Mitosis

• Mitosis

  • Nuclear division
  • Asexual
  • In all body cells
  • Produces 2 genetically identical diploid (2n) daughter cells
  • Provides genetic stability (no variation)
  • Damaged cells can be repaired by dividing neighbouring cells
  • Reproduction: Ability to produce new generations of same species
  • Cytokinesis (animal):
  • Ring of actin filaments form around equator
  • Tightens to form a cleavage furrow
  • Splits the cell in two
  • Cytokinesis (plant):
  • Vesicles move to equator, line up, and fuse
  • Form two membranes; cell plate
  • Cell wall laid down between membranes
  • Fuses with existing cell wall
• Mitosis Stages

  • Interphase: G_1 → S → G_2
  • Prophase (longest):
  • DNA condensation
  • Chromatids shorten + thicken
  • Nucleoli and nuclear envelope disappear
  • Centrioles migrate to opposite poles
  • Spindle fibres begin to form
  • Metaphase:
  • Chromosomes line up on equator
  • Centromere attached to spindle fibres
  • Anaphase:
  • Centromeres split
  • Sister chromatids pulled apart towards poles
  • Each chromosome is now one chromatid
  • Telophase:
  • Chromosomes reach poles and uncoil
  • Spindle fibres disintegrate
  • Centrioles replicate
  • Nuclear envelopes reform
  • Nucleoli reappear
  • Immediately cytokinesis