A certain metabolic pathway can be diagrammed as, where a, b, c, d are the intermediates, and x, y, z are the enzymes that catalyze the reactions

The succession of metabolic reactions that transform a certain initial substance into another is known as a metabolic route or pathway. The starting substance is known as substrate or raw material. The final substance is usually known as the final product or metabolite (a metabolic pathway can generate several end products) and intermediates as intermediate metabolites. An intermediate or final metabolite in one metabolic pathway may be the substrate in another, which makes the vast majority of metabolic pathways interconnected. Several enzymes that catalyze the chemical reactions that take place usually participate in each metabolic pathway. Since enzymes are proteins encoded in DNA, the damage to the genetic material that codes for a certain enzyme will cause the metabolic pathway in which it is involved not to work correctly or even block it completely, leading to hereditary metabolic diseases.