2.1.3 Cell fractionation

• What is the purpose of cell fractionation?

  To isolate different organelles for study
• Why is a cold solution used in cell fractionation?

  To reduce enzyme activity that could damage organelles
• What is the role of an isotonic solution in cell fractionation?

  To prevent osmosis that could damage organelles
• Why is a buffered solution used in cell fractionation?

  To maintain pH and prevent organelle damage
• How are cells homogenised in cell fractionation?

  By breaking them open using a blender
• What type of solution is used for homogenisation?

  A cold, isotonic, and buffered solution
• What is done to the solution after homogenisation?

  It is filtered to remove large debris
• What occurs during ultracentrifugation?

  The filtered solution is spun at different speeds
• How do organelles separate during ultracentrifugation?

  According to their densities
• What is the process of differential centrifugation?

  Spinning the centrifuge at increasing speeds
• What happens to the most dense organelles during centrifugation?

  They form pellets at the bottom
• What is done with the supernatant during centrifugation?

  It is removed to leave behind pellets
• How is the centrifuge operated for organelle separation?

  First at low speed, then increasing speeds
• What is the order of organelle fractionation based on centrifugation speed?

  1. Nucleus: 1000 x g for 10 mins
  2. Chloroplasts: 3500 x g for 10 mins
  3. Mitochondria: 16500 x g for 20 mins
  4. Lysosomes: 100,000 x g for 60 mins