Chromosomes

306 Comparing Protein Sequences 307 Comparing DNA Sequences 310 15.3 Molecular Clocks 313 Neanderthals Revisited 313 Choosing Clues 313 15.4 Eugenics 316 Part Five Immunity and Cancer 323 Chapter 16 Genetics of Immunity 323 16.1 The Importance of Cell Surfaces 324 Blood Groups 324 The Human Leukocyte Antigens 326 16.2 The Human Immune System 327 Physical Barriers and the Innate Immune Response 327 The Adaptive (Acquired) Immune Response 329 16.3 Abnormal Immunity 334 Inherited Immune Deficiencies 334 Acquired Immune Deficiency Syndrome 334 Autoimmunity 336 Allergies 338 16.4 Altering Immune Function 339 Vaccines 339 Immunotherapy 341 Transplantation 342 16.5 A Genomic View of Immunity-The Pathogen's Perspective 344 Crowd Diseases 345 Bioweapons 345 Chapter 17 The Genetics of Cancer 351 17.1 Cancer as a Genetic Disorder 352 Cancer in Families 352 Loss of Cell Cycle Control 353 Inherited Versus Sporadic Cancer 354 17.2 Characteristics of Cancer Cells 354 17.3 Genes That Cause Cancer 356 Oncogenes 356 Tumor Suppressors 358 17.4 A Series of Genetic Changes Causes Some Cancers 363 A Rapidly Growing Brain Tumor 363 Colon Cancer 363 17.5 Cancer Prevention, Diagnosis, and Treatment 364 Diet-Cancer Associations 364 Diagnosing and Treating Cancer 365 Part Six Genetic Technology 371 Chapter 18 Genetically Modified Organisms 371 18.1 Of Pigs and Patents 372 18.2 Recombinant DNA Technology 373 Constructing Recombinant DNA Molecules 374 Selecting Recombinant DNA Molecules 376 Isolating the Gene of Interest 376 Applications of Recombinant DNA Technology 377 18.3 Transgenic Organisms 378 Delivering DNA 378 Transgenic Pharming from Milk and Semen 379 18.4 Gene Targeting 382 Gene-Targeted Mice as Models 383 When Knockouts Are Normal 385 Chapter 19 Gene Therapy and Genetic Counseling 389 19.1 Gene Therapy Successes and Setbacks 390 Adenosine Deaminase Deficiency-Early Success 390 Ornithine Transcarbamylase Deficiency-A Setback 392 A Success in the Making-Canavan Disease 393 19.2 The Mechanics of Gene Therapy 394 Treating the Phenotype 394 Germline Versus Somatic Gene Therapy 395 Sites of Somatic Gene Therapy 395 Gene Delivery 398 19.3 A Closer Look: Treating Sickle Cell Disease 399 19.4 Genetic Screening and Genetic Counseling 401 Genetic Counselors Provide Diverse Services 401 Scene from a Sickle Cell Disease Clinic 403 Genetic Counseling Quandaries and Challenges 403 Perspective: A Slow Start, But Great Promise 403 Chapter 20 Agricultural Biotechnology 407 20.1 Traditional Breeding Compared to Biotechnology 409 Similar Steps, Different Degree of Precision 409 Government Regulation of Crops 411 Biotechnology Provides Different Routes to Solving a Problem 411 20.2 Types of Plant Manipulations 412 Altering Plants at the Gene Level 412 Altering Plants at the Cellular Level 415 20.3 Release of Genetically Modified Organisms into the Environment 417 Microcosm Experiments 417 Field Tests 417 Bioremediation 418 20.4 Economic, Ecological, and Evolutionary Concerns 418 20.5 The Impact of Genomics 420 Chapter 21 Reproductive Technologies 425 21.1 New Ways to Make Babies 426 Grandmother and Mother at the Same Time 426 Midlife Motherhood 426 A Five-Year Wait 426 21.2 Infertility and Subfertility 427 Male Infertility 427 Female Infertility 428 Infertility Tests 430 21.3 Assisted Reproductive Technologies 430 Donated Sperm-Artificial Insemination 430 A Donated Uterus-Surrogate Motherhood 431 In Vitro Fertilization 432 Gamete Intrafallopian Transfer 432 Oocyte Banking and Donation 433 Preimplantation Genetic Screening and Diagnosis 433 21.4 On the Subject of "Spares" 435 Chapter 22 The Human Genome Project and Genomics 441 22.1 Genome Sequencing: A Continuation of Genetics 442 22.2 The Origin of the Idea 446 The Sanger Method of DNA Sequencing 446 The Project Starts 448 22.3 Technology Drives the Sequencing Effort 448 22.4 Genome Information Answers and Raises Questions 450 The Definition of a Gene 450 Nonhuman Genome Projects 450 Epilogue: Genome Information Will Affect You 452 Answers to End-of-Chapter Questions A-1 Glossary G-1 Credits C-1 Index I-1

Contents About the Author iii List of Boxes v Preface xiv Part One Introduction 1 Chapter 1 Overview of Genetics 1 1.1 A Look Ahead 2 1.2 From Genes to Genomes 6 DNA 6 Gene 6 Chromosome 6 Genome 6 Cells, Tissues, and Organs 6 Individual 7 Family 7 Population 7 Evolution 7 1.3 Genes Do Not Usually Function Alone 7 1.4 Geneticists Use Statistics to Represent Risks 9 1.5 Applications of Genetics 10 Establishing Identity-From Forensics to Rewriting History 11 Health Care 11 Agriculture 12 A Word on Genetic Equity 14 Chapter 2 Cells 19 2.1 The Components of Cells 20 Chemical Constituents of Cells 21 Organelles 21 The Cell Membrane 26 The Cytoskeleton 28 2.2 Cell Division and Death 32 The Cell Cycle 32 Apoptosis 35 2.3 Cell-Cell Interactions 36 Signal Transduction 36 Cellular Adhesion 37 2.4 Stem Cells and Cell Specialization 38 2.5 Viruses and Prions-Not Cells, But Infectious 40 A Virus-Nucleic Acid in a Protein Coat 40 A Prion-One Protein That Takes Multiple Forms 41 Chapter 3 Development 47 3.1 The Reproductive System 48 The Male 48 The Female 48 3.2 Meiosis 49 3.3 Gamete Maturation 53 Sperm Development 53 Oocyte Development 55 3.4 Prenatal Development 56 Fertilization 56 Early Events-Cleavage and Implantation 57 The Embryo Forms 59 Supportive Structures 59 On the Matter of Multiples 59 The Embryo Develops 62 The Fetus 63 3.5 Birth Defects 64 The Critical Period 64 Teratogens 65 3.6 Maturation and Aging 67 Adult-Onset Inherited Disorders 67 Accelerated Aging Disorders 69 Is Longevity Inherited? 69 Part Two Transmission Genetics 75 Chapter 4 Mendelian Inheritance 75 4.1 Following the Inheritance of One Gene-Segregation 76 Mendel the Man 76 Mendel's Experiments 76 Terms and Tools to Follow Segregating Genes 79 4.2 Single Gene Inheritance in Humans 80 Modes of Inheritance 80 On the Meaning of Dominance and Recessiveness 84 4.3 Following the Inheritance of Two Genes-Independent Assortment 85 4.4 Pedigree Analysis 87 Pedigrees Then and Now 87 Pedigrees Display Mendel's Laws 89 Chapter 5 Extensions and Exceptions to Mendel's Laws 95 5.1 When Gene Expression Appears to Alter Mendelian Ratios 96 Lethal Allele Combinations 96 Multiple Alleles 96 Different Dominance Relationships 97 Epistasis-When One Gene Affects Expression of Another 98 Penetrance and Expressivity 99 Pleiotropy-One Gene, Many Effects 100 Phenocopies-When It's Not in the Genes 102 Genetic Heterogeneity-More than One Way to Inherit a Trait 102 5.2 Maternal Inheritance and Mitochondrial Genes 103 Mitochondrial Disorders 104 Heteroplasmy Complicates Mitochondrial Inheritance 105 Mitochondrial DNA Studies Clarify the Past 105 5.3 Linkage 106 Linkage Was Discovered in Pea Plants 106 Linkage Maps 107 Examples of Linked Genes in Humans 108 The Evolution of Gene Mapping 109 Chapter 6 Matters of Sex 115 6.1 Sexual Development 116 Sex Chromosomes 116 The Phenotype Forms 117 Gender Identity-Is Homosexuality Inherited? 119 6.2 Traits Inherited on Sex Chromosomes 120 X-Linked Recessive Inheritance 120 X-Linked Dominant Inheritance 125 6.3 X Inactivation Equalizes the Sexes 126 6.4 Gender Effects on Phenotype 128 Sex-limited Traits 129 Sex-influenced Traits 129 Genomic Imprinting 129 Chapter 7 Multifactorial Traits 137 7.1 Genes and the Environment Mold Most Traits 138 Polygenic Traits Are Continuously Varying 139 Fingerprint Patterns, Height, and Eye Color 139 A Closer Look at Skin Color 140 7.2 Methods Used to Investigate Multifactorial Traits 142 Empiric Risk 142 Heritability-The Genetic Contribution to a Multifactorial Trait 144 Adopted Individuals 145 Twins 145 Association Studies 147 7.3 Some Multifactorial Traits 149 Heart Health 149 Body Weight 151 Chapter 8 The Genetics of Behavior 155 8.1 Genes Contribute to Most Behavioral Traits 156 8.2 Eating Disorders 158 8.3 Sleep 159 8.4 Intelligence 160 8.5 Drug Addiction 161 8.6 Mood Disorders 163 8.7 Schizophrenia 164 Part Three DNA and Chromosomes 171 Chapter 9 DNA Structure and Replication 171 9.1 Experiments Identify and Describe the Genetic Material 172 DNA Is the Hereditary Molecule 172 DNA Is the Hereditary Molecule-and Protein Is Not 172 Deciphering the Structure of DNA 174 9.2 DNA Structure 176 9.3 DNA Replication-Maintaining Genetic Information 178 Replication Is Semiconservative 178 Steps and Participants in DNA Replication 180 9.4 PCR-Directing DNA Replication 183 Chapter 10 Gene Action and Expression 189 10.1 Transcription-The Link Between Gene and Protein 190 RNA Structure and Types 190 Transcription Factors 192 Steps of Transcription 193 RNA Processing 194 10.2 Translating a Protein 196 Deciphering the Genetic Code 196 Building a Protein 199 Protein Folding 201 10.3 The Human Genome Sequence Reveals Unexpected Complexity 203 Genome Economy: Reconciling Gene and Protein Number 204 What Does the Other 98.5 Percent of the Human Genome Do? 206 Chapter 11 Gene Mutation 211 11.1 Mutations Can Alter Proteins-Three Examples 212 The Beta Globin Gene 212 Disorders of Orderly Collagen 214 A Mutation That Causes Early-Onset Alzheimer Disease 215 11.2 Causes of Mutation 216 Spontaneous Mutation 216 Induced Mutations 218 Natural Exposure to Mutagens 219 11.3 Types of Mutations 220 Point Mutations 220 Deletions and Insertions Can Cause Frameshifts 221 Pseudogenes and Transposons Revisited 222 Expanding Repeats Lead to Protein Misfolding 222 11.4 The Importance of a Mutation's Position in the Gene 225 Globin Variants 225 Inherited Susceptibility to Prion Disorders 226 11.5 Factors That Lessen the Effects of Mutation 227 11.6 DNA Repair 227 Types of DNA Repair 227 DNA Repair Disorders 228 Chapter 12 Chromosomes 235 12.1 Portrait of a Chromosome 236 Telomeres and Centromeres Are Essential 237 Karyotypes Are Chromosome Charts 238 12.2 Visualizing Chromosomes 240 Obtaining Cells for Chromosome Study 240 Preparing Cells for Chromosome Observation 243 12.3 Abnormal Chromosome Number 246 Polyploidy 246 Aneuploidy 246 12.4 Abnormal Chromosome Structure 252 Deletions and Duplications 252 Translocations 253 Inversions 256 Isochromosomes and Ring Chromosomes 258 12.5 Uniparental Disomy-Two Genetic Contributions from One Parent 259 Part Four Population Genetics 263 Chapter 13 When Allele Frequencies Stay Constant 263 13.1 The Importance of Knowing Allele Frequencies 264 13.2 When Allele Frequencies Stay Constant-Hardy-Weinberg Equilibrium 264 13.3 Practical Applications of Hardy-Weinberg Equilibrium 267 13.4 DNA Fingerprinting-A Practical Test of Hardy-Weinberg Assumptions 268 DNA Patterns Distinguish Individuals 269 Population Statistics Are Used to Interpret DNA Fingerprints 269 DNA Fingerprinting to Identify World Trade Center Victims 272 Chapter 14 Changing Allele Frequencies 277 14.1 Nonrandom Mating 278 14.2 Migration 279 Historical Clues 279 Geographical and Linguistic Clues 279 14.3 Genetic Drift 280 The Founder Effect 280 Population Bottlenecks 282 14.4 Mutation 284 14.5 Natural Selection 284 Tuberculosis Ups and Downs-and Ups 284 Evolving HIV 285 Balanced Polymorphism 286 14.6 Gene Genealogy 292 PKU Revisited 292 CF Revisited 293 Chapter 15 Human Origins and Evolution 299 15.1 Human Origins 300 The Australopithecines-And Others? 301 Homo 303 Modern Humans 304 15.2 Molecular Evolution 305 Comparing Genomes 305 Comparing