Function

• Biologists begin by breaking or rupturing cell membranes by shearing the cells in a glass vessel or applying a detergent to create a mixture called a homogenate. Next, the homogenate is added to two tubes, each attached to the tip of an arm on a rotor. As the rotor turns, the contents of the tube are flung outwards and accumulate at the bottom of the tube. By spinning the rotor at up to 100,000 revolutions per minute, a centrifuge can produce forces up to 600,000 times the force of gravity.
  
  

Features

• Under the influence of the force produced by the centrifuge, some of the cell components in the homogenate separate. The larger and more dense components accumulate at the bottom of the tube while the smaller and less dense components remain in the solution. Higher centrifuge speeds will remove progressively smaller and smaller cell components from the homogenate, so that by repeating this process several times, a biologist can isolate different parts of the cell, such as nuclei, mitochondria and ribosomes.
  
  

Significance

• Biologists often need to isolate different proteins or different cell components in order to conduct experiments that illuminate the function of that protein or component. By centrifuging the cell homogenate, a biologist can extract the cell structures they want to study.