cell fractionation and ultracentrifugation

• Cell fractionation


  Technique used to break open cells and isolate different organelles to examine their structure and function
• Cell fractionation process


  1. Homogenization

  2. Ultracentrifugation
• Homogenization


  • Cells are broken open or homogenized using a blender
  • Solution must be cold, isotonic, and buffered to prevent organelle damage
• Ultracentrifugation


  • Filtrate containing organelles is placed in a centrifuge and spun at high speeds
  • Centrifugal forces cause more dense organelles to separate and move to the bottom
  • Process is repeated at increasing speeds to isolate organelles in order of density
• Order of organelle isolation

  • Nuclei
  • Chloroplasts and mitochondria
  • Lysosomes and endoplasmic reticulum
  • Ribosomes
• Cell fractionation allows the structure and function of organelles to be studied
• The solution must be cold, isotonic, and buffered to prevent organelle damage
• Differential ultracentrifugation separates organelles according to their density