Cell Fractionation

• What is Cell Fractionation?

  The process where cells are broken apart and the organelles are separated
• What is Cell Fractionation used for?

  To study cell structure and function
• What are the two stages of Cell Fractionation?

  Homogenation and Ultracentrifugation
• What must happen before Cell Fractionation can be performed?

  The tissue must be placed in a cold, isotonic, buffered solution
• Why must the tissue be placed in a cold solution?

  To slow down enzyme activity from breaking down organelles
• Why must the tissue be placed in an isotonic solution?

  To prevent organelles from bursting/shrinking due to osmatic gain/loss of water
• Why must the tissue be placed in a buffered solution?

  To keep the pH constant
• What is the first step of Cell Fractionation?

  The tissue must be cut into smaller pieces and placed into a cold, isotonic, buffered solution
• What is the second step of Cell Fractionation?

  The pieces are placed into a Homogenizer which releases the organelles from the cells
• What is the third step of Cell Fractionation?

  The homogenate is filtered to remove any complete cells and cell debris (Cell walls/membranes)
• What is the fourth step of Cell Fractionation?

  The Homogenate is suspended in test tubes and then centrifuged at a low speed
• What happens after step four?

  The larger fragments collect at the bottom and the smaller fragments suspend near the top in a liquid called a supernatant liquid
• What is the fifth step of Cell Fractionation?

  The supernatant liquid is decanted and re-spun in the centrifuge at a faster speed, while the remaining sediment pellets is collected and analysed
• What is the sixth step?

  The process is repeated until all organelles are separated, or the desired culture of organelles is aquired
• What order are the organelles found in?

  Nuclei

  Chloroplasts

  Mitochondria

  Lysosomes

  Endoplasmic Reticulum

  Ribosomes