Anabolic Pathways

In contrast to catabolism, anabolism is a divergent process in which a few biosynthetic precursors (such as amino acids) form a wide variety of polymeric, or complex, products (such as proteins [Fig. 1]).

Anabolic reactions require energy (are endergonic), which is generally provided by the hydrolysis of ATP to adenosine diphosphate (ADP) and inorganic phosphate (Pi). [Note: Catabolic reactions generate energy (are exergonic).] Anabolic reactions often involve chemical reductions in which the reducing power is most frequently provided by the electron donor NADPH (phosphorylated NADH).

Figure 1: Comparison of catabolic and anabolic pathways. NADH = nicotinamide adenine dinucleotide.