cell fractionation

• what are the two processes involved in cell fractionation?

  homogenisation and differential centrifugation
• what is homogenisation?


  breaks up tissue, breaks open cell membrane/cell wall
• what is differential centrifugation?

  allows us to separate organelles with different densities

  centrifuged at a low speed, larger/denser organelles move to bottom of tube forming a pellet

  supernatant moved to another tube and span at a higher speed
• what are the conditions needed for cell fractionation?

  ice cold

  pH buffered

  isotonic (same water potential)
• why does the solution need to be ice cold?

  enzymes work slower, preventing destructive enzymes from damaging organelles
• why does the solution need to be buffered?

  keeps the pH constant, so enzymes dont denature
• why does the solution need to be isotonic?

  prevents water moving in/out of the organelles via osmosis