Fermentation
Making ATP without oxygen by recycling NADH back to NAD+, so glycolysis can keep going. Humans make lactate. Yeast makes ethanol and carbon dioxide.
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Analogy
A backup generator: low output, but it keeps the lights on.
In practice
Sprinters feel muscle burn as lactate builds up. Yeast fermentation makes bread rise and beer fizzy.
Practice
Flashcards
- Why does fermentation make lactate or ethanol?To turn NADH back into NAD+ so glycolysis can continue without oxygen.
Questions people ask
Why do muscles produce lactate?
During hard exercise, muscles need ATP faster than oxygen can arrive. Glycolysis speeds up, and fermentation recycles NAD+ by turning pyruvate into lactate. This gives a quick but small supply of ATP. The lactate is later carried to the liver and turned back into glucose.
How much ATP does fermentation produce?
Only the 2 ATP made in glycolysis, per glucose. Full aerobic respiration makes about 30, so fermentation is roughly 15 times less efficient. Cells that depend on fermentation must therefore break down a lot more glucose to get the same energy, which is why anaerobic activity cannot last long.