ABSTRACT
Subcellular fractionation is the breaking open of a cell and the separation of the various organelles from one another by centrifugation. Differential velocity centrifugation separates the subcellular organelles on the basis of their size. A centrifuge is used to generate powerful forces to separate the various organelles which pellet to the bottom of the centrifuge tube. At lower forces, nuclei, mitochondria, chloroplasts and lysosomes pellet, whereas higher forces are needed to pellet the endoplasmic reticulum, Golgi apparatus and plasma membrane. In rate-zonal centrifugation, the sample is centrifuged through a weak sucrose solution until the organelles have separated from each other. If centrifuged for too long all the organelles will end up in the pellet at the bottom of the centrifuge tube. A marker enzyme is one that is found within only one particular compartment of the cell.
