Cellular respiration occurs in different parts of the cell depending on the stage and the type of organism:

• In eukaryotic cells (such as plants, animals, and fungi):
  • The first stage, glycolysis , takes place in the cytoplasm.
  • The subsequent stages-pyruvate oxidation , the citric acid (Krebs) cycle , and oxidative phosphorylation -occur inside the mitochondria. Specifically, the citric acid cycle happens in the mitochondrial matrix , and oxidative phosphorylation occurs across the mitochondrial inner membrane (cristae)

• In prokaryotic cells (which lack mitochondria), cellular respiration occurs entirely in the cytoplasm , as they do not have membrane-bound organelles

Thus, cellular respiration is primarily a cytoplasmic and mitochondrial process in eukaryotes, while in prokaryotes it is cytoplasmic.