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Cell fractionation is a technique used to study the
organelles that are present inside plant and animal cells.
It involves breaking up the cells and separating out
individual organelles according to their size. Each type of
organelle can then be studied in more detail.
The first step is to obtain a sample of tissue containing
the cells for study. This tissue, either animal or plant, is
then cut up into small pieces. The next step involves
homogenisation, putting into a blender to break up the cell
walls and cell membranes of the cells so that the contents
The homogenised mixture is filtered to remove any debris
then the filtrate is spun in a very powerful centrifuge. The
nuclei, the largest organelle in the cell forms one of the
first fractions, followed by mitochondria and chloroplasts
(if the tissue is from a plant). Rough endoplasmic reticulum
requires higher spinning to sediment and the tiny ribosomes
need the highest spinning speeds of all ~ around 300 000 g.
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This separates different parts and organelles of a cell so
study can be undertaken in detail.
1. Cut tissue and place in a cold isotonic buffer. Cold to
stop enzyme action, isotonic to stop osmosis and buffer to
stop changes in PH. Grind to break open cells.
2. Filter, removes insoluble tissue, e.g. fat connective
tissue, cell walls etc.
3. Centrifuge at low speed: 1000x g for 10 minutes: this