Clark1570247 978-0-12-378594-7 X0001

Molecular Biology

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Clark1570247 978-0-12-378594-7 X0001

Molecular Biology

Second Edition

D a v i d P . C l a r k

N a n e t t e J . P a z d e r n i k

AMSTERDAM • BOSTON • HEIDELBERG • LONDON NEW YORK • OXFORD • PARIS • SAN DIEGO

SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO

Academic Press is an imprint of Elsevier

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Academic Press is an imprint of Elsevier 225 Wyman Street, Waltham, MA 02451, USA The Boulevard, Langford Lane, Kidlington, Oxford, OX5 1GB, UK

Copyright © 2013 Elsevier Inc. All rights reserved

No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the Publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions

This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein).

Notices Knowledge and best practice in this fi eld are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary.

Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility.

To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, neg-ligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas con-tained in the material herein.

Library of Congress Cataloging-in-Publication Data Clark, David P. Molecular biology / David Clark, Nan Pazdernik. – 2nd ed. p. cm. Includes bibliographical references and index. ISBN 978-0-12-378594-7 (alk. paper) 1. Molecular biology. 2. Molecular genetics. I. Pazdernik, Nanette Jean. II. Title. QH506.C533 2013 572.8–dc23 2011038218

British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library

For information on all Academic Press publications visit our website at www.elsevierdirect.com

Printed in Canada 12 13 14 15 10 9 8 7 6 5 4 3 2 1

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Dedication

This book is dedicated to Lonnie Russell who was to have been my coauthor on the fi rst edition. A few months after we started this project together, in early

July 2001, Lonnie drowned in the Atlantic Ocean off the coast of Brazil in a tragic accident.

DPC

To my family, especially my husband and my three children. They have given me the gift of time, courage, and strength. Time to actually write, courage to

continue even when I was tired, and the strength to do my very best work no matter the circumstances.

NJP

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vii

Preface to second edition

The last quarter of the 20th century saw major scientifi c revolutions in genetics and computer technology. Indeed, handling the vast amounts of genetic information gen-erated nowadays depends on advanced computer technology. This book refl ects this massive surge in our understanding of the molecular foundations of genetics. Today, we now know that genes are much more than the abstract entities proposed over a century ago by Mendel. Genes are segments of DNA molecules, carrying encoded information. Indeed, genes have now become chemical reagents to be manipulated in the test tube in ever more complex ways. Over the next half century our understand-ing of how living organisms function at the molecular level, together with our ability to intervene, will expand in ways we are only just beginning to perceive.

A full understanding of how living organisms function includes an appreciation of how cells operate at the molecular level. This is of vital importance to all of us as it becomes ever more clear that molecular factors underlie many health problems and diseases. While cancer is the “classic” case of a disease that only became understand-able when its genetic basis was revealed, it is not the only one by any means. Today, the molecular aspects of medicine are expanding rapidly and it is becoming possible to tailor clinical treatment personally by taking into account the genetic make-up of individual patients, an area known as personal genomics.

This book is intended as a survey-oriented textbook for upper-division students in a variety of biological subdisciplines. In particular, it is aimed at fi nal-year under-graduates and beginning graduate students. This book does not attempt to be exhaus-tive in its coverage, even as a textbook. There is a second book in this series, entitled “Biotechnology,” which emphasizes the more practical applications of modern genet-ics. We hope that both books together effectively survey the foundations and applica-tions of modern molecular genetics.

Some of the students using this book will be well-versed in the basics of mod-ern molecular biology, having taken courses in genetics, biochemistry, and cell biol-ogy. However, others will not be so well-prepared, in part due to the continuing infl ux of students into molecular biology from biology programs that are not oriented in a molecular direction. For them we have tried to create a book whose early chapters cover the basics before launching out into the depths. The fi rst unit of fi ve chapters covers basic cell structure and genetics. This is followed by a survey of DNA, RNA, and proteins and how they interact to provide the cell with genetic information.

Because of the continuing interest in applying molecular biology to an ever-widening array of topics, we have tried to avoid overdoing detail (depth) in favor of breadth. Molecular biology is applicable to more than just human medicine and health. The genetic revolution has also greatly impacted other important areas such as agriculture, veterinary medicine, animal behavior, evolution, and microbiology. Students of these, and related disciplines, will all benefi t from an improved under-standing of molecular biology.

Changes in the Second Edition

This edition includes signifi cant changes in comparison to the fi rst edition of Molecular Biology .

The fl ood of new sequence information has necessitated updates to many areas of the book, especially Genomics and Systems Biology (Ch. 9), Proteomics (Ch. 15) Bacterial Genetics (Ch. 25), and Molecular Evolution (Ch. 26). Perhaps the most rapidly-changing area of molecular biology at present is the ever-expanding role of RNA. Although scattered items occur throughout the book, particularly in Unit 4, most of the major novel RNA topics, such as CRISPR and long-non-coding RNA, are grouped together in Chapter 18, Regulation at the RNA level.

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viii Preface

In this second edition we have re-ordered some of the chapters in a more logical order. In particular, chapters on DNA technology and genomics that were toward the end of the book have been moved far forward. This refl ects the much greater role that sequence analysis and genomics have come to play in the last two or three years.

We have also divided the book into modules, each of several related chapters. The fi rst module contains introductory material that experienced students can either skip or skim through rapidly for the reasons cited above. Sections within chapters have been numbered to aid in cross-reference. Review questions and conceptual problems are now provided at the end of each chapter.

A new text element, “Focus on Relevant Research,” now appears throughout the book. These feature discussions of recent papers in the fi eld published by Cell Press. The content focuses on helping the student learn how to read and understand primary literature in hopes of preparing them for the scientifi c world. The complete articles are also provided on the accompanying website for easy reference by students and instructors.

The website also includes access to the Focus on Relevant Research Case Studies that discuss the main topics of each chapter and build case studies around the content to help students understand the basics of primary literature while allowing them to make the appropriate connections to the text.

Other online materials to supplement the text include fl ashcards, animations, quizzes to prepare for tests, and PowerPoint® slides with images for note-taking. Students also have access to online references as they can then be directly linked to Internet databases, such as PubMed® or ScienceDirect®.

Instructors also have access to the images from the book and test banks based on the text and accompanying journal articles.

We look forward to hearing about your experiences, whether you use our book for teaching or studying. Please send your comments, criticisms, and advice to MolecularBiologyAC2@elsevier.com . Thank you!

David Clark and Nan Pazdernik, Carbondale, Illinois, April 2011

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ix

Acknowledgements

We would like to thank the following individuals for their help in providing infor-mation, suggestions for improvement and encouragement: Malikah Abdullah-Israel, Laurie Achenbach, Steven Ackerman, Rubina Ahsan, Kasirajan Ayyanathan, Marilyn Baguinon, Joan Betz, Blake Bextine, Gail Breen, Douglas Burks, Mehmet Candas, Jung-ren Chen, Helen Cronenberger, Phil Cunningham, Dennis Deluca, Linda DeVeaux, Elizabeth De Stasio, Justin DiAngelo, Susan DiBartolomeis, Brian Downes, Ioannis Eleftherianos, Robert Farrell, Elizabeth Blinstrup Good, Joyce Hardy, David L. Herrin, Walter M. Holmes, Karen Jackson, Mark Kainz, Nemat Keyhani, Rebecca Landsberg, Richard LeBaron, Richard Londraville, Larry Lowe, Charles Mallery, Boriana Marintcheva, Stu Maxwell, Michelle McGehee, Ana Medrano, Thomas Mennella, Donna Mueller, Khalil Nezhad , Dan Nickrent, Monica Oblinger, Rekha Patel, Marianna Patrauchan, Neena Philips, Wanda Reygaert, Veronica Riha, Phillip Ryals, Donald Seto, Dan Simmons, Joan Slonczewski, Malgosia Wilk-Blaszczak, Hongzhuan Wu and Ding Xue.

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UNIT 1 BASIC CHEMICAL AND BIOLOGICAL PRINCIPLES 1

CHAPTER 1 Cells and Organisms 2

1. What Is Life? 3 2. Living Creatures Are Made of Cells 4 3. Eubacteria and Archaea Are Genetically

Distinct 8 4. Eukaryotic Cells Are Subdivided into

Compartments 9 5. The Diversity of Eukaryotes 13 6. Haploidy, Diploidy, and the Eukaryote Cell Cycle 14 7. Organisms Are Classifi ed 15 8. Some Widely-Studied Organisms Serve as Models 16 9. Basic Characteristics of a Model Organism 27 10. Purifying DNA from Model Organisms 27 11. Viruses Are Not Living Cells 29 12. Bacterial Viruses Infect Bacteria 30 13. Human Viral Diseases Are Common 32 14. A Variety of Subcellular Genetic Entities Exist 32 Key Concepts 34 Review Questions 35 Conceptual Questions 36

CHAPTER 2 Basic Genetics 37

1. Gregor Mendel, The Father of Classical Genetics 37 2. Genes Determine Each Step in Biochemical

Pathways 39 3. Mutants Result from Alterations in Genes 40 4. Phenotypes and Genotypes 41 5. Chromosomes Are Long, Thin Molecules

That Carry Genes 42 6. Dominant and Recessive Alleles 45 7. Genes from Both Parents Are Mixed by Sexual

Reproduction 48 8. Neighboring Genes Are Linked During

Inheritance Unless the DNA Recombines 52 9. Identifying Genes that Cause Human Diseases 57 Key Concepts 58 Review Questions 59 Conceptual Questions 60

CHAPTER 3 DNA, RNA, and Protein 62

1. History of DNA as the Genetic Material 62 2. Nucleic Acid Molecules Carry Genetic

Information 63 3. Chemical Structure of Nucleic Acids 63 4. Double-Stranded DNA Forms a Double Helix 67

5. Constituents of Chromosomes 75 6. The Central Dogma Outlines the Flow of

Genetic Information 78 7. Ribosomes Read the Genetic Code 81 8. Various Classes of RNA Have Different Functions 82 9. Proteins Carry Out Many Cell Functions 84 Key Concepts 91 Review Questions 92 Conceptual Questions 93

CHAPTER 4 Genomes and DNA 94

1. Genome Organization 94 2. Repeated Sequences Are a Feature of

Eukaryotic DNA 100 3. Palindromes, Inverted Repeats, and Stem and

Loop Structures 105 4. Multiple A-Tracts Cause DNA to Bend 106 5. Supercoiling Is Necessary for Packaging

of Bacterial DNA 106 6. Separation of DNA Fragments by

Electrophoresis 111 7. Alternative Helical Structures of DNA Occur 113 8. Packaging DNA in Eukaryotic Nuclei 116 Key Concepts 121 Review Questions 122 Conceptual Questions 123

CHAPTER 5 Manipulation of Nucleic Acids 125

1. Manipulating DNA 126 2. Chemical Synthesis of DNA 135 3. Measuring the Concentration of DNA and

RNA with Ultraviolet Light 143 4. Radioactive Labeling of Nucleic Acids 144 5. Fluorescence in the Detection of DNA and RNA 146 6. The Electron Microscope 149 7. Hybridization of DNA and RNA 151 Key Concepts 158 Review Questions 158 Conceptual Questions 159

UNIT 2 THE GENOME 162

CHAPTER 6 Polymerase Chain Reaction 163

1. Fundamentals of the Polymerase Chain Reaction 164 2. Inverse PCR 171

Contents

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3. Randomly Amplifi ed Polymorphic DNA (RAPD) 172

4. Reverse Transcriptase PCR 174 5. Differential Display PCR 175 6. Rapid Amplifi cation of cDNA Ends (RACE) 176 7. PCR in Genetic Engineering 179 8. Directed Mutagenesis 179 9. Engineering Deletions and Insertions

by PCR 181 10. Real-Time Fluorescent PCR 182 11. Molecular Beacons and Scorpion Primers 184 12. Use of PCR in Medical Diagnosis 188 13. Environmental Analysis by PCR 189 14. Rescuing DNA from Extinct Life Forms

by PCR 190 Key Concepts 191 Review Questions 192 Conceptual Questions 193

CHAPTER 7 Cloning Genes for Analysis 194

1. Properties of Cloning Vectors 195 2. Detecting Insertions in Vectors 199 3. Moving Genes Between Organisms:

Shuttle Vectors 201 4. Bacteriophage Lambda Vectors 205 5. Cosmid Vectors 206 6. Yeast Artifi cial Chromosomes 208 7. Bacterial and P1 Artifi cial Chromosomes 208 8. Recombineering Increases the Speed of

Gene Cloning 209 9. A DNA Library is a Collection of Genes

from One Source 212 10. Cloning Complementary DNA Avoids

Introns 215 11. Chromosome Walking 217 12. Cloning by Subtractive Hybridization 219 13. Expression Vectors 220 Key Concepts 223 Review Questions 224 Conceptual Questions 225

CHAPTER 8 DNA Sequencing 227

1. DNA Sequencing—General Principles for Chain Termination Sequencing 228

2. Primer Walking Along a Strand of DNA 234 3. Automated Sequencing 235 4. Cycle Sequencing 236 5. The Emergence of DNA Chip Technology 237 6. Pyrosequencing 239 7. Second-Generation Sequencing 239

8. Third-Generation Sequencing 242 9. Nanopore Detectors for DNA 243 Key Concepts 244 Review Questions 246 Conceptual Questions 246

CHAPTER 9 Genomics & Systems Biology 248

1. Large-Scale Mapping with Sequence Tags 249 2. Assembling Small Genomes by Shotgun

Sequencing 250 3. Race for the Human Genome 253 4. Survey of the Human Genome 255 5. Pharmacogenomics—Genetically-

Individualized Drug Treatment 263 6. Personal Genomics and Comparative

Genomics 264 7. Bioinformatics and Computer Analysis 265 8. Systems Biology 266 9. Metagenomics and Community Sampling 268 10. Epigenetics and Epigenomics 268 Key Concepts 269 Review Questions 271 Conceptual Questions 271

UNIT 3 THE CENTRAL DOGMA OF MOLECULAR BIOLOGY 273

CHAPTER 10 Cell Division and DNA Replication 274

1. Cell Division and Reproduction Are Not Always Identical 275

2. DNA Replication Occurs at the Replication Fork 275 3. Properties of DNA Polymerase 279 4. Nucleotides Are the Precursors for

DNA Synthesis 280 5. DNA Polymerase Elongates DNA Strands 282 6. The Complete Replication Fork Is Complex 285 7. Discontinuous Synthesis of the Lagging Strand 286 8. Chromosome Replication Initiates at oriC 289 9. Chromosome Replication Terminates at terC 292 10. Cell Division in Bacteria Occurs after

Replication of Chromosomes 293 11. The Concept of the Replicon 297 12. Replicating Linear DNA in Eukaryotes 298 13. Cell Division in Higher Organisms 304 Key Concepts 305 Review Questions 307 Conceptual Questions 308

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CHAPTER 11 Transcription of Genes 309

1. Genes Are Expressed by Making RNA 310 2. How Is the Beginning of a Gene Recognized? 312 3. Manufacturing the Message 314 4. RNA Polymerase Knows Where to Stop 316 5. How Does the Cell Know Which Genes to

Turn On? 318 6. Transcription in Eukaryotes Is More

Complex 324 Key Concepts 333 Review Questions 334 Conceptual Questions 335

CHAPTER 12 Processing of RNA 336

1. RNA Is Processed in Several Ways 336 2. Coding and Non-Coding RNA 338 3. Processing of Ribosomal and Transfer RNA 338 4. Eukaryotic Messenger RNA Contains a

Cap and a Tail 340 5. Introns Are Removed from RNA by Splicing 344 6. Alternative Splicing Produces Multiple

Forms of RNA 349 7. Inteins and Protein Splicing 352 8. Base Modifi cation of rRNA Requires Guide

RNA 355 9. RNA Editing Alters the Base Sequence 358 10. Transport of RNA out of the Nucleus 360 11. Degradation of mRNA 361 Key Concepts 366 Review Questions 367 Conceptual Questions 367

CHAPTER 13 Protein Synthesis 369

1. Overview of Protein Synthesis 370 2. Proteins Are Chains of Amino Acids 371 3. Decoding the Genetic Information 376 4. The Ribosome: The Cell’s Decoding Machine 381 5. Three Possible Reading Frames Exist 386 6. The tRNA Occupies Three Sites During

Elongation of the Polypeptide 389 7. Bacterial mRNA Can Code for Several

Proteins 394 8. Some Ribosomes Become Stalled and Are

Rescued 395 9. Differences between Eukaryotic and

Prokaryotic Protein Synthesis 397 10. Protein Synthesis Is Halted When Resources

Are Scarce 401 11. A Signal Sequence Marks a Protein for

Export from the Cell 403

12. Protein Synthesis Occurs in Mitochondria and Chloroplasts 405

13. Mistranslation Usually Results in Mistakes in Protein Synthesis 407

14. Many Antibiotics Work by Inhibiting Protein Synthesis 408

15. Post-Translational Modifi cations of Proteins 408 16. Selenocysteine and Pyrrolysine: Rare Amino

Acids 410 17. Degradation of Proteins 412 Key Concepts 415 Review Questions 415 Conceptual Questions 416

CHAPTER 14 Protein Structure and Function 417

1. The Structure of Proteins Refl ects Four Levels of Organization 417

2. Determining Protein Structures 428 3. Nucleoproteins, Lipoproteins, and

Glycoproteins Are Conjugated Proteins 430 4. Proteins Serve Numerous Cellular Functions 433 5. Protein (Nano)-Machines 436 6. Enzymes Catalyze Metabolic Reactions 437 7. Binding of Proteins to DNA Occurs in Several

Different Ways 450 8. Denaturation of Proteins 454 Key Concepts 455 Review Questions 456 Conceptual Questions 457

CHAPTER 15 Proteomics: The Global Analysis of Proteins 459

1. The Proteome 460 2. Antibodies Are Essential Proteomics Tools 464 3. Western Blotting of Proteins 465 4. Isolating Proteins with Chromatography 466 5. Mass Spectrometry for Protein

Identifi cation 468 6. Protein-Tagging Systems 470 7. Selection by Phage Display 474 8. Protein Interactions: The Yeast Two-Hybrid

System 478 9. Protein Interaction by

Co-Immunoprecipitation 483 10. Protein Arrays 484 11. Metabolomics 487 Key Concepts 489 Review Questions 490 Conceptual Questions 491

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UNIT 4 REGULATING GENE EXPRESSION 492

CHAPTER 16 Regulation of Transcription in Prokaryotes 493

1. Gene Regulation Ensures a Physiological Response 493

2. Regulation at the Level of Transcription Involves Several Steps 496

3. Alternative Sigma Factors in Prokaryotes Recognize Different Sets of Genes 497

4. Activators and Repressors Participate in Positive and Negative Regulation 502

5. Two-Component Regulatory Systems 511 6. Specifi c versus Global Control 515 7. Accessory Factors and Nucleoid-Binding

Proteins 517 8. Anti-Termination as a Control Mechanism 520 Key Concepts 523 Review Questions 524 Conceptual Questions 524

CHAPTER 17 Regulation of Transcription in Eukaryotes 526

1. Transcriptional Regulation in Eukaryotes Is More Complex Than in Prokaryotes 526

2. Specifi c Transcription Factors Regulate Protein-Encoding Genes 527

3. Negative Regulation of Transcription Occurs in Eukaryotes 533

4. Heterochromatin Blocks Access to DNA in Eukaryotes 537

5. Methylation of Eukaryotic DNA Controls Gene Expression 543

6. X-Chromosome Inactivation Occurs in Female XX Animals 547

Key Concepts 550 Review Questions 550 Conceptual Questions 551

CHAPTER 18 Regulation at the RNA Level 553

1. Regulation at the Level of mRNA 553 2. Basic Principles of RNA Interference (RNAi) 564 3. Long Non-coding Regulatory RNA 572 4. CRISPR: Anti-Viral Defense in Bacteria 573

5. Premature Termination Causes Attenuation of RNA Transcription 574

6. Riboswitches—RNA Acting Directly as a Control Mechanism 576

Key Concepts 579 Review Questions 579 Conceptual Questions 580

CHAPTER 19 Analysis of Gene Expression 581

1. Monitoring Gene Expression 581 2. Reporter Genes for Monitoring Gene

Expression 582 3. Deletion Analysis of the Upstream Region 590 4. DNA-Protein Complexes Can Be Isolated by

Chromatin Immunoprecipitation 594 5. Location of the Start of Transcription by Primer

Extension 596 6. Transcriptome Analysis 600 7. DNA Microarrays for Gene Expression 601 8. TaqMan Quantitative PCR to Assay Gene

Expression 608 9. Serial Analysis of Gene Expression (SAGE) 610 Key Concepts 613 Review Questions 613 Conceptual Questions 614

UNIT 5 SUBCELLULAR LIFE FORMS 615

CHAPTER 20 Plasmids 616

1. Plasmids as Replicons 616 2. General Properties of Plasmids 619 3. Plasmid DNA Replicates by Two Alternative

Methods 622 4. Many Plasmids Help their Host Cells 628 5. Plasmids may Provide Aggressive Characters 635 6. Ti Plasmids are Transferred from

Bacteria to Plants 640 7. The 2μ Plasmid of Yeast 644 8. Certain DNA Molecules May Behave as

Viruses or Plasmids 645 Key Concepts 646 Review Questions 647 Conceptual Questions 648

CHAPTER 21 Viruses 649

1. Viruses Are Infectious Packages of Genetic Information 650

2. The Great Diversity of Viruses 658

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3. Viruses with RNA Genomes Have Very Few Genes 666

4. Retroviruses Use both RNA and DNA 672 5. Subviral Infectious Agents 678 Key Concepts 684 Review Questions 684 Conceptual Questions 685

CHAPTER 22 Mobile DNA 686

1. Subcellular Genetic Elements as Gene Creatures 686

2. Most Mobile DNA Consists of Transposable Elements 687

3. Retroelements Make an RNA Copy 703 4. The Multitude of Transposable Elements 708 5. Junk DNA and Selfi sh DNA 716 Key Concepts 717 Review Questions 718 Conceptual Questions 719

UNIT 6 CHANGING THE DNA BLUEPRINT 720

CHAPTER 23 Mutations and Repair 721

1. Mutations Alter the DNA Sequence 721 2. The Major Types of Mutation 722 3. Chemical Mutagens Damage DNA 733 4. Overview of DNA Repair 742 5. Mutations Occur More Frequently at Hotspots 758 6. Reversions Are Genetic Alterations That

Change the Phenotype Back to Wild-Type 759 7. Site-Directed Mutagenesis 763 Key Concepts 764 Review Questions 765 Conceptual Questions 766

CHAPTER 24 Recombination 767

1. Overview of Recombination 767 2. Molecular Basis of Homologous Recombination 769

3. Site-Specifi c Recombination 773 4. Recombination in Higher Organisms 776 5. Gene Conversion 778 Key Concepts 781 Review Questions 781 Conceptual Questions 782

CHAPTER 25 Bacterial Genetics 783

1. Reproduction versus Gene Transfer 783 2. Fate of the Incoming DNA after Uptake 784 3. Transformation Is Gene Transfer by Naked DNA 785 4. Gene Transfer by Virus—Transduction 792 5. Transfer of Plasmids between Bacteria 795 6. Gene Transfer among Gram-Positive Bacteria 801 7. Archaeal Genetics 804 8. Whole-Genome Sequencing 805 Key Concepts 808 Review Questions 809 Conceptual Questions 810

CHAPTER 26 Molecular Evolution 812

1. Getting Started—Formation of the Earth 812 2. Oparin’s Theory of the Origin of Life 814 3. Origin of Informational Macromolecules 818 4. The Autotrophic Theory of the Origin of

Metabolism 823 5. Evolution of DNA, RNA, and Protein Sequences 824 6. Different Proteins Evolve at Very Different Rates 830 7. Symbiotic Origin of Eukaryotic Cells 835 8. DNA Sequencing and Biological Classifi cation 841 9. Evolving Sideways: Horizontal Gene Transfer 847 Key Concepts 850 Review Questions 851 Conceptual Questions 852

Glossary 855

Index 883

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