- Takes place in the mitochondria of cells.

- Breaks down glucose to produce ATP, the energy currency of the cell.

- Carbon dioxide is produced as a byproduct of the citric acid cycle, a series of chemical reactions that occur during cellular respiration.

Fermentation

- Occurs in the cytoplasm of cells, in the absence of oxygen.

- Breaks down glucose to produce ATP without the use of oxygen.

- Carbon dioxide is produced as a byproduct of fermentation, when pyruvate, a product of glycolysis, is converted into ethanol or lactic acid.