Principles of Biochemistry (2+1)

3.4.1.4.Lipid metabolism

                                    3.4.1.4.Lipid metabolism

          Lipid metabolism is concerned mainly with fatty acids and cholesterol.The source of long-chain fatty acids is either dietary lipid or de novo synthesis from acetyl-CoA derived from carbohydrate. In the tissues, fatty acids may be oxidized to acetyl-CoA (β-oxidation) or esterified to acylglycerols, where, as triacylglycerol (fat) they constitute the body’s main caloric reserve. Acetyl-CoA fromed by β-oxidation has several important fate.

(1)As in the case of acetyl-CoA derived from carbohydrate, it is oxidized completely to CO₂ + H₂O via the citric acid cycle. Fatty acids yield considerable energy both in β-oxidation and in the citric acid cycle and are therefore very effective tissue fuels.

(2) It is a source of the carbon atoms in cholesterol and other steroids.

(3) In the liver, it forms ketone bodies, alternative water-soluble tissue fuels that become important sources of energy under certain conditions (eg, starvation)

                                Fig. 4.1.3Fatty acid metabolism