Cell Division

• Cell Cycle is made up of 3 stages:

  • Interphase - G1, S, G2 where the cells grow, organelles double and DNA replicates
  • Nuclear Division - mitosis/meiosis
  • Cytokinesis - division of cytoplasms
• Mitosis is division creating 2 identical diploid cells
• In Prophase, the chromosomes condense, centrioles seperate and move to opposite poles and the nuclear envelope breaks down
• In Metaphase, chromosomes align along the equator, spindle fibres are released from centrioles and attach to centromeres
• In Anaphase, fibres retract, centromeres divide and are pulled to opposite ends (requiring ATP)
• In Telophase, chromosomes become longer and thinner, fibres disintergrate, nucleus reforms and cytoplasm splits (cytokinesis)
• Mitotic Index Formula

  (No. of Cells in Mitosis / Total No. of Cells) x 100
• Binary Fission is prokaryotic cell division in which replication of circular DNA and plasmids occur, cytoplasm divides producing 2 daughter cells
• Binary Fission produces daughter cells each with a singular copy of circular DNA and a variable number of plasmids
• Viruses do not undergo cell division, instead they inject their hosts with nucleic acids and hosts replicate for them