apoptosis

• apoptosis:

  • programmed cell death in development
  • series of biochemical events leading to an orderly cell death
• rate of apoptosis:

  • rate of apoptosis should be balanced with rate of mitosis
  • too little apoptosis -> formation of tumour
  • too much apoptosis -> cell loss + degeneration
• control of apoptosis: hox genes regulate mitosis and apoptosis. can be either internal or external
• INTERNAL control of apoptosis:

  • damage to DNA (detected in cell cycle)
  • genes are expressed that cause the cycle to pause/trigger apoptosis
  • release of hormones
  • psychological stress
• EXTERNAL control of apoptosis:

  • change in light intensity
  • pathogen attack
  • lack of nutrients
  • drugs
• steps of apoptosis:

  1. 'bleb' - bubbles in the membrane and nucleus starts to disintergrate
  2. cell fragments are produced and plasma membrane and organelles are still intact
  3. cell fragments are ingested and digested by neutrophils