Metabolic pathways

A metabolic pathway consists of a series of interconnected biochemical reactions that convert substrate molecules, to final products. These transformations occur step-by-step and create a series of metabolic intermediate molecules. Each reaction step is facilitated, or catalyzed, by proteins called enzymes.

It is important to note that metabolic pathways are not closed systems: substrates, intermediates, and products of one pathway can be reactants in other pathways. For example, catabolic breakdown of carbohydrates, proteins and lipids converge in cellular respiration (see connections of catabolism).