Prophase

PROPHASE

Prophase

  • The first phase of mitosis within M phase is called prophase.
  • The nucleolus fades and chromatin (replicated DNA and associated proteins) condenses into chromosomes and each chromosome has two chromatids joined at a centromere.
  • The mitotic spindle initially appears as structures called asters which surround each centriole pair.
  • The two pair of centrioles (formed from the replication of one pair in Interphase) move away from one another toward opposite ends of the cell due to the lengthening of the microtubules that form between them.
  • The nuclear envelope breaks up.
  • Polar fibers, which are microtubules that make up the spindle fibers, reach from each cell pole to the cell's equator.
  • The kinetochore (protein bundles at the centromere region on the chromosomes where sister chromatids are joined) fibers "interact" with the spindle polar fibers connecting the kinetochores to the polar fibers.
  • The chromosomes begin to migrate toward the cell center.
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Last modified: Saturday, 19 November 2011, 7:08 AM