All cells arise from other cells

• What is the role of spindle fibres?

  Attach to centromeres and pull chromatids apart
• What is cytokinesis?

  Splitting of the cytoplasm into two daughter cells
• What is mitosis used for?

  • Growth and repair
  • Replaces cells
• 3 stages of the cell cycle

  • Interphase
  • Mitosis
  • Cytokenisis
• What phase of the cell cycle do most cells stay in?

  Interphase
• Stages of mitosis?

  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
• Prophase

  • Chromosomes CONDENSE and become VISIBLE
  • Centrioles separate and form spindle fibres
  • Nucleoulus breaks down
• Metaphase

  • Chromosomes align at the EQUATOR of the cell
  • Spindle fibres released from the poles attach to the CENTROMERE and CHROMATID
• Anaphase

  • Centromere DIVIDE into 2 sister chromatids
  • CHROMATIDS pulled to OPPOSITE poles of cell (known as chromosomes)
  • Requires ATP
• Telophase

  • Chromosomes are now at each pole of cell and become LONGER and THINNER again
  • Spindle fibres disintegrate
  • Nucleus reforms
• Cytokenisis

  • Cytomplasm splits in 2
  • Creates 2 genetically identical daughter cells
• Mitotic index

  • The % of cells undergoing mitosis
  • MI = number of cells with condensed chromosomes / total number of cells x 100
• Benign tumours

  • SLOWER growing
  • Do not spread
  • Not harmful
• Malignant tumours

  • FAST and UNCONTROLLED cell division
  • Cancerous
  • SPREADS to other tissues (metastatise)
  • Forms SECONDARY cancers