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Lipids

Lipids. Broadly defined as naturally occurring non-polar compounds having simple functional groups. Major Categories of Lipids. Fats / Oils Biosynthesis of fatty acids Phospholipids Waxes Terpenes Steroids Prostaglandins. Fats. Esters of fatty (long chain carboxylic) acids

mckenzie-alvarado
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Lipids

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  1. Lipids Broadly defined as naturally occurring non-polar compounds having simple functional groups.

  2. Major Categories of Lipids • Fats / Oils • Biosynthesis of fatty acids • Phospholipids • Waxes • Terpenes • Steroids • Prostaglandins

  3. Fats • Esters of fatty (long chain carboxylic) acids • Common are triacyl glycerols, which can be hydrolyzed (saponified) into soaps:

  4. Micelles: mode of action of soap H2O Soap (above) can be represented as: H2O H2O H2O H2O Oil Soap (and detergents) form spherical clusters (right) called micelles; micelles surround and dissolve non-polar substances (oily stains) and render them “soluble.” H2O H2O

  5. Oils (polyunsaturated fats) Presence of cis double bonds in oils makes it difficult for the molecules to pack regularly in a solid structure; oils have lower melting points than fats, and are liquids at RT.

  6. Biosynthesis of Fatty Acids Repetitive applications of thio-Claisen reactions; explains why most fatty acids have an even number of carbon atoms

  7. Enolization / Carboxylation of Acetyl Coenzyme A

  8. Acylation of Malonyl Coenzyme A with 2 Carbon unit Enol form

  9. Decarboxylation, Reduction, Dehydration and Reduction

  10. Acylation of Malonyl Co A with 4 carbon unit (4 carbon unit)

  11. Conversion to 6 carbon unit (6 carbon unit)

  12. Acylation of Malonyl Co A with 6 carbon unit (6 carbon unit)

  13. Conversion to 8 carbon unit...etc. (8 carbon unit)

  14. Common Saturated Fatty Acids

  15. Common Unsaturated Fatty Acids

  16. Composition of Fats and Oils C12 C14 C16 C18 C18(1) C18(2) _________________________________________________________________________________________________________________________________________________________________________________ Animal Fats Lard - 1 25 15 50 6 Butter 2 10 25 10 25 5 Human Fat 1 3 25 8 46 10 Whale Blubber - 8 12 3 35 10 Vegetable Oils Coconut oil 50 18 8 2 6 1 Corn oil - 1 10 4 35 45 Olive oil - 1 5 5 80 7 Peanut oil - - 7 5 60 20

  17. Phospholipids • Phospholipids are long-chain fatty esters of glycerol also containing a phosphoric acid derivative • They contain a glycerol backbone, like fats and oils, but they have a phosphate group with an ionic alkyl ammonium group also attached

  18. Representative Phospholipids Phosphatidylcholine (lecithin) Phosphatidylethanolamine (cephalin)

  19. Phospholipids… Can be represented as:

  20. Lipid Bilayer of Cell Membranes

  21. Waxes • Long chain esters of long chain fatty acids (present in beeswax)

  22. Terpenes • Derived biosynthetically from a branched five carbon unit, isopentyl pyrophosphate:

  23. Terpenes... • Common monoterpenes (C10):

  24. Some more common terpenes

  25. Steroids • involved in regulatory processes and in sexual characteristics and functions • common steroids include cholesterol, estradiol, testosterone, estrogen and progesterone

  26. Prostaglandins • C20 carboxylic acids that contain a 5-member ring and have two long side chains • They were first isolated from prostate glands of sheep, but now they are known to have widespread distribution among tissues, and to exhibit an extraordinarily wide range of biological effects.

  27. Representative Structures Biosynthetic source: arachidonic acid Prostaglandin E1 (PGE1) Prostaglandin F2a(PGF2a)

  28. Some Varied Biological Effects of Prostaglandins • Lower blood pressure • Affect clotting of blood • Lower gastric secretions • Promote inflammation (countered by aspirin, which inhibits PG biosynthesis) • Affect reproductive systems • Stimulate uterine contractions during childbirth

  29. Final Exam Review: The Tuesday, December 10 class will be primarily for review; bring questions! I will be available all day Tuesday, December 17 to answer questions. A review session will be held in Dobo 205 on Tuesday, Dec. 17 at 11:00 am. Final Exam: Wednesday, December 18, 11:30 am - 2:30 pm in Dobo Hall Room 205.

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