ABSTRACT
Oxygen is responsible for providing us with the necessary energy for the daily operation of the cell. The foodstuffs are oxidized (electrons are removed) via the mitochondrial respiratory electron transport chain in a series of steps involving many enzymes. The final electron acceptor in this sequence is oxygen, which is reduced in the last step by 4 electrons to give 2 H
in the form of chemical energy. This is the process of oxidative phosphorylation, which forms adenosine triphosphate (ATP) from adenosine diphosphate (ADP). ATP is used as an energy source for cellular function. Without oxygen life on earth as we know it today would not exist. The atmosphere we breath consists of 21% oxygen. There is a very limited range of oxygen concentration in which we humans can exist. Lowering or increasing the oxygen concentration by just a few percentage points causes serious damage. Why should this be so? Oxygen is reduced to water, which is certainly not toxic, so increased formation of water should be no problem. Electrons are transported along the respiratory chain via 2 e!
