1 Lipids Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

Good Fats vs. Bad Fats 2

3 Lipids Lipids are  Macromolecules that contain fatty acids  Insoluble (will not dissolve in water)  Named for the Greek word lipos, which means “fat.”

4 Lipids Six functions of lipids: 1.Long term energy storage 2.Protection against heat loss (insulation) 3.Protection against physical shock 4.Protection against water loss 5.Chemical messengers (hormones) 6.Major component of membranes (phospholipids) copyright cmassengale

5 Types of Lipids The types of lipids containing fatty acids are  Waxes.  Fats  Steroids

6 Fatty Acids Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

7 Fatty Acids Fatty acids  Are long-chain carboxylic acids.  Typically contain carbon atoms.  Are insoluble in water.  Can be saturated or unsaturated. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

8 Lipids Triglycerides: c1 glycerol3 fatty acids Triglycerides: composed of 1 glycerol and 3 fatty acids. H H-C----O H glycerol O C-CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 3 = fatty acids O C-CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 3 = O C-CH 2 -CH 2 -CH 2 -CH =CH-CH 2 -CH 2 -CH 2 -CH 2 -CH 3 = copyright cmassengale

View Presentation on the 2 types of FATTY ACIDS  Discovery Ed Fatty Acids Video 9

10 Saturated fatty acids have  Single C–C bonds.  High melting points that make them solids at room temperature.  The unhealthy fats Saturated Fatty Acids – BAD! Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings O C-CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 3 = saturated

11 Unsaturated Fatty Acids- GOOD! Unsaturated fatty acids  Have one or more double C=C bond  Liquids at room temperature  The healthy fats  O-C-CH 2 -CH 2 -CH 2 -CH=CH-CH 2 -CH 2 - CH 2 -CH 2 -CH 3 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

Dr. Thomas J. Montville12 Summary of Fats SaturatedUnsaturated Single bond (straight)Double bonds SolidLiquid Animal (cholesterol)Plants (cholesterol free) “Unhealthy”Essential Fatty Acids and ώ-3s Cooling as Solid  liquid

ANOTHER GROUP OF LIPIDS ARE THE WAXES 13

14 Waxes Waxes are  Coatings that prevent loss of water by leaves of plants. TABLE 17.2 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

ANOTHER GROUP OF LIPIDS ARE THE STEROIDS 15

16 Cholesterol  Is the most abundant steroid in the body.

Cholesterol Explanation View Discovery Ed Video 17

18 Cholesterol in the Body Cholesterol in the body  Is obtained from meats, milk, and eggs.  Is synthesized in the liver.  Is needed for cell membranes, brain and nerve tissue, steroid hormones, and Vitamin D.  Clogs arteries when high levels form plaque. A normal, open artery. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings An artery clogged by cholesterol plaque

19 Cholesterol in Foods Cholesterol is  Synthesized in the liver.  Obtained from foods.  Considered elevated if plasma cholesterol exceeds 200 mg/dL. TABLE 17.4 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

STOP 20

21 Oils with Unsaturated Fatty Acids Oils  Have more unsaturated fats.  Have cis double bonds that cause “kinks” in the fatty acid chains.  Cannot pack triacylglycerol molecules as close together as in fats.  Have lower melting points than saturated fats.  Are liquids at room temperature.

22 Diagram of Triacylglycerol with Unsaturated Fatty Acids Unsaturated fatty acid chains have kinks that do not allow close packing. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

23 Chemical Properties of Triacylglycerols Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

24 Cis and Trans Fatty Acids Unsaturated fatty acids can be  Cis with bulky groups on same side of C=C. CH 3 ─ (CH 2 ) 5 (CH 2 ) 7 ─ COOH cis C=C H H  Trans have bulky groups on opposite sides of C=C. CH 3 ─ (CH 2 ) 5 H C=C trans H (CH 2 ) 7 ─ COOH

25 Trans Fatty Acids and Hydrogenation Trans fatty acids  Are formed during hydrogenation when cis double bonds are converted to trans double bonds.  In the body behave like saturated fatty acids.  Are estimated to make up 2-4% of our total Calories.  Are reported in several studies reported to raise LDL-cholesterol and lower HDL-cholesterol.

26 Learning Check (1) True or (2) False A. There are more unsaturated fats in vegetable oils. B. Vegetable oils have higher melting points than fats. C. Hydrogenation of oils converts some cis-double bonds to trans- double bonds. D. Animal fats have more saturated fats.

27 Solution (1) True or (2) False A. T There are more unsaturated fats in vegetable oils. B. F Vegetable oils have higher melting points than fats. C. T Hydrogenation of oils converts some cis-double bonds to trans- double bonds. D. T Animal fats have more saturated fats.

28 Solution Write a fatty acid with 10 carbon atoms that is: A. saturated CH 3 —CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —COOH B. monounsaturated omega-3 CH 3 —CH 2 —CH=CH—CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —COOH C. monounsaturated omega-6 CH 3 —CH 2 —CH 2 —CH 2 —CH 2 —CH=CH—CH 2 —CH 2 —COOH

29 Solution Write a fatty acid with 10 carbon atoms that is: A. saturated CH 3 —CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —COOH B. monounsaturated omega-3 CH 3 —CH 2 —CH=CH—CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —COOH C. monounsaturated omega-6 CH 3 —CH 2 —CH 2 —CH 2 —CH 2 —CH=CH—CH 2 —CH 2 —COOH

30 Steroids: Cholesterol, Bile Salts, and Steroid Hormones Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

31 Steroid Nucleus A steroid nucleus consists of  3 cyclohexane rings.  1 cyclopentane ring.  No fatty acids. steroid nucleus

32 Cholesterol  Is the most abundant steroid in the body.  Has methyl CH 3 - groups, alkyl chain, and -OH attached to the steroid nucleus.

33 Cholesterol in the Body Cholesterol in the body  Is obtained from meats, milk, and eggs.  Is synthesized in the liver.  Is needed for cell membranes, brain and nerve tissue, steroid hormones, and Vitamin D.  Clogs arteries when high levels form plaque. A normal, open artery. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings An artery clogged by cholesterol plaque

34 Cholesterol in Foods Cholesterol is  Synthesized in the liver.  Obtained from foods.  Considered elevated if plasma cholesterol exceeds 200 mg/dL. TABLE 17.4 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

35 Steroid Hormones Steroid hormones  Are chemical messengers in cells.  Are produced from cholesterol.  Include sex hormones such as androgens (testosterone) in males and estrogens (estradiol) in females. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

Dr. Thomas J. Montville36 Summary of Fats SaturatedUnsaturated Single bond (straight)Double bond (kinked) SolidLiquid Animal (cholesterol)Plants (cholesterol free) FlakyTenderization “Unhealthy”Essential Fatty Acids and ώ-3s Chemically stableD.B.s reactive, free radicals Cooling as Solid  liquid

37 Solution Write a fatty acid with 10 carbon atoms that is: A. saturated CH 3 —CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —COOH B. monounsaturated omega-3 CH 3 —CH 2 —CH=CH—CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —COOH C. monounsaturated omega-6 CH 3 —CH 2 —CH 2 —CH 2 —CH 2 —CH=CH—CH 2 —CH 2 —COOH

38 Cell Membranes Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

39 Cell Membranes Cell membranes  Separate cellular contents from the external environment.  Consist of a lipid bilayer made of two rows of phospholipids.  Have an inner portion made of the nonpolar tails of phospholipids with the polar heads at the outer and inner surfaces.

40 Fluid Mosaic Model of Cell Membranes The lipid bilayer  Contains proteins, carbohydrates, and cholesterol.  Has unsaturated fatty acids that make cell membranes fluid-like rather than rigid.  Has proteins and carbohydrates on the surface that communicate with hormones and neurotransmitters.

41 Fluid Mosaic Model Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

42 Transport Through Cell Membranes The transport of substances through cell Membranes involves  Diffusion (passive transport), which moves particles from a higher to a lower concentration.  Facilitated transport, which uses protein channels to increase the rate of diffusion.  Active transport, which moves ions against a concentration gradient.

43 Transport Pathways Through Cell Membranes Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

44 Learning Check The transport of particles across a cell membrane from high concentration to low concentration is called 1. Facilitated transport 2. Diffusion 3. Active transport

45 Solution The transport of particles across a cell membrane from high concentration to low concentration is called 2. Diffusion