- Homogenate filtered
- Low speed: remove unbroken cells
- 600g: nuclei
- supernatant spun 15000g: mitochondria, chloroplasts, lyosomes and peroxisomes
- 100,000g: plasma membrane, endoplasmic reticulum, large polyribosomes.
- Additional centrifugation: ribosomes, enzyme complex
- 300,000g: Only the cytosol remains after centrifugation
- This process means that at each stage of centrifugation, the next heaviest organelle is separated out.
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- Cellular homogenate is the liquid that contains the biological material. It must first be filtered to remove clumps.
- The supernatant is the undeposited material left over after centrifugation.
- Cytosol is the soluble aqueous portion of the cytoplasm.
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Information about the process
- Vacuum conditions are used because this reduces heating caused by friction between air and the spinning rotor.
- Tissue is placed into a cold isotonic buffered solution before cell fractionation occurs.
- It is cold because this reduces enzyme activity which could break down organelles.
- It is isotonic to prevent organelles bursting or shrinking as a result of osmotic water gain or loss.
- It is buffered so that a constant pH is maintained.
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