Here's why:
* Breakdown of the Nuclear Envelope: The nuclear envelope, which encloses the nucleus, is composed of a double membrane. During prophase, the nuclear envelope breaks down into small vesicles. This allows the chromosomes, which have already replicated, to become accessible to the spindle fibers.
* Spindle Fiber Formation: The spindle fibers, which are made of microtubules, begin to form from the centrosomes (microtubule-organizing centers). These fibers will attach to the chromosomes and guide them to the opposite poles of the cell.
* Chromatin Condensation: The chromatin, the DNA within the nucleus, condenses into visible chromosomes. This makes it easier to separate the chromosomes during cell division.
Therefore, the fading of the nuclear membrane is a crucial step in prophase, allowing for the proper separation of chromosomes during cell division.
