cell fractionation

• Cell fractionation involves two stages: Homogenation, where cells are broken and different organelles are released, and Ultracentrifugation, where the exposed organelles are separated to isolate them.
• In the first step of cell fractionation, tissue is placed in an ice cold, buffered, isotonic solution to reduce enzyme activity, prevent PH change that may alter protein structure, and keep water potential inside and outside a cell to prevent osmosis from bursting organelles.
• In the second step of cell fractionation, the cells are broken up to release organelles, the fluid is called homogenate, and this is filtered to remove complete cells and large cellular debris.
• In the third step of cell fractionation, the filtered homogenate is placed and spun in a centrifuge at high speeds to separate organelles.
• Those organelles that settle at the bottom form the pellet and the fluid at the top is called supernatant.
• The order of cells that settle in differential ultracentrifugation is: Nuclei, Chloroplasts, Mitochondria, Lysosomes, Endoplasmic reticulum, Ribosomes.