Cell Division - Mitosis

• Why do we need new cells?


  For growth and to replace damaged tissues
• The period when a cell is not dividing is called?

  Interpahse
• The stage of mitosis where the chromosomes are first visible in distinct structures


  Prophase
• During this stage thin threads develop that span the cell from end to end? Together form a structure called?

  Anaphase
• The stage when chromosomes arrange themselves across the centre of the cells?

  Metaphase
• During this stage the chromatids move to opposite poles of the cells

  Anaphase
• Chromosomes have reached the poles of the cell and become indistinct. Nuclear envelope and nucleolus reforms and spindles disintegrate. What is the stage called?

  Telophase
• What is the structure of chromosomes?

  Chromosomes are made of two strands joined in the middle by a centromere. The separate strands are called sister chromatids
• What are the four stages of mitosis?

  Prophase, Metaphase, Anaphase, Telophase
• What happens during prophase?

  Chromosome condenses, getting shorter and fatter. Chromosomes pair up. Nuclear envelope (membrane around nuclues) breaks down and chromosomes lie free in cytoplasm.
• What happens during metaphase?

  Chromosomes each with two chromatids line up along the middle of cell and become attached to the spindle by their centromere
• What happens during Anaphase?

  Centromeres divide, separating each pair of sister chromatids
• What happens in Telophase?

  Chromatids reach the opposite poles on the spindle. They uncoil and become long and thin again. A nuclear envelope forms around each group of chromosomes so there are now two nuclei
• How is Mitosis and cell cycle controlled?

  By Genes
• What happens when there's a mutation in a gene that controls cell division?

  Cells grow out of control - the cell keeps dividing to make more and more cells which causes tumours.
• What is Cancer?

  A tumour that invades surrounding tissues.