Anaerobic Respiration
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When oxygen is not available, the anaerobic version of respiration occurs.
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The Electron Transport Chain stops working, and electron carriers have nowhere to drop their electrons.
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The mitochondrial production of acetyl- CoA and The Krebs Cycle cease too.
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Glycolysis, however, can continue to run. This means that Glucose can be broken down to give net two ATP. Only two instead of 30!
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Glycolysis also gives two pyruvates and two NADH. The pyruvate and NADH make a deal with each other, and pyruvate helps NADH get recycled back into NAD+ and takes its electrons.
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The pyruvate turns into either lactic acid (in muscles) or ethanol (in yeast).
- There is a byproduct of co2, which needs to be exhaled (ex. bubbles in beer)
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Since these two things are toxic at high concentrations, this process, called fermentation, is done only in emergencies. Aerobic Respiration is a better option
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What types of organisms undergo fermentation?
- Yeast cells and some bacteria make ethanol and carbon dioxide. Other bacteria produce lactic acid.