Metabolism in contemporary biology and biochemistry refers to the aggregate of chemical transformations taking place in living organisms or in ecosystems. It consists of anabolism, the buildup of compounds, catabolism, the breakdown of compounds, and the alteration of compounds for energy transformation or usage. The word itself comes from Hellenic Greek, where it refers to change.
The contemporary usage seems to go back to the 1870s where it occurs in physiology books in the sense of chemical change. In present day ecological systems, the overall metabolic activity consists of the incorporation of carbon, hydrogen, nitrogen, phosphorous, and sulfur driven by photosynthesis or chemosynthesis, the transformation of the inputs into metabolites, the buildup of these small molecules into macromolecules and other cell structures; and, ultimately, the decay due to respiration, predation, and decay. There are common features of metabolism across all taxa: the same amino...