In prophase, what happens?

In prophase, what happens?

• A. Chromosomes condense and spindle apparatus begins to form.
• B. Nuclear membrane reforms.
• C. DNA replication occurs.
• D. Cytokinesis begins.

Answer: (A)

During prophase, chromosomes condense from thread-like chromatin into visible structures, and the mitotic spindle begins to form outside the nucleus as centrosomes move to opposite poles. The nuclear envelope starts to break down, and the nucleolus often disappears as chromosomes condense and become ready for segregation. DNA replication has already occurred earlier in interphase, so it is not happening during prophase. Cytokinesis, which divides the cytoplasm, happens after mitosis, not in prophase. The combination of chromosome condensation and the initial assembly of the spindle best describes prophase.

During prophase, chromosomes condense from thread-like chromatin into visible structures, and the mitotic spindle begins to form outside the nucleus as centrosomes move to opposite poles. The nuclear envelope starts to break down, and the nucleolus often disappears as chromosomes condense and become ready for segregation. DNA replication has already occurred earlier in interphase, so it is not happening during prophase. Cytokinesis, which divides the cytoplasm, happens after mitosis, not in prophase. The combination of chromosome condensation and the initial assembly of the spindle best describes prophase.