3. Help and maintain cell membranes. Protect and insulate nerve fibers. Involved in the formation of sex hormones, such as estrogen. Production of bile salts, which help digesting fats.

4. 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. An artery clogged by cholesterol plaque

5. 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

6. Lipoproteins Combine lipids with proteins and phospholipids. Are soluble in water because the surface consists of polar lipids. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

7. Lipoproteins Differ in density, composition, and function. Include low-density lipoprotein (LDLs) and high- density lipoprotein (HDLs). TABLE 17.5 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

13. Hen eggEgg whiteAlbuminEgg yolk Lipids + glycoproteins

14. Egg yolk 5% Cholesterol 28% phospholipids 66% glycerides

15. 15

17. 17

19. 1. Using a funnel and a filter paper, filter the 50 ml of acetone extract into a clean 100 ml beaker. 2.Evaporate the acetone by placing the beaker on the steam bath in the hood until about 10 ml of extract is left. 3.Cover the warm acetone extract and immediately transfer it on ice and let it stand for 20 min. A white precipitate will form (this is the crude cholesterol). Remove the flask from ice. Get rid of the liquid phase. 1. Using a funnel and a filter paper, filter the 50 ml of acetone extract into a clean 100 ml beaker. 2.Evaporate the acetone by placing the beaker on the steam bath in the hood until about 10 ml of extract is left. 3.Cover the warm acetone extract and immediately transfer it on ice and let it stand for 20 min. A white precipitate will form (this is the crude cholesterol). Remove the flask from ice. Get rid of the liquid phase.