Cellular respiration primarily occurs in the mitochondrion, the organelle often called the "powerhouse of the cell." Within the mitochondrion, different stages of cellular respiration take place:
- Glycolysis occurs in the cytoplasm (not an organelle, but a cellular component).
- Pyruvate oxidation and the citric acid (Krebs) cycle occur in the mitochondrial matrix.
- The electron transport chain and oxidative phosphorylation occur in the inner mitochondrial membrane folds called cristae.
Thus, the mitochondrion is the main organelle where most of cellular respiration takes place, producing the majority of ATP used as energy by the cell.
