1. Lecture 3: Lipids: Fats, Phospholipids, Steroids 1

2. Yesterday’s Exit Ticket What element(s) (i.e. atom types) do all 4 molecules have in common? –C and H: they are all organic molecules! MacromoleculeMonomer or Types Function(s)Key Element(s) (e.g. carbon) CarbohydratesMonosaccharideEnergy supplyC, H, O LipidsFats, Steroids, Phospholipids Energy storage, hormones, cell membranes C, H ProteinsAmino acidJust about everything… C, H, O, N Nucleic AcidsNucleotideInformation storage and transmission C, H, O, N, P 2

3. Key Themes (2) “Think Like a Biologist”: Understand What Life Is. “Unity” of life: What are the common features of all life? Structure and function of the molecules of life 3

4. The Basics: General properties of lipids 1.Lipids are macromolecules, but technically not polymers No long chains of many repeated subunits 4

5. We will discuss three lipid classes: Fats Phospholipids Steroids http://wiki.faithlutheranlv.org/groups/carmanbio/wiki/ dbc5b/Lipids.html Mostly hydrophobic 5

6. We will discuss three lipid classes: Fats Phospholipids Steroids Fat = glycerol + 3 fatty acid chains 6

7. Removal of H 2 O (dehydration synthesis) Fig. 5.11 How is a fat constructed? From glycerol + fatty acids 7

8. Removal of H 2 O (dehydration synthesis) forms new bond between glycerol & fatty acid Fat with 3 fatty acids = triacylglycerol = triglyceride Fig. 5.11 How is a fat constructed? From glycerol + fatty acids 8

9. Fats Fats are constructed from two types of smaller molecules: glycerol and 3 fatty acids http://www.colorado.edu/ebio/genbio/05_11Fats_A.html (end when box turns orange) 9

10. Energy storage in fat versus carbohydrate Gram-for-gram, fats store twice as much energy as carbohydrates and proteins Carbohydrates = 4 kcal/gram(CHOH) n Proteins = 4 kcal/gram(CH”R”) n Fats = 9 kcal/gram(CH 2 ) n I H - C - OH I “Carb” I H - C - H I Fat 10

11. Fat is used to store energy when a compact energy source with minimum weight is needed. What organisms (or stages of organisms) would you predict to store fats (rather than polysaccharides)? 11

12. Functions of dietary fats Energy supply (all fats) Building blocks for body (omega-6 & omega-3 fatty acids needed for brain / heart muscle …) Diet-gene interaction (omega-6 & omega-3 fatty acids converted to hormone messengers) 12

13. http://www.colorado.edu/ebio/genbio/05_11Fats_A.html Saturated – single bonds – straight – solid Unsaturated – double bonds – L-shaped – liquid 13

14. Which of the fats below (all with the same number of carbon atoms) has the highest energy content? A)a fat composed of saturated fatty acids B) a fat composed of monounsaturated fatty acids C) a fat composed of polyunsaturated fatty acids Think-Pair-Share http://spaceflight.esa.int/impress/text/education/ Glossary/Glossary_T.html 14

15. Saturated and Unsaturated Fats Saturated fats are solid Unsaturated fats are liquid How can you tell them apart? 15

16. Real World Connection: Saturated and Unsaturated Fats in the News Which is better for your health? Consumption of saturated fats raises cholesterol levels. Most of the cholesterol in human body is synthesized from saturated fats! 16

17. a) Saturated fatty acid Stearic acid (b) Monounsaturated fatty acid (MUFA) Oleic acid 17

18. http://wiki.faithlutheranlv.org/groups/carmanbio/wiki/dbc5b/Lipids.html MUFA Mono Unsaturated Fatty Acid 18

19. (a)Saturated fatty acid Stearic acid (b) Monounsaturated fatty acid (MUFA) Oleic acid Fig. 5.12 Recommended changes to current US diet: Reduce saturated fats. Increase monounsaturated fats. 19

20. http://instruct.westvalley.edu/svensson/Cells/07molecules.htm 20

21. Difference between Omega-3 and Omega-6 PUFAs http://www.supplementquality.com/news/fatty_acid_structure.html (Note that all PUFAs are highly “kinked”, even though the simple image on the right does not reflect this.) Recommended changes cont: Reduce omega-6 polyunsaturated fatty acids (PUFAs). Increase omega-3 PUFAs. 21

22. A saturated fat is saturated with the maximal number of A) carbon atoms (C). B) hydrogen atoms (H). C) C=C bonds. D) carbon and hydrogen atoms. E) hydrogen atoms and C-H bonds. Think-Pair-Share http://spaceflight.esa.int/impres s/text/education/Glossary/Glos sary_T.html saturated monounsaturated polyunsaturated 22

23. http://sabrebrains.blogspot.com/2011/02/lipids.html 23

24. Predict the result(s) of removing hydrogen atoms from the fatty acid tails of saturated animal fat (lard): A) The number of carbon-carbon double bonds in the fat molecules increases. B) The number of carbon-carbon double bonds in the fat molecules decreases. C) The fat becomes more fluid. D) A and C E) B and C Think-Pair-Share 24

25. Latest recommendation for ideal fat composition in the human diet: 70-80% monounsaturated fatty acids 10-15% polyunsaturated fatty acids (omega-6 to omega-3 ratio 2:1) 10-15% saturated fatty acids (animal) 25

26. http://www.canola-council.org/canola_resources/product45.aspx 10-15% 70-80% Ratio of ≤2 to 1 26

27. Polyunsaturated Fatty Acids (PUFAs) = Essential Fatty Acids (EFAs) Omega-3Omega-6 Converted to hormones that slow down cell division and dampen inflammation Converted to hormones that speed up cell division and trigger inflammation Healthy, balanced ratio of omega-6 to omega-3 fatty acids is 2:1, whereas estimate for modern US diet is 20:1 = highly unbalanced Why a 2:1 ratio? 27

28. Polyunsaturated Fatty Acids = Essential Fats Omega-3Omega-6 (ALA, alpha-linolenic acid) In flax seed, nuts, canola oil (LA, linoleic acid) Lots in corn, sunflower, soybean oil EPA and DHA In fatty fish (AA) In meat, milk of grain-fed cattle Converted to hormones that slow down cell division and dampen inflammation Converted to hormones that speed up cell division and trigger inflammation 28

29. The Yin & Yang of Inflammation The “GOOD”:Upon injury/infection, pro- inflammatory prostaglandins “call” white blood cells to engulf & destroy injured body cells & invaders. The “BAD”: Overproduction of pro- inflammatory messengers causes white blood cells to attack uninjured body cells. http://taoism.about.com/od/visualsymbols/ig/Taoist-Symbols/Yin-Yang-Symbol.--jj.htm 29

30. PREVENT Healthful diet PROMOTE Modern western diet High saturated fat High omega-6:3 fatty acid ratio Low saturated fat Balanced omega-6:3 fatty acid ratio Chronic disease and disorders Impact of dietary fats on human health 30

31. Good source of omega-3 fatty acids, ± low in mercury & PCBs Salmon (wild, farmed?) Mackerel (but not king mackerel!) Mussels, oysters Anchovies Rainbow trout Herring Sardines Tuna (but not bluefin, white/albacore?) Stay away from Highly mercury contaminated fish (>1 ppm) Shark Swordfish King mackerel Tilefish And also Bluefin tuna Chilean sea bass Rockfish Grouper Bluefish Just FYI: Real World Advice http://www.montereybayaquarium.org/cr/cr_seafoodwatch/download.aspxwww.montereybayaquarium.org/cr/cr_seafoodwatch/download.aspx 31

32. Which is correct? A)omega-3 fatty acids are good and omega-6 fatty acids are bad B) omega-6 fatty acids have no positive effects A)both omega-3 fatty acids and omega-6 fatty acids have vital roles in the human body D) the ratio of omega-6 to omega-3 fatty acids is not important for human health E) B, C, and D are all correct 32

33. 5 minute break blog.famasalescoffee.com 33

34. Three types of lipids: Fats Phospholipids Steroids Phospholipid = phosphate + glycerol + 2 fatty acid chains 34

35. How is a phospholipid constructed? Fig. 5.13 35

36. How is a phospholipid constructed? Fig. 5.13 36

37. A phospholipid is shown below. Predict which of the structures A-D, also shown below, is MOST LIKELY to form when a phospholipid is dispersed in water. hydrophilic (water-loving) polar head group hydrophobic (water-fearing) non-polar tails Think-Pair-Share 37

38. Interactions of phospholipid molecules with water The basis of phospholipid bilayers Hydrophilic head Hydrophobic tail WATER Fig. 5.14 38

39. Hydrophilic head Hydrophobic tail WATER Fig. 5.14 Structure-function relationship: Phospholipids are key to the existence of biological cells 39

40. Fa t Fig. 5.11 Phospholipid Fig. 5.13 40

41. (Three types of lipids:) Fats Phospholipids Steroids Steroids = 4 carbon-hydrogen rings 41

42. http://www.uv.es/EBRIT/macro/m acro_5009_2_284.html http://www.sciencephoto.com/media/97627/enlarge 42

43. Steroids: What are they? pictureschat.com; ellies-whole-grains.com; medicalinsider.com; genesistraining.org.uk 43

44. Testosterone Estradiol (an estrogen) Fig. 4.9 See pages 977 & 993-994 in textbook for more information Sex hormones are steroids. 44

45. Cholesterol Fig. 5.15 Made from saturated dietary fat Stabilizes biological membranes in animals (will be visited later) Has a role in heart disease (will be visited later) Is an important precursor for other steroids 45

46. Fig. 5.15 Precursor in synthesis of: Sex hormones, stress hormones, Vitamin D Roles of cholesterol 46

47. http://www.neurosci.pharm.utoledo.edu/MBC3320/steroid_hormones.htm Synthesis of steroid stress hormones (corticosteroids) from cholesterol 47

48. How does eating NO saturated fats negatively affect your health? a)It wouldn’t. Saturated fats are bad. b)It would reduce sex hormones, but who wants to be hormonal anyway? c)It would reduce steroid hormones, so the body is less muscular. d)It would reduce sex hormones, and there are negative effects of this. 48

49. Fig. 5.15 Precursor in synthesis of: Sex hormones, stress hormones, Vitamin D Roles of cholesterol 49

50. Vitamin D2 http://en.wikipedia.org/wiki/Vitamin_D + UV Cholesterol 50

51. Which lipid is most hydrophilic? “Water and oil don’t mix!” Fats Fig. 5.11 Phospholipids Steroids Fig. 5.15 Fig. 5.13 51

52. Fats Fig. 5.11 Phospholipids Steroids Fig. 5.15 Fig. 5.13 What are the roles of these lipids? Energy supply? Cellular building blocks? Hormone-like messengers? 52

53. Today’s Exit Ticket Describe the key differences between: –Saturated fats –Monounsaturated fats –Polyunsaturated fats Give an example of each that you have consumed in the last week 53