Catabolic pathways are processes of degradation, during which large organic molecules that often enter the body as food are destroyed (usually in oxidative reactions) to simple cellular components with a simultaneous release of free chemical energy. This energy is then used by the body to support vital activity, for growth and replication, and is also converted into other forms of energy - mechanical, electrical and thermal. Anabolic pathways are processes of enzymatic synthesis associated with the synthesis of complex organic biomolecules from relatively simple precursors. The synthesis often includes recovery steps and is accompanied by the expenditure of free chemical energy. The convergence of catabolic pathways is based on the fact that at the first stage of catabolism, many different cellular components are involved, but at the end, all paths converge into one common metabolic pathway, and the number of final products is small. The divergence of anabolic pathways is associated with the formation of many complex biomolecules from a small number of simple components. For example, oxidation of fatty acids, carbohydrates, and some amino acids leads to the formation of acetyl-CoA that is directly used in the Krebs cycle. However, acetyl-CoA can also be used for the synthesis of multiple organic compounds comprising fatty acids, sterols, some amino acids, etc.