Figure 2

Representation of the enzyme-centric view of metabolism. The horizontal rows of arrows represent the various groups of enzymes that are associated with the systematic changing of an input metabolite(s) to an end product, be it a fuel, an effector/controller of another reaction, or a building block for a biopolymer, such as protein or nucleic acid. The vertical green arrows denote the gene-to-messenger RNA-to-protein sequence of reactions that occur for the approximately 5,000 different enzymes of human metabolism.