This new edition of the iconic IUBMB-Nicholson Metabolic Pathways Chart brings increased functionality to a canonical tool. Now, all metabolites, enzymes, and selected pathways are searchable and interactive. The "backbone" of the map is the Glycolytic Pathway followed by the TCA (Krebs) Cycle and the Respiratory Chain which together lead to the synthesis of ATP by ATP Synthase. ATP is the source of most of the energy required for all life. Many biosynthetic and breakdown pathways of metabolism such as carbohydrates lipids are associated with this backbone and are differentiated by the use of color. Human metabolism is distiguished where possible by the use of black arrows. Some 550 reactions are identified by their IUBMB Enzyme Commission (EC) numbers which are then indexed