Metabolism describes the build-up (anabolism) and break-down (catabolism) of chemical compouns in living organisms. In more detail, catabolism describes the breakdown of larger chemical molecules for the production of energy, as well as the processing of chemical components in order to build structures and new cells. Anabolism on the other hand describes the construction, often de-novo synthesis, of molecules which usually happens under consumption of energy.

The basis of these chemical compounds is carbon which is utilized for the synthesis of the most various building blocks of life, such as proteins (nucleic acids), DNA (amino acids), lipids, carbohydrates (such as sugars) and others. Enzymes catalyze most of the chemical processes in metabolism. Indirectly, these chemical processes are controlled by proteins that facilitate transport of molecules like sugars, fatty acids, energy carriers etc.

Complex mechanisms regulated by signaling cascades that exist of small signaling molecules, such as cAMP and networks of signaling molecules have evolved, regulating the harvest, transfer, and storage of energy from various sources, as well as the synthesis of compounds for the maintenance of life and procreation. These biochemical processes are collectively termed metabolic pathways. Some of the metabolic pathways are highly conserved in various species, ranging from bacteria to mammals hinting to their early invention in the evolution of life.