Question
What is the prophase stage of mitosis? State its characteristics.
Answer
The prophase stage is the first stage of mitosis, during which the chromatin condenses into visible chromosomes and the nuclear envelope breaks down. Here are some characteristics of prophase:
- Chromosome condensation: The chromatin fibers condense into visible chromosomes, each consisting of two identical sister chromatids joined at the centromere.
- Nuclear envelope breakdown: The nuclear envelope, which encloses the genetic material in the nucleus, disintegrates, allowing the spindle fibers to access the chromosomes.
- Spindle formation: The spindle fibers, which are composed of microtubules and proteins, begin to form and extend from opposite poles of the cell towards the equator.
- Centrosome movement: The centrosomes, which are microtubule-organizing centers, move towards opposite poles of the cell, and the spindle fibers emanate from them.
- Mitotic apparatus organization: The spindle fibers attach to the kinetochores, which are protein structures on the centromeres of the chromosomes, and begin to organize the mitotic apparatus.
