In prokaryotic cells, respiration occurs in the cytoplasm; in eukaryotic cells, the process begins in the cytoplasm but a majority of the chemical reactions occur in the mitochondria. Respiration is the process of releasing energy for biological processes in the form of ATP (adenosine triphosphate).
Respiration is a series of chemical reactions that can occur both in the presence of oxygen and its absence to produce a high-energy molecule utilized by all life on earth on a cellular level. Cells with nuclei typically utilize aerobic respiration. Aerobic cellular respiration takes the product of glycolysis, which occurs in the cytoplasm, and uses it in a series of chemical reactions in the cell’s mitochondria.
Mitochondria are bean shaped organelles present in all eukaryotic cells. Within the mitochondria, there are a large number of inner ridges that increase the surface area through which a concentration gradient can be utilized in the chemical transformations that create cellular energy.
ATP production, with the additional processes that the addition of oxygen allows, produces far more energy for the cell than anaerobic respiration. Aerobic respiration produces a total of 38 ATP per glucose molecule, where anaerobic produces only 2 ATP. When eukaryotic cells run out of oxygen, they can still produce energy through anaerobic respiration.