Mitosis- Prophase

By Tessa

Prophase is the first stage of mitosis. In the process of chromatin condensation, the chromatin forms itself into a chromosome. Each chromosome has two chromatids joined at the centromere (an area in the middle of the chromosome). The mitotic spindles or fibers, that are made out of proteins and microtubules, form in the cytoplasm. The chromosomes move towards opposite edges of the cells. This occurs because of the lengthening of microtubules between them.

Late Prophase: The nuclear envelope begins to break up. Then, the polar fibers (microtubules that form the spindle fibers) extend from each cell's pole to the cell's equator. Kinetocheres are specialized parts of centromeres of chromosomes. They attach to a specific type of microtubules called kinetochere fibers.

Sources:

About.com had detailed info on each phase. Click here to go there, but the language can be somewhat confusing.

This is a site that simplifies some of the harder concepts, by University of California San Francisco. Not much detail though.