Fatty acid synthesis and beta-oxidation

This session centers on fatty acid synthesis and beta oxidation, offering a structured look at the key pathways of fatty acid synthesis and beta oxidation, highlighting how they function in opposite directions, one building and the other breaking down fatty acids. We will explain the cellular locations, key enzymes, and regulation mechanisms of each process, emphasizing the importance of strict metabolic control. Finally, we will discuss how these pathways adapt to feeding and fasting states, their physiological significance, and the consequences of their dysregulation for human health. We will explore fatty acid synthesis and beta oxidation, two essential yet fundamentally opposite pathways in lipid metabolism. Fatty acid synthesis builds long chain fatty acids for membranes, energy storage, and signaling, mainly in the cytosol. In contrast, beta oxidation is the breakdown of fatty acids for cellular energy, occurring in the mitochondrial matrix. These pathways are distinct, do not share enzymes and are regulated to meet cellular needs. Fatty acid synthesis starts with acetyl coa, which is produced in the mitochondria, but must be transported into the cytosol as citrate, since the mitochondrial membrane is impermeable to coa. In the cytosol, acetyl coa is carboxylated to melonal coa by acetyl coa carboxylase, a highly regulated step. Fatty acid synthase, a multi enzyme complex, then elongates the fatty acid chain