Apoptosis and mitosis

• Apoptosis


  programmed cell death
• Process of apoptosis


  1. enzymes break down cell CYTOSKELETON
  2. cytoplasm becomes dense, organelles are tightly packed together
  3. cell surface membrane changes - BLEBS form
  4. chromatin condenses, nuclear envelope breaks, DNA breaks into fragments
  5. cell breaks into vesicles which are engulfed by phagocytes
• Apoptosis in the body plan


  Used to remove unwanted structures in body plan development
• Apoptosis uses in the body plan

  • removal of skin between fingers
  • removal of tails on tadpoles
  • neurones in the nervous system
  • lymphocytes that target self-antigens
• What triggers apoptosis


  • DNA damage (internal stimulus)
  • stress - pathogen attack, lack of nutrients (external stimulus)
• Balancing apoptosis and mitosis

  • too much mitosis - tumour formation
  • too much apoptosis - degeneration of organ function
• How mitosis and apoptosis is regulated

  • mitosis checkpoints
  • mitochondria involved in cell checks
  • cell signalling
  • homeobox genes