cell cycle

• cell cycle

  = sequence of events that takes place in a cell resulting in division of the cell and formation of two genetically identical daughter cells.
• Interphase

  = cell is actively preparing for cell division.

  • DNA is replicated and checked for errors in the nucleus.
  • protein synthesis, mitochondria and organelles grow and divide.
• stages of interphase

  G1= first growth stage, organelles synthesised are produced and replicated, cells increase in size.

  s= synthesis phase- DNA is replicated in the nucleus.

  G2= second growth stage- cell continues to increase in size, duplicated DNA is checked for errors.
• Go


  = phase when cell leaves the cycle due to:

  • differentiation= cell that becomes specialised to carry out a particular function, can no longer divide.- it will carry out it's function indefinitely and not enter the cycle again.
  • DNA may be damaged, so can no longer divide and enters a period of permanent cell arrest= senescent.
  • age increases the number of senescent.
• checkpoints

  = control of mechanisms of the cell cycle.- if mistakes are found, cells kill themselves= apoptasis.

  • G1= cell size, nutrient, growth factors, DNA damage.
  • G2= cell size, DNA replication, DNA damage.
  • metaphase= spindle assembly.