Chapter 3

Summary		Questions		Media Resources
3.1 Molecules are the building blocks of life.
• The chemistry of living systems is the chemistry of carbon-containing compounds. • Carbon's unique chemical properties allow it to polymerize into chains by dehydration synthesis, forming the four key biological macromolecules: proteins, nucleic acids, lipids, and carbohydrates.		1.  What types of molecules are formed by dehydration reactions? What types of molecules are formed by hydrolysis?		•Organic Chemistry
3.2 Proteins perform the chemistry of the cell.
• Proteins are polymers of amino acids. • Because the 20 amino acids that occur in proteins have side groups with different chemical properties, the function and shape of a protein are critically affected by its particular sequence of amino acids.		2.  How are amino acids linked to form proteins? 3.  Explain what is meant by the primary, secondary, tertiary, and quaternary structure of a protein.		•Explorations: How Proteins Function •Proteins •Student Research: A New Protein in Insects • Student Research: Heat Shock Proteins • Art Quiz: Peptide Bond
3.3 Nucleic acids store and transfer genetic information.
• Hereditary information is stored as a sequence of nucleotides in a linear polymer called DNA, which exists in cells as a double helix. • Cells use the information in DNA by producing a complementary single strand of RNA which directs the synthesis of a protein whose amino acid sequence corresponds to the nucleotide sequence of the DNA from which the RNA was transcribed.		4.  What are the three components of a nucleotide? How are nucleotides linked to form nucleic acids? 5.  Which of the purines and pyrimidines are capable of forming base-pairs with each other?		•DNA Structure •Nucleic Acids •Art Quiz: DNA Base Pairing and Hydrogen Bonds
3.4 Lipids make membranes and store energy.
• Fats are one type of water-insoluble molecules called lipids. • Fats are molecules that contain many energy-rich C-H bonds and, thus, provide an efficient form of long-term energy storage. • Types of lipids include phospholipids, fats, terpenes, steroids, and prostaglandins.		6.  What are the two kinds of subunits that make up a fat molecule, and how are they arranged in the molecule? 7.  Describe the differences between a saturated and an unsaturated fat.		•Lipids • How Scientists Think:Amino Acid Sequence Determines Protein Shape (Anfinsen) •Art Quiz: Unsaturated Fat
3.5 Carbohydrates store energy and provide building materials.
• Carbohydrates store considerable energy in their carbon-hydrogen (C-H) bonds. • The most metabolically important carbohydrate is glucose, a six-carbon sugar. • Excess energy resources may be stored in complex sugar polymers called starches (in plants) and glycogen (in animals and fungi).		8.  What does it mean to say that glucose, fructose, and galactose are isomers? Which two are structural isomers, and how do they differ from each other? Which two are stereoisomers, and how do they differ from each other?		• Carbohydrates • Art Quiz: Disaccharides

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