Cell cycle

• Cell cycle

  Three key stages: Interphase (G1,S,G2), Nuclear division (mitosis/meiosis) and cytokinesis
• Stages of cell cycle


  • G1 (Growth)
  • S (DNA synthesis / replication)
  • G2 (Growth and prep for mitosis)
  • M (Mitosis)
• Interphase


  Longest stage in the cell cycle, when organelles double, the cell grows and then DNA replicates
• Nuclear division


  Can be either mitosis (creating two identical diploid cells) or meiosis (creating four genetically different haploid cells)
• Mitosis


  Creates cells with identical DNA for growth and repair
• Meiosis


  Creates gametes
• Mitosis

  1. Prophase - Chromosomes condense and become visible, centrioles separate and form spindle

  2. Metaphase - Chromosomes align along equator, spindle fibres attach to centromere and chromatids

  3. Anaphase - Spindle fibres retract, pulling centromere and chromatids to opposite poles

  4. Telophase - Chromosomes at poles become longer and thinner, spindle fibres disintegrate, nucleus reforms

  5. Cytokinesis - Cytoplasm splits to create two new genetically identical cells
• Mitotic index

  [ The number of cells in mitosis / total number of cells ] X100