This 22nd edition of the IUBMB-Nicholson Metabolic Pathways Chart features an enhanced ATP metabolism in mitochondria and chloroplasts. It illustrates the sequences of reactions involved in different aspects of metabolism and how they are integrated. The backbone of the map is the Glycolytic Pathway, followed by the TCA (Krebs) Cycle and the ElectronTransport System, which together produce most of the energy (ATP) required for all life. Most other aspects of metabolism are associated with this backbone and are differentiated by the use of color. Human metabolism is distinguished by the use of black arrows. Some 550 reactions are identified by their IUBMB Enzyme Commission (EC) numbers which are then indexed.