1. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.1 Chapter 17 Lipids 17.2 Fatty Acids

2. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.2 Fatty Acids Fatty acids  are long-chain carboxylic acids  typically contain 12 to 18 carbon atoms  are insoluble in water  can be saturated or unsaturated

3. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.3 Fatty Acid Formulas The formulas for fatty acids are written as  condensed structural formulas  line-bond formulas

4. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.4 Saturated fatty acids have  single C—C bonds  molecules that fit closely together in a regular pattern  strong attractions between fatty acid chains  high melting points that make them solids at room temperature Saturated Fatty Acids

5. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.5 Some Saturated Fatty Acids

6. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.6 Unsaturated Fatty Acids Unsaturated fatty acids  have one or more double C═C bond  typically contain cis double bonds

7. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.7 Some Unsaturated Fatty Acids

8. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.8 Properties of Unsaturated Fatty Acids Unsaturated fatty acids  have “kinks” in the fatty acid chains  do not pack closely  have fewer attractions between chains  have lower melting points  are liquids at room temperature “kinks” in chain

9. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.9 Learning Check Assign the melting point (mp) of –17 °C, 13 °C, or 69 °C to each one of the following 18-carbon fatty acids, and list the fatty acids in order from highest to lowest mp. Explain. 1) Oleic acid 2) Stearic acid 3) Linoleic acid

10. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.10 Solution Stearic acid is saturated and would have a higher melting point than the unsaturated fatty acids. Oleic acid, which has one double bond, has a higher mp than linoleic oleic acid, which has two double bonds. 2) Stearic acid mp 69°C saturated 1) Oleic acid mp 13°Cunsaturated with one double bond 3) Linoleic acid mp -17°C unsaturated with two double bonds

11. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.11 Prostaglandins Prostaglandins have  20 carbon atoms in their fatty acid chains  an OH on carbons 11 and 15  a trans double bond at carbon 13 C11 C15 C13

12. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.12 Omega-6 and Omega-3 Fatty Acids Fatty acids  in vegetable oils are mostly omega-6 with the first C═C at C6 CH 3 ─(CH 2 ) 4 ─CH═CH─CH 2 ─CH═CH─(CH 2 ) 7 ─COOH 1 6 Linoleic acid  in fish oils are mostly omega-3 with the first C═C at C3 CH 3 ─CH 2 ─(CH═CH─CH 2 ) 3 ─(CH 2 ) 6 ─COOH 1 3 Linolenic acid

13. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.13 Prostaglandins in the Body Prostaglandins are  produced by injured tissues  involved in pain, fever, and inflammation  not produced when anti-inflammatory drugs such as aspirin inhibit their synthesis

14. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.14 Some Omega-6 and Omega-3 Fatty Acids

15. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.15 Learning Check Draw the condensed structural formula for a fatty acid with 10 carbon atoms that is: A. saturated B. monounsaturated omega-3 C. monounsaturated omega-6

16. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.16 Solution Draw the condensed structural formula for a fatty acid with 10 carbon atoms that is: A. saturated CH3—CH2—CH2—CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —CH 2 — COOH B. monounsaturated omega-3 CH3—CH2—CH═CH—C H 2—C H 2—CH2—CH2 — CH2 — COO H C. monounsat urated omega-6 CH3—CH2—CH2—C H2 — CH2 — CH═ C H—C H 2—C H 2—COOH