Genes and DNA : a beginner's guide to genetics and its applications

Acknowledgments xiii List of Contributors xv Preface: Why Is Genetics Important? xvii Chapter 1. What Are Genes? 1 DNA 1 DNA Can Be Specifically Stained and Observed in Cells 2 DNA Determines Genetic Properties in Bacteria 3 DNA Is a Double Helix 6 Transfer of Genetic Information to Progeny 9 DNA Can Be Replicated in the Test Tube 10 Summary 17 Try This at Home: Extract DNA from Vegetables in Your Kitchen 17 Box 1.1. PCR and Identification 15 Chapter 2. Inheritance of Single-Gene Traits 19 Plants Are Good Organisms for the Study of Inheritance 20 Genes Do Not Blend 21 Rules of Inheritance 22 Behavior of Chromosomes 23 The Punnett Square 24 Incomplete Dominance 28 Sex Is Also Determined by Inheritance Rules 29 Summary 33 Chapter 3. Mendelian Traits in Humans 34 Blood Types 34 Sex-Linked Traits: Hemophilia 35 Sex-Linked Traits: Color Blindness 37 Prostate and Breast Cancer 37 Genetic Metabolic Diseases 39 Sickle-cell Anemia 41 Hemochromatosis 42 Another Sex-Influenced Trait: Male Pattern Baldness 44 Dominant Genetic Diseases 44 Pedigree Analysis 45 Summary 50 Try This at Home: Pedigree Game 50 Box 3.1. Warning on Diet Products 40 Chapter 4. From Genes to Phenotype 53 Transcription 54 Translation 56 Changes in DNA Modify the Amino Acid Sequences of Proteins 61 Gene Regulation 63 Summary 67 Try This at Home: DNA Replication, Transcription, and Translation Game 68 Box 4.1 Why People Are Saving Their Babies’ Cord Blood 65 Chapter 5. Using Bacteria as Protein Factories 70 Tools for Manufacturing Proteins 70 Using Restriction Enzymes and Plasmids to Clone a Gene 73 Producing Human Proteins in E. Coli 74 Medically Important Human Proteins Made in E. Coli 76 Summary 78 Chapter 6. Genetically Modified Plants 79 What Are Genetically Modified Organisms (GMOs)? 79 viii CONTENTS Agrobacterium-Mediated Gene Transfer 80 Biolistics 81 Genetic Modifications 86 Genetically Modified Nonfood Plants 88 Ecological Issues 90 Labeling Issues and Food Safety 91 Summary 92 Box 6.1: Detecting Foreign Genes in Genetically Modified Plants 85 Chapter 7. When Things Go Wrong 93 Errors in Chromosome Number 94 Multiple Sets of Chromosomes 94 Looking at Our Chromosomes 96 Changes in the DNA Base Sequence 97 Triplet Repeat Errors 102 Summary 103 Chapter 8. Mutagens, Teratogens, and Human Reproduction 104 Spontaneous Mutations 104 Mutagens 105 How Do We Detect Mutagens? 107 Teratogens 109 Human Reproduction 112 Summary 113 Box 8.1: Why There Were Few Thalidomide-Caused Birth Defects in the United States 110 Chapter 9. Linkage and Mapping: Gene Discovery 114 There Are Many Genes on Each Chromosome 114 Independent Assortment of Genes 115 Linkage 118 Recombination 119 Linkage to a DNA Marker 123 The Human Genome Project and Others 131 Discovering Disease Genes in Humans 132 Summary 133 Try This at Home: Independent Assortment of Chromosomes and the Making of a Unique Individual 133 Try This at Home: Explore Genetics Databases 135 CONTENTS ix Box 9.1: Identifying Disease Genes Using Restriction Fragment Length Polymorphism 126 Box 9.2: Identifying a Disease-Resistance Gene in Barley Through Map-Based Cloning 128 Chapter 10. Genetics of Populations and Genetic Testing 138 Why Don’t We Observe 3 to 1 Ratios of Dominant Versus Recessive Traits in Populations? 138 Predicting the Genotype of the Next Generation Using the Punnett Square 139 Conditions for Observing Constant Gene and Genotype Frequencies 142 Another Application of the Hardy-Weinberg Law 143 Predicting Gene Frequency for a Recessive Trait 145 Gene Frequencies Vary in Different Populations 147 Newborn Testing and Conditional Probability 148 Predicting Genotype Frequency for Sex-Linked Traits 151 Summary 152 Chapter 11. Survival of the Fittest? 153 What Is Meant by Fitness? 153 Selection Requires Variation. 154 Selection Can Result in Reduced Genetic Diversity 155 Natural Selection Determined Skin Color in Humans 156 Fitness Depends Upon the Environment 157 Selection and Antibiotic-Resistant Bacteria 158 Heterozygous Advantage 161 Why Do Dominant Genetic Diseases Exist? 163 Small Populations 164 Summary 170 Box 11.1: DNA Sequences Provide Clues to Human Evolution: The Founder Effect in Prehistoric Africa 165 Try This at Home: Demonstrations of the Effects of Small Population Size 171 Chapter 12. Nature Versus Nurture 175 Polygenic Traits Are Additive 176 Polygenic Traits Exhibit Continuous Variation in Phenotype 178 Polygenic Traits Are Influenced by the Environment 180 x CONTENTS Measuring Variance in Traits and Estimating Heritability 181 Twin Studies Are Helpful in Studying Polygenic Traits in Humans 183 Quantitative Traits in Medicine and Agriculture 184 Summary 186 Chapter 13. Genetically Modified Animals and the Applications of Gene Technology for Humans 187 Cloning Animals by the Nuclear-Transfer Technique 187 Genetically Modifying Animals Using Embryonic Stem Cells 188 Uses of Genetically Modified Animals 190 Human Gene Therapy 192 Human Reproductive Cloning 195 Human Therapeutic Cloning 197 Summary 197 Appendix A. Internet Resources 199 Appendix B. Glossary of Scientific Names of Organisms 203 Appendix C. Glossary of Human Genetic Diseases 205 Appendix D. Glossary of Terms 207 Index 213