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Description: When the first edition of GENES published, Benjamin Lewin set the standard for teaching molecular biology and molecular genetics with a unified approach. The Ninth Edition of this classic text continues this tradition, presenting gene structure and function in both eukaryotic and prokaryotic organisms. Dr. Lewin maintains his commitment to providing students, researchers, and educators with the most current presentation of concepts in this rapidly changing field. The Ninth Edition of Genes includes updated content and expanded coverage of critical topics with a new organization that allows the student to focus more sharply on genes and their expression. GENES IX also boasts a fresh, modern design and a contemporary art program.
New and Key Features of GENES IX
Expanded coverage in many areas including:
• DNA replication
• Recombination and repair
• The replicon
• Chromatin regulation and gene regulation
• Evolution of genes
• The Y chromosome
• Reorganized to allow instructors to build on critical concepts throughout the course
• New contemporary design and stunning 4-color art program
• New updates throughout, including the most current information on genome organization, DNA replication, gene regulation, and much more
Resources include an instructor’s ToolKit CD-ROM with Image Bank, PowerPoint® Lecture Outline Slides, and an all-new Test Bank as well as the GENES IX companion website with numerous eLearning Tools.
Contents:
Chapter 1: Genes are DNA: Introduction • DNA is the Genetic Material of Bacteria • DNA is the Genetic Material of Viruses • DNA is the Genetic Material of Animal Cells • Polynucleotide Chains Have Nitrogenous Bases Linked to a Sugar-Phosphate Backbone • DNA is a Double Helix • DNA Replication is Semiconservative • DNA Strands Separate at the Replication Fork • Genetic Information Can Be Provided by DNA or RNA • Nucleic Acids Hybridize by Base Pairing • Mutations Change the Sequence of DNA • Mutations May Affect Single Base Pairs or Longer Sequences • The Effects of Mutations Can Be Reversed • Mutations are Concentrated at Hotspots • Many Hotspots Result from Modified Bases • Some Hereditary Agents are Extremely Small • Summary Chapter 2: Genes Code for Proteins: Introduction • A Gene Codes for a Single Polypeptide • Mutations in the Same Gene Cannot Complement • Mutations May Cause Loss-of-Function or Gain-of-Function • A Locus May Have Many Different Mutant Alleles • A Locus May Have More than One Wild-type Allele • Recombination Occurs by Physical Exchange of DNA • The Genetic Code is Triplet • Every Sequence Has Three Possible Reading Frames • Prokaryotic Genes are Colinear with Their Proteins • Several Processes are Required to Express the Protein Product of a Gene • Proteins are Trans-acting, but Sites on DNA are Cis-acting • Summary
Chapter 3: The Interrupted Gene: Introduction • An Interrupted Gene Consists of Exons and Intron Restriction Endonucleases are a Key Tool in Mapping DNA • Organization of Interrupted Genes May Be Conserved • Exon Sequences are Conserved but Introns Vary • Genes Show a Wide Distribution of Sizes • Some DNA Sequences Code for More Than One Protein • How Did Interrupted Genes Evolve? • Some Exons Can Be Equated with Protein Functions • The Members of a Gene Family Have a Common Organization • Is All Genetic Information Contained in DNA? • Summary
Chapter 4: The Content of the Genome • Introduction • Genomes Can Be Mapped by Linkage, restriction Cleavage, or DNA Sequence • Individual Genomes Show Extensive Variation • RFLPs and SNPs Can Be Used for Genetic Mapping • Why are Genomes So Large? • Eukaryotic Genomes Contain Both Nonrepetitive and Repetitive DNA Sequences • Genes Can Be Isolated by the conservation of Exons • The Conservation of Genome Organization Helps to Identify Genes • Organelles Have DNA • Organelle Genomes are Circular DNAs That Code for Organelle Proteins • Mitochondrial DNA Organization is Variable • The Chloroplast Genome Codes for Many Proteins and RNAs • Mitochondria Evolved by Endosymbiosis • Summary
Chapter 5: Genome Sequences and Gene Numbers • Introduction • Bacterial Gene Numbers Range Over an Order of Magnitude • Total Gene Number is Known for Several Eukaryotes • How Many Different Types of Genes are There? • The Human Genome Has Fewer Genes Than Expected • How are Genes and Other Sequences Distributed in the Genome? • The Y Chromosome Has Several Male-Specific Genes • More Complex Species Evolve by Adding New Gene Functions • How Many Genes are Essential? • Genes are Expressed at Widely Differing Levels • How Many Genes are Expressed • Expressed Gene Number Can Be Measured En Masse • Summary
Chapter 6: Clusters and Repeats • Introduction • Gene Duplication is a Major Force in Evolution • Globin Clusters are Formed by Duplication and Divergence • Sequence Divergence is the Basis for the Evolutionary Clock • The Rate of Neutral Substitution Can Be Measured from Divergence of Repeated Sequences • Pseudogenes are Dead Ends of Evolution • Unequal Crossing-over Rearranges Gene Clusters • Genes for rRNA Form Tandem Repeats • The Repeated Genes for rRNA Maintain Constant Sequence • Crossover Fixation Could Maintain Identical Repeats • Satellite DNAs Often Lie in Heterochromatin • Arthropod Satellites Have Very Short Identical Repeats • Mammalian Satellites Consist of Hierarchical Repeats • Minisatellites are Useful for Genetic Mapping • Summary
Chapter 7: Messenger RNA • Introduction • mRNA is Produced by Transcription and is Translated • Transfer RNA Forms a Cloverleaf • The Acceptor Stem and Anticodon are at Ends of the Tertiary Structure • Messenger RNA is Translated by Ribosomes • Many Ribosomes Bind to One mRNA • The Life Cycle of Bacterial Messenger RNA • Eukaryotic mRNA is Modified During or after Its Transcription • The 5" End of Eukaryotic mRNA is Capped • The 3" Terminus is Polyadenylated • Bacterial mRNA Degradation Involves Multiple Enzymes • mRNA Stability Depends on Its Structure and Sequence • mRNA Degradation Involves Multiple Activities • Nonsense Mutations Trigger a Surveillance System • Eukaryotic RNAs are Transported • mRNA Can Be Specifically Localized • Summary
Chapter 8: Protein Synthesis: Introduction • Protein Synthesis Occurs by Initiation, Elongation, and Termination • Special Mechanisms Control the Accuracy of Protein Synthesis • Initiation in Bacteria Needs 30S Subunits and Accessory Factors • A Special Initiator tRNA Starts the Polypeptide Chain • Use of fMet-tRNAf is Controlled by IF-2 and the Ribosome • Initiation Involves Base Pairing Between mRNA and rRNA • Small Subunits Scan for Initiation Sites on Eukaryotic mRNA• Eukaryotes Use a Complex of Many Initiation Factors • Elongation Factor Tu Loads Aminoacyl-tRNA into the A Site • The Polypeptide Chain is Transferred to Aminoacyl-tRNA • Translocation Moves the Ribosome • Elongation Factors Bind Alternately to the Ribosome • Three Codons Terminate Protein Synthesis • Termination Codons are Recognized by Protein Factors • Ribosomal RNA Pervades Both Ribosomal Subunits • Ribosomes Have Several Active Centers • 16S rRNA Plays an Active Role in Protein Synthesis • 23S rRNA Has Peptidyl Transferase Activity • Ribosomal Structures Change When the Subunits Come Together • Summary
Chapter 9: Using the Genetic Code • Introduction • Related Codons Represent Related Amino Acids • Codon-Anticodon Recognition Involves Wobbling • tRNAs are Processed from Longer Precursors • tRNA Contains Modified Bases • Modified Bases Affect Anticodon-Codon Pairing • There are Sporadic Alterations of the Universal Code • Novel Amino Acids Can Be Inserted at Certain Stop Codons • tRNAs are Charged with Amino Acids by Synthetases • Aminoacyl-tRNA Synthetases Fall into Two Groups • Synthetases Use Proofreading to Improve Accuracy • Suppressor tRNAs Have Mutated Anticodons That Read New Codons • There are Nonsense Suppressors for Each Termination Codon • Suppressors May Compete with Wild-Type Reading of the Code • The Ribosome Influences the Accuracy of Translation • Recoding Changes Codon Meanings • Frameshifting Occurs at Slippery Sequences • Bypassing Involves Ribosome Movement • Summary
Chapter 10: Protein Localization • Introduction • Passage Across a Membrane Requires a Special Apparatus • Protein translocation May Be Posttranslational or Cotranslational • Chaperones May Be Required for Protein Folding • Chaperones are Needed by Newly Synthesized and by Denatured Proteins • The Hsp70 Family is Ubiquitous • Signal Sequences Initiate Translocation • The Signal Sequence Interacts with the SRP • The SRP Interacts with the SRP Receptor • The Translocon Forms a Pore • Translocation Requires Insertion into the Translocon and (Sometimes) a Ratchet in the ER • Reverse Translocation Sends Proteins to the Cytosol for Degradation • Proteins Reside in Membranes by Means of Hydrophobic Regions • Anchor Sequences Determine Protein Orientation • How Do Proteins Insert into Membranes? • Posttranslational Membrane Insertion Depends on Leader Sequences • A Hierarchy of Sequences Determines Location within Organelles • Inner and Outer Mitochondrial Membranes Have Different Translocons • Peroxisomes Employ Another Type of Translocation System • Bacteria Use Both Cotranslational and Posttranslational Translocation • The Sec System Transports Proteins into and Through the Inner Membrane • Sec-Independent Translocation Systems in E.coli • Summary
Chapter 11: Transcription • Introduction • Transcription Occurs by Base Pairing in a “Bubble” of Unpaired DNA • The Transcription Reaction Has Three Stages • Phage T7 RNA Polymerase is a Useful Model System • A Model for Enzyme Movement is Suggested by the Crystal Structure • Bacterial RNA Polymerase Consists of Multiple Subunits • RNA Polymerase Consists of the Core Enzyme and Sigma Factor • The Association with Sigma Factor Changes at Initiation • A Stalled RNA Polymerase Can Restart • How Does RNA Polymerase Find Promoter Sequences? • Sigma Factor Controls Binding to DNA • Promoter Recognition Depends on Consensus Sequences • Promoter Efficiencies Can Be Increased or Decreased by Mutation • RNA Polymerase Binds to One Face of DNA • Supercoiling is an Important Feature of Transcription • Substitution of Sigma Factors May Control Initiation • Sigma Factors Directly Contact DNA • Sigma Factors May Be Organized into Cascades • Sporulation is Controlled by Sigma Factors • Bacterial RNA Polymerase Terminates at Discrete Sites • There are Two Types of Terminators in E. coli • How Does Rho Factor Work? • Antitermination is a Regulatory Event • Antitermination Requires Sites That are Independent of the Terminators • Termination and Antitermination Factors Interact with RNA Polymerase • Summary
Chapter 12: The Operon • Introduction • Regulation Can Be Negative or Positive • Structural Gene Clusters are Coordinately Controlled • The lac Genes are Controlled by a Repressor • The lac Operon Can Be Induced • Repressor is Controlled by a Small-Molecule Inducer • cis-Acting Constitutive Mutations Identify the Operator • trans-Acting Mutations Identify the Regulator Gene • Multimeric Proteins Have Special Genetic Properties • The Repressor Monomer Has Several Domains • Repressor is a Tetramer Made of Two Dimers • DNA-Binding is Regulated by an Allosteric Change in Conformation • Mutant Phenotypes Correlate with the Domain Structure • Repressor Protein Binds to the Operator • Binding of Inducer Releases Repressor from the Operator • Repressor Binds to Three Operators and Interacts with RNA Polymerase • Repressor is Always Bound to DNA • The Operator Competes with Low-Affinity Sites to Bind Repressor • Repression Can Occur at Multiple Loci • Cyclic AMP is an Effector That Activates CRP to Act at Many Operons • CRP Functions in Different Ways in Different Target Operons • Translation Can Be Regulated • r-Protein Synthesis is Controlled by Autogenous Regulation • Phage T 4 p32 is Controlled by an Autogenous Circuit • Autogenous Regulation is Often Used to Control Synthesis of Macromolecular assemblies • Summary
Chapter 13: Regulatory RNA • Introduction • Alternative Secondary Structures Control Attenuation • Termination of Bacillus subtilis trp Genes is Controlled by Tryptophan and by tRNATrp • The Escherichia coli tryptophan Operon is Controlled by Attenuation • Attenuation Can Be Controlled by Translation • Antisense RNA Can Be Used to Inactivate Gene Expression • Small RNA Molecules Can Regulate Translation • Bacteria Contain Regulator RNAs • MicroRNAs are Regulators in Many Eukaryotes • RNA Interference is Related to Gene Silencing • Summary
Chapter 14: Phage Strategies: Introduction • Lytic Development is Divided into Two Periods • Lytic Development is Controlled by a Cascade • Two Types of Regulatory Event Control the Lytic Cascade • The T7 and T Genomes Show Functional Clustering • Lambda Immediate Early and Delayed Early Genes are Needed for Both Lysogeny and the Lytic Cycle • The Lytic Cycle Depends an Antitermination • Lysogeny is Maintained by Repressor Protein • The Repressor and Its Operators Define the Immunity Region • The DNA-Binding Form of Repressor is a Dimer • Repressor Uses a Helix- Turn-Helix Motif to Bind DNA ·The Recognition Helix Determines Specificity for DNA • Repressor Dimers Bind Cooperatively to the Operator • Repressor at OR2 Interacts with RNA Polymerase at PRM • Repressor Maintains an Autogenous Circuit • Cooperative Interactions Increase the Sensitivity of Regulation • The cII and cIII Genes are Needed to Establish Lysogeny • A Poor Promoter Requires cII Protein • Lysogeny Requires Several Events • The cro Repressor is Needed for Lytic Infection • What Determines the Balance Between Lysogeny and the Lytic Cycle? • Summary
Chapter 15:The Replicon: Introduction • Replicons Can Be Linear or Circular • Origins Can Be Mapped by Autoradiography and Electrophoresis • Does Methylation at the Origin Regulate Initiation? • Origins May Be Sequestered after Replication • Each Eukaryotic Chromosome Contains Many Replicons • Replication Origins Can Be Isolated in Yeast • Licensing Factor Controls Eukaryotic Rereplication • Licensing Factor Consists of MCM Proteins • D Loops Maintain Mitochondrial Origins • Summary
Chapter 16: Extrachromosomal Replicons: Introduction • The Ends of Linear DNA are a Problem for Replication • Terminal Proteins Enable Initiation at the Ends of Viral DNAs • Rolling Circles Produce Multimers of a Replicon • Rolling Circles are Used to Replicate Phage Genomes • The F Plasmid is Transferred by Conjugation between Bacteria • Conjugation Transfers Single-Stranded DNA • The Bacterial Ti Plasmid Causes Crown Gall Disease in Plants • T-DNA Carries Genes Required for Infection • Transfer of T-DNA Resembles Bacterial Conjugation • Summary
Chapter 17: Bacterial Replication is Connected to the Cell Cycle: Introduction • Replication is Connected to the Cell Cycle • The Septum Divides a Bacterium into Progeny That Each Contain a Chromosome • Mutations in Division or Segregation Affect Cell Shape • FtsZ is Necessary for Septum Formation • min Genes Regulate the Location of the Septum • Chromosomal Segregation May Require Site-Specific Recombination • Partitioning Involves Separation of the Chromosomes • Single-Copy Plasmids Have a Partitioning System • Plasmid Incompatibility is Determined by the Replicon • The ColE1 Compatibility System is Controlled by an RNA Regulator • How Do Mitochondria Replicate and Segregate? • Summary
Chapter 18:DNA Replication: Introduction • DNA Polymerases are the Enzymes That Make DNA • DNA Polymerases Have Various Nuclease Activities • DNA Polymerases Control the Fidelity of Replication • DNA Polymerases Have a Common Structure • DNA Synthesis is Semidiscontinuous • The ØX Model System Shows How Single-Stranded DNA is Generated for Replication • Priming is Required to Start DNA Synthesis • DNA Polymerase Holoenzyme Has Three Subcomplexes • The Clamp Controls Association of Core Enzyme with DNA. • Coordinating Synthesis of the Lagging and Leading Strands • Okazaki Fragments are Linked by Ligase • Separate Eukaryotic DNA Polymerases Undertake Initiation and Elongation • Phage T Provides Its Own Replication Apparatus • Creating the Replication Forks at an Origin • Common Events in Priming Replication at the Origin • The Primosome is Needed to Restart Replication • Summary
Chapter 19:Homologous and Site-Specific Recombination: Introduction • Homologous Recombination Occurs between Synapsed Chromosomes • Breakage and Reunion Involves Heteroduplex DNA • Double-Strand Breaks Initiate Recombination • Recombining Chromosomes are Connected by the Synaptonemal Complex • The Synaptonemal Complex Forms after Double-Strand Breaks • Pairing and Synaptonemal Complex Formation are Independent • The Bacterial RecBCD System is Stimulated by chi Sequences • Strand-Transfer Proteins Catalyze Single-Strand Assimilation • The Ruv System Resolves Holliday Junctions • Gene Conversion Accounts for Interallelic Recombination • Supercoiling Affects the Structure of DNA • Topoisomerases Relax or Introduce Supercoils in DNA • Topoisomerases Break and Reseal Strands • Gyrase Functions by Coil Inversion • Specialized Recombination Involves Specific Sites • Site-Specific Recombination Involves Breakage and Reunion • Site-Specific Recombination Resembles Topoisomerase Activity • Lambda Recombination Occurs in an Intasome • Yeast Can Switch Silent and Active Loci for Mating Type. • The MAT Locus Codes for Regulator Proteins • Silent Cassettes at HML and HMR are Repressed • Unidirectional Transposition is Initiated by the Recipient MAT Locus • Regulation of HO Expression Controls Switching • Summary
Chapter 20: Repair Systems: Introduction • Repair Systems Correct Damage to DNA • Excision Repair Systems in E. coli • Excision-Repair Pathways in Mammalian Cells • Base Flipping is Used by Methylases and Glycosylases • Error-Prone Repair and Mutator Phenotypes • Controlling the Direction of Mismatch Repair • Recombination-Repair Systems in E. coli • Recombination is an Important Mechanism to Recover from Replication Errors • RecA Triggers the SOS System • Eukaryotic Cells Have Conserved Repair Systems • A Common System Repairs Double-Strand Breaks • Summary
Chapter 21: Transposons • Introduction • Insertion Sequences are Simple Transposition Modules • Composite Transposons Have IS Modules • Transposition Occurs by Both Replicative and Nonreplicative Mechanisms • Transposons Cause Rearrangement of DNA • Common Intermediates for Transposition • Replicative Transposition Proceeds through a Cointegrate • Nonreplicative Transposition Proceeds by Breakage and Reunion • TnA Transposition Requires Transposase and Resolvase • Transposition of Tn10 Has Multiple Controls • Controlling Elements in Maize Cause Breakage and Rearrangements • Controlling Elements Form Families of Transposons • Spm Elements Influence Gene Expression • The Role of Transposable Elements in Hybrid Dysgenesis • P Elements are Activated in the Germline • Summary
Chapter 22: Retroviruses and Retroposons • Introduction • The Retrovirus Life Cycle Involves Transposition-Like Events • Retroviral Genes Code for Polyproteins • Viral DNA is Generated by Reverse Transcription • Viral DNA Integrates into the Chromosome • Retroviruses May Transduce Cellular Sequences • Yeast Ty Elements Resemble Retroviruses • Many Transposable Elements Reside in Drosophila melanogaster • Retroposons Fall into Three Classes • The Alu Family Has Many Widely Dispersed Members • Processed Pseudo genes Originated as Substrates for Transposition • LINES Use an Endonuclease to Generate a Priming End • Summary
Chapter 23: Immune Diversity • Introduction • Clonal Selection Amplifies Lymphocytes That Respond to Individual Antigens • Immunoglobulin Genes are Assembled from Their Parts in Lymphocytes • Light Chains are Assembled by a Single Recombination • Heavy Chains are Assembled by Two Recombinations • Recombination Generates Extensive Diversity • Immune Recombination Uses Two Types of Consensus Sequence • Recombination Generates Deletions or Inversions • Allelic Exclusion is Triggered by Productive Rearrangement • The RAG Proteins Catalyze Breakage and Reunion • Early Heavy Chain Expression Can Be Changed by RNA Processing • Class Switching is Caused by DNA Recombination • Switching Occurs by a Novel Recombination Reaction • Somatic Mutation Generates Additional Diversity in Mouse and Human Being • Somatic Mutation is Induced by Cytidine Deaminase and Uracil Glycosylase • Avian Immunoglobulins are Assembled from Pseudogenes • B Cell Memory Allows a Rapid Secondary Response • T cell Receptors are Related to Immunoglobulins • The T Cell Receptor Functions in Conjunction with the MHC. • The Major Histocompatibility Locus Codes for Many Genes of the Immune System • Innate Immunity Utilizes Conserved Signaling Pathways • Summary
Chapter 24: Promoters and Enhancers • Introduction • Eukaryotic RNA Polymerases Consist of Many Subunits • Promoter Elements are Defined by Mutations and Footprinting • RNA Polymerase I Has a Bipartite Promoter • RNA Polymerase III Uses Both Downstream and Upstream Promoters • TFIIIB is the Commitment Factor for Pol III Promoters • The Startpoint for RNA Polymerase II • TBP is a Universal Factor • TBP Binds DNA in an Unusual Way • The Basal Apparatus Assembles at the Promoter • Initiation is Followed by Promoter Clearance • A Connection between Transcription and Repair • Short Sequence Elements Bind Activators • Promoter Construction is Flexible but Context Can Be Important • Enhancers Contain Bidirectional Elements That Assist Initiation • Enhancers Contain the Same Elements That are Found at Promoters • Enhancers Work by Increasing the Concentration of Activators Near the Promoter • Gene Expression is Associated with Demethylation • CpG Islands are Regulatory Targets • Summary
Chapter 25: Activating Transcription • Introduction • There are Several Types of Transcription Factors • Independent Domains Bind DNA and Activate Transcription • The Two Hybrid Assay Detects Protein-Protein Interactions • Activators Interact with the Basal Apparatus • Some Promoter-Binding Proteins are Repressors • Response Elements are Recognized by Activators • There are Many Types of DNA-Binding Domains • A Zinc Finger Motif is a DNA-Binding Domain • Steroid Receptors are Activators • Steroid Receptors Have Zinc Fingers • Binding to the Response Element is Activated by Ligand-Binding • Steroid Receptors Recognize Response Elements by a Combinatorial Code • Homeodomains Bind Related Targets in DNA • Helix-Loop-Helix Proteins Interact by Combinatorial Association • Leucine Zippers are Involved in Dimer Formation • Summary
Chapter 26: RNA Splicing and Processing • Introduction • Nuclear Splice Junctions are Short Sequences • Splice Junctions are Read in Pairs • Pre-mRNA Splicing Proceeds through a Lariat • snRNAs are Required for Splicing • U1 snRNP Initiates Splicing • The E Complex Can Be Formed by Intron Definition or Exon Definition • snRNPs Form the Spliceosome • An Alternative Splicing Apparatus Uses Different snRNPs • Splicing is Connected to Export of mRNA • Group II Introns Autosplice via Lariat Formation • Alternative Splicing Involves Differential Use of Splice Junctions • trans-Splicing Reactions Use Small RNAs • Yeast tRNA Splicing Involves Cutting and Rejoining • The Splicing Endonuclease Recognizes tRNA • tRNA Cleavage and Ligation are Separate Reactions • The Unfolded Protein Response is Related to tRNA Splicing • The 3‘ Ends of poll I and polIII Transcripts are Generated by Termination • The‘ Ends of mRNAs are Generated by Cleavage and Polyadenylation • Cleavage of the 3‘ End of Histone mRNA May Require a Small RNA • Production of rRNA Requires Cleavage Events • Small RNAs are Required for rRNA Processing • Summary
Chapter 27: Catalytic RNA • Introduction • Group I Introns Undertake Self-Splicing by Transesterification • Group I Introns Form a Characteristic Secondary Structure • Ribozymes Have Various Catalytic Activities • Some Group I Introns Code for Endonucleases That Sponsor Mobility • Group II Introns May Code for Multifunction Proteins • Some Autosplicing Introns Require Maturases • The Catalytic Activity of RNAase P is Due to RNA • Viroids Have Catalytic Activity • RNA Editing Occurs at Individual Bases • RNA Editing Can Be Directed by Guide RNAs • Protein Splicing is Autocatalytic • Summary
Chapter 28: Chromosomes • Introduction • Viral Genomes are Packaged into Their Coats • The Bacterial Genome is a Nucleoid • The Bacterial Genome is Supercoiled • Eukaryotic DNA Has Loops and Domains Attached to a Scaffold • Specific Sequences Attach DNA to an Interphase Matrix • Chromatin is Divided into Euchromatin and Heterochromatin • Chromosomes Have Banding Patterns • Lampbrush Chromosomes are Extended • Polytene Chromosomes Form Bands • Polytene Chromosomes Expand at Sites of Gene Expression • The Eukaryotic Chromosome is a Segregation Device • Centromeres May Contain Repetitive DNA • Centromeres Have Short DNA Sequences in S.cerevisiae • The Centromere Binds a Protein Complex • Telomeres Have Simple Repeating Sequences • Telomeres Seal the Chromosome Ends • Telomeres are Synthesized by a Ribonucleoprotein Enzyme • Telomeres are Essential for Survival • Summary
Chapter 29: Nucleosomes • Introduction • The Nucleosome is the Subunit of All Chromatin • DNA is Coiled in Arrays of Nucleosomes • Nucleosomes Have a Common Structure • DNA Structure Varies on the Nucleosomal Surface • The Periodicity of DNA Changes on the Nucleosome • Organization of the Histone Octamer • The Path of Nucleosomes in the Chromatin Fiber • Reproduction of Chromatin Requires Assembly of Nucleosomes • Do Nucleosomes Lie at Specific Positions? • are Transcribed Genes Organized in Nucleosomes? • Histone Octamers are Displaced by Transcription • Nucleosome Displacement and Reassembly Require Special Factors • Insulators Block the Actions of Enhancers and Heterochromatin • Insulators Can Define a Domain • Insulators May Act in One Direction • Insulators Can Vary in Strength • DNAase Hypersensitive Sites Reflect Changes in Chromatin Structure • Domains Define Regions That Contain Active Genes • An LCR May Control a Domain • What Constitutes a Regulatory Domain? • Summary
Chapter 30: Controlling Chromatin Structure • Introduction • Chromatin Can Have Alternative States • Chromatin Remodeling is an Active Process • Nucleosome Organization May Be Changed at the Promoter • Histone Modification is a Key Event • Histone Acetylation Occurs in Two Circumstances • Acetylases are Associated with Activators • Deacetylases are associated with Repressors • Methylation of Histones and DNA is Connected • Chromatin States are Interconverted by Modification • Promoter Activation Involves an Ordered Series of Events • Histone Phosphorylation Affects Chromatin Structure • Some Common Motifs are Found in Proteins That Modify Chromatin • Summary
Chapter 31: Epigenetic Effects are Inherited • Introduction • Heterochromatin Propagates from a Nucleation Event • Heterochromatin Depends on Interactions with Histones • Polycomb and Trithorax are .Antagonistic Repressors and Activators • X Chromosomes Undergo Global Changes • Chromosome Condensation is Caused by Condensins • DNA Methylation is Perpetuated by a Maintenance Methylase • DNA Methylation is Responsible for Imprinting • Oppositely Imprinted Genes Can Be Controlled by a Single Center • Epigenetic Effects Can Be Inherited • Yeast Prions Show Unusual Inheritance • Prions Cause Diseases in Mammals • Summary ISBN - 9789380108537
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