1. Organic Chemistry 4 th Edition Paula Yurkanis Bruice Irene Lee Case Western Reserve University Cleveland, OH ©2004, Prentice Hall Chapter 26 Lipids

2. Lipids are soluble in nonpolar organic compounds They have a variety of structures and functions

3. Fatty Acids Are Carboxylic Acid with Hydrocarbon Chains

4. The double bonds in naturally occurring fatty acids have the cis configuration Double bonds in naturally occurring unsaturated fatty acids are separated by one methylene group Polyunsaturated fatty acids have more than one double bond

5. Triacylglycerols The three OH groups of glycerol are esterified with fatty acids glycerol fatty acids a triacylglycerol a fat or an oil

6. Fats are triacylglycerols existing as solid or semisolid state at room temperature

7. Oils are liquid triacylglycerols

8. Some or all of the double bonds of polyunsaturated oils can be reduced by catalytic hydrogenation

9. Oxidation of Polyunsaturated Fats and Oils by O 2

10. Phosphoacylglycerols The terminal OH group of glycerol is esterified with phosphoric acid They are the major components of cell membranes

11. The most common phosphoacylglycerols in membranes have a second phosphate ester linkage Phosphoacylglycerols are classified as phospholipids

12. Phosphoacylglycerols form membranes by arranging themselves into a lipid bilayer Saturated fatty acids decrease membrane fluidity because their hydrocarbon chains can pack closely together Unsaturated fatty acids have the opposite effect

13. Sphingolipids They contain sphingosine instead of glycerol They are the major lipid components in the myelin sheaths of nerve fiber They are also found in membranes

14. Two of the Most Common Kinds of Sphingolipids

15. Prostaglandins are synthesized from arachidonic acid They are responsible for regulating a variety of physiological responses Prostaglandins postaglandin skeleton Name in the format PGX, with X designating the functional groups of the five-membered ring

16. PGE 1 PGE 2 PGF 2n Naming Prostaglandins

18. Aspirin Inhibits the Synthesis of Prostaglandins (prostaglandin endoperoxide synthase)

19. Terpenes contain carbon atoms in multiples of five They are made by joining together 5-carbon isoprene units Terpenes Oxygen-containing terpenes are sometimes called terpenoids

20. The Isoprene Rule

23. Squalene, a triterpene, is a precursor of steroid molecules

24. Lycopene and  -carotene are tetraterpenes called carotenoids

27. The five-carbon compound used for biosynthesis of terpenes is isopentyl pyrophosphate

29. The Conversion of Mevalonic Acid into Mevalonyl Phosphate

30. Both isopentyl pyrophosphate and dimethylallyl pyrophosphate are needed for the biosynthesis of terpenes

31. Formation of geranyl pyrophosphate Terpene Biosynthesis

33. Formation of Farnesyl Pyrophosphate

34. Formation of Squalene, the Precursor of Cholesterol

35. Hormones are chemical messengers Many hormones are steroids All steroids contain a tetracyclic ring system Steroids

36. Methyl groups at C-10 and C-13 are called angular methyl groups The B, C, and D rings are trans fused

37. Those  on the opposite side of the plane of the ring system are  -substituents Substituents on the same side of the steroid ring system as the angular methyl groups are  -substituents The A and B rings are also trans fused in most naturally occurring steroids

38. Cholesterol Is a Steroid

39. Examples of Steroids

40. Biosynthesis of Cholesterol

41. Examples of Synthetic Steroids