Britannica Sources used in this answer

What is beta-oxidation and where does it occur in a cell?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Fluorescent confocal image of HeLa cells with green microtubules outlining cell shapes, red mitochondria, and blue nuclei. — mitochondrion Mitochondria (red) are found throughout the cytoplasm of almost all eukaryotic cells (cell nucleus is shown in blue; cytoskeleton is shown in yellow).

Beta-oxidation is a metabolic process involving the stepwise catabolism of fatty acids, during which two-carbon fragments are successively removed from the carboxyl end of the fatty acid chain.1

In this process, fatty acids are converted into acetyl-CoA fragments through a repeating cycle of four enzymatic reactions. Each cycle shortens the fatty acid chain by two carbons and produces molecules of FADH2 and NADH, which are subsequently used to generate ATP through oxidative phosphorylation.23

Regarding its location, beta-oxidation primarily occurs within the matrix of the mitochondrion. While the process takes place in the mitochondrial matrix in most cells, it also occurs to a minor extent within peroxisomes in animals and glyoxysomes in plants, where the energy released is typically dissipated as heat.2