Mitosis - AS Biology

v  Chromosomes not visible at this stage

v  DNA replicates; cell enters reproductive cycle

v  Not mitosis

v  Nuclear membrane breaks down, chromosomes become visible

v  Centrioles migrate to poles to form spindles

v  Chromosomes line up in the centre

v  Centriole’s spindles grip the centromeres

v  Spindles grip centromeres

v  Chromosomes migrate to poles as the spindles pull on them

• Nuclear membranes reform; chromosomes disperse
• Cytokinesis begins.

The number of cells per unit undergoing mitosis during a given time.  The ratio used primarily as an estimate of the rate of tissue growth.

Number of cells in mitosis / Total number of cells