LIPIDS

1. LIPIDS Ryan Jeffery, Ali Loperena, Neil Jethani, Dee White, Sammy Soliman, Nicolette Canale, Jon Chernov, Keith Wright

2. OBJECTIVE B.4.1 Ryan Jeffery

3. WELCOME BACK! • It’s very nice to see you all again! • Now let’s get to work

4. OBJECTIVE 4.1 • Assessment Statement • Compare the composition of the three types of lipids found in the human body. • Teacher’s Notes • Examples include triglycerides (fats and oils), phospholipids (lecithin), and steroids (cholesterol).

5. TRIGLYCERIDES Fatty Acid Chains can very in length! Chains are always EVENLY numbered in length!

6. COMPOSITION OF A TRIGLYCERIDE • Triglycerides have two parts • Glycerol • Fatty Acids • Glycerol • Seen in Green • 3 Carbon atoms bonded to 3 Hydroxyl Groups • Fatty Acids • Carboxyl group • Bonded to a hydrocarbon chain approximately 16 to 18 carbons long

7. EXAMPLES • Fat Molecules and Oils • Both are found in abundance in fast food • Both are linked to an increased risk of heart disease and stroke.

8. PHOSPHOLIPIDS Fatty Acid Chain Glycerol Choline Group

9. PHOSPHOLIPIDS • Make up most of the plasma membrane • PHOSPHOLIPID Bi-layer • First discovered in egg yolk by Theodore Nicolas in 1847

10. LECITHIN • First phospholipid discovered • Specifically Phosphatidylcholine • Composed of: • Glycerophosphoric Acid (one saturated, one unsaturated fatty acid) • Choline Head • Found in: • Animal Tissue • Plant Tissue • Egg Yolks

11. STEROIDS*

12. STRUCTURE • 20 Carbon Atoms • Form Four Rings • Three Cyclohexane rings (C6H12) (A,B,C) • One Cyclopentane ring (C5H10) (D) • Yes, that’s more than 20 C – They share • Varying functional groups • Varying oxidation states

13. CHOLESTEROL

14. OBJECTIVE B.4.2 Ali Loperena

15. B.4.2 Outline the difference between HDL and LDL cholesterol and outline its importance. • Cholesterol has a four ring structure characteristic of all steroids. • The structure of cholesterol is called the steroid backbone • Look for this in the hormones section and in the medicines and drugs unit. • Cholesterol is transported around the body by lipoproteins. • Both LDL and HDL have the same chemical structure.

16. 4.2 OUTLINE THE DIFFERENCE BETWEEN HDL AND LDL CHOLESTEROL AND OUTLINE ITS IMPORTANCE. • LDL transports cholesterol to the arteries where it lines the walls. Atherosclerosis (thickened arteries) can lead to cardiovascular disease. • Major sources of LDL are saturated fats. In particular those derived from lauric (C12 ), mystiric (C14 ), and palmitic (C16 ). • HDL can remove cholesterol from the arteries and transport it back to the liver.

17. OBJECTIVE B.4.3 Neil Jethani

18. B.4.3 DESCRIBE THE DIFFERENCE IN STRUCTURE BETWEEN SATURATED AND UNSATURATED FATTY ACIDS. • SATURATED- carboxyl group connected to ONLY single bonded C atoms bonded to H atoms. (C-C) • UNSATURATED- carboxyl group connected to c atoms with at least one group of double bonded C atoms. (C=C) • The double bond causes fats (ex. triglyceerides) to have a lower melting/boiling point-the double bond tends to keep the fat flat-linear----usually oils at room temp • Steric effect (relevant to shape): the interjection of double bonded C atoms prevent the fatty acid molecules from approaching each other closely and hence interacting via Van der Waals’ forces.

19. B.4.3 DESCRIBE THE DIFFERENCE IN STRUCTURE BETWEEN SATURATED AND UNSATURATED FATTY ACIDS. • Most naturally occurring fats and oils contain a mixture of saturated, mono-unsaturated and polyunsaturated fatty acids and are classified according to the predominant type in the mixture. • Examples: • Unsaturated: Linseed soil (flax plant) has a low percentage of saturated fatty acid. • Vegetable lipids are usually unsaturated • Saturated: Beef tallow (from beef fat) has a high percentage of saturated fatty acids. • Animal lipids tend to be saturated

20. B.4.3 DESCRIBE THE DIFFERENCE IN STRUCTURE BETWEEN SATURATED AND UNSATURATED FATTY ACIDS. Saturated Unsaturated

21. B.4.3 DESCRIBE THE DIFFERENCE IN STRUCTURE BETWEEN SATURATED AND UNSATURATED FATTY ACIDS. Summative Table

22. OBJECTIVE B.4.4 Dee White

23. Linoleic (omega-6 fatty acid) Poly-unsaturated fatty acid Carboxylic acid with an 18 carbon chain and two cis double bonds (C=C) cis means on the same side The firstdouble bond is located at the sixth carbon from the methyl end (aka- the omega end) and the second is located at the ninth. Linolenic (omega-3 fatty acid) Poly-unsaturated fatty acid Carboxylic acid with an 18 carbon chain and three cis double bonds (C=C) cis means on the same side The first double bond is located at the third carbon from the methyl end (aka- the omega end), the second is located at the sixth, and the third is located at the ninth. B.4.4 COMPARE THE STRUCTURES OF THE TWO ESSENTIAL FATTY ACIDS LINOLEIC (OMEGA–6 FATTY ACID) AND LINOLENIC (OMEGA–3 FATTY ACID) AND STATE THEIR IMPORTANCE.

24. omega end omega end Carboxylic Acid Carboxylic Acid

25. Why so important? Linoleic (omega-3 fatty acid) and Linolenic (omega-6 fatty acid) are ESSENTIAL for human health. We must have them in our diets because our metabolism cannotsynthesize them from food components. A lack of omega-6 fatty acids causes dry hair, hair loss, and poor wound healing. Omega-3 fatty acids are thought to decrease the chances of cardiovascular diseases and prostate cancer. Both of these fatty acids are thought to help lower LDL cholesterol. Linoleic and linolenic are found in vegetable oils such as sunflower oil, poppy seed oil, corn oil, and canola oil; as well as in soybeans, hemp, and walnuts.

26. OBJECTIVE B.4.5 Ms M

27. B.4.5 DEFINE THE TERM IODINE NUMBER AND CALCULATE THE NUMBER OF C=C DOUBLE BONDS IN AN UNSATURATED FAT/OIL USING ADDITION REACTIONS.

28. OBJECTIVE B.4.6 Sammy Soliman

29. B.4.6 DESCRIBE THE CONDENSATION OF GLYCEROL AND THREE FATTY ACID MOLECULES TO MAKE A TRIGLYCERIDE (2) • Glycerol: • 3-carbon backbone • carbon 1 and 3 have two hydrogen and one hydroxyl group attached • carbon 2 has one hydrogen and one hydroxyl group attached • all bonds are covalent • the hydroxyl groups are polar allowing for dipole-dipole interactions • Fatty Acid: • long carbon chain backbone • all bonds are covalent and non-polar

30. B.4.6 DESCRIBE THE CONDENSATION OF GLYCEROL AND THREE FATTY ACID MOLECULES TO MAKE A TRIGLYCERIDE (2) • Fatty Acid (continued): • two types: • Saturated – all single bonds (no more hydrogen atoms can be accepted) • Unsaturated – at least one or more double bonds between carbon atoms (can accept at least or more hydrogen atoms making it saturated) • Carbon 1 has a single bond with a hydroxyl group and a double bond with an oxygen (carboxyl group) • Middle carbons have 2 hydrogen attached in saturated fats and can vary between two, one, or no hydrogen attached in unsaturated fats depending on the placement of double bonds • End carbons have three hydrogen attached

31. B.4.6 Describe the condensation of glycerol and three fatty acid molecules to make a triglyceride (2) • Triglyceride: • Composed of three fatty acids attached to one glycerol molecule via three separate ester bonds • Formed by a condensation reaction • Condensation Reaction: • Requires three fatty acids and one glycerol • The three fatty acids are bonded to the glycerol molecule through a process known as esterification • The hydroxyl groups of the glycerol and the hydrogen in the hydroxyl groups of the acids are lost during the process • Each oxygen from the hydroxyl groups of the fatty acids are then bonded to a separate carbon of the glycerol by an ester bond forming a triglyceride

32. B.4.6 Describe the condensation of glycerol and three fatty acid molecules to make a triglyceride (2) • Condensation Reaction (continued): • The three hydroxyl groups and the three hydrogen atoms that were lost form three water molecules (the reason the reaction is called a condensation reaction)

33. B.4.6 DESCRIBE THE CONDENSATION OF GLYCEROL AND THREE FATTY ACID MOLECULES TO MAKE A TRIGLYCERIDE (2) Hydroxyl Group Fatty Acid Tail Glycerol Carboxyl Group Ester bond Triglyceride

34. B.4.6 DESCRIBE THE CONDENSATION OF GLYCEROL AND THREE FATTY ACID MOLECULES TO MAKE A TRIGLYCERIDE (2) • Condensation Reaction

35. OBJECTIVE B.4.7 Nicolette Canale

36. B.4.7 DESCRIBE THE ENZYME-CATALYSED HYDROLYSIS OF TRIGLYCERIDES DURING DIGESTION • Essentially the reverse of B.4.6 • During digestion • Triglycerides broken down (hydrolyzed) by enzymes (lipases)  glycerol and fatty acids • In turn these are broken down by a series of redox reactions  carbon dioxide, water, and energy

37. B.4.7

38. OBJECTIVE B.4.8 Jonathan Chernov

39. B.4.8 EXPLAIN THE HIGHER ENERGY VALUE OF FATS AS COMPARED TO CARBOHYDRATES (3) • Fats: Long hydrocarbon chains; most of the mass in a fatty acid or triglyceride is from carbon, and a small percentage is from oxygen • Ex: C18H38O6 • Carbohydrates: Contain equal proportions of carbon and oxygen and twice as much hydrogen atoms • Ex: C6H12O6 (fructose) • When fats and carbohydrates are metabolized, the main products are CO2 and H2O • The carbon and hydrogen form strong bonds with oxygen which result in the large release of energy

40. B.4.8 EXPLAIN THE HIGHER ENERGY VALUE OF FATS AS COMPARED TO CARBOHYDRATES • Reason: Amount of oxidation that takes place as the compounds are converted to CO2 and H2O • Fats require more oxidation to be converted than carbohydrates • Carbohydrates have one oxygen atom for every carbon atom, so each carbon atom needs only one more oxygen and each pair of hydrogen atoms need one more oxygen • Carbohydrates make fewer C-O bonds because the bonds already exist • In fats most carbons are bonded to hydrogen atoms, so when fats are metabolized they form more new C-O bonds, releasing more energy than carbohydrates • Each carbon atom needs two oxygen atoms instead of one, while each hydrogen needs one oxygen • The bond enthalpy of the C-O bond is high, so when it forms a large amount of energy is released • Fat molecules require about half as much oxygen for the same number of carbon atoms • Oxidation of fats is longer, but produces more energy

41. B.4.8 Explain the higher energy value of fats as compared to carbohydrates • When comparing fats and carbohydrates gram to gram: • More oxygen is included in the weight of a carbohydrate • Fats have more carbon atoms per gram when weighed, which means they will release about twice as much energy as carbohydrates • Fats: 9 kilocalories/gram • Carbohydrates: 4 kilocalories/gram

42. B.4.8 Explain the higher energy value of fats as compared to carbohydrates • Examples of metabolization reactions: • Fat: O2 + C58H112O6 CO2 + H2O + energy • Carbohydrate: C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy

43. OBJECTIVE B.4.9 Keith Wright

44. OBJECTIVE B.4.9 Describe the important roles of lipids in the human body and the negative effects that can have on health.

45. Membranes • Lipids compose the selectively-permeable membranes required for diffusion. • Phospholipids consist of a polar, hydrophilic phosphate ‘head’ and two hydrophobic fatty acid ‘tails’.

46. Membranes • The fact that one end of the phospholipid will always point toward water and one will always point away creates the structure of the phospholipid bilayer.

47. Energy Storage • Triglyceride lipids are used to store energy. • Because the three hydrocarbon chains of a triglyceride are hydrophobic, they remain stable in the presence of less water. • Thus, lipids require only one-sixth the amount of water to be activated that glycogen does. • When fully metabolised, one triglyceride yields NADH, FADH2 and Acetyl CoA, which are used in Cellular Respiration to produce 14 ATP.

48. Steroids • Steroid Hormones are cholesterol-based molecules that are used in cell-signalling. • Steroids consist of the cyclohexane rings and one cyclopentane ring, to which various functional groups are attatched.

49. Steroids • Steroids act by binding to surface proteins on the cell membrane, or in the cytoplasm. The hormone-protein complex enters the nucleus and binds to a specific gene sequence, increasing or decreasing the frequency of transcription. • Video: http://www.youtube.com/watch?v=oOj04WsU9ko

50. Insulation • Lipids are natural insulators. • Lipids are covalent compounds that do not conduct heat or electricity easily. • Lipid-filled cells called adipocytes found in the subcutaneous layer of skin for an insular barrier to help maintain body temperature.