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

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Presentation on theme: "Lipids Broadly defined as naturally occurring non- polar compounds having simple functional groups."— Presentation transcript:

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

2 Major Categories of Lipids Fats and 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 Soap (above) can be represented as: Soap (and detergents) form spherical clusters (right) called micelles; micelles surround and dissolve non-polar substances (oily stains) and render them “soluble.” Oil H2OH2OH2OH2O H2OH2OH2OH2O H2OH2OH2OH2O H2OH2OH2OH2O H2OH2OH2OH2O H2OH2OH2OH2O

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 Polyunsaturated Fatty Acids Polyunsaturated fatty acids (PUFAs) include those having two and three double bonds. Omega-3 fatty acids are those unsaturated fatty acids that have a double bond between the third and fourth carbon from the end of the carbon chain (opposite the CO 2 H group). A common omega-3 fatty acid found in fish oil is linolenic acid: Omega-3 fatty acids are considered beneficial for brain function.

17 Composition of Fats and Oils lauric myristic palmitic stearic oleic linoleic C 12 C 14 C 16 C 18 C 18(1) C 18(2) Animal Fats Lard - 125 85010 Beef Fat - - 27 14 50 3 Butter Fat 210291027 5 Human Fat 1 325 84610 Whale Blubber - 812 33510 Vegetable Oils Coconut oil 481811 2 7 1 Corn oil - 110 34535 Olive oil - 1 7 382 6 Peanut oil - - 7 55824 Soybean oil - - 10 22951

18 Fats and Oils in Nuts Nut g. prot./oz. g. fat/oz % sat’d % MUFAs % PUFAs Walnuts4 18 10 15 75 Almonds 6 14 10 65 25 Hazelnuts 4 17 9 77 14 Cashews 4 13 21 62 17 Macadamia 2 22 16 76 8 Pecans 3 20 9 53 28 Peanuts 7 14 16 52 32

19 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.

20 Representative Phospholipids Phosphatidylcholine (lecithin) Phosphatidylethanolamine (cephalin)

21 Phospholipids… Can be represented as:

22 Lipid Bilayer of Cell Membranes Cell membrane Outside the cell (aqueous) Inside the cell (aqueous)

23 Waxes Long chain esters of long chain fatty acids (present in beeswax)

24 Terpenes Derived biosynthetically from a branched five carbon unit, isopentenyl pyrophosphate: isopentenyl pyrophosphate

25 Terpenes... Common monoterpenes (C 10 ):

26 Some more common terpenes

27 Steroids Involved in regulatory processes and in sexual characteristics and functions Common steroids include cholesterol, estradiol, testosterone, estrone and progesterone A B C D A B C D

28 Some Common Steroids

29 …More Common Steroids


31 Prostaglandins C 20 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.

32 Representative Structures Biosynthetic source: arachidonic acid Prostaglandin E 1 (PGE 1 )Prostaglandin F 2  (PGF 2  )

33 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

34 Final Exam Review: A review session are scheduled for class on Monday, April 26 in DO 205. Bring questions, and bring the last 4 sheets of the Course-Pack. Final Exam: Monday, May 3, 8:00 am – 11:00 am (Dobo Hall, Room 205)

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