since we know cells are made up of a lot of different parts it's useful to understand what each part does as well as their individual structures in order to do this you have to be able to study each part separately a process called cell fractionation was developed to help with this it takes cells apart and separates the major organel and other cellular structures from one another tissue cells are first homogenized or broken apart their plasma membranes are broken up so that their internal contents spill out and mix together in what we call a homogenate the homogenate is then spun at a high rate of speed in a process called centrifugation and that speed can be varied so we call it differential centrifugation depending on what speed you use different parts of the cell will accumulate in the bottom of the test tube in a pellet the reason for this is because different parts of the cell are bigger or smaller and the bigger they are the quicker they'll sink to the bottom so you don't have to spin it as fast whereas other pieces are very small and you have to spin it at a very high rate of speed to force them to the bottom of the tube for example if we first spin the tube at something like a th000 G's or a thousand times the force of gravity you'll get a pellet rich in nuclei and cell debris but there'll still be a liquid portion above that pellet called the supernatant and within that supernatant there'll be other parts of the cell that are smaller if we pour that supernon off and spin it at a higher rate of speed at something like 20,000 G's you'll get a pellet rich in mitochondria if you repeat that process and spin that supernatent down at something like 880,000 G's the pellet will be rich in microsomes or pieces of plas membrane and internal membranes and if you spin that supernant down at 150,000 G's you'll get a pellet rich in ribosomes this technique allows for the isolation and subsequent research of subcellular components so that you can determine more about their individual roles in the cell