Cell Cycle and Cell Division

    Cards (5)

    • A mutation of a tumour suppressor gene can result in the formation of a tumour, explain how.
      Cell division will speed up at an uncontrollable rate
      so tumour is formed
    • Describe the appearance and behaviour of chromosomes during mitosis (5)
      During prophase, chromosomes supercoil and condense to become visible
      Chromosomes appear as 2 identical sister chromatids joined by a centromere
      During metaphase chromosomes line up on the equator of the left of the cell
      Chromosomes attach to spindle fibres by their centromeres
      During anaphase the centromere splits
      Sister chromatids are pulled to the opposite poles of the cell making it V-shaped
      During telophase, chromatids uncoil and become thinner
    • Stages of meiosis, stage 1
      P1 + M1 - Chromosomes supercoil, condense and become visible
      Homologous pairs of chromosomes form a bivalent and align along the equator.
      Spindle fibres attach to the centromere.
      A1 - Spindle fibres contract and separate homologous pairs, pulling each to opposite poles
      T1 - Nuclear membrane reforms around the separated homologous chromosomes
    • Meiosis 2
      P2 - Each daughter cell only contains one chromosome from each homologous pair
      M2 - Each chromosome aligns along the equator
      A2 - Non-sister chromatids are split by their centromere and pulled to opposite poles
      T2 - Nuclear membrane reforms
      4 genetically different haploid daughter cells are produced
    • Crossing over (key points)
      The homologous chromosomes associate / bivalent is formed
      Chiasmata form
      Equal lengths of chromatids / alleles are exchanged
      Producing new combinations of alleles