CHAPTER 10

1. CHAPTER 10 Lipids

2. Lipids Learning Goals: Know: • Biological roles of lipids • Structure and properties of storage lipids • Structure and properties of membrane lipids • Structure and properties of signaling lipids • Methods of Lipid Structure Determination EOC Problem 1 starts off with “what is a lipid” see next slide for the diversity of lipids.

3. Organic molecules that are characterized by low solubility in water, that is, are relatively hydrophobic. Thought question: would some amino acids act like lipids ? …consider I, L, F, W, Y Lipids: Structurally Diverse Class

4. Biological Functions of Lipids • Storage of energy • Reduced compounds: lots of available energy • Hydrophobic nature: good packing • Insulation from environment • Low thermal conductivity • High heat capacity (can “absorb” heat) • Mechanical protection (can absorb shocks) • Water repellant • Hydrophobic nature: keeps surface of the organism dry • Prevents excessive wetting (birds) • Prevents loss of water via evaporation • Buoyancy control and acoustics in marine mammals • Increased density while diving deep helps sinking (just a hypothesis) • Spermaceti organ may focus sound energy: sound stun gun?

5. More Functions • Membrane structure • Main structure of cell membranes • Cofactors for enzymes • Vitamin K: blood clot formation • Coenzyme Q: ATP synthesis in mitochondria • Signaling molecules • Paracrine hormones (act locally) • Steroid hormones (act body-wide) • Growth factors • Vitamins A and D (hormone precursors) • Pigments • Color of tomatoes, carrots, pumpkins, some birds • Antioxidants • Vitamin E

6. Fatty Acid Naming Systems

7. Effect of cis – unsaturation on Stearic Acid 18:0 EOC Problem 8: Draw the structure of omega-6 fatty acid 16:1. You can pause here and do it !

8. Fatty Acids

9. Go Back to the Table…Look at Melting Points + Their Meaning EOC Problem 2a and 2c Get Into Melting Points and Unsaturation

10. Glycerol = Heart of Some Complex Lipids

11. Triacylglycerol When Unsat’d acids are there, they are first at C-2.

12. Guinea Pig Adipocytes

13. Arabidopsis Seed Section

14. Sperm Whales – Fatheads of the Deep Adjusts buoyancy with Deep dives (1000m deep) by crystallizing and becoming denser…less energy is used by the whale (to overcome buoyancy).

15. Saturated and Unsaturated Fats in Food Lipids

16. Trans Fatty Acids • Trans fatty acids form by partial dehydrogenation of unsaturated fatty acids • Done to increase shelf life or stability at high temperature of oils used in cooking (especially deep frying) • A trans double bond allows a given fatty acid to adopt an extended conformation • Trans fatty acids can pack more regularly and show higher melting points than cis forms • Consuming trans fats increases risk of cardiovascular disease • Avoid deep-frying partially hydrogenated vegetable oils • Current trend: reduce trans fats in foods (Wendy’s, KFC) EOC Problem 9: Calalytic hydrogenation of Veggie Oils

18. Wax EOC Problem 13 on the impermeability of waxes.

19. Ear Wax (Cerumen) is Not Wax The primary components of ear wax are shed layers of skin: 60% of the earwax consisting of keratin 12–20% saturated and unsaturated long-chain fatty acids, alcohols and squalene, 6–9% cholesterol

20. Major Types of Lipids

21. What “X” Can Be: 5th Edition Why are these arrows here?

22. 6th Edition

23. Phosphatidylcholine • Phosphatidylcholine is the major component of most eukaryotic cell membranes • Many prokaryotes, including E. coli, cannot synthesize this lipid; their membranes do not contain phosphatidylcholine

24. PhosphatidylInositol – Membrane Signaling

25. Phospholipases

26. Ether Lipids: Plasmalogen • Vinyl ether analog of phosphatidylethanolamine • Common in vertebrate heart tissue • Also found in some protozoa and anaerobic bacteria • Function is not well understood • Resistant to cleavage by common lipases but cleaved by few specific lipases • Increase membrane rigidity? • Sources of signaling lipids? • May be antioxidants?

27. Two Ether Linked aliphatic groups High concentration in Heart Lipids Active at 10-9 M … Part of many things including Inflammation

28. Galactolipids – in Chloroplasts 70-80% of Lipids in Thylakoid Membranes

29. One Type of Achaea Membrane Lipid in Hyperthermophiles

30. Sphingolipids Sphingolipids

31. Discoverer of Sphingolipids

32. Neuraminic Acid = Sialic Acid

33. Shapes of these Phospholipids

34. ABO Blood Groups Glc-Gal-GalNAc-Gal Fuc

35. ABO Blood Group Substances, 5th Ed

36. Recycling Sphingolipids

37. Membrane Lipid as Progenitor to Prostaglandins - 1 Arachidonic Acid C20:4Δ5,8,11,14

38. Eicosanoids Smooth Muscle Contraction Hormones Part of Blood Clotting Asprin and Ibuprofin Inhibit Synthesis of Prostaglandins + Thromboxanes NSAID’s = Non Steroid Anti Inflammatory Drugs

39. Cholesterol – Steroid (= 4 fused rings)

40. Steroid Hormones Made from Cholesterol Multistep Glucose Metabolism Salt Excretion Cholesterol Anti-inflammatory

41. Synthesis of Vitamin-D Regulate Calcium Metabolism

42. A child who began life in a closet

43. Retinal Comes from Carotene

44. Isoprene Vitamins

45. Mitochondrial and Chloroplast Membrane Electron Carriers

46. Carotenoids

47. Outline of Lipid Structure Identification

48. Saponification and Methylation

49. Gas or HPLC to separate and identify the Fatty Acid Methyl Esters

50. Mass Spectrometry of a Lipid