Becker's World of the Cell, Global Edition

Jeff Hardin; Gregory Paul Bertoni; Lewis J. Kleinsmith

BOOK

Becker's World of the Cell, Global Edition

Jeff Hardin | Gregory Paul Bertoni | Lewis J. Kleinsmith

(2017)

Additional Information

Book Details

ISBN: 978-1-292-17777-9
Edition: 9
Language: English
Pages: 920
Subjects

Abstract

For courses in cell biology.

Explore the world of the cell

Widely praised for its strong biochemistry coverage and clear, easy-to-follow explanations and figures, Becker’s World of the Cell provides a beautifully-illustrated, up-to-date introduction to cell biology concepts, processes, and applications. Informed by many years of classroom experience in the sophomore-level cell biology course, the dramatically-revised Ninth Edition introduces molecular genetics concepts earlier in the text and includes more extensive coverage of key techniques in each chapter. Becker’s World of the Cell provides accessible and authoritative descriptions of all major principles, as well as unique scientific insights into visualization and applications of cell and molecular biology.

MasteringBiology^™not included. Students, if MasteringBiology is a recommended/mandatory component of the course, please ask your instructor for the correct ISBN and course ID. MasteringBiology should only be purchased when required by an instructor. Instructors, contact your Pearson representative for more information.

MasteringBiology is an online homework, tutorial, and assessment program designed to work with this text to engage students and improve results. Interactive, self-paced tutorials provide individualized coaching to help students stay on track. With a wide range of activities available, students can actively learn, understand, and retain even the most difficult concepts.

Section Title	Page	Action	Price
Front Cover	Front Cover
About the Authors	3
Brief Contents	4
Detailed Contents	5
Preface	18
Acknowledgments	24
Chapter 1: A Preview of Cell Biology	25
1.1: The Cell Theory: A Brief History	26
Advances in Microscopy Allowed Detailed Studies of Cells	26
The Cell Theory Applies to All Organisms	26
1.2: The Emergence of Modern Cell Biology	27
The Cytological Strand Deals with Cellular Structure	29
The Biochemical Strand Studies the Chemistry of Biological Structure and Function	33
The Genetic Strand Focuses on Information Flow	35
1.3: How Do We Know What We Know?	38
Biological “Facts” May Turn Out to Be Incorrect	38
Experiments Test Specific Hypotheses	38
Model Organisms Play a Key Role in Modern Cell Biology Research	39
Well-Designed Experiments Alter Only One Variable at a Time	41
Summary of Key Points	42
Problem Set	43
Key Technique: Using Immunofluorescence to Identify Specific Cell Components	32
Human Connections: The Immortal Cells of Henrietta Lacks	40
Chapter 2: The Chemistry of the Cell	45
2.1: The Importance of Carbon	46
Carbon-Containing Molecules Are Stable	47
Carbon-Containing Molecules Are Diverse	48
Carbon-Containing Molecules Can Form Stereoisomers	49
2.2: The Importance of Water	50
Water Molecules Are Polar	51
Water Molecules Are Cohesive	52
Water Has a High Temperature-Stabilizing Capacity	52
Water Is an Excellent Solvent	52
2.3: The Importance of Selectively Permeable Membranes	55
A Membrane Is a Lipid Bilayer with Proteins Embedded in It	55
Lipid Bilayers Are Selectively Permeable	56
2.4: The Importance of Synthesis by Polymerization	56
Macromolecules Are Critical for Cellular Form and Function	56
Cells Contain Three Different Kinds of Macromolecular Polymers	58
Macromolecules Are Synthesized by Stepwise Polymerization of Monomers	59
2.5: The Importance of Self-Assembly	60
Noncovalent Bonds and Interactions Are Important in the Folding of Macromolecules	61
Many Proteins Spontaneously Fold into Their Biologically Functional State	61
Molecular Chaperones Assist the Assembly of Some Proteins	62
Self-Assembly Also Occurs in Other Cellular Structures	62
The Tobacco Mosaic Virus Is a Case Study in Self-Assembly	62
Self-Assembly Has Limits	63
Hierarchical Assembly Provides Advantages for the Cell	63
Summary of Key Points	64
Problem Set	65
Key Technique: Determining the Chemical Fingerprint of a Cell Using Mass Spectrometry	50
Human Connections: Taking a Deeper Look: Magnetic Resonance Imaging (MRI)	54
Chapter 3: The Macromolecules of the Cell	66
3.1: Proteins	67
The Monomers Are Amino Acids	67
The Polymers Are Polypeptides and Proteins	69
Several Kinds of Bonds and Interactions Are Important in Protein Folding and Stability	70
Protein Structure Depends on Amino Acid Sequence and Interactions	73
3.2: Nucleic Acids	82
The Monomers Are Nucleotides	82
The Polymers Are DNA and RNA	83
A DNA Molecule Is a Double-Stranded Helix	85
3.3: Polysaccharides	86
The Monomers Are Monosaccharides	86
The Polymers Are Storage and Structural Polysaccharides	88
Polysaccharide Structure Depends on the Kinds of Glycosidic Bonds Involved	90
3.4: Lipids	90
Fatty Acids Are the Building Blocks of Several Classes of Lipids	91
Triacylglycerols Are Storage Lipids	93
Phospholipids Are Important in Membrane Structure	93
Glycolipids Are Specialized Membrane Components	94
Steroids Are Lipids with a Variety of Functions	94
Terpenes Are Formed from Isoprene	95
Summary of Key Points	95
Problem Set	96
Human Connections: Aggregated Proteins and Alzheimer’s	71
Key Technique: Using X-Ray Crystallography to Determine Protein Structure	80
Chapter 4: Cells and Organelles	99
4.1: Where Did the First Cells Come From?	99
Simple Organic Molecules May Have Formed Abiotically in the Young Earth	99
RNA May Have Been the First Informational Molecule	100
Liposomes May Have Defined the First Primitive Protocells	101
4.2: Properties and Strategies of Cells	101
All Organisms Are Bacteria, Archaea, or Eukaryotes	101
There Are Several Limitations on Cell Size	102
Bacteria, Archaea, and Eukaryotes Differ from Each Other in Many Ways	104
4.3: The Eukaryotic Cell in Overview: Structure and Function	107
The Plasma Membrane Defines Cell Boundaries and Retains Contents	107
The Nucleus Is the Information Center of the Eukaryotic Cell	108
Mitochondria and Chloroplasts Provide Energy for the Cell	109
The Endosymbiont Theory Proposes That Mitochondria and Chloroplasts Were Derived From Bacteria	111
The Endomembrane System Synthesizes Proteins for a Variety of Cellular Destinations	113
Other Organelles Also Have Specific Functions	116
Ribosomes Synthesize Proteins in the Cytoplasm	119
The Cytoskeleton Provides Structure to the Cytoplasm	119
The Extracellular Matrix and Cell Walls Are Outside the Plasma Membrane	122
4.4: Viruses, Viroids, and Prions: Agents That Invade Cells	123
A Virus Consists of a DNA or RNA Core Surrounded by a Protein Coat	123
Viroids Are Small, Circular RNA Molecules That Can Cause Plant Diseases	124
Prions Are Infectious Protein Molecules	125
Summary of Key Points	125
Problem Set	126
Human Connections: When Cellular “Breakdown” Breaks Down	116
Key Technique: Using Centrifugation to Isolate Organelles	120
Chapter 5: Bioenergetics: The Flow of Energy in the Cell	128
5.1: The Importance of Energy	129
Cells Need Energy to Perform Six Different Kinds of Work	129
Organisms Obtain Energy Either from Sunlight or from the Oxidation of Chemical Compounds	130
Energy Flows Through the Biosphere Continuously	131
The Flow of Energy Through the Biosphere Is Accompanied by a Flow of Matter	133
5.2: Bioenergetics	133
Understanding Energy Flow Requires Knowledge of Systems, Heat, and Work	133
The First Law of Thermodynamics States That Energy Is Conserved	134
The Second Law of Thermodynamics States That Reactions Have Directionality	136
Entropy and Free Energy Are Two Means of Assessing Thermodynamic Spontaneity	137
5.3: Understanding ∆G and Keq	140
The Equilibrium Constant Keq Is a Measure of Directionality	140
∆G Can Be Calculated Readily	141
The Standard Free Energy Change Is ∆G Measured Under Standard Conditions	141
Summing Up: The Meaning of ∆G´ and ∆G˚´	144
Free Energy Change: Sample Calculations	145
Jumping Beans Provide a Useful Analogy for Bioenergetics	146
Life Requires Steady-State Reactions That Move Toward Equilibrium Without Ever Getting There	147
Summary of Key Points	148
Problem Set	149
Human Connections: The “Potential” of Food to Provide Energy	135
Key Technique: Measuring How Molecules Bind to One Another Using Isothermal Titration Calorimetry	142
Chapter 6: Enzymes: The Catalysts of Life	151
6.1: Activation Energy and the Metastable State	152
Before a Chemical Reaction Can Occur, the Activation Energy Barrier Must Be Overcome	152
The Metastable State Is a Result of the Activation Barrier	153
Catalysts Overcome the Activation Energy Barrier	153
6.2: Enzymes as Biological Catalysts	154
Most Enzymes Are Proteins	154
Substrate Binding, Activation, and Catalysis Occur at the Active Site	157
Ribozymes Are Catalytic RNA Molecules	159
6.3: Enzyme Kinetics	161
Monkeys and Peanuts Provide a Useful Analogy for Understanding Enzyme Kinetics	161
Most Enzymes Display Michaelis–Menten Kinetics	162
What Is the Meaning of Vmax and Km?	163
Why Are Km and Vmax Important to Cell Biologists?	164
The Double-Reciprocal Plot Is a Useful Means of Visualizing Kinetic Data	164
Enzyme Inhibitors Act Either Irreversibly or Reversibly	165
6.4: Enzyme Regulation	168
Allosteric Enzymes Are Regulated by Molecules Other than Reactants and Products	168
Allosteric Enzymes Exhibit Cooperative Interactions Between Subunits	170
Enzymes Can Also Be Regulated by the Addition or Removal of Chemical Groups	170
Summary of Key Points	172
Problem Set	173
Human Connections: ACE Inhibitors: Enzyme Activity as the Difference Between Life and Death	160
Key Technique: Determining Km and Vmax Using Enzyme Assays	166
Chapter 7: Membranes: Their Structure, Function, and Chemistry	176
7.1: The Functions of Membranes	177
Membranes Define Boundaries and Serve as Permeability Barriers	177
Membranes Are Sites of Specific Proteins and Therefore of Specific Functions	177
Membrane Proteins Regulate the Transport of Solutes	178
Membrane Proteins Detect and Transmit Electrical and Chemical Signals	178
Membrane Proteins Mediate Cell Adhesion and Cell-to-Cell Communication	178
7.2: Models of Membrane Structure: An Experimental Perspective	179
Overton and Langmuir: Lipids Are Important Components of Membranes	179
Gorter and Grendel: The Basis of Membrane Structure Is a Lipid Bilayer	179
Davson and Danielli: Membranes Also Contain Proteins	180
Robertson: All Membranes Share a Common Underlying Structure	180
Further Research Revealed Major Shortcomings of the Davson–Danielli Model	180
Singer and Nicolson: A Membrane Consists of a Mosaic of Proteins in a Fluid Lipid Bilayer	181
Unwin and Henderson: Most Membrane Proteins Contain Transmembrane Segments	181
Recent Findings Suggest Membranes Are Organized into Microdomains	182
7.3: Membrane Lipids: The “Fluid” Part of the Model	183
Membranes Contain Several Major Classes of Lipids	183
Fatty Acids Are Essential to Membrane Structure and Function	185
Thin-Layer Chromatography Is an Important Technique for Lipid Analysis	185
Membrane Asymmetry: Most Lipids Are Distributed Unequally Between the Two Monolayers	186
The Lipid Bilayer Is Fluid	187
Membranes Function Properly Only in the Fluid State	187
Most Organisms Can Regulate Membrane Fluidity	190
Lipid Rafts Are Localized Regions of Membrane Lipids That Are Involved in Cell Signaling	191
7.4: Membrane Proteins: The “Mosaic” Part of the Model	192
The Membrane Consists of a Mosaic of Proteins: Evidence from Freeze-Fracture Microscopy	192
Membranes Contain Integral, Peripheral, and Lipid-Anchored Proteins	192
Membrane Proteins Can Be Isolated and Analyzed	195
Determining the Three-Dimensional Structure of Membrane Proteins Is Becoming Easier	198
Molecular Biology Has Contributed Greatly to Our Understanding of Membrane Proteins	199
Membrane Proteins Have a Variety of Functions	199
Membrane Proteins Are Oriented Asymmetrically Across the Lipid Bilayer	200
Many Membrane Proteins and Lipids Are Glycosylated	200
Membrane Proteins Vary in Their Mobility	202
The Erythrocyte Membrane Contains an Interconnected Network of Membrane-Associated Proteins	204
Summary of Key Points	205
Problem Set	206
Key Technique: SDS–Polyacrylamide Gel Electrophoresis (SDS-PAGE) of Membrane Proteins	196
Chapter 8: Transport Across Membranes: Overcoming the Permeability Barrier	209
8.1: Cells and Transport Processes	210
Solutes Cross Membranes by Simple Diffusion, Facilitated Diffusion, and Active Transport	210
The Movement of a Solute Across a Membrane Is Determined by Its Concentration Gradient or Its Electrochemical Potential	210
The Erythrocyte Plasma Membrane Provides Examples of Transport Mechanisms	212
8.2: Simple Diffusion: Unassisted Movement Down the Gradient	212
Diffusion Always Moves Solutes Toward Equilibrium	213
Osmosis Is the Diffusion of Water Across a Selectively Permeable Membrane	213
Simple Diffusion Is Typically Limited to Small, Nonpolar Molecules	215
The Rate of Simple Diffusion Is Directly Proportional to the Concentration Gradient	216
8.3: Facilitated Diffusion: Protein-Mediated Movement Down the Gradient	216
Carrier Proteins and Channel Proteins Facilitate Diffusion by Different Mechanisms	217
Carrier Proteins Alternate Between Two Conformational States	217
Carrier Proteins Are Analogous to Enzymes in Their Specificity and Kinetics	217
Carrier Proteins Transport Either One or Two Solutes	218
The Erythrocyte Glucose Transporter and Anion Exchange Protein Are Examples of Carrier Proteins	218
Channel Proteins Facilitate Diffusion by Forming Hydrophilic Transmembrane Channels	221
8.4: Active Transport: Protein-Mediated Movement Up the Gradient	225
The Coupling of Active Transport to an Energy Source May Be Direct or Indirect	225
Direct Active Transport Depends on Four Types of Transport ATPases	226
Indirect Active Transport Is Driven by Ion Gradients	228
8.5: Examples of Active Transport	229
Direct Active Transport: The Na+/K+ Pump Maintains Electrochemical Ion Gradients	229
Indirect Active Transport: Sodium Symport Drives the Uptake of Glucose	230
The Bacteriorhodopsin Proton Pump Uses Light Energy to Transport Protons	232
8.6: The Energetics of Transport	233
For Uncharged Solutes, the ∆G of Transport Depends Only on the Concentration Gradient	233
For Charged Solutes, the ∆G of TransportDepends on the Electrochemical Potential	234
Summary of Key Points	235
Problem Set	236
Key Technique: Expression of Heterologous Membrane Proteins in Frog Oocytes	220
Human Connections: Membrane Transport, Cystic Fibrosis, and the Prospects for Gene Therapy	222
Chapter 9: Chemotrophic Energy Metabolism: Glycolysis and Fermentation	239
9.1: Metabolic Pathways	240
9.2: ATP: The Primary Energy Molecule in Cells	240
ATP Contains Two Energy-Rich Phosphoanhydride Bonds	240
ATP Hydrolysis Is Highly Exergonic Due to Several Factors	241
ATP Is Extremely Important in Cellular Energy Metabolism	242
9.3: Chemotrophic Energy Metabolism	244
Biological Oxidations Usually Involve the Removal of Both Electrons and Protons and Are Highly Exergonic	244
Coenzymes Such as NAD+ Serve as Electron Acceptors in Biological Oxidations	245
Most Chemotrophs Meet Their Energy Needs by Oxidizing Organic Food Molecules	245
Glucose Is One of the Most Important Oxidizable Substrates in Energy Metabolism	246
The Oxidation of Glucose Is Highly Exergonic	246
Glucose Catabolism Yields Much More Energy in the Presence of Oxygen Than in Its Absence	246
Based on Their Need for Oxygen, Organisms Are Aerobic, Anaerobic, or Facultative	246
9.4: Glycolysis: ATP Generation Without the Involvement of Oxygen	247
Glycolysis Generates ATP by Catabolizing Glucose to Pyruvate	247
9.5: Fermentation	250
In the Absence of Oxygen, Pyruvate Undergoes Fermentation to Regenerate NAD	250
Fermentation Taps Only a Fraction of the Substrate’s Free Energy but Conserves That Energy Efficiently as ATP	252
Cancer Cells Ferment Glucose to Lactate Even in the Presence of Oxygen	252
9.6: Alternative Substrates for Glycolysis	253
Other Sugars and Glycerol Are Also Catabolized by the Glycolytic Pathway	253
Polysaccharides Are Cleaved to Form Sugar Phosphates That Also Enter the Glycolytic Pathway	254
9.7: Gluconeogenesis	255
9.8: The Regulation of Glycolysis and Gluconeogenesis	259
Key Enzymes in the Glycolytic and Gluconeogenic Pathways Are Subject to Allosteric Regulation	259
Fructose-2,6-Bisphosphate Is an Important Regulator of Glycolysis and Gluconeogenesis	260
9.9: Novel Roles for Glycolytic Enzymes	261
Summary of Key Points	262
Problem Set	263
Key Technique: Using Isotopic Labeling to Determine the Fate of Atoms in a Metabolic Pathway	256
Human Connections: What Happens to the Sugar?	258
Chapter 10: Chemotrophic Energy Metabolism: Aerobic Respiration	266
10.1: Cellular Respiration: Maximizing ATP Yields	267
Aerobic Respiration Yields Much More Energy than Fermentation Does	267
Respiration Includes Glycolysis, Pyruvate Oxidation, the Citric Acid Cycle, Electron Transport, and ATP Synthesis	267
10.2: The Mitochondrion: Where the Action Takes Place	267
Mitochondria Are Often Present Where the ATP Needs Are Greatest	269
Are Mitochondria Interconnected Networks Rather than Discrete Organelles?	269
The Outer and Inner Membranes Define Two Separate Compartments and Three Regions	270
Mitochondrial Functions Occur in or on Specific Membranes and Compartments	271
In Bacteria, Respiratory Functions Are Localized to the Plasma Membrane and the Cytoplasm	273
10.3: The Citric Acid Cycle: Oxidation in the Round	274
Pyruvate Is Converted to Acetyl Coenzyme A by Oxidative Decarboxylation	275
The Citric Acid Cycle Begins with the Entry of Acetate as Acetyl CoA	275
Two Oxidative Decarboxylations Then Form NADH and Release CO2	276
Direct Generation of GTP (or ATP) Occurs at One Step in the Citric Acid Cycle	276
The Final Oxidative Reactions of the Citric Acid Cycle Generate FADH2 and NADH	276
Summing Up: The Products of the Citric Acid Cycle Are CO2, ATP, NADH, and FADH2	278
Several Citric Acid Cycle Enzymes Are Subject to Allosteric Regulation	279
The Citric Acid Cycle Also Plays a Central Role in the Catabolism of Fats and Proteins	279
The Citric Acid Cycle Serves as a Source of Precursors for Anabolic Pathways	282
The Glyoxylate Cycle Converts Acetyl CoA to Carbohydrates	282
10.4: Electron Transport: Electron Flow from Coenzymes to Oxygen	284
The Electron Transport System Conveys Electrons from Reduced Coenzymes to Oxygen	284
The Electron Transport System Consists of Five Kinds of Carriers	285
The Electron Carriers Function in a Sequence Determined by Their Reduction Potentials	286
Most of the Carriers Are Organized into Four Large Respiratory Complexes	288
The Respiratory Complexes Move Freely Within the Inner Membrane	290
10.5: The Electrochemical Proton Gradient: Key to Energy Coupling	292
Electron Transport and ATP Synthesis Are Coupled Events	292
Coenzyme Oxidation Pumps Enough Protons to Form Three ATP Molecules per NADH and Two ATP Molecules per FADH2	293
The Chemiosmotic Model Is Affirmed by an Impressive Array of Evidence	293
10.6: ATP Synthesis: Putting It All Together	295
F1 Particles Have ATP Synthase Activity	295
Proton Translocation Through Fo Drives ATP Synthesis by F1	297
ATP Synthesis by FoF1 Involves Physical Rotation of the Gamma Subunit	298
The Chemiosmotic Model Involves Dynamic Transmembrane Proton Traffic	300
10.7: Aerobic Respiration: Summing It All Up	301
The Maximum ATP Yield of Aerobic Respiration Is 38 ATP Molecules per Glucose	302
Aerobic Respiration Is a Highly Efficient Process	303
Summary of Key Points	303
Problem Set	304
Key Technique: Visualizing Cellular Structures with Three-Dimensional Electron Microscopy	272
Human Connections A Diet Worth Dying For?	296
Chapter 11: Phototrophic Energy Metabolism: Photosynthesis	307
11.1: An Overview of Photosynthesis	308
The Energy Transduction Reactions Convert Solar Energy to Chemical Energy	308
The Carbon Assimilation Reactions Fix Carbon by Reducing Carbon Dioxide	308
The Chloroplast Is the Photosynthetic Organelle in Eukaryotic Cells	310
Chloroplasts Are Composed of Three Membrane Systems	310
11.2: Photosynthetic Energy Transduction I: Light Harvesting	313
Chlorophyll Is Life’s Primary Link to Sunlight	313
Accessory Pigments Further Expand Access to Solar Energy	314
Light-Gathering Molecules Are Organized into Photosystems and Light-Harvesting Complexes	315
Oxygenic Phototrophs Have Two Types of Photosystems	316
11.3: Photosynthetic Energy Transduction II: NADPH Synthesis	316
Photosystem II Transfers Electrons from Water to a Plastoquinone	316
The Cytochrome b6/f Complex Transfers Electrons from a Plastoquinol to Plastocyanin	319
Photosystem I Transfers Electrons from Plastocyanin to Ferredoxin	319
Ferredoxin-NADP+ Reductase Catalyzes the Reduction of NADP	319
11.4: Photosynthetic Energy Transduction III: ATP Synthesis	322
The ATP Synthase Complex Couples Transport of Protons Across the Thylakoid Membrane to ATP Synthesis	322
Cyclic Photophosphorylation Allows a Photosynthetic Cell to Balance NADPH and ATP Synthesis	322
A Summary of the Complete Energy Transduction System	323
Bacteria Use a Photosynthetic Reaction Center and Electron Transport System Similar to Those in Plants	323
11.5: Photosynthetic Carbon Assimilation I: The Calvin Cycle	324
Carbon Dioxide Enters the Calvin Cycle by Carboxylation of Ribulose-1,5-Bisphosphate	325
3-Phosphoglycerate Is Reduced to Form Glyceraldehyde-3-Phosphate	325
Regeneration of Ribulose-1,5-Bisphosphate Allows Continuous Carbon Assimilation	327
The Complete Calvin Cycle and Its Relation to Photosynthetic Energy Transduction	327
11.6: Regulation of the Calvin Cycle	328
The Calvin Cycle Is Highly Regulated to Ensure Maximum Efficiency	328
Rubisco Activase Regulates Carbon Fixation by Rubisco	328
11.7: Photosynthetic Carbon Assimilation II: Carbohydrate Synthesis	329
Glucose-1-Phosphate Is Synthesized from Triose Phosphates	329
The Biosynthesis of Sucrose Occurs in the Cytosol	330
The Biosynthesis of Starch Occurs in the Chloroplast Stroma	330
Photosynthesis Also Produces Reduced Nitrogen and Sulfur Compounds	330
11.8: Rubisco’s Oxygenase Activity Decreases Photosynthetic Efficiency	331
The Glycolate Pathway Returns Reduced Carbon from Phosphoglycolate to the Calvin Cycle	331
C4 Plants Minimize Photorespiration by Confining Rubisco to Cells Containing High Concentrations of CO2	333
CAM Plants Minimize Photorespiration and Water Loss by Opening Their Stomata Only at Night	335
Summary of Key Points	336
Problem Set	337
Key Technique: Determining Absorption and Action Spectra via Spectrophotometry	312
Human Connections: How do Plants Put on Sunscreen?	320
Chapter 12: The Endomembrane System	338
12.1: The Endoplasmic Reticulum	339
The Two Basic Kinds of Endoplasmic Reticulum Differ in Structure and Function	340
Rough ER Is Involved in the Biosynthesis and Processing of Proteins	340
Smooth ER Is Involved in Drug Detoxification, Carbohydrate Metabolism, Calcium Storage, and Steroid Biosynthesis	341
The ER Plays a Central Role in the Biosynthesis of Membranes	343
12.2: The Golgi Apparatus	343
The Golgi Apparatus Consists of a Series of Membrane-Bounded Cisternae	343
Two Models Account for the Flow of Lipids and Proteins Through the Golgi Apparatus	344
12.3: Roles of the ER and Golgi Apparatus in Protein Glycosylation	345
Initial Glycosylation Occurs in the ER	345
Further Glycosylation Occurs in the Golgi Apparatus	346
12.4: Roles of the ER and Golgi Apparatus in Protein Trafficking	348
ER-Specific Proteins Contain Retention and Retrieval Tags	348
Golgi Apparatus Proteins May Be Sorted According to the Lengths of Their Membrane-Spanning Domains	349
Targeting of Soluble Lysosomal Proteins to Endosomes and Lysosomes Is a Model for Protein Sorting in the TGN	349
12.5: Exocytosis and Endocytosis: Transporting Material Across the Plasma Membrane	351
Secretory Pathways Transport Molecules to the Exterior of the Cell	351
Exocytosis Releases Intracellular Molecules Outside the Cell	352
Endocytosis Imports Extracellular Molecules by Forming Vesicles from the Plasma Membrane	353
12.6: Coated Vesicles in Cellular Transport Processes	360
Clathrin-Coated Vesicles Are Surrounded by Lattices Composed of Clathrin and Adaptor Protein	360
The Assembly of Clathrin Coats Drives the Formation of Vesicles from the Plasma Membrane and TGN	361
COPI- and COPII-Coated Vesicles Travel Between the ER and Golgi Apparatus Cisternae	362
SNARE Proteins Mediate Fusion Between Vesicles and Target Membranes	362
12.7: Lysosomes and Cellular Digestion	364
Lysosomes Isolate Digestive Enzymes from the Rest of the Cell	364
Lysosomes Develop from Endosomes	364
Lysosomal Enzymes Are Important for Several Different Digestive Processes	365
Lysosomal Storage Diseases Are Usually Characterized by the Accumulation of Indigestible Material	367
12.8: The Plant Vacuole: A Multifunctional Organelle	368
12.9: Peroxisomes	368
Most Peroxisomal Functions Are Linked to Hydrogen Peroxide Metabolism	369
Plant Cells Contain Types of Peroxisomes Not Found in Animal Cells	370
Peroxisome Biogenesis Can Occur by Division of Preexisting Peroxisomes or by Vesicle Fusion	370
Summary of Key Points	371
Problem Set	372
Key Technique: Visualizing Vesicles at the Cell Surface Using Total Internal Reflection (TIRF) Microscopy	354
Human Connections: It’s All in the Family	357
Chapter 13: Cytoskeletal Systems	375
13.1: Major Structural Elements of the Cytoskeleton	376
Eukaryotes Have Three Basic Types of Cytoskeletal Elements	376
Bacteria Have Cytoskeletal Systems That Are Structurally Similar to Those in Eukaryotes	376
The Cytoskeleton Is Dynamically Assembled and Disassembled	376
13.2: Microtubules	378
Two Types of Microtubules Are Responsible for Many Functions in the Cell	378
Tubulin Heterodimers Are the Protein Building Blocks of Microtubules	378
Microtubules Can Form as Singlets, Doublets, or Triplets	379
Microtubules Form by the Addition of Tubulin Dimers at Their Ends	379
Addition of Tubulin Dimers Occurs More Quickly at the Plus Ends of Microtubules	381
Drugs Can Affect the Assembly and Stability of Microtubules	381
GTP Hydrolysis Contributes to the Dynamic Instability of Microtubules	382
Microtubules Originate from Microtubule-Organizing Centers Within the Cell	383
MTOCs Organize and Polarize Microtubules Within Cells	384
Microtubule Stability Is Tightly Regulated in Cells by a Variety of Microtubule-Binding Proteins	386
13.3: Microfilaments	388
Actin Is the Protein Building Block of Microfilaments	389
Different Types of Actin Are Found in Cells	389
G-Actin Monomers Polymerize into F-Actin Microfilaments	389
Specific Drugs Affect Polymerization of Microfilaments	390
Cells Can Dynamically Assemble Actin into a Variety of Structures	390
Actin-Binding Proteins Regulate the Polymerization, Length, and Organization of Microfilaments	390
Proteins That Link Actin to Membranes	393
Phospholipids and Rho Family GTPases Regulate Where and When Actin-Based Structures Assemble	394
13.4: Intermediate Filaments	396
Intermediate Filament Proteins Are Tissue Specific	397
Intermediate Filaments Assemble from Fibrous Subunits	398
Intermediate Filaments Confer Mechanical Strength on Tissues	398
The Cytoskeleton Is a Mechanically Integrated Structure	399
Summary of Key Points	399
Problem Set	400
Key Technique: Studying the Dynamic Cytoskeleton	386
Human Connections: When Actin Kills	395
Chapter 14: Cellular Movement: Motility and Contractility	401
14.1: Microtubule-Based Movement Inside Cells: Kinesins and Dyneins	403
Motor Proteins Move Cargoes Along MTs During Axonal Transport	403
Classic Kinesins Move Toward the Plus Ends of Microtubules	404
Kinesins Are a Large Family of Proteins	404
Dyneins Are Found in Axonemes and the Cytosol	404
Microtubule Motors Direct Vesicle Transport and Shape the Endomembrane System	408
14.2: Microtubule-Based Cell Motility: Cilia and Flagella	408
Cilia and Flagella Are Common Motile Appendages of Eukaryotic Cells	408
Cilia and Flagella Consist of an Axoneme Connected to a Basal Body	409
Doublet Sliding Within the Axoneme Causes Cilia and Flagella to Bend	410
14.3: Microfilament-Based Movement Inside Cells: Myosins	411
Myosins Are a Large Family of Actin-Based Motors with Diverse Roles in Cell Motility	411
Many Myosins Move Along Actin Filaments in Short Steps	413
14.4: Microfilament-Based Motility: Muscle Cells in Action	413
Skeletal Muscle Cells Contain Thin and Thick Filaments	413
Sarcomeres Contain Ordered Arrays of Actin, Myosin, and Accessory Proteins	414
The Sliding-Filament Model Explains Muscle Contraction	416
Cross-Bridges Hold Filaments Together, and ATP Powers Their Movement	418
The Regulation of Muscle Contraction Depends on Calcium	418
The Coordinated Contraction of Cardiac Muscle Cells Involves Electrical Coupling	421
Smooth Muscle Is More Similar to Nonmuscle Cells than to Skeletal Muscle	422
14.5: Microfilament-Based Motility in Nonmuscle Cells	423
Cell Migration via Lamellipodia Involves Cycles of Protrusion, Attachment,Translocation, and Detachment	423
Chemotaxis Is a Directional Movement in Response to a Graded Chemical Stimulus	425
Amoeboid Movement Involves Cycles of Gelation and Solation of Actin	425
Actin-Based Motors Move Components Within the Cytosol of Some Cells	426
Summary of Key Points	426
Problem Set	427
Key Technique: Watching Motors Too Small to See	406
Human Connections: Dyneins Help Us Tell Left from Right	412
Chapter 15: Beyond the Cell: Cell Adhesions, Cell Junctions, and Extracellular Structures	429
15.1: Cell-Cell Junctions	430
Adhesive Junctions Link Adjoining Cells	430
Transient Cell-Cell Adhesions Are Importantf or Many Cellular Events	433
Tight Junctions Prevent the Movement of Molecules Across Cell Layers	434
Gap Junctions Allow Direct Electrical and Chemical Communication Between Cells	438
15.2: The Extracellular Matrix of Animal Cells	439
Collagens Are Responsible for the Strength of the Extracellular Matrix	439
Elastins Impart Elasticity and Flexibility to the Extracellular Matrix	440
Collagen and Elastin Fibers Are Embedded in a Matrix of Proteoglycans	441
Free Hyaluronate Lubricates Joints and Facilitates Cell Migration	443
Adhesive Glycoproteins Anchor Cells to the Extracellular Matrix	443
Fibronectins Bind Cells to the ECM and Guide Cellular Movement	443
Laminins Bind Cells to the Basal Lamina	444
Integrins Are Cell Surface Receptors That Bind ECM Components	444
The Dystrophin/Dystroglycan Complex Stabilizes Attachments of Muscle Cells to the ECM	448
15.3: The Plant Cell Surface	449
Cell Walls Provide a Structural Framework and Serve as a Permeability Barrier	449
The Plant Cell Wall Is a Network of Cellulose Microfibrils, Polysaccharides, and Glycoproteins	449
Cell Walls Are Synthesized in Several Discrete Stages	450
Plasmodesmata Permit Direct Cell-Cell Communication Through the Cell Wall	451
Summary of Key Points	452
Problem Set	453
Human Connections: The Costly Effects of Weak Adhesion	435
Key Technique: Building an ECM from Scratch	446
Chapter 16: The Structural Basis of Cellular Information: DNA, Chromosomes, and the Nucleus	455
16.1: Chemical Nature of the Genetic Material	456
The Discovery of DNA Led to Conflicting Proposals Concerning the Chemical Nature of Genes	456
Avery Showed That DNA Is the Genetic Material of Bacteria	457
Hershey and Chase Showed That DNA Is the Genetic Material of Viruses	457
RNA Is the Genetic Material in Some Viruses	459
16.2: DNA Structure	461
Chargaff’s Rules Reveal That A = T and G = C	461
Watson and Crick Discovered That DNA Is a Double Helix	462
DNA Can Be Interconverted Between Relaxed and Supercoiled Forms	464
The Two Strands of a DNA Double Helix Can Be Denatured and Renatured	466
16.3: DNA Packaging	467
Bacteria Package DNA in Bacterial Chromosomes and Plasmids	467
Eukaryotes Package DNA in Chromatin and Chromosomes	470
Nucleosomes Are the Basic Unit of Chromatin Structure	470
A Histone Octamer Forms the Nucleosome Core	471
Nucleosomes Are Packed Together to Form Chromatin Fibers and Chromosomes	471
Changes in Histones and Chromatin Remodeling Proteins Can Alter Chromatin Packing	473
Chromosomal DNA Contains Euchromatin and Heterochromatin	474
Some Heterochromatin Plays a Structural Role in Chromosomes	474
Chromosomes Can Be Identified by Unique Banding Patterns	474
Eukaryotic Chromosomes Contain Large Amounts of Repeated DNA Sequences	475
Eukaryotes Package Some of Their DNA in Mitochondria and Chloroplasts	477
16.4: The Nucleus	478
A Double-Membrane Nuclear Envelope Surrounds the Nucleus	478
Molecules Enter and Exit the Nucleus Through Nuclear Pores	480
The Nucleus Is Mechanically Integrated with the Rest of the Cell	483
Chromatin Is Located Within the Nucleus in a Nonrandom Fashion	484
The Nucleolus Is Involved in Ribosome Formation	484
Summary of Key Points	486
Problem Set	486
Key Technique: FISHing for Specific Sequences	468
Human Connections: Lamins and Premature Aging	485
Chapter 17: DNA Replication, Repair, and Recombination	488
17.1: DNA Replication	489
DNA Synthesis Occurs During S Phase	489
DNA Replication Is Semiconservative	489
DNA Replication Is Usually Bidirectional	491
Replication Initiates at Specialized DNA Elements	494
DNA Polymerases Catalyze the Elongation of DNA Chains	495
DNA Is Synthesized as Discontinuous Segments That Are Joined Together by DNA Ligase	498
In Bacteria, Proofreading Is Performed bythe 3‘ -> 5‘ Exonuclease Activity of DNA Polymerase	499
RNA Primers Initiate DNA Replication	500
The DNA Double Helix Must Be Locally Unwound During Replication	502
DNA Unwinding and DNA Synthesis Are Coordinated on Both Strands Via the Replisome	503
Eukaryotes Disassemble and Reassemble Nucleosomes as Replication Proceeds	503
Telomeres Solve the DNA End-Replication Problem	505
17.2: DNA Damage and Repair	508
Mutations Can Occur Spontaneously During Replication	508
Mutagens Can Induce Mutations	510
DNA Repair Systems Correct Many Kinds of DNA Damage	512
17.3: Homologous Recombination and Mobile Genetic Elements	517
Homologous Recombination Is Initiated by Double-Stranded Breaks in DNA	517
Transposons Are Mobile Genetic Elements	519
Transposons Differ Based on Their Autonomy and Mechanism of Movement	519
Bacterial Transposons Can Be Composite or Non-composite	520
Eukaryotes Also Have Transposons	521
Summary of Key Points	521
Problem Set	521
Key Technique: The Polymerase Chain Reaction (PCR)	500
Human Connections: Children of the Moon	514
Chapter 18: Gene Expression: I. The Genetic Code and Transcription	523
18.1: The Genetic Code and the Directional Flow of Genetic Information	524
Transcription and Translation Involve Many of the Same Components in Prokaryotes and Eukaryotes	524
Where Transcription and Translation Occur Differs in Prokaryotes and Eukaryotes	524
In Some Cases RNA Is Reversed Transcribed into DNA	526
The Genetic Code	527
The Genetic Code Is a Triplet Code	529
The Genetic Code Is Degenerate and Nonoverlapping	530
Messenger RNA Guides the Synthesis of Polypeptide Chains	531
The Codon Dictionary Was Established Using Synthetic RNA Polymers and Triplets	532
Of the 64 Possible Codons in Messenger RNA, 61 Encode Amino Acids	532
The Genetic Code Is (Nearly) Universal	533
18.2: Mechanisms of Transcription	534
Transcription Involves Four Stages: RNA Polymerase Binding, Initiation, Elongation, and Termination	534
Bacterial Transcription Involves σ Factor Binding, Initiation, Elongation, andTermination	534
Transcription in Eukaryotic Cells Has Additional Complexity Compared with Prokaryotes	540
RNA Polymerases I, II, and III Carry Out Transcription in the Eukaryotic Nucleus	540
Three Classes of Promoters Are Found in Eukaryotic Nuclear Genes, One for Each Type of RNA Polymerase	541
General Transcription Factors Are Involved in the Transcription of All Nuclear Genes	543
Elongation, Termination, and RNA Cleavage Are Involved in Completing Eukaryotic RNA Synthesis	544
18.3: RNA Processing and Turnover	545
The Nucleolus Is Involved in Ribosome Formation	545
Ribosomal RNA Processing Involves Cleavage of Multiple rRNAs from a Common Precursor	546
Transfer RNA Processing Involves Removal, Addition, and Chemical Modification of Nucleotides	548
Messenger RNA Processing in Eukaryotes Involves Capping, Addition of Poly(A), and Removal of Introns	549
Spliceosomes Remove Introns from Pre-mRNA	551
Some Introns Are Self-Splicing	552
The Existence of Introns Permits Alternative Splicing and Exon Shuffling	553
Cells Localize Nuclear RNAs in Several Types of Processing Centers	554
Nucleic Acid Editing Allows Sequences to Be Altered	554
The C-Terminal Domain of RNA Polymerase II Coordinates RNA Processing	555
Most mRNA Molecules Have a Relatively Short Life Span	555
The Abundance of mRNA Allows Amplification of Genetic Information	555
Summary of Key Points	556
Problem Set	556
Key Technique: Hunting for DNA-Protein Interactions	536
Chapter 19: Gene Expression: II. Protein Synthesis and Sorting	559
19.1: Translation: The Cast of Characters	560
Ribosomes Carry Out Polypeptide Synthesis	560
Transfer RNA Molecules Bring Amino Acids to the Ribosome	561
Aminoacyl-tRNA Synthetases Link Amino Acids to the Correct Transfer RNAs	564
Messenger RNA Brings Polypeptide Coding Information to the Ribosome	565
Protein Factors Are Required for Translational Initiation, Elongation, and Termination	566
19.2: The Mechanism of Translation	566
Translational Initiation Requires Initiation Factors, Ribosomal Subunits, mRNA, and Initiator tRNA	566
Chain Elongation Involves Cycles of Aminoacyl tRNA Binding, Peptide Bond Formation, and Translocation	570
Most mRNAs Are Read by Many Ribosomes Simultaneously	572
Termination of Polypeptide Synthesis Is Triggered by Release Factors That Recognize Stop Codons	572
Polypeptide Folding Is Facilitated by Molecular Chaperones	572
Protein Synthesis Typically Utilizes a Substantial Fraction of a Cell’s Energy Budget	574
A Summary of Translation	575
19.3: Mutations and Translation	575
Suppressor tRNAs Overcome the Effects of Some Mutations	576
Nonsense-Mediated Decay and Nonstop Decay Promote the Destruction of Defective mRNAs	577
19.4: Posttranslational Processing	577
19.5: Protein Targeting and Sorting	580
Cotranslational Import Allows Some Polypeptides to Enter the ER as They Are Being Synthesized	580
The Signal Recognition Particle (SRP) Attachesthe Ribosome-mRNA-Polypeptide Complex to the ER Membrane	584
Protein Folding and Quality Control Take Place Within the ER	585
Proteins Released into the ER Lumen Are Routed to the Golgi Apparatus, Secretory Vesicles, Lysosomes, or Back to the ER	585
Stop-Transfer Sequences Mediate the Insertion of Integral Membrane Proteins	586
Posttranslational Import Is an Alternative Mechanism for Import into the ER Lumen	586
Posttranslational Import Across Two Membranes Allows Some Polypeptides to Enter Mitochondria and Chloroplasts	588
Summary of Key Points	590
Problem Set	591
Key Technique: Protein Localization Using Fluorescent Fusion Proteins	578
Human Connections: To Catch a Killer: The Problem of Antibiotic Resistance in Bacteria	583
Chapter 20: The Regulation of Gene Expression	593
20.1: Bacterial Gene Regulation	594
Catabolic and Anabolic Pathways Are Regulated Through Induction and Repression, Respectively	594
The Genes Involved in Lactose Catabolism Are Organized into an Inducible Operon	595
The lac Operon Is Negatively Regulated by the lac Repressor	595
Studies of Mutant Bacteria Revealed How the lac Operon Is Organized	597
Catabolite Activator Protein (CAP) Positively Regulates the lac Operon	599
The lac Operon Is an Example of the Dual Control of Gene Expression	599
The Structure of the lac Repressor/Operator Complex Confirms the Operon Model	600
The Genes Involved in Tryptophan Synthesis Are Organized into a Repressible Operon	600
Sigma Factors Determine Which Sets of Genes Can Be Expressed	600
Attenuation Allows Transcription to Be Regulated After the Initiation Step	601
Riboswitches Allow Transcription and Translation to Be Controlled by Small-Molecule Interactions with RNA	603
The CRISPR/Cas System Protects Bacteria Against Viral Infection	604
20.2: Eukaryotic Gene Regulation: Genomic Control	605
Multicellular Eukaryotes Are Composed of Numerous Specialized Cell Types	605
Eukaryotic Gene Expression Is Regulated at Five Main Levels	605
The Cells of a Multicellular Organism Usually Contain the Same Set of Genes	606
Gene Amplification and Deletion Can Alter the Genome	608
DNA Rearrangements Can Alter the Genome	609
Chromatin Decondensation Is Involved in Genomic Control	610
DNA Methylation Is Associated with Inactive Regions of the Genome	611
20.3: Eukaryotic Gene Regulation: Transcriptional Control	615
Different Sets of Genes Are Transcribed in Different Cell Types	615
Proximal Control Elements Lie Close to the Promoter	616
Enhancers and Silencers Are DNA Elements Located at Variable Distances from the Promoter	617
Coactivators Mediate the Interaction Between Regulatory Transcription Factors and the RNA Polymerase Complex	619
Multiple DNA Control Elements and Transcription Factors Act in Combination	620
DNA-Binding and Activation Domains of Regulatory Transcription Factors Are Functionally Separable	620
Several Common Types of Transcription Factors Bind to DNA and Activate Transcription	621
DNA Response Elements Coordinate the Expression of Nonadjacent Genes	623
Steroid Hormone Receptors Act as Transcription Factors That Bind to Hormone Response Elements	623
CREBs and STATs Are Examples of Transcription Factors Activated by Phosphorylation	624
The Heat-Shock Response Element Coordinates Stress Responses	625
Homeotic Genes Encode Transcription Factors That Regulate Embryonic Development	625
20.4: Eukaryotic Gene Regulation: Posttranscriptional Control	627
Control of RNA Processing and Nuclear Export Follows Transcription	627
Translation Rates Can Be Controlled by Initiation Factors and Translational Repressors	627
Translation Can Also Be Controlled by Regulation of mRNA Degradation	629
RNA Interference Utilizes Small RNAs to Silence Gene Expression	630
MicroRNAs Produced by Normal Cellular Genes Silence the Translation of mRNAs	631
Piwi-interacting RNAs Are Small Regulatory RNAs That Protect the Germline of Eukaryotes	634
Long Noncoding RNAs Play a Variety of Roles in Eukaryotic Gene Regulation	634
Posttranslational Control Involves Modifications of Protein Structure, Function, and Degradation	634
Ubiquitin Targets Proteins for Degradation by Proteasomes	635
A Summary of Eukaryotic Gene Regulation	636
Summary of Key Points	637
Problem Set	638
Human Connections: The Epigenome: Methylation and Disease	613
Key Technique: Gene Knockdown via RNAi	632
Chapter 21: Molecular Biology Techniques for Cell Biology	640
21.1: Analyzing and Manipulating DNA	640
Gel Electrophoresis Allows DNA to Be Separated by Size	641
Restriction Endonucleases Cleave DNA Molecules at Specific Sites	642
Restriction Mapping Can Characterize DNA	643
Restriction Endonucleases Can Identify Methylated DNA	644
Southern Blotting Identifies Specific DNAs from a Mixture	644
Restriction Enzymes Allow Production of Recombinant DNA	645
PCR Is Widely Used to Clone Genes	646
Genomic and cDNA Libraries Are Both Useful for DNA Cloning	646
Rapid Procedures Exist for DNA Sequencing	651
21.2: Analyzing Genomes	654
Whole Genomes Can Be Sequenced	654
Comparative Genomics Allows Comparison of Genomes and Genes Within Them	656
The Field of Bioinformatics Helps to Decipher Genomes	657
Tiny Differences in Genome Sequence Distinguish People from One Another	660
21.3: Analyzing RNA and Proteins	663
Several Techniques Allow Detection of mRNAs in Time and Space	663
The Transcription of Thousands of Genes Can Be Assessed Simultaneously	664
Proteins Can Be Studied Using Electrophoresis	665
Antibodies Can Be Used to Study Specific Proteins	665
Proteins Can Be Isolated by Size, Charge, or Affinity	667
Proteins Can Be Identified from Complex Mixtures Using Mass Spectrometry	668
Protein Function Can Be Studied Using Molecular Biology Techniques	669
Protein-Protein Interactions Can Be Studied in a Variety of Ways	670
21.4: Analyzing and Manipulating Gene Function	672
Transgenic Organisms Carry Foreign Genes That Are Passed On to Subsequent Generations	672
Transcriptional Reporters Are Useful for Studying Regulation of Gene Expression	674
The Role of Specific Genes Can Be Assessed By Identifying Mutations and by Knockdown	674
Genetic Engineering Can Produce Valuable Proteins That Are Otherwise Difficult to Obtain	677
Food Crops Can Be Genetically Modified	678
Gene Therapies Are Being Developed for the Treatment of Human Diseases	678
Summary of Key Points	679
Problem Set	680
Key Technique: DNA Cloning	648
Human Connections: More Than Your Fingertips: Identifying Genetic “Fingerprints”	662
Chapter 22: Signal Transduction Mechanisms: I. Electrical and Synaptic Signaling in Neurons	682
22.1: Neurons and Membrane Potential	683
Neurons Are Specially Adapted for the Transmission of Electrical Signals	683
Neurons Undergo Changes in Membrane Potential	684
Resting Membrane Potential Depends on Ion Concentrations and Selective Membrane Permeability	685
The Nernst Equation Describes the Relationship Between Membrane Potential and Ion Concentration	686
Steady-State Ion Concentrations Affect Resting Membrane Potential	686
The Goldman Equation Describes the Combined Effects of Ions on Membrane Potential	687
22.2: Electrical Excitability and the Action Potential	688
Patch Clamping and Molecular Biological Techniques Allow Study of Single Ion Channels	688
Specific Domains of Voltage-Gated Channels Act as Sensors and Inactivators	688
Action Potentials Propagate Electrical Signals Along an Axon	692
Action Potentials Involve Rapid Changes in the Membrane Potential of the Axon	692
Action Potentials Result from the Rapid Movement of Ions Through Axonal Membrane Channels	692
Action Potentials Are Propagated Along the Axon Without Losing Strength	694
The Myelin Sheath Acts Like an Electrical Insulator Surrounding the Axon	695
22.3: Synaptic Transmission and Signal Integration	697
Neurotransmitters Relay Signals Across Nerve Synapses	697
Elevated Calcium Levels Stimulate Secretion of Neurotransmitters from Presynaptic Neurons	700
Secretion of Neurotransmitters Involves the Docking and Fusion of Vesicles with the Plasma Membrane	701
Neurotransmitters Are Detected by Specific Receptors on Postsynaptic Neurons	703
Neurotransmitters Must Be Inactivated Shortly After Their Release	704
Postsynaptic Potentials Integrate Signals from Multiple Neurons	704
Summary of Key Points	705
Problem Set	706
Key Technique: Patch Clamping	690
Human Connections: In the Search for the Fountain of Youth, Are People Paying for Poison?	702
Chapter 23: Signal Transduction Mechanisms: II. Messengers and Receptors	708
23.1: Chemical Signals and Cellular Receptors	709
Chemical Signaling Involves Several Key Components	709
Receptor Binding Involves Quantitative Interactions Between Ligands and Their Receptors	710
Cells Can Amplify Signals Once They Are Received	711
Cell-Cell Signals Act Through a Limited Number of Receptors and Signal Transduction Pathways	711
23.2: G Protein–Coupled Receptors	713
G Protein–Coupled Receptors Act Via Hydrolysis of GTP	713
Cyclic AMP Is a Second Messenger Whose Production Is Regulated by Some G Proteins	715
Disruption of G Protein Signaling Causes Human Disease	716
Many G Proteins Act Through Inositol Trisphosphate and Diacylglycerol	717
The Release of Calcium Ions Is a Key Event in Many Signaling Processes	718
23.3: Protein Kinase-Associated Receptors	722
Growth Factors Often Bind Protein Kinase-Associated Receptors	723
Receptor Tyrosine Kinases Aggregate and Undergo Autophosphorylation	723
Receptor Tyrosine Kinases Initiate a Signal Transduction Cascade Involving Ras and MAP Kinase	724
The Key Steps in RTK Signaling Can Be Dissected Using Mutants	725
Receptor Tyrosine Kinases Activate a Variety of Other Signaling Pathways	727
Other Growth Factors Transduce Their Signals via Receptor Serine-Threonine Kinases	727
23.4: Putting It All Together: Signal Integration	728
Scaffolding Complexes Can Facilitate Cell Signaling	729
Different Signaling Pathways Are Integrated Through Crosstalk	730
23.5: Hormones and Other Long-Range Signals	731
Hormones Can Be Classified by Their Chemical Properties	731
The Endocrine System Controls Multiple Signaling Pathways to Regulate Glucose Levels	731
Steroid Hormones Bind Hormones in the Cytosol and Carry Them into the Nucleus	733
Gases Can Act as Cell Signals	734
Summary of Key Points	736
Problem Set	737
Key Technique: Calcium Indicators and Ionophore	721
Human Connections: The Gas That Prevents a Heart Attack	735
Chapter 24: The Cell Cycle and Mitosis	738
24.1: Overview of the Cell Cycle	739
24.2: Nuclear and Cell Division	743
Mitosis Is Subdivided into Prophase, Prometaphase, Metaphase, Anaphase, and Telophase	743
The Mitotic Spindle Is Responsible for Chromosome Movements During Mitosis	746
Cytokinesis Divides the Cytoplasm	749
Bacteria and Eukaryotic Organelles Divide in a Different Manner from Eukaryotic Cells	752
24.3: Regulation of the Cell Cycle	753
Cell Cycle Length Varies Among Different Cell Types	753
Cell Cycle Progression Is Controlled at Several Key Transition Points	754
Cell Fusion Experiments and Cell Cycle Mutants Identified Molecules That Control the Cell Cycle	755
Progression Through the Cell Cycle Is Controlled by Cyclin-Dependent Kinases (Cdks)	755
Cdk-Cyclin Complexes Are Regulated	756
The Anaphase-Promoting Complex Allows Exit from Mitosis	758
Checkpoint Pathways Monitor Key Steps in the Cell Cycle	758
Putting It All Together: The Cell Cycle Regulation Machine	761
24.4: Growth Factors and Cell Proliferation	762
Stimulatory Growth Factors Activate the Ras Pathway	762
Stimulatory Growth Factors Can Also Activate the PI 3-Kinase–Akt Pathway	763
Inhibitory Growth Factors Act Through Cdk Inhibitors	764
24.5: Apoptosis	764
Apoptosis Is Triggered by Death Signals or Withdrawal of Survival Factors	765
Summary of Key Points	767
Problem Set	768
Key Technique: Measuring Cells Millions at a Time	740
Human Connections: What Do Ethnobotany and Cancer Have in Common?	750
Chapter 25: Sexual Reproduction, Meiosis, and Genetic Recombination	770
25.1: Sexual Reproduction	771
Sexual Reproduction Produces Genetic Variety	771
Gametes Are Haploid Cells Specialized for Sexual Reproduction	771
25.2: Meiosis	771
The Life Cycles of Sexual Organisms Have Diploid and Haploid Phases	772
Meiosis Converts One Diploid Cell into Four Haploid Cells	772
Meiosis I Produces Two Haploid Cells That Have Chromosomes Composed of Sister Chromatids	773
Meiosis II Resembles a Mitotic Division	778
Defects in Meiosis Lead to Nondisjunction	779
Sperm and Egg Cells Are Generated by Meiosis Accompanied by Cell Differentiation	781
Meiotic Maturation of Oocytes is Tightly Regulated	782
25.3: Genetic Variability: Segregation and Assortment of Alleles	784
Meiosis Generates Genetic Diversity	784
Information Specifying Recessive Traits Can Be Present Without Being Displayed	784
Alleles of Each Gene Segregate from Each Other During Gamete Formation	785
Alleles of Each Gene Segregate Independently of the Alleles of Other Genes	786
Chromosome Behavior Explains the Laws of Segregation and Independent Assortment	787
The DNA Molecules of Homologous Chromosomes Have Similar Base Sequences	787
25.4: Genetic Variability: Recombination and Crossing Over	789
Chromosomes Contain Groups of Linked Genes That Are Usually Inherited Together	789
Homologous Chromosomes Exchange Segments During Crossing Over	789
Gene Locations Can Be Mapped by Measuring Recombination Frequencies	791
25.5: Genetic Recombination in Bacteria and Viruses	792
Co-infection of Bacterial Cells with Related Bacteriophages Can Lead to Genetic Recombination	792
Recombination in Bacteria Can Occur Via Transformation or Transduction	793
Conjugation Is a Modified Sexual Activity That Facilitates Genetic Recombination in Bacteria	793
25.6: Mechanisms of Homologous Recombination	796
DNA Breakage and Exchange Underlie Homologous Recombination Between Chromosomes	796
The Synaptonemal Complex Facilitates Homologous Recombination During Meiosis	796
Homologous Recombination Between Chromosomes Relies on High-Fidelity DNA Repair	797
Summary of Key Points	799
Problem Set	799
Human Connections: When Meiosis Goes Awry	780
Key Technique: Using Mendel’s Rules to Predict Human Disease	790
Chapter 26: Cancer Cells	802
26.1: How Cancers Arise	802
Tumors Arise When the Balance Between Cell Division and Cell Differentiation or Death Is Disrupted	803
Cancer Cell Proliferation Is Anchorage Independent and Insensitive to Population Density	804
Cancer Cells Are Immortalized by Mechanisms That Maintain Telomere Length	804
Defects in Signaling Pathways, Cell Cycle Controls, and Apoptosis Contribute to Cancer	804
Cancer Arises Through a Multistep Process Involving Initiation, Promotion, and Tumor Progression	805
26.2: How Cancers Spread	806
Angiogenesis Is Required for Tumors to Grow Beyond a Few Millimeters in Diameter	806
Blood Vessel Growth Is Controlled by a Balance Between Angiogenesis Activators and Inhibitors	807
Cancer Cells Spread by Invasion and Metastasis	808
Changes in Cell Adhesion, Motility, and Protease Production Promote Metastasis	808
Relatively Few Cancer Cells Survive the Voyage Through the Bloodstream	809
Blood Flow and Organ-Specific Factors Determine Sites of Metastasis	809
The Immune System Influences the Growth and Spread of Cancer Cells	810
The Tumor Microenvironment Influences Tumor Growth, Invasion, and Metastasis	810
26.3: What Causes Cancer?	811
Epidemiological Data Have Allowed Many Causes of Cancer to Be Identified	811
Many Chemicals Can Cause Cancer, Often After Metabolic Activation in the Liver	812
DNA Mutations Triggered by Chemical Carcinogens Lead to Cancer	812
Ionizing and Ultraviolet Radiation Also Cause DNA Mutations That Lead to Cancer	813
Viruses and Other Infectious Agents Trigger the Development of Some Cancers	814
26.4: Oncogenes and Tumor Suppressor Genes	815
Oncogenes Are Genes Whose Products Can Trigger the Development of Cancer	815
Proto-oncogenes Are Converted into Oncogenes by Several Distinct Mechanisms	815
Most Oncogenes Encode Components of Growth-Signaling Pathways	817
Tumor Suppressor Genes Are Genes Whose Loss or Inactivation Can Lead to Cancer	820
The RB Tumor Suppressor Gene Was Discovered by Studying Families with Hereditary Retinoblastoma	821
The p53 Tumor Suppressor Gene Is the Most Frequently Mutated Gene in Human Cancers	822
The APC Tumor Suppressor Gene Encodes a Protein That Inhibits the Wnt Signaling Pathway	823
Inactivation of Some Tumor Suppressor Genes Leads to Genetic Instability	824
Cancers Develop by the Stepwise Accumulation of Mutations Involving Oncogenes and Tumor Suppressor Genes	825
Epigenetic Changes in Gene Expression Influence the Properties of Cancer Cells	828
Summing Up: Carcinogenesis and the Hallmarks of Cancer	828
26.5: Diagnosis, Screening, and Treatment	829
Cancer Is Diagnosed by Microscopic and Molecular Examination of Tissue Specimens	830
Screening Techniques for Early Detection Can Prevent Cancer Deaths	830
Surgery, Radiation, and Chemotherapy Are Standard Treatments for Cancer	831
Using the Immune System to Target Cancer Cells	831
Molecular Targeting Can Attack Cancer Cells More Specifically Than Chemotherapy	834
Cancer Treatments Can Be Tailored to Individual Patients	834
Summary of Key Points	834
Problem Set	835
Key Technique: Targeting Molecules in the Fight Against Cancer	832
Human Connections: Molecular Sleuthing in Cancer Diagnosis	826
Appendix: Visualizing Cells and Molecules	837
Optical Principles of Microscopy	837
The Illuminating Wavelength Sets a Limit on How Small an Object Can Be Seen	837
Resolution Refers to the Ability to Distinguish Adjacent Objects as Separate from One Another	838
The Practical Limit of Resolution Is Roughly 200 nm for Standard Light Microscopes and 2 nm for Electron Microscopes	840
The Light Microscope	840
Compound Microscopes Use Several Lenses in Combination	840
Phase-Contrast Microscopy Detects Differences in Refractive Index and Thickness	841
Differential Interference Contrast (DIC) Microscopy Utilizes a Split Light Beam to Detect Phase Differences	842
Digital Microscopy Can Enhance Captured Images	843
Fluorescence Microscopy Can Detect the Presence of Specific Molecules or Ions Within Cells	844
Confocal Microscopy Minimizes Blurring by Excluding Out-of-Focus Light from an Image	846
Other Techniques Minimize Blurring by Exciting a Thin Strip of Fluorescent Molecules	848
Digital Deconvolution Microscopy Can Be Used to Generate Sharp Three-Dimensional Images After Acquisition	849
Optical Methods Can Be Used to Measure and Manipulate Macromolecules	850
Superresolution Microscopy Has Broken the Diffraction Limit	851
Specimen Preparation Often Involves Fixation, Sectioning, and Staining	852
The Electron Microscope	852
Transmission Electron Microscopy Forms an Image from Electrons That Pass Through the Specimen	852
Scanning Electron Microscopy Reveals the Surface Architecture of Cells and Organelles	854
Sample Preparation Techniques for Electron Microscopy	854
Ultrathin Sectioning and Staining Are Common Techniques in Transmission Electron Microscopy	854
Radioisotopes and Antibodies Can Localize Molecules in Electron Micrographs	856
Negative Staining Can Highlight Small Objects in Relief Against a Stained Background	856
Shadowing Techniques Use Metal Vapor Sprayed Across a Specimen’s Surface	856
Freeze Fracturing and Freeze Etching Are Useful for Examining Membranes	857
Stereo Electron Microscopy and 3-D Electron Tomography Allow Specimens to Be Viewed in Three Dimensions	858
Specimen Preparation for Scanning Electron Microscopy Involves Fixation but Not Sectioning	859
Other Imaging Methods	860
Scanning Probe Microscopy Reveals the Surface Features of Individual Molecules	860
CryoEM Bridges the Gap Between X-Ray Crystallography and Electron Microscopy	861
Answer Key to Concept Check and Key Technique Box Questions	862
Glossary	869
Photo, Illustration, and Text Credits	895
Index	901
Back Cover	Back Cover

Becker's World of the Cell, Global Edition

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