3053802
Description
Flashcards by mitzigolsorkhi, updated more than 1 year ago
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Created by mitzigolsorkhi
almost 9 years ago
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| Question | Answer |
| Fractionation consists of 3 steps, these are... | 1. Homogenisation 2. Centrifugation 3. Differential centrifugation/ cell fractionation |
| Homogenisation is | breaking up cellular material - buffer solution may be added to maintain CONSTANT pH - WATER POTENTIAL IS CONSTANT (may use isotonic solution) - Ice cold solution inactivates enzymes |
| Centrifugation... | - the mixture (homogenate) is filtered to remove debris - spun at high speeds so solid material sediments separate as a pellet |
| Differential centrifugation/ cell fractionation | - centrifugation at increasingly higher speeds - larger denser organelles sediment first |
| Chromatography... | - separates out the components of a mixture so they can be identified. - use a type of paper and solvent - solvent moves up the paper carrying components with it |
| how do you identify substances once they have been separated with chromatography? | calculate their Rf value |
| Rf = | x/y x = distance moved by spot y = distance moved by solvent |
| Rf has to be... | less than 1 |
| if the substance does not separate well, you must use.. | two-way chromatography |
| two-way chromatography... | - turn paper 90 degrees - use different solvent |
| Radio-active tracer techniques allows cells to be traced in what two ways? | - chemically: trace biochemical pathway + see what substances are converted and what they are converted to - physically: find out which organelles a substance travels to/ from |
| Electrophoresis is | - substances are made to move through the background material by being subjected to an electric field |
| Electrophoresis is suitable for | - large charged molecules such as proteins and DNA |
| The distance moved by a substance depends on... | - its mass - its electrical charge |
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