Differential centrifugation

Differential Centrifugation is a common procedure in microbiology and biochemistry, which is used to separate and isolate cell components and organelles. This process is based on the principle of sedimentation of particles in a centrifuge.

Overview

Differential centrifugation involves a series of centrifugation steps, where the speed and duration of centrifugation are varied to separate cellular components according to their size, shape, and density. The process begins with a low-speed centrifugation to pellet the largest particles, such as whole cells and nuclei. The supernatant is then subjected to a higher speed centrifugation to pellet the next largest particles, such as mitochondria. This process is repeated with increasing speeds until all desired components are separated.

Process

The process of differential centrifugation involves the following steps:

1. Homogenization: The cells are first broken up to release their contents. This can be done mechanically or chemically.
2. Low-speed centrifugation: The homogenate is centrifuged at a low speed to pellet the largest particles, such as whole cells and nuclei.
3. Intermediate-speed centrifugation: The supernatant from the previous step is centrifuged at a higher speed to pellet the next largest particles, such as mitochondria.
4. High-speed centrifugation: The supernatant from the previous step is centrifuged at an even higher speed to pellet smaller particles, such as lysosomes and peroxisomes.
5. Ultracentrifugation: The supernatant from the previous step is centrifuged at the highest speed to pellet the smallest particles, such as ribosomes and viruses.

Applications

Differential centrifugation is widely used in the field of cell biology to isolate specific cell components for further analysis. It is also used in the field of virology to concentrate viruses from a dilute solution.

See Also

• Centrifuge
• Cell biology
• Virology

References

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