Enhanced descriptions from Syndetics:

Extensively reorganized and revised with the latest data from this rapidly changing field, Lewin's Essential GENES, Fourth Edition, provides students with a comprehensive overview of molecular biology and molecular genetics. The authors took care to carefully modify the chapter order in an effort to provide a more clear and student-friendly presentation of course material. Chapter material has been updated throughout, including a completely revised chapter on regulatory RNA, to keep pace with this advancing field. The Third Editions exceptional pedagogy enhances student learning and helps readers understand and retain key material like never before. Concept and Reasoning Checks at the end of each chapter section, End-of-Chapter Questions and Further Readings sections, as well as several categories of special topics boxes, expand and reinforce important concepts.

Table of contents provided by Syndetics

• Preface (p. xvi)
• Acknowledgements (p. xix)
• About the Authors (p. xx)
• Part 1 Genes and Chromosomes (p. 1)
• Chapter 1 Genes Are DNA and Encode RNAs and Polypeptides (p. 3)
• 1.1 Introduction (p. 4)
• 1.2 DNA as the Genetic Material (p. 7)
• Historical Perspectives: Determining That DNA Is the Genetic Material (p. 9)
• 1.3 Polynucleotide Chains: Nitrogenous Bases and Sugar-Phosphate Backbone (p. 10)
• 1.4 DNA Is a Double Helix (p. 12)
• 1.5 Supercoiling Affects the Structure of DNA (p. 15)
• 1.6 DNA Replication Is Semiconservative (p. 17)
• 1.7 Polymerases Act on Separated DNA Strands (p. 19)
• 1.8 Genetic Information Can Be Provided by DNA or RNA (p. 20)
• 1.9 Nucleic Acids Hybridize by Base Pairing (p. 23)
• 1.10 Mutations Change the Sequence of DNA (p. 25)
• 1.11 The Effects of Mutations (p. 27)
• 1.12 The Effects of Mutations Can Be Reversed (p. 29)
• 1.13 Mutations Are Concentrated at Hotspots (p. 31)
• 1.14 Some Hereditary Agents Are Extremely Small (p. 34)
• 1.15 Most Genes Encode Polypeptides (p. 36)
• Historical Perspectives: One Gene-One Enzyme-George W. Beadle and Edward L. Tatum, 1941 (p. 38)
• 1.16 Mutations in the Same Gene Cannot Complement (p. 38)
• 1.17 Mutations May Cause Loss or Gain of Function (p. 40)
• 1.18 A Locus May Have Many Alleles (p. 42)
• 1.19 Recombination Occurs by Physical Exchange of DNA (p. 44)
• 1.20 The Genetic Code is Triplet (p. 47)
• 1.21 Every Coding Sequence Has Three Possible Reading Frames (p. 49)
• 1.22 Bacterial Genes Are Colinear with Their Products (p. 51)
• 1.23 Several Processes Are Required to Express the Product of a Gene (p. 52)
• 1.24 Proteins Are trans-Acting; Sites on DNA Are cis-Acting (p. 55)
• 1.25 Summary (p. 57)
• Chapter Questions (p. 58)
• Key Terms (p. 61)
• Further Reading (p. 62)
• Chapter 2 Methods in Molecular Biology and Genetic Engineering (p. 63)
• 2.1 Introduction (p. 63)
• 2.2 Nucleases (p. 64)
• 2.3 Cloning (p. 67)
• 2.4 Cloning Vectors Can Be Specialized (p. 70)
• 2.5 Nucleic Acid Detection (p. 75)
• 2.6 DNA Separation Techniques (p. 78)
• 2.7 DNA Sequencing (p. 83)
• 2.8 PCR and RT-PCR (p. 85)
• 2.9 Blotting Methods (p. 92)
• 2.10 DNA Microarrays (p. 96)
• 2.11 Chromatin Immunoprecipitation (p. 100)
• 2.12 Gene Knockouts, Transgenics, and Genome Editing (p. 102)
• 2.13 Summary (p. 109)
• Chapter Questions (p. 110)
• Key Terms (p. 111)
• Further Reading (p. 111)
• Chapter 3 The Interrupted Gene (p. 113)
• 3.1 Introduction (p. 113)
• 3.2 An Interrupted Gene Consists of Exons and Introns (p. 115)
• 3.3 Organization of interrupted Genes May Be Conserved (p. 116)
• Historical Perspectives: Discovery of Introns by DNA-RNA Hybridization (p. 119)
• 3.4 Exon Sequences Are Usually Conserved; Introns Vary (p. 122)
• 3.5 Genes Show a Wide Distribution of Sizes (p. 123)
• 3.6 Some DNA Sequences Encode Multiple Polypeptides (p. 126)
• 3.7 Some Exons Can Be Equated with Protein Functional Domains (p. 128)
• 3.8 Members of a Gene Family Have a Common Organization (p. 130)
• 3.9 Summary (p. 133)
• Chapter Questions (p. 133)
• Key Terms (p. 135)
• Further Reading (p. 135)
• Chapter 4 The Content of the Genome (p. 137)
• 4.1 Introduction (p. 137)
• 4.2 Genome Mapping Reveals Extensive Variation (p. 139)
• 4.3 SNPs Can Be Associated with Genetic Disorders (p. 141)
• 4.4 What Do Eukaryotic Genomes Contain? (p. 143)
• 4.5 How Are Eukaryotic Protein-Coding Genes identified? (p. 145)
• 4.6 Some Eukaryotic Organelles Have DNA (p. 148)
• Methods and Techniques: Using mtDNA to Reconstruct Human Phylogenies (p. 151)
• 4.7 Organelle Genomes Are Circular DNAs (p. 153)
• 4.8 The Chloroplast Genome Encodes Proteins and RNAs (p. 157)
• 4.9 Mitochondria and Chloropiasts Evolved by Endosymbiosis (p. 158)
• 4.10 Summary (p. 160)
• Chapter Questions (p. 161)
• Key Terms (p. 162)
• Further Reading (p. 163)
• Chapter 5 Genome Sequences and Evolution (p. 165)
• 5.1 Introduction (p. 166)
• 5.2 Prokaryotic Gene Numbers Span an Order of Magnitude (p. 167)
• 5.3 Total Gene Number Is Known for Several Eukaryotes (p. 170)
• 5.4 How Many Different Types of Genes Are There? (p. 173)
• 5.5 The Human Genome Has Fewer Genes than Expected (p. 176)
• 5.6 How Are Genes and Other Sequences Distributed? (p. 179)
• 5.7 The Y Chromosome Has Several Male-Specific Genes (p. 180)
• Methods and Techniques: Tracing Human History through the Y Chromosome (p. 182)
• 5.8 How Many Genes Are Essential? (p. 184)
• 5.9 About 10,000 Genes Are Expressed at Different Levels (p. 188)
• 5.10 Expressed Gene Number Can Be Measured En Masse (p. 189)
• 5.11 DNA Sequences Evolve by Mutation and a Sorting Mechanism (p. 191)
• 5.12 Selection Can Be Detected by Measuring Sequence Variation (p. 194)
• 5.13 A Constant Rate of Sequence Divergence Is a Molecular Clock (p. 199)
• 5.14 The Rate of Neutral Substitution Can Be Measured (p. 202)
• 5.15 How Did Interrupted Genes Evolve? (p. 204)
• 5.16 Why Are Some Genomes So Large? (p. 207)
• 5.17 Morphological Complexity Evolves by Adding Gene Functions (p. 210)
• 5.18 Gene Duplication Contributes to Genome Evolution (p. 212)
• 5.19 Globin Clusters Arise by Duplication and Divergence (p. 214)
• 5.20 Pseudogenes Have Lost Their Original Functions (p. 217)
• 5.21 Genome Duplication Affects Plant and Vertebrate Evolution (p. 220)
• 5.22 The Role of Transposable Elements in Genome Evolution (p. 222)
• 5.23 Biases in Mutation, Gene Conversion, and Codon Usage (p. 223)
• 5.24 Summary (p. 224)
• Chapter Questions (p. 226)
• Key Terms (p. 229)
• Further Reading (p. 229)
• Chapter 6 Clusters and Repeats (p. 231)
• 6.1 Introduction (p. 231)
• 6.2 Unequal Crossing Over Rearranges Gene Clusters (p. 234)
• 6.3 Genes for rRNA Form Tandem Repeats (p. 238)
• 6.4 Crossover Fixation Could Maintain Identical Repeats (p. 242)
• 6.5 Satellite DNAs Often Lie in Heterochromatin (p. 246)
• 6.6 Arthropod Satellites Have Short Identical Repeats (p. 249)
• 6.7 Mammalian Satellites Consist of Hierarchical Repeats (p. 250)
• 6.8 Minisatellites Are Useful for DNA Profiling (p. 254)
• 6.9 Summary (p. 256)
• Chapter Questions (p. 257)
• Key Terms (p. 258)
• Further Reading (p. 259)
• Chapter 7 Chromosomes (p. 261)
• 7.1 Introduction (p. 261)
• 7.2 Viral Genomes Are Packaged into Coats (p. 262)
• 7.3 The Bacterial Genome Is a Supercoiled Nucleoid (p. 265)
• 7.4 Loops and Domains Organize Eukaryotic DNA (p. 268)
• 7.5 Chromatin Is Divided into Euchromatin and Heterochromatin (p. 269)
• 7.6 Chromosomes Have Banding Patterns (p. 272)
• Methods and Techniques: FISH, Chromosome Painting, and Spectral Karyotyping (p. 273)
• 7.7 Polytene Chromosomes Form Bands (p. 275)
• 7.8 The Eukaryotic Chromosome Is a Segregation Device (p. 278)
• 7.9 Regional Centromeres Contain Histone H3 Variants (p. 280)
• 7.10 Point Centromeres in S. cerevisiae (p. 281)
• 7.11 Telomeres Have Simple Repeating Sequences (p. 283)
• 7.12 Summary (p. 289)
• Chapter Questions (p. 290)
• Key Terms (p. 291)
• Further Reading (p. 292)
• Chapter 8 Chromatin (p. 293)
• 8.1 Introduction (p. 293)
• 8.2 The Nucleosome Is the Subunit of All Chromatin (p. 294)
• 8.3 Nucleosomes Have a Common Structure (p. 298)
• 8.4 Nucleosomes Are Covalently Modified (p. 300)
• 8.5 Histone Variants Produce Alternative Nucleosomes (p. 304)
• 8.6 DNA Structure Varies on the Nucleosomal Surface (p. 307)
• 8.7 The Path of Nucleosomes in the Chromatin Fiber (p. 310)
• 8.8 Replication of Chromatin Requires Assembly of Nucleosomes (p. 313)
• 8.9 Do Nucleosomes Lie at Specific Positions? (p. 316)
• 8.10 DNase Sensitivity Detects Changes in Chromatin Structure (p. 322)
• 8.11 An LCR May Control a Domain (p. 323)
• 8.12 Insulators Define independent Domains (p. 326)
• Methods and Techniques: Position-Effect Variegation (PEV) and the Discovery of Insulators (p. 329)
• 8.13 Summary (p. 331)
• Chapter Questions (p. 333)
• Key Terms (p. 334)
• Further Reading (p. 334)
• Part II DNA Replication and Recombination (p. 335)
• Chapter 9 Replication Is Connected to the Cell Cycle (p. 337)
• 9.1 Introduction (p. 337)
• 9.2 Bacterial Replication Is Connected to the Cell Cycle (p. 339)
• Historical Perspectives: John Cairns and the Bacterial Chromosome (p. 341)
• 9.3 The Septum Divides a Bacterium into Progeny (p. 342)
• 9.4 Mutations in Division or Segregation Affect Cell Shape (p. 344)
• 9.5 FtsZ Is Necessary for Septum Formation (p. 345)
• 9.6 Min and slm Genes Regulate the Location of the Septum (p. 346)
• 9.7 Chromosomal Segregation May Require Site-Specific Recombination (p. 348)
• 9.8 Partitioning Separates the Chromosomes (p. 351)
• 9.9 The Eukaryotic Growth Factor Signal Transduction Pathway (p. 353)
• 9.10 Checkpoint Control for Entry into S Phase: p53 (p. 356)
• 9.11 Checkpoint Control for Entry into S Phase: Rb (p. 358)
• 9.12 Summary (p. 360)
• Chapter Questions (p. 361)
• Key Terms (p. 362)
• Further Reading (p. 362)
• Chapter 10 The Replicon: Initiation of Replication (p. 363)
• 10.1 Introduction (p. 363)
• 10.2 An Origin Usually Initiates Bidirectional Replication (p. 365)
• Historical Perspectives: The Meselson-Stahl Experiment (p. 366)
• 10.3 The Bacterial Genome Is (Usually) a Single Circular Replicon (p. 368)
• 10.4 Methylation of the Bacterial Origin Regulates Initiation (p. 369)
• 10.5 Initiation: Creating the Replication Forks at the Origin (p. 371)
• 10.6 Each Eukaryotic Chromosome Contains Many Replicons (p. 374)
• 10.7 Replication Origins Bind the ORC (p. 375)
• 10.8 Licensing Factor Controls Eukaryotic Rereplication (p. 377)
• 10.9 Summary (p. 380)
• Chapter Questions (p. 381)
• Key Terms (p. 382)
• Further Reading (p. 383)
• Chapter 11 DNA Replication (p. 385)
• 11.1 Introduction (p. 385)
• 11.2 DNA Polymerases Are the Enzymes That Make DNA (p. 386)
• 11.3 DNA Polymerases Have Various Nuclease Activities (p. 388)
• 11.4 DNA Polymerases Control the Fidelity of Replication (p. 389)
• 11.5 DNA Polymerases Have a Common Structure (p. 391)
• 11.6 The Two New DNA Strands Have Different Modes of Synthesis (p. 393)
• 11.7 Replication Requires a Helicase and Single-Strand Binding Protein (p. 394)
• 11.8 Priming Is Required to Start DNA Synthesis (p. 396)
• 11.9 Coordinating Synthesis of the Lagging and Leading Strands (p. 399)
• 11.10 DNA Polymerase Holoenzyme Consists of Subcomplexes (p. 400)
• 11.11 The Clamp Controls Association of Core Enzyme with DNA (p. 401)
• 11.12 Okazaki Fragments Are Linked by Ligase (p. 405)
• 11.13 Separate Eukaryotic DNA Polymerases Undertake initiation and Elongation (p. 407)
• 11.14 Lesion Bypass Requires Polymerase Replacement (p. 410)
• 11.15 Termination of Replication (p. 413)
• 11.16 Summary (p. 414)
• Chapter Questions (p. 415)
• Key Terms (p. 415)
• Further Reading (p. 416)
• Chapter 12 Extrachromosomal Replication (p. 417)
• 12.1 Introduction (p. 417)
• 12.2 The Ends of Linear DNA Are a Problem for Replication (p. 419)
• 12.3 Terminal Proteins Enable initiation at the Ends of Viral DNAs (p. 420)
• 12.4 Rolling Circles Produce Multimers of a Replicon (p. 422)
• 12.5 Roiling Circles Are Used to Replicate Phage Genomes (p. 424)
• 12.6 The F Plasmid Is Transferred by Conjugation between Bacteria (p. 426)
• 12.7 Conjugation Transfers Single-Stranded DNA (p. 428)
• 12.8 Single-Copy Plasmids Have a Partitioning System (p. 431)
• 12.9 Plasmid Incompatibility Is Determined by the Replicon (p. 433)
• 12.10 The Bacterial Ti Plasmid Transfers Genes into Plant Cells (p. 434)
• 12.11 Transfer of T-DNA Resembles Bacterial Conjugation (p. 438)
• 12.12 How Do Mitochondria Replicate and Segregate? (p. 440)
• 12.13 Summary (p. 442)
• Chapter Questions (p. 443)
• Key Terms (p. 444)
• Further Reading (p. 444)
• Chapter 13 Homologous, Somatic, and Site-Specific Recombination (p. 445)
• 13.1 Introduction (p. 445)
• 13.2 Homologous Recombination Occurs between Synapsed Chromosomes in Meiosis (p. 448)
• 13.3 Double-Strand Breaks Initiate Recombination (p. 451)
• 13.4 Recombining Chromosomes Are Connected by the Synaptonemal Complex (p. 454)
• 13.5 Specialized Enzymes Catalyze 5' End Resection and Single-Strand Invasion (p. 456)
• 13.6 Holliday Junctions Must Be Resolved (p. 458)
• 13.7 Immunoglobulin Genes Are Assembled from Discrete DNA Segments by Recombination (p. 461)
• 13.8 Immune Recombination Uses Two Types of Consensus Sequences (p. 467)
• Medical Applications: ARTEMIS and SCID-A (p. 472)
• 13.9 Topoisomerases Relax or Introduce Supercoils in DNA (p. 474)
• Medical Applications: Camptothecin and Topoisomerase I Inhibition (p. 477)
• 13.10 Site-Specific Recombination Resembles Topoisomerase Activity (p. 478)
• 13.11 Yeast Use a Specialized Recombination Mechanism to Switch Mating Type (p. 482)
• Medical Applications: Trypanosomes Use Gene Switching to Evade the Host Immune System (p. 484)
• 13.12 Summary (p. 488)
• Chapter Questions (p. 489)
• Key Terms (p. 491)
• Further Reading (p. 492)
• Chapter 14 Repair Systems (p. 493)
• 14.1 Introduction (p. 493)
• 14.2 Repair Systems Correct Damage to DNA (p. 496)
• 14.3 Nucleotide Excision Repair Systems Repair Several Classes of Damage (p. 498)
• Medical Applications: Xeroderma Pigmentosum (p. 503)
• 14.4 Base Excision Repair Systems Require Glycosylases (p. 504)
• 14.5 Error-Prone Repair and Translesion Synthesis (p. 507)
• 14.6 Controlling the Direction of Mismatch Repair (p. 509)
• 14.7 Recombination Repair Systems (p. 512)
• 14.8 Nonhomologous End Joining Repairs Double-Strand Breaks (p. 516)
• Medical Applications: p53 Is the "Guardian of the Genome" (p. 517)
• 14.9 DNA Repair in Eukaryotes Occurs in the Context of Chromatin (p. 520)
• 14.10 Summary (p. 524)
• Chapter Questions (p. 525)
• Key Terms (p. 526)
• Further Reading (p. 526)
• Chapter 15 Transposable Elements and Retroviruses (p. 527)
• 15.1 Introduction (p. 527)
• 15.2 Insertion Sequences Are Simple Transposition Modules (p. 530)
• 15.3 Transposition Occurs by Replicative and Nonreplicative Pathways (p. 533)
• 15.4 Mechanisms of Transposition (p. 536)
• 15.5 Transposons Form Superfamilies and Families (p. 540)
• Historical Perspectives: Barbara McCSintock, 1950: The Origin and Behavior of Mutable Loci in Maize (p. 541)
• 15.6 Transposition of P Elements Causes Hybrid Dysgenesis (p. 545)
• 15.7 The Retrovirus Lifecycle Involves Transposition-like Events (p. 549)
• 15.8 Retroviral RNA Is Converted to DNA and Integrates into the Host Genome (p. 552)
• 15.9 Retroviruses May Transduce Cellular Sequences (p. 555)
• 15.10 Retroelements Fall into Three Classes (p. 557)
• 15.11 Summary (p. 561)
• Chapter Questions (p. 562)
• Key Terms (p. 564)
• Further Reading (p. 565)
• Part III Gene Expression (p. 567)
• Chapter 16 Prokaryotic Transcription (p. 569)
• 16.1 Introduction (p. 569)
• 16.2 Transcription Occurs by Base Pairing (p. 571)
• 16.3 The Transcription Reaction Has Three Stages (p. 573)
• 16.4 Core Enzyme and Sigma Factor Comprise Bacterial RNA Polymerase (p. 575)
• 16.5 How Does RNA Polymerase Find Promoter Sequences? (p. 576)
• 16.6 Sigma Factor Controls Binding to Promoters (p. 578)
• 16.7 Promoter Recognition Depends on Consensus Sequences (p. 581)
• 16.8 Promoter Efficiencies Can Be Increased or Decreased by Mutation (p. 583)
• 16.9 Multiple Regions in RNA Polymerase Directly Contact Promoter DNA (p. 585)
• 16.10 A Model for Enzyme Movement Is Suggested by the Crystal Structure (p. 587)
• 16.11 Bacterial Transcription Termination (p. 589)
• 16.12 Intrinsic Termination Structural Requirements (p. 591)
• 16.13 Rho Factor is a Site-Specific Terminator Protein (p. 592)
• 16.14 Supercoiling Is an Important Feature of Transcription (p. 595)
• 16.15 Substitution of Sigma Factors May Control initiation (p. 596)
• 16.16 Antitermination May Be a Regulated Event (p. 599)
• 16.17 The Cycle of Bacteria! Messenger RNA (p. 602)
• 16.18 Summary (p. 605)
• Chapter Questions (p. 607)
• Key Terms (p. 608)
• Further Reading (p. 608)
• Chapter 17 Eukaryotic Transcription (p. 609)
• 17.1 Introduction (p. 609)
• 17.2 Eukaryotic RNA Polymerases Consist of Many Subunits (p. 612)
• 17.3 RNA Polymerase I Has a Bipartite Promoter (p. 613)
• 17.4 RNA Polymerase III Uses Downstream and Upstream Promoters (p. 615)
• 17.5 The Start Point for RNA Polymerase II (p. 618)
• 17.6 TBP Is a (Nearly) Universal Factor (p. 620)
• 17.7 The Basal Apparatus Assembles at the Promoter (p. 623)
• 17.8 Initiation Is Followed by Promoter Clearance and Elongation (p. 626)
• 17.9 Enhancers Contain Bidirectional Elements That Assist Initiation (p. 628)
• 17.10 How Enhancers Work (p. 630)
• 17.11 Summary (p. 631)
• Chapter Questions (p. 632)
• Key Terms (p. 633)
• Further Reading (p. 633)
• Chapter 18 RNA Splicing and Processing (p. 635)
• 18.1 Introduction (p. 635)
• 18.2 The 5' End of Eukaryotic mRNA Is Capped (p. 636)
• 18.3 Nuclear Splice Sites Are Short Sequences (p. 639)
• 18.4 Splice Sites Are Read in Pairs (p. 640)
• 18.5 Pre-mRNA Splicing Proceeds through a Lariat (p. 642)
• 18.6 snRNAs Are Required for Splicing (p. 644)
• 18.7 Commitment of Pre-mRNA to the Splicing Pathway (p. 646)
• 18.8 The Spliceosome Assembly Pathway (p. 649)
• 18.9 Splicing Is Coupled to Multiple Steps in Gene Expression (p. 653)
• 18.10 Pre-mRNA Splicing Shares a Mechanism with Group II Autocatalytic Introns (p. 654)
• Medical Applications: Alternative Splicing and Cancer (p. 656)
• 18.11 Alternative Splicing Occurs in Most Transcripts in Multicellular Eukaryotes (p. 659)
• 18.12 Trans-Splicing Reactions Use Small RNAs (p. 661)
• 18.13 tRNA Splicing Involves Cutting and Rejoining in Separate Reactions (p. 664)
• 18.14 The 3' Ends of mRNAs Are Generated by Cleavage and Polyadenylation (p. 668)
• 18.15 Production of rRNA Requires Cleavage Events and Involves Small RNAs (p. 670)
• 18.16 Summary (p. 674)
• Chapter Questions (p. 675)
• Key Terms (p. 676)
• Further Reading (p. 677)
• Chapter 19 mRNA Stability and Localization (p. 679)
• 19.1 Introduction (p. 679)
• 19.2 Messenger RNAs Are Unstable Molecules (p. 681)
• 19.3 Eukaryotic mRNAs Are mRNPs from Synthesis to Degradation (p. 683)
• 19.4 Prokaryotic mRNA Degradation Involves Multiple Enzymes (p. 685)
• 19.5 Most Eukaryotic mRNA Is Degraded via Two Deadenylation-Dependent Pathways (p. 687)
• 19.6 Other Degradation Pathways Target Specific mRNAs (p. 690)
• 19.7 mRNA-Specific Half-Lives Are Controlled by Sequences or Structures (p. 693)
• 19.8 Newly Synthesized RNAs Are Checked for Defects in the Nucleus (p. 695)
• 19.9 Quality Control of mRNA Translation in the Cytoplasm (p. 698)
• 19.10 Some Eukaryotic mRNAs Are Localized to Specific Regions of a Cell (p. 701)
• 19.11 Summary (p. 706)
• Chapter Questions (p. 707)
• Key Terms (p. 708)
• Further Reading (p. 709)
• Chapter 20 Catalytic RNA (p. 711)
• 20.1 Introduction (p. 711)
• 20.2 Group I Introns Undertake -Self-Splicing by Transesterification (p. 712)
• 20.3 Group I Introns Form a Characteristic Secondary Structure (p. 716)
• 20.4 Ribozymes Have Various Catalytic Activities (p. 717)
• 20.5 Some Group I Introns Encode Endonucleases That Sponsor Mobility (p. 722)
• 20.6 Group II Introns May Encode Multifunction Proteins (p. 723)
• 20.7 Some Autosplicing Introns Require Maturases (p. 725)
• 20.8 Viroids Have Catalytic Activity (p. 726)
• 20.9 RNA Editing Occurs at Individual Bases (p. 729)
• 20.10 RNA Editing Can Be Directed by Guide RNAs (p. 731)
• 20.11 Protein Splicing Is Autocataiytic (p. 734)
• 20.12 Summary (p. 736)
• Chapter Questions (p. 737)
• Key Terms (p. 739)
• Further Reading (p. 739)
• Chapter 21 Translation (p. 741)
• 21.1 Introduction (p. 741)
• 21.2 Translation Occurs by initiation, Elongation, and Termination (p. 743)
• 21.3 Special Mechanisms Control the Accuracy of Translation (p. 746)
• 21.4 Initiation in Bacteria Needs 30S Subunits and Accessory Factors (p. 748)
• 21.5 A Special Initiator tRNA Starts the Polypeptide Chain (p. 751)
• 21.6 mRNA Binds a 30S Subunit to Create a Binding Site for Initiation Factors (p. 753)
• 21.7 Small Subunits Scan for Initiation Sites on Eukaryotic mRNA (p. 755)
• 21.8 Elongation Factor Tu Loads Aminoacyl-tRNA into the A Site (p. 758)
• 21.9 The Polypeptide Chain Is Transferred to Aminoacyl-tRNA (p. 760)
• 21.10 Translocation Moves the Ribosome (p. 762)
• 21.11 Elongation Factors Bind Alternately to the Ribosome (p. 764)
• 21.12 Three Codons Terminate Translation and Are Recognized by Protein Factors (p. 765)
• Historical Perspectives: The Naming of the Amber, Ochre, and Opal Codons (p. 767)
• 21.13 Ribosomai RNA Is Found throughout Both Ribosomal Subunits (p. 770)
• 21.14 Ribosomes Have Several Active Centers (p. 772)
• 21.15 Two rRNAs Play Active Roles in Translation (p. 775)
• 21.16 Translation Can Be Regulated (p. 777)
• 21.17 Summary (p. 780)
• Chapter Questions (p. 782)
• Key Terms (p. 783)
• Further Reading (p. 784)
• Chapter 22 Using the Genetic Code (p. 785)
• 22.1 Introduction (p. 785)
• 22.2 Related Codons Represent Chemically Similar Amino Acids (p. 786)
• 22.3 Codon-Anticodon Recognition Involves Wobbling (p. 788)
• 22.4 tRNA Contains Modified Bases (p. 791)
• 22.5 Modified Bases Affect Anticodon-Codon Pairing (p. 792)
• 22.6 The Universal Code Has Experienced Sporadic Alterations (p. 794)
• 22.7 Novel Amino Acids Can Be Inserted at Certain Stop Codons (p. 797)
• 22.8 tRNAs Are Charged with Amino Acids by Aminoacy-tRNA Synthetases (p. 798)
• 22.9 Aminoacyl-tRNA Synthetases Fall into Two Classes (p. 800)
• 22.10 Synthetases Use Proofreading to Improve Accuracy (p. 802)
• 22.11 Suppressor tRNAs Have Mutated Anticodons That Read New Codons (p. 805)
• Medical Applications: Therapies for Nonsense Mutations (p. 808)
• 22.12 Recoding Changes Codon Meanings (p. 810)
• 22.13 Frameshifting Occurs at Slippery Sequences (p. 812)
• 22.14 Bypassing Involves Ribosome Movement (p. 814)
• 22.15 Summary (p. 815)
• Chapter Questions (p. 816)
• Key Terms (p. 817)
• Further Reading (p. 817)
• Part IV Gene Regulation (p. 819)
• Chapter 23 The Operon (p. 821)
• 23.1 Introduction (p. 821)
• 23.2 Structural Gene Clusters Are Coordinately Controlled (p. 826)
• Historical Perspectives: An Unstable Intermediate Carrying Information (p. 827)
• 23.3 The lac Operon Is Negative Inducible (p. 828)
• 23.4 The lac Repressor Is Controlled by a Small Molecule Inducer (p. 830)
• 23.5 cis-Acting Constitutive Mutations identify the Operator (p. 832)
• 23.6 Trans-Acting Mutations Identify the Regulator Gene (p. 834)
• 23.7 The lac Repressor is a Tetramer Made of Two Dimers (p. 835)
• 23.8 How lac Repressor Binding to the Operator Is Regulated (p. 838)
• 23.9 The lac Repressor Binds to Three Operators and Interacts with RNA Polymerase (p. 841)
• 23.10 The Operator Competes with Low-Affinity Sites to Bind Repressor (p. 843)
• 23.11 The lac Operon Is Controlled By Catabolite Repression (p. 845)
• 23.12 The trp Operon Is a Repressible Operon with Three Transcription Units (p. 848)
• 23.13 The trp Operon Is Also Controlled by Attenuation (p. 850)
• 23.14 Attenuation Can Be Controlled by Translation (p. 852)
• 23.15 Stringent Control by Stable RNA Transcription (p. 855)
• 23.16 Summary (p. 857)
• Chapter Questions (p. 859)
• Key Terms (p. 860)
• Further Reading (p. 861)
• Chapter 24 Phage Strategies (p. 863)
• 24.1 Introduction (p. 863)
• 24.2 Lytic Development Is Divided into Two Periods (p. 865)
• 24.3 Lytic Development Is Controlled by a Cascade (p. 867)
• 24.4 Two Types of Regulatory Events Control the Lytic Cascade (p. 868)
• 24.5 Both Lysogeny and Lytic Cycle Require Immediate Early and Delayed Early Genes (p. 870)
• 24.6 The Lytic Cycle Depends on Antitermination by pN (p. 872)
• 24.7 Lysogeny Is Maintained by the Lambda Repressor Protein (p. 874)
• 24.8 The Lambda Repressor and Its Operators Define the Immunity Region (p. 876)
• 24.9 The DNA-Binding Form of the Lambda Repressor Is a Dimer (p. 877)
• 24.10 The Lambda Repressor Uses a Helix-Turn-Helix Motif to Bind DNA (p. 879)
• 24.11 Lambda Repressor Dimers Bind Cooperatively to the Operator (p. 881)
• 24.12 The Lambda Repressor Maintains an Autoregulatory Circuit (p. 883)
• 24.13 Cooperative Interactions Increase the Sensitivity of Regulation (p. 884)
• 24.14 The cll and cll Genes Are Needed to Establish Lysogeny (p. 886)
• 24.15 Lysogeny Requires Several Events (p. 887)
• Essential Ideas: The Mechanism of pQ Antitermination (p. 889)
• 24.16 The Cro Repressor Is Needed for Lytic Infection (p. 890)
• 24.17 What Determines the Balance Between Lysogeny and the Lytic Cycle? (p. 892)
• 24.18 Summary (p. 894)
• Chapter Questions (p. 895)
• Key Terms (p. 896)
• Further Reading (p. 897)
• Chapter 25 Eukaryotic Transcription Regulation (p. 899)
• 25.1 Introduction (p. 899)
• 25.2 How Is a Gene Turned On? (p. 902)
• 25.3 Mechanism of Action of Activators and Repressors (p. 903)
• 25.4 Independent Domains Bind DNA and Activate Transcription (p. 907)
• 25.5 Activators Interact with the Basal Apparatus (p. 909)
• 25.6 There Are Many Types of DNA-Binding Domains (p. 911)
• 25.7 Chromatin Remodeling Is an Active Process (p. 914)
• 25.8 Nucleosome Organization or Content May Be Changed (p. 919)
• 25.9 Histone Acetylation Is Associated with Transcription Activation (p. 921)
• Methods and Techniques: A Tale of Two Nuclei-Tetrahymena thermophila (p. 924)
• 25.10 Methylation of Histones and Methylation of DNA Are Connected (p. 927)
• 25.11 Gene Activation Involves Multiple Changes to Chromatin (p. 928)
• 25.12 Histone Phosphorylation Affects Chromatin Structure (p. 930)
• 25.13 Summary (p. 932)
• Chapter Questions (p. 934)
• Key Terms (p. 935)
• Further Reading (p. 935)
• Chapter 26 Epigenetics (p. 937)
• 26.1 Introduction (p. 937)
• 26.2 Heterochromatin Propagates from a Nucleation Event (p. 939)
• 26.3 Heterochromatin Depends on Interactions with Histones (p. 942)
• 26.4 Polycomb and Trithorax Are Antagonistic Repressors and Activators (p. 945)
• 26.5 X Chromosomes Undergo Global Changes (p. 948)
• 26.6 CpG Islands Are Subject to Methylation (p. 952)
• 26.7 DNA Methylation Is Responsible for Imprinting (p. 956)
• 26.8 Yeast Prions Show Unusual Inheritance (p. 960)
• 26.9 Prions Cause Diseases in Mammals (p. 963)
• 26.10 Summary (p. 965)
• Chapter Questions (p. 966)
• Key Terms (p. 968)
• Further Reading (p. 968)
• Chapter 27 Noncoding RNA (p. 969)
• 27.1 Introduction (p. 969)
• 27.2 A Riboswitch Can Control Expression of an mRNA (p. 970)
• 27.3 Noncoding RNAs Can Be Used to Regulate Gene Expression (p. 972)
• 27.4 Summary (p. 976)
• Chapter Question (p. 977)
• Key Terms (p. 977)
• Further Reading (p. 977)
• Chapter 28 Regulatory RNA (p. 979)
• 28.1 Introduction (p. 979)
• 28.2 Bacteria Contain Regulator RNAs (p. 980)
• Medical Applications: Artificial Antisense Genes Can Be Used to Turn Off Viruses and Cancer Genes (p. 983)
• 28.3 MicroRNAs Are Widespread Regulators in Eukaryotes (p. 986)
• 28.4 How Does RNA Interference Work? (p. 990)
• 28.5 Heterochromatin Formation Requires MicroRNAs (p. 994)
• 28.6 Summary (p. 996)
• Chapter Questions (p. 996)
• Key Terms (p. 996)
• Further Reading (p. 996)
• Glossary (p. 997)
• Appendix: Answers to Even-Numbered End-of-Chapter Questions (p. 1019)
• Index (p. 1021)