In animal cells, the mitochondrion is the organelle associated with energy production. It does this by taking a molecule of a simple sugar, such as glucose, C6H12O6, and combining it with oxygen to release energy, which is stored in the form of ATP (adenosine triphosphate). Carbon dioxide and water are also produced as waste products. The overall chemical reaction looks something like this:
C6H12O6 + O2 ---> energy (ATP) + CO2 +H2O
In an electron transport chain, an electron donor and an electron receptor combine with the transport of a hydrogen ion (H+) across a membrane to generate chemical energy in the form of ATP. This is done by the oxygen being converted to water, NADH being converted to NAD+, and succinate being converted to fumurate. Thirty eight molecules of ATP may be generated from the breakdown of one molecule of glucose. Most of the ATP comes from the electron transport chain.