Overview of Fatty Acid Metabolism

Fatty acid metabolism includes the synthesis of fatty acids in the cytoplasm and their breakdown in the mitochondria and peroxisomes. Both of these processes are tightly regulated depending on nutrient availability.

For example, consider the breakdown of an eight-carbon fatty acid molecule. It is first esterified to produce fatty acyl-CoA in the cytoplasm and subsequently transported into mitochondria for beta-oxidation.

Here, the fatty acyl-CoA molecule loses two carbon atoms to produce a six carbon fatty acid chain along with a molecule of acetyl coenzyme A, NADH, and FADH₂. This process is repeated until the fatty acid is completely converted into acetyl CoA, which then enters the citric acid cycle producing more NADH and FADH₂.

These reduced coenzymes donate their electrons to the electron transport chain to produce ATP.

During fatty acid synthesis, malonyl-CoA, a three-carbon molecule, donates two carbons to an acetyl group forming a four-carbon fatty acid molecule, while the third carbon is released as carbon dioxide. This process repeats until the desired eight-carbon fatty acid is formed.