Total metabolism

Total metabolism (also called metabolism) is all of a certain living organism's chemical processes. The organism's metabolism can be dichotomized into the synthesis of organic molecules (anabolism) and their breakdown (catabolism). This is to be distinguished from cell metabolism which is the process of metabolism occurring within a single cell.

The halt of metabolism in a living organism is usually defined as its death. Some organisms can reduce their metabolism to almost zero for certain periods of time. Spores of fungi can survive thousands of years in that state. But every lifeform is bound to have metabolism at some point of its life cycle, with the possible exception of viruses, which use their hosts' metabolism.

Human cells obtain most of their energy from chemical reactions involving oxygen. A starting point in measuring human metabolism is with basal metabolic rate. Some microbes metabolise the wrought iron on shipwrecks, forming structures known as rusticles with the waste compounds they produce.