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Chapter 8

Chapter 8. Lipids to accompany Biochemistry, 2/e by Reginald Garrett and Charles Grisham.

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Chapter 8

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  1. Chapter 8 Lipids to accompany Biochemistry, 2/e by Reginald Garrett and Charles Grisham All rights reserved. Requests for permission to make copies of any part of the work should be mailed to: Permissions Department, Harcourt Brace & Company, 6277 Sea Harbor Drive, Orlando, Florida 32887-6777

  2. Outline • 8.1 Fatty Acids • 8.2 Triacylglycerols • 8.3 Glycerophospholipids • 8.4 Sphingolipids • 8.5 Waxes • 8.6 Terpenes • 8.7 Steroids

  3. Classes of Lipids All biological lipids are amphipathic • Fatty acids • Triacylglycerols • Glycerophospholipids • Sphingolipids • Waxes • Isoprene-based lipids (including steroids)

  4. 8.1 Fatty acids Know the common names and structures for fatty acids up to 20 carbons long • Saturated • Lauric acid (12 C) • Myristic acid (14 C) • Palmitic acid (16 C) • Stearic acid (18 C) • Arachidic acid (20 C)

  5. Fatty acids - II • Unsaturated fatty acids • Palmitoleic acid (16:1) • Oleic acid (18:1) • Linoleic acid (18:2) • -Linolenic acid (18:3) • -Linolenic acid (18:3) • Arachidonic acid (20:4)

  6. Fatty acids - III Structural consequences of unsaturation • Saturated chains pack tightly and form more rigid, organized aggregates (i.e., membranes) • Unsaturated chains bend and pack in a less ordered way, with greater potential for motion

  7. 8.2 Triacylglycerols Also called triglycerides • A major energy source for many organisms • Why? • Most reduced form of carbon in nature • No solvation needed • Efficient packing

  8. Triacylglycerols - II Other advantages accrue to users of triacylglycerols • Insulation • Energy without nitrogen • Metabolic water

  9. 8.3 Glycerophospholipids Glycerophospholipids are phospholipids but not necessarily vice versa • Know the names and structures in Figure 8.6 • Understand the prochirality of glycerol • Remember that, if phospholipid contains unsaturation, it is at the 2-position

  10. Ether Glycerophospholipids An ether instead of an acyl group at C-1 • See Figure 8.8 • Plasmalogens are ether glycerophospholipids in which the alkyl chain is unsaturated

  11. Ether Glycerophospholipids • Platelet activating factor (PAF) is an ether glycerophospholipid • PAF is a potent biochemical signal molecule • Note the short (acetate) fatty acyl chain at the C-2 position in PAF

  12. 8.4 Sphingolipids Base structure is sphingosine • Sphingosine is an 18-carbon amino alcohol • Ceramides are amide linkages of fatty acids to the nitrogen of sphingosine • Glycosphingolipids are ceramides with one or more sugars in beta-glycosidic linkage at the 1-hydroxyl group

  13. 8.4 Sphingolipids • Glycosphingolipids with one sugar are cerebrosides • Gangliosides - ceramides with 3 or more sugars, one of which is a sialic acid

  14. 8.5 Waxes Esters of long-chain alcohols with long-chain fatty acids • Highly insoluble • Animal skin and fur are wax-coated • Leaves of many plants • Bird feathers

  15. 8.6 Terpenes Based on the isoprene structure • Know nomenclature • Understand linkage modes (Figure 8.16) • See structures in Figure 8.17 • All sterols (including cholesterol) are terpene-based molecules • Steroid hormones are terpene-based

  16. 8.7 Steroids • Based on a core structure consisting of three 6-membered rings and one 5-membered ring, all fused together • Cholesterol is the most common steroid in animals and precursor for all other steroids in animals • Steroid hormones serve many functions in animals - including salt balance, metabolic function and sexual function

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