3.7 + 3.8 - Mitosis and the cell cycle

• What does mitosis produce ?

  Two identical daughter cells that each have the same number of chromosomes as the parent cell
• What are the 3 phases of the cell cycle ?

  Interphase, Nuclear division (mitosis or meiosis), Cytokinesis
• What’s the first stage of the cell cycle ?

  Interphase
• What are the 3 phases of Interphase ?

  G1, S, G2
• What occurs during G1 of interphase ?

  Organelles replicate and more cytoplasm is made so the cell grows
• What happens during S of interphase ?

  DNA replication occurs
• What happens to the number of chromosomes during interphase ?

  Stays the same, one strand is a chromosome and when this replicates the form 2 sister chromatids, this is still considered a chromosome
• What are the sister chromatids joined at ?

  The centromere
• What happens in G2 of interphase ?


  Preparation for cell division
• What are the 4 main stages of mitosis ?

  Prophase, Metaphase, Anaphase, Telophase
• What 4 things occurs during prophase ?

  Chromosomes condense and become visible when stained, Spindle fibres emerge from centrosomes, Centrosomes move toward opposite poles, Nuclear envelope breaks down
• What 4 things occurs during metaphase ?

  Chromosomes line up in the middle, Centrosomes reach opposite poles, Spindle fibres extend from Centrosomes, Spindle fibres attach to centromere
• What 3 things occur during Anaphase ?

  Centromere id split in 2, Spindle fibre shorten, Sister chronatids are pulled apart to opposite poles (now chromosomes)
• What 3 things occurs during telophase ?

  Chromosomes arrive at opposite poles and decondense, Nuclear envelope material surrounds each set of chromosomes, The mitotic spindle breaks down
• What occurs during cytokinesis ?

  Division of the cytoplasm, producing 2 new cells with their own identical nuclei
• How to find the mitotic index ?

  No. of cells in mitosis / Total no. of cells in view
• What can uncontrolled cell division lead to ?

  The formation of tumours and cancers
• What are many cancer treatments directed at controlling ?

  The rate of cell division
• Why do mutations occur when the cell cycle speeds up ?

  More frequent cell cycles, faster DNA replication, less time to correct errors
• Which is worse, benign or malignant ?


  Malignant