Catabolic pathways are pathways in human metabolism that involve the breakdown of larger molecules into smaller ones. These pathways involve the release of energy that is then used to drive other chemical reactions in the organism.
Some examples of molecules that may be involved with catabolic reactions include proteins, polysaccharides and nucleic acids. These units are broken down into amino acids, monosaccharides and nucleotides, respectively. Lipids undergo catabolism to produce glycerol and fatty acids. This process is driven by lipase enzymes. Fatty acids and hydrocarbons are then further catabolized by beta-oxidation. Glycolysis and the Krebs cycle are two pathways that break catabolic products down further.