Mitosis

• Mitosis produces 2 new genetically identical cells from one parent cell
• New cells are used for growth, differentiation/specialisation or replacing damaged or old cells
• Stages of mitosis = interphase, prophase, metaphase, anaphase, telophase
• Mitotic index = number of cells with visible chromosomes/total number of cells x100
• Prophase

  • chromosomes first become visible
  • spindle fibres develop from centrioles
  • nucleolus disappears and nuclear envelope breaks down
  • chromosomes drawn towards equator
• Metaphase

  • chromosomes seen to be made of two chromatids
  • joined by the centromere
  • chromosomes pulled along the spindle apparatus and arranged across the equator
• Anaphase

  • centromeres divide into two and spindle fibres pull the individual chromatids to the opposite poles of the cell
  • energy provided by mitochondria which gather around spindle fibres
• Telophase

  • chromosomes reach respective poles and disappear leaving a widely spread chromatin
  • spindle fibres disintegrate and the nucleus and nucleolus reforms