During Prophase, which events occur?

• A. Spindle fibers disassemble.
• B. Chromosomes align at the metaphase plate.
• C. Sister chromatids separate.
• D. Chromosomes condense and the nuclear membrane disappears.

Answer: (D)

In Prophase, the genetic material condenses from chromatin into visible chromosomes, each made of two sister chromatids held at the centromere. The nuclear envelope breaks down, and the nucleolus disappears, allowing the spindle apparatus to interact with the chromosomes. Spindle fibers begin to form and move toward the poles, setting up the framework for later separation. These events prepare the cell for alignment and separation in the following stages. The other events listed happen later: spindle fibers disassemble later in the cycle, chromosomes align at the metaphase plate during metaphase, and sister chromatids separate during anaphase.