Cellular respiration occurs in the cytoplasm of prokaryotic cells and the mitochondria of eukaryotic cells. The process can be aerobic or anaerobic, and is used as a means of energy production for the cell.
For a cell to go through the process of cellular respiration, it must use glucose as an initial source of energy. There are two phases of cellular respiration: glycolysis, whereby glucose is broken down into pyruvic acid, and the oxidation of pyruvic acid into carbon dioxide and water. In both phases of cellular respiration, adenosine triphosphate, or ATP, an energy source, is also released. While glycolysis takes place in the cytosol of cells, the rest of the process of cellular respiration occurs in the mitochondria.