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| Understanding the concepts
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| 1.
| Chapter 20 provides a brief introduction to biochemistry. Four classes of biomolecules are discussed in this chapter: proteins, carbohydrates, nucleic acids and lipids. Read the chapter Overview on the CD to review important characteristics of these classes of molecules.
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| 2.
| Approximately 30 elements are essential for human life to exist. Open the Some Essential Elements Table on the Web site to view some of these elements. Not surprisingly, oxygen, hydrogen, and carbon are the most abundant. Why is this not a surprise? For interesting reading, note the varied functions for each element.
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| 3.
| Explain why proteins are polymers. What are the monomers called that make up the primary structure of proteins? What is a peptide linkage? How do the various amino acids differ from each other? To review some functions of proteins, open the Common Functions of Proteins Table on the Web site. For some good exercises on proteins and amino acids, do Questions 20.6, 20.8, 20.10, and Problem 20.12 in the text.
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| 4.a.
| Explain why carbohydrates are also polymers. Open the Some Important Monosaccharides Table on the Web site to view some common monosaccharides found in
living organisms.
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| b.
| Sucrose, or common table sugar, is a disaccharide. What does this mean? What are glycoside linkages? The most common polysaccharides are starch, cellulose and glycogen. What is a polysaccharide? What monomer is used to produce starch, cellulose, and glycogen?
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| 5.a.
| DNA and RNA are also polymers; however, the monomers used to form these polymers are more complicated than in proteins and carbohydrates. For DNA and RNA, each monomer contains three parts. What are the three parts?
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| b.
| What are the base pairs in the DNA double-helix structure? |
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| 6.a.
| Lipids are a class of substances that are water insoluble; they contain mostly carbon and hydrogen atoms. Does this make sense in view of lipids' inability to dissolve in water?
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| b.
| One type of lipid is fats. The most common fats are triglycerides. What is a triglyceride? Open the Some Common Fatty Acids Table on the Web site to view some different fatty acids found in triglycerides. What do the terms "saturated" and "unsaturated" indicate?
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| c.
| Steroids are another type of lipid. List some common steroids and steroid derivatives. What common structural feature do steroids have?
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| 7.
| Open Key Words on the CD and test your ability to define important terms presented in Chapter 20.
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| 8.
| Test your understanding of Chapter 20 by taking the ACE quizzes on the Website.
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