Centrifugation

Centrifugation can be used to break up cells into fragments and is the first step in most fractionations. The suspension of cells produced from this process is called a homogenate or extract. There are different speeds of centrifugation ranging from a low speed to extremely high speeds of centrifugation. After centrifugation, the cell homogenate separates into the pellet and supernatant. The pellet is usually components of the cell that collects at the bottom of the centrifugation tube and the supernatant refers to the top layer in the tube. It is possible to subject the supernatant to multiple rounds of centrifugation to further purify the components in them.

A preparative ultracentrifuge separates cell components by size and density by generating enormous centrifugal forces. It does this by rotating extracts of broken cells at high speeds.