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Fig 10.5 PowerPoint Presentation

Fig 10.5

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Fig 10.5

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  1. Fig 10.5 • Overview of catabolic pathways Chapter 16

  2. 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 Chapter 16

  3. Dietary Lipid (Triacylglycerol) Metabolism • In the small intestine, fat particles are coated with bilesalts and digested by pancreatic lipases

  4. Lipoproteins • Triacylglycerols, cholesterol and cholesterol esters assemble with phospholipids and apolipoproteinsto form spherical particles called lipoproteins withHydrophobiccores: triacylglycerols and cholesteryl estersHydrophilicsurfaces: cholesterol, phospholipids, apolipoproteins

  5. Summary of lipoprotein metabolism

  6. Table 16.1

  7. Fig 16.7 Triacylglycerol degradation Chapter 16

  8. Activation and Transport of fatty acids into the mitochondria • Fatty acids in the cytosol are activated by conversion to CoAthioesterscosting twoATPequivalents • The carnitine shuttle system transfers long-chain fatty acylCoA from the cytosol into the mitochondria • The b-oxidation cycle enzymes (mitochondrial) can then degrade the fatty acylCoA

  9. Beta Oxidation of Fatty Acids

  10. Net yield of ATP per palmitate oxidized to 16 CO2 ATP generated 8 acetyl CoA 807 QH2 10.57 NADH 17.5 108 ATP ATP expended to activate palmitate -2 Net yield: 106 ATP Chapter 16

  11. Ketone Bodies Are Fuel Molecules • During fasting or starvation, glucose is decreased, and excess acetyl CoA from fat metabolism can be converted to ketone bodies: • b-Hydroxybutyrate Acetoacetate Acetone • Ketone bodies can fuel brain cells during starvation • Synthesis in the liver Chapter 16

  12. Cholesterol Biosynthesis

  13. Lovastatinresembles mevalonate and inhibits the enzyme HMG-CoAreductase

  14. Cholesterol Biosynthesis