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Biochem Lipids I
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Biochem Lipids I

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(c) Geromil J. Lara, RMT, MSMT

(c) Geromil J. Lara, RMT, MSMT

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  • 1. LIPIDSGeromil J. Lara, RMT, MSMT
  • 2. LIPIDS• Refers to a collection of organic molecules of varying chemical composition• Are grouped together on the basis of their solubility in nonpolar solvents• 4 main groups – Fatty Acids (Saturated and Unsaturated) – Glycerides (Glycerol-containing Lipids) – Nonglyceride Lipids (Sphingolipids,Steroids,Wax) – Complex Lipids (Lipoproteins) 2
  • 3. Saturated Fatty Acids Unsaturated Neutral Glycerides Glycerides PhosphoglyceridesLIPIDS Complex Lipids Lipoproteins Sphingomyelins Sphingolipids Glycolipids Nonglycerides Lipids Steroids Waxes 3
  • 4. BIOLOGICAL FUNCTIONS OF LIPIDS• Energy Source – When oxidized, each gram of fat releases 9 kcal of energy, or more than twice the energy released by oxidation of a gram of carbohydrate• Energy Storage – In the form of triglycerides (TAG) in adipocytes• Cell Membrane Structural Components – Phosphoglycerides, sphingolipids, and steroids make up the basic structure of all cell membranes 4
  • 5. BIOLOGICAL FUNCTIONS OF LIPIDS• Hormones – Steroid Hormones• Vitamins – Lipid-soluble vitamins (A,D,E, and K)• Vitamin Absorption – Dietary fat serves as a carrier of the lipid-soluble vitamins• Protection – fats as shock absorber• Insulation – subcutaneous fat 5
  • 6. (1) FATTY ACIDS• Are long-chain O monocarboxylic acids R C OH• Generally contain an even number of #1 Carbon Acid Group carbon atoms O R C OH Polar End - Hydrophilic End Non-polar End - Hydrophobic End (F at-soluble tail) 6
  • 7. CLASSIFICATIONS OF FATTY ACID• Length of the Carbon Chain – Long-chain, medium-chain, short-chain• Degree of Unsaturation – Saturated, Unsaturated (Mono, Poly)• Location of Double Bonds – Omega-3 Fatty Acid, Omega-6 Fatty Acid 7
  • 8. (1) FATTY ACIDS• Short-Chain Fatty Acids – Less than 6 carbons• Medium-Chain Fatty Acids – 6-10 carbons• Long-Chain Fatty Acids – More than 12 carbons 8
  • 9. (1) FATTY ACIDS• Saturated Fatty Acids – Each C being “saturated” with H – General Formula: CH3(CH2)nCOOH 9
  • 10. LAURIC ACID 10
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  • 13. (1) FATTY ACIDS• Unsaturated Fatty Acids – Composed of at least one carbon-to- carbon double bond – Almost are in the cis configuration 13
  • 14. (1) FATTY ACIDS• Monounsaturated Fatty Acids (MUFA) – Composed of one carbon-to-carbon double bond 14
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  • 16. (1) FATTY ACIDS• Polyunsaturated Fatty Acids (MUFA) – Composed of more than one carbon-to- carbon double bond 16
  • 17. (1) FATTY ACIDS• Polyunsaturated Fatty Acids (MUFA) – are identified by position of the double bond nearest the methyl end (CH3) of the carbon chain; this is described as an omega number; – If PUFA has first double bond 3 carbons away from the methyl end = omega 3 FA – 6 carbons from methyl end = omega 6 FA 17
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  • 20. (1) FATTY ACIDS• cis-Fatty Acid – H’s on same side of the double bond; fold into a U-like formation; naturally occurring 20
  • 21. (1) FATTY ACIDS• trans-Fatty Acid – H’s on the opposite side of the double bond; occur in partially hydrogenated food 21
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  • 24. PROPERTY SATURATED UNSATURATED FATTY ACIDS FATTY ACIDC-C Bonds within Only C-C single At least one C-Cthe hydrocarbon bonds double bond chainHydrocarbon chains are Alkanes Alkenes characteristic of what group of hydrocarbon “Shape” of Linear, Fully Bend in carbonHydrocarbon chain extended chain at site of C-C double bond Physical state at Solid Liquidroom temperature Melting Point Higher Lower 24
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  • 27. BUT, ARE ALL TRANS-FAT BAD?• Omega-3: – Eicosopentaenoic acid (EPA) – Docosahexaenoic acid (DHA) – Alpha-linolenic acid (ALA) • flaxseed--most, canola (rapeseed), soybean, walnut, wheat germ • body can make some EPA and DHA from ALA• Omega-6 – corn, safflower, cottonseed, sesame, sunflow er – Linoleic acid 27
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  • 29. CHEMICAL REACTIONS OF FATTY ACID• Esterification – Fatty acids react with alcohols to form esters and water 29
  • 30. CHEMICAL REACTIONS OF FATTY ACID• Acid Hydrolysis – Producing fatty acids from esters – Opposite of esterification• Saponification – Is the base-catalyzed hydrolysis of an ester – the product of this reaction, an ionized salt, is a soap • Have a long uncharged hydrocarbon tail and a negatively charged terminus (the carboxylate terminus 30
  • 31. CHEMICAL REACTIONS OF FATTY ACID• Saponification – Is the base-catalyzed hydrolysis of an ester – the product of this reaction, an ionized salt, is a soap • Have a long uncharged hydrocarbon tail and a negatively charged terminus (the carboxylate terminus), they form micelles that dissolve oil and dirt particles 31
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  • 33. CHEMICAL REACTIONS OF FATTY ACID• Reaction at the Double Bond (Unsaturated Fatty Acids) – Hydrogenation • Used in the food industry to convert polyunsaturated vegetable oils into saturated solid fats – Partial Hydrogenation • Carried out to add hydrogen to some, but not all, double bonds in polyunsaturated oils • In this way liquid vegetable oils are converted into solid form (Crisco and margarine) 33
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  • 37. (2) GLYCERIDES• Are lipid esters that contain the glycerol molecule and fatty acids – 2 Classes • Neutral Glycerides – nonionic and nonpolar • Phosphoglycerides – have polar region, the phosphoryl group, in addition to the nonpolar fatty acid tails 37
  • 38. (2) GLYCERIDES• Neutral Glycerides – Produce after the esterification of glycerol with a fatty acid – Esterification may occur at one, two, or all three positions, producing: • Monoglycerides • Diglycerides • Triglycerides – most important and main storage form of lipids in man (adipocytes) 38
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  • 41. FAT vs. OIL• Fat – A mixture of triglycerides containing high proportion of long-chain, saturated fatty acids • Animals – generally solids • Plants or Fish – usually liquids• Oil – Liquid fat – Contain high proportion of unsaturated fatty acids and saturated fatty acids 41
  • 42. (2) GLYCERIDES• Neutral Glycerides – There are no charges (+ or -) on these molecules – These long molecules readily stack with one another and constitute the majority of the lipids stored in the body’s fat cells – Primary function is to store energy • More energy-rich nutrients are consumed than are required for metabolic processes, much of the excess is converted to neutral glycerides and stored as TAG in fat cells 42
  • 43. (2) GLYCERIDES• Phosphoglycerides – Phospholipids – are group of lipids that are phosphate esters • The presence of the phosphoryl group results in a molecule with a polar head (the phosphoryl group) and a nonpolar tail (the alkyl chain of the fatty acid) 43
  • 44. (2) GLYCERIDES• Phosphoglycerides – Most abundant membrane lipids and derived from glycerol-3-phosphate – Contain acyl groups derived from long chain fatty acids at C-11 and C-2 of glycerol-3-phosphate – At C-3 the phosphoryl group is joined to glycerol by a phosphoester bond • Phosphatidate – simplest phosphoglyceride contains a free phosphoryl group 44
  • 45. 4/30/2012 Free Template from www.brainybetty.com 45