Why does the nuclear envelope break down during prometaphase?

• A. To allow the chromosomes to condense.
• B. To allow the sister chromatids to form
• C. To allow the mitotic spindle to form.
• D. To allow spindle fibers to attach to chromosomes.

Answer: (D)

Verified step by step guidance

1. Understand the context of prometaphase in the cell cycle. Prometaphase is a stage in mitosis following prophase and preceding metaphase.
2. Recognize the role of the nuclear envelope. It surrounds the nucleus and separates the genetic material from the cytoplasm.
3. During prometaphase, the nuclear envelope breaks down. This process is crucial for the progression of mitosis.
4. The breakdown of the nuclear envelope allows spindle fibers, which are part of the mitotic spindle, to access the chromosomes.
5. Spindle fibers attach to the chromosomes at the kinetochores, which are protein structures on the chromosome. This attachment is necessary for the chromosomes to be aligned and separated during mitosis.