Prentice Hall c2002Chapter 161 Fig 10.5 Overview of catabolic pathways

Prentice Hall c2002Chapter 162 Chapter 16 - Lipid Metabolism Triacylglycerols and glycogen are the two major forms of stored energy in vertebrates Glycogen can supply ATP for muscle contraction for less than an hour Sustained work is fueled by metabolism of triacylglycerols Fatty acids (FA) and glycerol for metabolic fuels are obtained from triacylglycerols: (1) In the diet (2) Stored in adipocytes (fat storage cells) An enzyme (hormone-sensitive lipase) converts triacylglycerols to free fatty acids and glycerol

Dietary Lipid (Triacylglycerol) Metabolism In the small intestine, fat particles are coated with bile salts and digested by pancreatic lipases

Lipoproteins Triacylglycerols, cholesterol and cholesterol esters assemble with phospholipids and apolipoproteins to form spherical particles called lipoproteins with Hydrophobic cores: triacylglycerols and cholesteryl esters Hydrophilic surfaces: cholesterol, phospholipids, apolipoproteins

Summary of lipoprotein metabolism

Table 16.1

Prentice Hall c2002Chapter 167 Fig 16.7 Triacylglycerol degradation

Activation and Transport of fatty acids into the mitochondria Fatty acids in the cytosol are activated by conversion to CoA thioesters costing two ATP equivalents The carnitine shuttle system transfers long-chain fatty acyl CoA from the cytosol into the mitochondria The  -oxidation cycle enzymes (mitochondrial) can then degrade the fatty acyl CoA

Beta Oxidation of Fatty Acids

Prentice Hall c2002Chapter 1610 Net yield of ATP per palmitate oxidized to 16 CO 2 ATP generated 8 acetyl CoA80 7 QH NADH ATP ATP expended to activate palmitate -2 Net yield: 106 ATP

Cholesterol Biosynthesis

Lovastatin resembles mevalonate and inhibits the enzyme HMG-CoA reductase

Cholesterol Biosynthesis