Mitosis

• What are the two strands of a chromosome called?

  Sister chromatids
• What connects the two chromatids in a chromosome?

  Centromere
• When are chromosomes visible in a cell?

  During cell division
• What mnemonic can be used to remember the stages of mitosis?

  I.P.M.A.T
• Give the equation for calculating mitotic index.

  Complete the equation:

  A) Number of cells in mitosis

  B) total number of cells

  
• Name the three stages of the cell cycle?

  • Interphase
  • nuclear division - mitosis or meiosis
  • cytokinesis
• Describe interphase.

  • Longest stage in the cell cycle when DNA replicates and organelles duplicate while cell grows
  • DNA replicates and appears as two sister chromatids held by centromere
• Describe mitosis.

  • One round of cell division
  • two diploid, genetically identical daughter cells
  • growth and repair (e.g. clonal expansion)
  • comprised of prophase, metaphase, anaphase and telophase
• Summarise what happens in prophase.

  • Chromosomes condense and become visible
  • nuclear envelope disintegrates in animals - centrioles separate & spindle fibre structure forms
• Summarise what happens in metaphase.

  • Chromosomes align along equator of cell
  • spindle fibres released from poles now attach to centromere and chromatid
• Summarise what happens in anaphase.

  • Spindle fibre contracts (using ATP) to pull chromatids, centromere first, towards opposite poles of cell
  • centromere divides in two
• Summarise what happens in telophase.

  • Chromosomes at each pole become longer and thinner again
  • spindle fibres disintegrate + nucleus reforms