Mitosis

• Mitosis is the phase when the cell actually divides, making up about 10% of the cell cycle.
• It can be broken into four stages:
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase

1. Prophase

• The chromosomes become visible as short, thick, double-stranded structures.
• Each strand is held together at a point called the centromere.
• The two strands are identical copies of each other.
• At the poles of the cell (either end of the cell), the centriole starts to form spindle fibres.
• The nuclear membrane starts to break down.

2. Metaphase

• The nuclear membrane completely breaks down.
• The chromosomes line up along the equator of the cell.
• The spindle fibres attach to the centromeres.

3. Anaphase

• The spindle fibres contract.
• The centromeres split.
• The chromosomes are pulled to opposite poles (ends) of the cell.

4. Telophase

• A nuclear membrane forms around each group of chromosomes.
• Chromosomes elongate to become chromatin.
• The spindle fibres break down.