1. Lipids

2. Biological compound soluble in non-polar solvent Chemically heterogeneous: Simple or Complex Simple Lipid: alcohol + one or more fatty acids Complex lipid: alcohol + fatty acid + something else

3. Lipid molecule

4. Classification of Lipids

5. Fatty Acids Linear Molecules 10-20 carbons in length Even number of carbons No other functional groups but carboxyl Sometimes alkene groups C=C – Saturated vs. unsaturated

7. Water Solubility Hydrophobic part of molecule dominates: very insoluble in water Forms micelles in water

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9. Fatty Acid Nomenclature Nomenclature reflects location of double bonds also used are common names (e.g., oleic, stearic, palmitic) linoleic is also known as 18:2 n-6 this means the FA is 18 carbons in length, has 2 double bonds, the first of which is on the 6th carbon arachidonic = 20:4 n-6 this means the FA is 18 carbons in length, has 4 double bonds, the first of which is on the 6th carbon

10. Saturated vs. Unsaturated Fatty Acids saturated: the SFA’s of a lipid have no double bonds between carbons in chain polyunsaturated: more than one double bond in the chain most common polyunsaturated fats contain the polyunsaturated fatty acids (PUFAs) oleic, linoleic and linolenic acid unsaturated fats have lower melting points stearic (SFA) melts at 70 o C, oleic (PUFA) at 26 o C

11. saturated Fatty Acids Fatty Acid # of Carbons # of C=C lauric120 myristic140 palmitic160 stearic180

12. Unsaturated Fatty Acids Fatty Acid # of Carbons # of C=C oleic181 linoleic182 linolenic183 arachadonic204

14. 14 Properties of Fats and Oils Triacylglycerols in natural fats and oils are nonpolar, hydrophobic molecules with no ionic charges. Oil: A mixture of triacylglycerols that is liquid because it contains a high proportion of unsaturated fatty acids. Fat: A mixture of triacylglycerols that is solid because it contains a high proportion of saturated fatty acids.

15. 15 The hydrocarbon chains in saturated acids are flexible and uniform in shape, allowing them to nestle together. By contrast, the carbon chains in unsaturated acids have rigid kinks wherever they contain cis double bonds. The kinks make it difficult for such chains to fit next to each other in the orderly fashion necessary to form a solid.

16. Melting Points Increases with size (lesser effect) Decreases with unsaturation (greater effect)

17. Cis vs Trans Fatty Acids Cis fatty acids occur naturally Trans fatty acids occur during hydrogenation reactions

18. Triglycerides: Fats and Oils Glycerol + 3 Fatty Acids Connected by ester bonds

19. Triglyceride

20. Fat or Oil Depends on melting point- solid or liquid at room temperature Depends mostly on degree of unsaturation Animal Fats more saturated, plant oils more unsaturated

21. Waxes Long chain fatty acid + long chain fatty alcohol Myristyl palmitate

22. Wax Block Diagram

23. Phosphoglycerides Glycerol, 2 fatty acids, phosphate + another alcohol Glycerol Fatty Acid Phosphate alcohol

24. Phosphatidic acid

25. Alcohols used in phosphoglycerides serine ethanolamine choline

26. Phosphatidyl Choline (lecithin) Lectithin used as emulsifier Dipalmitoyl phosphatidyl choline formed as surfactant in lung cells

27. Phosphatidyl serine: a cephalin found in cell memranes

28. Sphinglipids: Sphingosine + fatty acid + something else Sphingosine

29. Ceramide: sphingosine + fatty acid Sphingosine

30. Sphingomyelin: sphingosine, fatty acid, phosphate and choline Sphingomyelins found in myelin sheath around neurons

31. Sphingomyelin Fatty acid phosphate choline

32. Glycolipid: Lipid + Carbohydrate Cerebroside: Sphingosine + fatty acid + carbohydrate

33. Lipid Storage Diseases

34. Steroids Non-saponifiable lipids derived from cholesterol Steroid Ring System

35. Cholesterol Found in Diet (animal fats) Endogenous synthesized in liver

36. Cholesterol Essential component of cell membranes Used as raw material for sex hormones and adrenocorticoid hormones Used to make bile salts High blood levels also associated with heart disease, atherosclerosis, arterial plaques

37. Cholesterol transported as Lipoprotein complex (LDL)

38. lipoproteins Low Density Lipoproteins (LDL) – is made by the liver and is comprised of cholesterol that is delivered to the cells in the body – High levels of LDL is strongly correlated with heart disease High Density Lipoproteins (HDL) - made by the liver and picks up cholesterol from the cells fro recycling or excretion – High levels of HDL is inversely correlated with heart disease – It is protective

39. Lipoproteins classified by Density HDL: High-density Lipoprotein LDL: Low-density Lipoprotein VLDV: Very low-density Lipoprotein – Triglycerides and cholesterol Chylomicron – Mostly triglycerides

40. Biological flow of Cholesterol

41. Bile Salts: Glycocholate Act as emulsifying agents to digest fats Method for excreting cholesterol- bile is emulsion of cholesterol and bile salts Gall stones form when cholesterol gets too concentrated

42. Adrenocorticoid hormones Glucocorticoids: – regulate blood glucose levels – Cortisol and Cortisone – Also regulate inflammation, used to treat inflammatory diseases Mineralcorticoids: – influences blood Na + and Cl - levels – Aldosterone most important

43. cortisol cortisone aldosterone

44. Male Sex Hormones Testosterone – Produced by testes – Male genitals and secondary sex characteristics – Muscle growth Anabolic Steroids (fake testosterone) – Intended to prevent muscle atrophy – Used by athletes, widely banned – Bad side effects

45. Female Sex Hormones Estrogen(estradiol, estrone) and progersterone – Produced by ovaries – Reproductive cycle and secondary female characteristics Mimicked by birth control pills

46. Prostaglandins Hormone like action – Regulates fever, contractions, inflammation – Induces labor, and asthma – Made from arachadonic acid – Synthesis inhibited by aspirin and cyclooxygenase inhibitors

47. Functions of lipids Excellent energy reserves Structure of cell membranes Organ padding Body thermal insulation Essential fatty acids (EFA) Hormone synthesis Fat soluble vitamin absorption

48. Biological Membranes Separates cell interior from exterior, or cellular organelles from cytoplasml About 60% lipid and 40% protein – Lipid mostly phosphoglyceride, sphingomyelin and cholesterol Found as Lipid Bilayer

49. Lipid Bilayer