Liposünteesi

Liposünteesi, also known as lipogenesis, is the metabolic process by which fatty acids and triglycerides are synthesized within cells. This process primarily occurs in the cytoplasm of liver cells, adipose tissue, and mammary glands, playing a crucial role in energy storage and cellular structure.

The synthesis of fatty acids begins with acetyl-CoA, a molecule derived from the breakdown of carbohydrates and amino acids. Acetyl-CoA is transported from the mitochondria to the cytoplasm, where it serves as the primary building block for fatty acid chains. The enzyme acetyl-CoA carboxylase catalyzes the first committed step, converting acetyl-CoA into malonyl-CoA. Subsequently, the fatty acid synthase complex elongates the fatty acid chain, adding two-carbon units derived from malonyl-CoA. This process requires energy in the form of ATP and reducing power from NADPH.

Triglyceride synthesis, or esterification, involves the formation of ester bonds between glycerol and fatty acids. Glycerol-3-phosphate, derived from glucose metabolism, serves as the backbone. Through a series of enzymatic reactions, three fatty acids are sequentially attached to the glycerol molecule, forming a triglyceride. These triglycerides are then stored as lipid droplets within cells or transported in lipoproteins to other tissues for energy utilization or storage. Liposünteesi is tightly regulated by hormonal signals, such as insulin, which promotes the process, and glucagon and adrenaline, which inhibit it, reflecting the body's response to nutrient availability and energy demands.