BRAINCAKEInvestigating the Site of ATP Synthesis
How do we know which parts of the cell carry out each stage of respiration? The evidence comes from separating cell parts by cell fractionation and testing each fraction.
Tissue such as liver is homogenised in a solution that is ice-cold (to slow enzymes that would damage organelles), isotonic (so organelles do not burst or shrink by osmosis) and buffered (to keep the pH constant). The homogenate is filtered and spun at increasing speeds, called differential centrifugation. Nuclei form a pellet first, mitochondria at a higher speed, and the final supernatant contains the cytoplasm.
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Key terms in this lesson
- luciferase
- An enzyme, from fireflies, that produces light in proportion to the amount of ATP present, used to measure ATP levels.
More in Cellular Respiration
- Respiration in the Cytoplasm
- Mitochondria
- Hydrogen Acceptors
- Investigating the Rate of Respiration
- Glycolysis
- Anaerobic Respiration in Mammals
- Lactate
- Sprint Athletes
All 20 lessons in Cellular Respiration · All Edexcel A-level Biology topics