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7 Cards in this Set
- Front
- Back
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What is cell fractionation? |
Process where cells are broken up and the different organelles they contain are separated |
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Why is the tissue placed in a cold, isotonic, buffered solution? |
Cold-Reduce enzyme activity that might break down the organelles
Isotonic-Prevent organelles bursting or shrinking as a result of osmotic gain or loss of water
Buffered-Maintain a constant pH to reduce enzyme activity |
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What is an isotonic solution? |
Two solutions, separated by a semipermeable membrane, have equal concentrations of solutes and water |
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What are the two stages of cell fractionation? |
Homogenation Ultracentrifugation |
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What is the process of homogenation? |
When cells are broken up by a homogeniser (blender) This releases the organelles from the cell.
Resultant fluid known as the homogenate is then filtered to remove any complete cells and large pieces of debris |
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What is the process of ultracentrifugation? |
Fragments in the filtered homogenate are separated in a machine called ultracentrifuge. This spins tubes of homogenate at high speeds in order to create a centrifugal force |
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How does the process of ultracentrifugation take place for animal cells? |
1. Tube of homogenate is placed in the ultracentrifuge and spun at a slow speed 2. The heaviest organelles, nuclei, are forced to the bottom of tube where they form a pellet 3. Fluid at top of tube (supernatant) is removed, leaving the pellet of nuclei 4. Supernatant is transferred to another tube and spun in the ultracentrifuge at a faster speed than before 5. Next heaviest organelles, mitochondria, are forced to bottom of tube 6. Process continues |
