of a chromosome) separate in anaphase. In prophase, the chromatids are still tightly condensed and connected at the centromere. The separation of chromatids happens later in the process, during anaphase when the sister chromatids are pulled apart toward opposite poles of the cell.
Key Events in Prophase:
- Chromosomes condense and become visible under a microscope.
- The nuclear envelope begins to break down.
- The mitotic spindle starts to form and grow, connecting to the centromeres of chromosomes.
- The centrosomes move toward opposite poles of the cell.
Prophase is a critical step that sets the stage for the subsequent phases of mitosis, ensuring that each daughter cell receives an exact copy of the genetic material.
