Every living cell contains Nicotinamide adenine dinucleotide (NADH). It is a coenzyme that plays an important role in cellular respiration, more specifically in the processes of glycolysis and oxidative phosphorylation.
NADH is involved in the synthesis of the energy intermediate Adenosine triphosphate. This ATP is produced as a direct result of oxidative phosophoryltion which takes place in the mitochondria of living cells. An electron transport chain is established in which electrons are removed from NADH molecules via the enzyme NADH dehydrogenase. These electrons are used as energy throughout the electron transport chain until they reach the Cytochrome C complex. Here the energy is used to drive ATP synthesis.
ATP is an important energy source for all cells within a given organism.