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ATP from glucose

ATP is the energy currency the cell can use directly. With oxygen, cellular respiration gives about 30 to 32 ATP per glucose. In the problems you can reckon with 30 when you need a single number. Without oxygen the breakdown stops after glycolysis, which gives only 2 ATP. That is called fermentation. In muscles the leftover is lactic acid. In yeast it is ethanol and carbon dioxide. Fermentation keeps life going for a short time, but it gives far less energy than respiration with oxygen.

1 glucose→about 30 ATP1\ \text{glucose} \rightarrow \text{about } 30\ \text{ATP}with oxygen
1 glucose→2 ATP1\ \text{glucose} \rightarrow 2\ \text{ATP}fermentation, without oxygen

Symbols

3030ATP per glucose with oxygen, in the problems
22ATP per glucose without oxygen

Example

Eight glucose molecules with oxygen: 8⋅30=2408 \cdot 30 = 240 ATP.

The same eight without oxygen: 8⋅2=168 \cdot 2 = 16 ATP.

30 to 32 is a range. Say which number you use when you calculate.
Practise photosynthesis and cellular respiration for free →

← The photosynthesis equation · With and without oxygen →

Part of Biology 1: Photosynthesis and cellular respiration.