WAYNE M.BECKER taught cell biology at the University of Wisconsin Madison,for 30 years until his recent retirement.His interest in textbook writing grew out of notes,outlines,and problem sets that he assembled for his students,culminating in Energy and the Living Cell,a paperback text on bioenergetics pubfished in 1977,and The World of the Cell,the first edition of which appeared in 1986.He earned all his degrees at the University of Wisconsin-Madison.All three degrees are in biochemistry,an orientation that is readily dis-cernible in his textbooks.His research interests have been in plant molecular biology,focused specifically on the regulatinn of theexpression of genes that encode enzymes of the photorespiratorypathway.His interests in teaching,learning,and research have taken him on sabbatical leaves at Harvard University,Edinburgh University,the University of Indonesia,the University of Puerto Rico,Canterbury University in Christchurch,New Zealand,the Chinese University of Hong Kong,and the Charles University in Prague.His honors include a Chancellor''s Award for Distin-gnished Teaching,Guggenheim and Pulbright Fellowships,and a Visiting Scholar Award from the Royal Society of London.
LEWIS J.KLEINSMITH is an Arthur F.Thurnau Professor Emeritus of Molecular,Cellular,and Developmental biology at the University of Michigan,where he has served on the faculty since receiving his Ph.D.from Rockefeller University in 1968.His teaching experiences have involved courses in introductory biology,cell biology,and cancer biology,and his research interests have included studies of growth control in cancer cells,the role of protein phosphorylation in eukaryotic gene regulation,and the control of gene expression during development.Amonghis numerous publications,he is the author of Principles of Cancer Biology as well as several award winning educational software programs.His honors include a Guggenheim Feblowship,the Henry Russell Award,a Michigan Distinguished Service Award,citations for outstanding teaching from the Michigan Students Association,an NIH Plain Language Award,and a Best Curriculum innovafion Award from the EDUCOM Higher Education Software Awards Competition.
JEFF HARDIN is a Professor in the Zoology Department at the University of Wisconsln-Madlson.His research interests center on how cells migrate and adhere to one another to change the shape of ainmal embryos.Dr.Hardin''s teaching is enhanced by his extensive use of videomicroscopy and his Web based teaching materials,which areused on many campuses in the United States and other countries.As part of his interest in teaching biology,Dr.Hardin has been involved in several teaching initiatives.He was a founding member of the University of Wisconsin Teaching Academy and a cofounder of a Univer-sity of Wisconsin system wide instructional technology initiative known as BioWeh.He is currently thcudy directorof the Biology Core Curriculum,a four-semester honors biology sequence for undergraduates.His teaching award sinclude a Lily Teaching Fellowship and a National Science Foundation Young Investigator Award.He is also on theeditorial board of CBE: Life Sciences Education.
GREGORY PAUL BERTONI,the newest member of the author team,has been active in teaching and research for over 20 years.He earned a Ph.D.in Cellular and Molecular Biology from the University of Wisconsin Madison,where his teaching experiences included introductory and graduate level biochemistry,sophomore cell biology,and plant physiology.He also helped to develop a new course entitled "Ways of Knowing" designed to introduce entering,freshmen to the learning process itself.His puhdshed research includes studies in bacterial pathogenesis,plant-microbe interactions,and plant gene expression.He is currently teaching biology and medical microbiology at Columbus State Community College in Columbus,Ohio,where he has just been nominated for a Distinguished Teaching Award.In addition,Dr.Bertoni is a freelance scientific writer who has contributed to text- and web based projects in biology,physics,and microbiology.He is also a science editor for The Plant Cell,a leading research journal in plant biology and molecular biology.
目錄：
Brief Contents
About the Authors
Preface
Acknowledgments
Detailed Contents
1 A Preview of the Cell
2 The Chemistry of the Cell
3 The Macromolecules of the Cell
4 Cells and Organelles
5 Bioenergetics:The Flow of Energy in the Cell
6 Enzymes:The Catalysts of Life
7 Membranes:Their Structure,Function,and Chemistry
8 Transport Across Membranes:Overcoming the Permeability Barrier
9 Chemotrophic Energy Metabolism:Glycolysis and Fermentation
10 Chemotrophic Energy Metabolism:Aerobic Respiration
11 Phototrophic Energy Metabolism:Photosynthesis
12 The Endomembrane System and Peroxisomes
13 Signal Transduction Mechanisms:I.Electrical and Synaptic Signaling in Neurons
14 Signal Transduction Mechanisms:II.Messengers and Receptors
15 Cytoskeletal Systems
16 Cellular Movement:Motility and Contractility
17 Beyond the Cell:Cell Adhesions,Cell Junctions,and Extracellular Structures
18 The Sturctural Basis of Cellular Information:DNA,Chromosomes,and the Nucleus
19 The Cell Cycle,DNA Replication,and Mitosis
20 Sexual Reproduction,Meiosis,and Genetic Recombination
21 Gene Expression:I.The Genetic Code and Transcription
22 Gene Expression:II.Protein Synthesis and Sorting
23 The Regulation of Gene Expression
24 Cancer Cells
Appendix:Visualizing Cells and Molecules
Glossary
Photo,Illustration,and Text Credits
Index
Detailed Contents
About the Authors
Preface
Acknowledgments
1 A Preview of the Cell
The Cell Theory:A Brief History
The Emergence of Modern Cell Biology
The Cytological Strand Deals with Cellular Structure
The Biochemical Strand Covers the Chemistry of Biological Structure and Function
The Genetic Strand Focuses on Information Flow
"Facts"and the Scientific Method
Summary of Key Points
Making Connections
Problem Set
Suggested Reading
Box 1A Experimmental Techniques:Units of Measurement in Cell Biology
Box 1B Further Insights:Biology,"Facts,"and the Scientific Method
2 The Chemistry of the Cell
The Importance of Carbon
Carbon-Containing Molecules Are Stable
Carbon-Containing Molecules Are Diverse
Carbon-Containing Molecules Can Form Stereoisomers
The Importance of Water
Water Molecules Are Polar
Water Molecules Are Cohesive
Water Has a High Timperature-Stabilizing Capacity
Water Is an Excellent Solvent
The Importance of Selectively Permeable Membranes
A Membrane Is a Lipid Bilayer with Proteins Embedded in It
Membranes Are Selectively Permeable
The Importance of Synthesis by Polymerization
Macromolecules Are Responsible for Most of the Form and Function in Living Systems
Cells Contain Three Different Kinds of Macromolecules
Macromolecules Are Synthesized by Stepwise Polymerization of Monomers
The Importance of Self-Assembly
Many Proteins Self-Assemble
Molecular Chaperones Assist the Assembly of Some Proteins
Noncovalent Bonds and Interactions Are Important in the Folding of Macromolecules
Self-Assembly Also Occurs in Othe Cellular Structures
The Tobacco Mosaic Birus Is a Case Study in Self-Assembly
Self-Assembly Has Limits
Hierarchical Assembly Provides Advantages for the Cell
Summary of Key Points
Making Connections
Problem Set
Suggested Reading
Box 2A Further Insights:Tempus Fugit and Fine Art of Watchmaking
3 The Macromolecules of the Cell
Proteins
The Monomers Are Amino Acids
The Polymers Are Polypepitdes and Proteins
Several Kinds of Bonds and Interactions Are Important in Protein Folding and Stability
Protein Structure Depends on Amino Acid Sequence and Interactions
Nucleic Acids
The Monomers Are Nucleotides
The Polymers Are DNA and RNA
A DNA Molecule Is a Double-Stranded Helix
Polysaccharides
The Monomers Are Monosaccharides
The Polymers Are Storage and Structural Polysaccharides
Polysaccharide Structure Depends on the Kinds of Glycosidic Bonds Involved
Lipids
Fatty Acids Are the Building Blocks of Several Classes of Lipids
Triacylglycerols Are Storage Lipids
Phospholipids Are Important in Membrane Structure
Glycolipids Are Specialized Membrane Components
Steroids Are Lipids with a Variety of Functions
Terpenes Are Formed from Isoprene
Summary of Key Points
Making Connections
Problem Set
Suggested Reading
Box 3A Further Insights:On the Trail of the Double Helix
4 Cells and Organelles
Properties and Strategies of Cells
All Organisms Are Bacteria,Archaea,or Eukaryotes
Limitations on Cell Size
Eukaryotic Cells Use Organelles to Compartmentalize Cellular Function
Bacteria,Archaea,and Eukaryotes Differ from Each Other in Many Ways
Cell Specialization Demonstrates the Unity and Diversity of Biology
The Eudaryotic Cell in Overview:Pictures at an Exhibition
The Plasma Membrane Defines Cell Boundaries and Retaions Contents
The Nucleus Is the Information Center of the Eukaryotic Cell
Intracellular Membranes and Organelles Define Compartments
The Cytoplasm of Eukaryotic Cells Contaions the Cytosol and Cytoskeleton
The Extracellular Matrix and the Cell Wall Are the "Outside "of the Cell
Viruses,Biroids,and Prions:Agents That Invade Cells
A Virus Consists of a DNA or RNACore Surrounded by a Protein Coat
Viroids Are Small,Circular RNA Molecules
Prions Are "proteinaceous Infective Particles"
Summary of Key Points
Making Connections
Problem Set
Suggested Reading
Box 4A Human Applications:Organelles and Human Diseases
Box 4B Further Insights:Discovering Organelles:The Importance of Centrifuges and Chance Observations
5 Bioenergetics:The Flow of Energy in the Cell
The Importance of Energy
Cells Need Energy to Drive Six Different Kinds of Changes
Organisms Obtain Energy Either from Sunlight or from the Oxidation of Chemical Compounds
Energy Flows Through the Biosphere Continuously
The Flow of Energy Through the Biosphere Is Accompanied by a Flow of Matter
Bioenergetics
To Understand Energy Flow,We Need to Understand Systems,Heat,and Work
The First Law of Thermodynamics Tells Us That Energy Is Conserved
The Second Law of Thermodynamics Tells Us That Reactions Have Directionality
Entropy and Free Energy Are Two Alternative Means of Assessing Thermodynamic Spontaneity
Understanding △G
The Equilibrium Constant Is a Measure of Directionality
△G Can Be Calculated Readily
The Standard Free Energy Change Is △G Measured Under Standard Conditions
Summing Up:The Meaning of △G''and △Go''
Free Energy Change:Sample Calculations
Life and the Steady State:Reactions That Move Toward Equilibrium Without Ever Getting There
Summary of Key Points
Making Connections
Problem Set
Suggested Reading
Box 5A Further Insights:Jumping Beans and Free Energy
6 Enzymes:The Catalysts of Life
Activation Energy and the Metastable State
Before a Chemical Reaction Can Occur,the Activation Energy Barrier Must Be Overcome
The Metastalbe State Is a Resule of the Activation Barrier
Catalysts Overcome the Activation Energy Barrier
Enzymes as Biological Catalysts
Most Enzymes Are Proteins
Substrate Binding,Activation,and Reaction Occur at the Active Site
Enzyme Kinetics
Most Enzymes Display Michaelis-Menten Kinetics
What Is the Meaning of Vmax and Km?
Why Are Km and Vmax Important to Cell Biologists?
The Double-Reciprocal Plot Is a Useful Means of Linearizing Kinetic Data
Determing Km and Vmax:An Example
Enzyme Inhibitors Act Irreversibly or Reversibly
Enzyme Regulation
Allosteric Enzymes Are Regulated by Molecules Other than Reactants and Products
Allosteric Enzymes Exhibit Cooperative Interactions Between Subunits
Enzymes Can Also Be Regulated be the Addition or Removal of Chemical Groups
RNA Molecules as Enzymes:Ribozymes
Summary of Key Points
Making Connetious
Problem Set
Suggested Reading
Box 6A Further Insights:Monkeys and Peanuts
7 Membranes:Their Structure,Function,and Chemistry
The Functions of Membranes
Membranes Define Boundaries and Serve as Permeability Barriers
Membranes Are Sites of Specific Proteins and Therefore of Specific Functions
Membrane Proteins Regulate the Transport of Solutes
Membrane Proteins Detect and Transmit Electrical and Chemical Signals
Membrane Proteins Mediate Cell Adhesion and Cell-to-Cell Communication
Models of Membrane Structure:An Experimental Perspective
Overton and Langmuir:Lipids Are Important Components of Membranes
Gorter and Grendel:The Basis of Membrane Structure Is a Lipid Bilayer
Davson and Danielli:Membranes Also Contain Proteins
Robertson:All Membranes Share a Common Underlying Structure
Further Research Revealed Major Shortcomings of the Davson-Danielli Model
Singer and Nicolson:A Membrane Consists of a Mosaic of Proteins in a Fluid Lipid Bilayer
Unwin and Henderson:Most Membrane Proteins Contain Transmembrane Segments
Recent Findings Further Refine Our Understanding of Membrane Structure
Membrane Lipids:The "Fluid"Part of the Model
Membranes Contain Several Major Classes of Lipids
Thin-Layer Chromatography Is an Importangt Technique for Lipid Analysis
Fatty Acids Are Essential to Membrane Structure and Function
Membrane Asymmetry:Most Lipids Are Distributed Unequally Between the Two Monolayers
The Lipid Bilayer Is Fluid
Membranes Function Properly Only in the Fluid State
Most Organisms Can Regulate Membrane Fluidity
Lipid Rafts Are Localized Regions of Membrane Lipids That Are Involved in Cell Signaling
Membrane Proteins:The "Mosaic"Part of the Model
The Membrane Consists of a Mosaic of Proteins:Evidence from Freezi-Fracture Microscopy
Membranes Contain Integral,Peripheral,and Lipid-Anchored Proteins
Proteins Can Be Separated by SDS-Polyacrylamide Gel Electrophoresis
Determing the Three-Dimensional Structure of Membrane Proteins Is Becoming More Feasible
Molecular Biology Has Contributed Greatly to Our Understanding of Membrane Proteins
Membrane Proteins Have a Variety of Functions
Membrane Proteins Are Oriented Asymmetrically Across the Lipid Bilayer
Many Membrane Proteins Are Glycosylated
Membrane Proteins Vary in Their Mobility
Summary of Key Points
Making Connections
Problem Set
Suggested Reading
Box 7A Experimental Techniques:Revolutionizing the Study of Membrane Proteins:The Impact of Molecular Biology
8 Transport Across Membranes:Overcoming the Permeability Barrier
Cells and Transport Processes
Solutes Cross Membranes by Simple Diffusion,Facilitated Diffusion,and Active Transport
The Movement of a Solute Across a Membrane Is Determined by Its Concentration Gradient or Its Electrochemical Potential
The Erythrocyte Plasma Membrane Provides Examples of Transport Mechanisms
Simple Diffusion:Unassisted Movement Down the Gradient
Diffusion Always Moves Solutes Toward Equilibrium
Osmosis Is the Diffusion of Water Across a Selectively Permeable Membrane
Simple Diffusion Is Limited to Small,Nonpolar Molecules
The Rate of Simple Diffusion Is Directly Proportional to the Concentration Gradient
Facilitated Diffusion:Proteln-Mediated Movement Down the Gradient
Carrier Proteins and Channel Proteins Facgitate Diffusion by Different Mechanisms
Carrier Proteins Alternate Between Two Conformational States
Carrier Proteins Are Analogous to Enzymes in Their Specificity and Kinetics
Carrier Proteins Transport Either One or Two Solutes
The Erythrocyte Glucose Transporter and Anion Exchange Protein Are Examples of Carrier Proteins
Channel Proteins Facilitate Diffusion by Forming Hydrophilic Transmembrane Channels
Active Transport:Protein-Mediated Movement Up the Gradient
The Coupling of Active Transport to an Energy Source May Be Direct or Indirect
Direct Active Transport Depends on Four Types of Transport ATPases
Indirect Active Transport Is Driven by Ion Gradients
Examples of Active Transport
Direct Active Transport:The Na+K+ Pump Maintains Electrochemical Ion Gradients
Indirect Active Transport:Sodium Symport Drives the Uptake of Glucose
The Bacteriorhodopsin Proton Pump Uses Light Energy to Transport Protons
The Energetics of Transport
For Uncharged Solutes,the △G of Transport Depends Only on the Concentration Gradient
For Charged Solutes,the △G of Transport Depends on the Electrochemical Potential
Summary of Key Points
Making Connections
Problem Set
Suggested Reading
Box 8A Further Insights:Osmosis:The Diffusion of Water Across a Selectively Permeable Membrane
Box 8B Human,Applications:Membrane Transport,Cystic Fibrosis,and the Prospects for Gene Therapy
9 Chemotrophic Energy Metabolism:Glycolysis and Fermentation
Metabolic Pathways
ATP:The Universal Energy Coupler
ATP Contains Two Energy Rich Phosphoanhydride Bonds
ATP Hydrolysis Is Highly Exergonic Because of Charge Repulsion and Resonance Stabilition
ATP Is an Important Intermediate in Cellular Energy Metabolism
Chemotrophic Energy Metabolism
Biological Oxidations Usuagy Involve the Removal of Both Electrons and Protons and Are Highly Exergonic
Coenzymes Such as NAD+ Serse as Electron Acceptors in Biological Oxidations
Most Chemotrophs Meet Their Energy Needs by Oxidizing Organic Food Molecules
Glucose Is One of the Most Important Oxidizable Substrates in Energy Metabolism
The Oxidation of Glucose Is Highly Exergonic
Glucose Catabolism Yields Much More Energy in the Presence of Oxygen than in Its Absence
Based on Their Need for Oxygen,Organisms Are Aerobic,Anaerobic,or Facultative
Glycolysis and Fermentation:ATP Generation Without the Involvement of Oxygen
Glyeolysis Generates ATP by Catabolizing Glucose to Pyruvate
The Fate of Pyruvate Depends on Whether Oxygen Is Available
In the Absence of Oxygen,Pyruvate Undergoes Fermentation to Regenerate NAD+
Fermentation Taps Only a Fraction of the Substrate''s Free Energy but Conserves That Energy Efficiendy as ATP
Alternative Substrates for Glycolysis
Other Sugars and Glycerol Are Also Catabolized by the Glyeolytic Pathway
Polysaccharides Are Cleaved to Form Sugar Phosphates That Also Enter the Glycolytic Pathway
Ginconeogenesis
The Regulation of Glycolysis and Ginconeogenesis
Key Enzymes in the Glycolytic and Gluconeogenic Pathways Are Subject to Allosteric Regulalion
Fructose-2,6-Bisphospbate Is an Important Regulator of Glyolysis and Gluconeogenesis
Novel Roles for Glycolytic Enzymes
Summary of Key Points
Making ConneCtions
Problem Set
Suggested Reading
Box 9A Further Insights:"What Happens to the Sugar?"
10 Chemotrophic Energy Metabolism:Aerobic Respiration
Cellular Respiration:Maximizing ATP Yieds
Aerobic Respiration Yields Much More Energy than Fermentation Does
Respiration Includes Glycolysis,Pyruvate Oxidation,the TCA Cycle,Electron Transport,and ATP Synthesis
The Mitochondrion:Where the Action Takes Place
Mitochondria Are Often Present Where the ATP Needs Are Greatest
Are Mitochondria Interconnected Networks Rather than Discrete Organelles?
The Outer and Inner Membranes Define Two Separate Compartments and Three Regions
Mitochondrial Functions Occur in or on Specific Membranes and Compartments
In Bacteria,Respiratory Functions Are Localized to the Plasma Membrane and tile Cytoplasm
The Tricarboxylic Acid Cycle:Oxidation in the Round
Pyruvate Is Converted to Acetyl Coenzyme A by Oxidative Decar boxylation
The TCA Cycle Begins with the Entry of Acetate as Acetyl CoA
Two Oxidative Decarboxylations Then Form NADH and ReleaseCO2
Direct Generation of GTPor ATP Occurs at One Step in the TCA Cycle
The Final Oxidative Reactions of the TCA Cyde Generate FADH2 and NADH
Summing Up:The Products of the TCA Cycle Are CO2,ATP,NADH,and FADH2
Several TCA Cycle Enzymes Are Subject to Allosteric Regulation
The TCA Cycle Mso Plays a Central Role in the Catabolism of Fats and Proteins
The TeA Cycle Serves as a Source of Precursors tor Anabolic Pathways
The Glyoxylate Cycle Converts Acetyl CoA to Carbohydrates
Electron Transport:Electron Flow from Coenzymes to Oxygen
The Electron Transport System Conveys Electrons from Reduced Coenzymes to Oxygen
The Electron Transport System Consists of Five Kinds of Carriers
The Electron Carriers Function in a Sequence Determined by Their Reductkm Potentials
Most of the Carriers Are Organized into Four Large Respiratory CompIexes
The Respiratory Complexes Move Freely Within the Inner Membrane
The Electrochemical Proton Gradient:Key to Energy Coupling
Electron Transport and ATP Synthesis Are Coupled Events
The Chemiosmotic Model:The "Missing Link" Is a Proton Gradient
Coenzyme Oxidation Pumps Enough Protons to Form 3 ATP per NADH and 2 ATP per FADH2
The Cbemiosmotie Model Is Affirmed by an Impressive Array of Evidence
ATP Synthesis:Putting It All Together
F1 Particles Have ATP Synthase Activity
The F0F1 Complex:Proton Translocation Through F0 Drives ATP Synthesis by F1
ATP Synthesis by P0P1 Involves Physical Rotation of the Gamma Subunit
The Chemiosmotic Model involves Dynamic Transmembrane Proton Traffic
Aerobic Respiration:Summing It All Up
The Maximum ATP Yield of Aerobic Respiration Is 36-38 ATPs per Glucose
Aerobic Respiration [s a Highly Efficient Process
Summary of Key Points
Making Connections
Problem Set
Suggested Reading
Box 10A Further InsightS:The Glyoxylate Cycle,Glyoxysomes,and Seed Germination
11 Phototrophic Energy Metabolism:Photosynthesis
An Overview of Photosynthesis
The Energy Transduction Reactions Convert Solar Energy to Chemical Energy
The Carbon Assimilation Reactions Fix Carbon by Reducing Carbon Dioxide
The Chloroplast Is the Photosynthetic Organege in Eukaryotic Cells
Chloroplasts Are Composed of Three Membrane Systems
Photosynthetic Energy Transduction I:Light Harvesting
Chlorophyll Is Life''s Primary Link to Sunlight
Accessory Pigments Further Expand Access to Solar Energy
Light-Gathering Molecules Are Organized into Photosystems and Light-Harvesting Complexes
Oxygenic Phototrophs Have Two Types of Photosystems
Photosynthetic Energy Transduction ll:NADPH Synthesis
Photosystem II Transfers Electrons from Water to a Plastoquinone
The Cytochrome b6fComplex Transfers Electrons from a Plastoquinol to Plastocyanin
Photosystem 1 Transfers Electrons from Plastocyanin to Ferredoxin
Ferredoxin NADP+ Reductase Catalyzes the Reduction of NADP+
Photosynthetic Energy Transduetion III:ATP Synthesis
The ATP Synthase Complex Couples Transport of Protons Across the Thylakoid Membrane to ATP Synthesis
Cyclic Photophosphorylation Allows a Photosynthetic Cell to Balance NADPH and ATP Synthesis
A Summary of the Complete Energy Transduction System
Photosynthetic Carbon Assimilation 1:The Calvin Cyde
Carbon Dioxide Enters the Calvin Cycle by Carboxylation of Ribulose-1,5-Bisphosphate
3-Phosphoglycerate is Reduced to Form Glyceraldehyde-3-Phosphate
Regeneration of Ribulose 1,5 Bisphosphate Allows Continuous Carbon Assimilation
The Complete Calvin Cycle and Its Relation to Photosynthetic Energy Transduction
Regulation of the Calvin Cycle
The Calvin Cycle Is Highly Regulated to Ensure Maximum Efficiency
Regulation of Rubisco Carbon Fixation by Rubisco Activase
Photosynthetic Carbon Assimilation II:Carbohydrate Synthesis
Glucose-l-Phosphate fs Synthesized from Triose Phosphates
The Biosynthesis of Sucrose Occurs in the Cytosol
The Biosynthesis of Starch Occurs in the Chloroplast Stroma
Photosynthesis Also Produces Reduced Nitrogen and Sulfur Compounds
Rubisco''s Oxygenase Activity Decreases Photosynthetic Efficiency
The Glyzolate Pathway Returns Reduced Carbon from Phosphoglyzolate to the Calvin Cycle
C4 Plants Minimize Photorespiration by Confining Rubisco to Cells Containing High Concentrations of CO2
CAM Plants Minimize Photorespiration and Water Loss by Opening Their Stomata Ouly at Night
Summary of Key Points
Making Connections
Problem Set
Suggested Reading
Box 11A Further insights:The Endosymbiont Theory and the Evolution of Mitochondria and Chloroplasts from Ancient Bacteria
Box 11B Further InsightS:A Photosynthetic Reaction Center from a Purple Bacterium
12 The Endomembrane Systemand Peroxisomes
The Endoplasmic Reticulum
The Two Basic Kinds of Endoplasmic Reticulum Differ in Structure and Function
Rough ER Is Involved in the Biosynthesis and Processing of Proteins
Smooth ER Is Involved in Drug Detoxification,Carbohydrate Metabolism,Calcium Storage,and Steroid Biosynthesis
The ER Plays a Central Role in the Biosynthesis of Membranes
The Golgi Complex
The Golgi Complex Consists of a Series of Membrane-Bounde Cisternae
Two Models Depict the Flow of Lipids and Proteins Through the Golgi Complex
Roles of the ER and Golgi Complex in Protein Glycosylation
Roles of the ER and Golgl Complex in Protein Trafficking
ER-Specific Proteins Contain Retention and Retrieval Tags
Golgi Complex Proteins May Be Sorted According to the Lengths of Their Membrane-Spanning Domains
Targeting of Soluble Lysosomal Proteins to Endosomes and Lysosomes Is a Model for Protein Sorting in the TGNTargeting of Soluble Lysosomal Proteins to Endosomes and Lysosomes Is a Model for Protein Sorting in the TGN
Secretory Pathways Transport Molecules to the Exterior of the Cell
Exocytosis and Endocytosis:Transporting Material Across the Plasma Membrane
Exocytosis Releases Intracellular Molecules to the Extracellular Medium
Endocytosis Imports Extracellular Molecules by Forming Vesicles from the Plasma Membrane
Coated Vesicles in Cellular Transport Processes
Clathrin-Coated Vesicles Are Surrounded by Lattices Compose of Clathrin and Adaptor Protein
The Assembly of Clathrin Coats Drives the Formation of Vesicles from the Plasma Membrane and TGN
COPI-and COPll-Coated Vesicles Travel Between the ER and Golgi Complex Cisternae
SNARE Proteins Mediate Fusion Between Vesicles and Target Membranes
Lysosomes and Cellular Digestion
Lysosomes Isolate Digestive Enzymes from the Rest of the Cell
Lysosomes Develop from Endosomes
LysosomalEnzymes Are Important for Several Different Digestive Processes
Lysosomal Storage Diseases Are Usually Characterized by the Accumulation of Indigestible Material
The Plant Vacuole:A Multifunctional Organelle
Peroxisomes
The Discovery of Peroxisomes Depended on Innovations in Equilibrium Density Centrifugation
Most Peroxisomal Functions Are Linked to Hydrogen Peroxide Metabolism
Plant Cells Contain Types of Peroxisomes Not Found in Animal Cells
Peroxisome Biogenesis Occurs by Division of Preexisting Peroxisomes
Summary of Key Points
Making Connections
Problem Set
Suggested Reading
Box 12A Experimental Techniques:Centrifugation:An Indispensable Tehnique of Cell Biology
Box 12B Human Applications:Cholesterol,the LDL Receptor,and Receptor-Mediated Endocytosis
13 Signal Transduction Mechanisms:I.Electrical and Synaptic Signaling in Neurons
Neurons
Neurons Ate Specially Adapted for the Transmission of Electrical Signals
Understanding Membrane Potential
The Resting Membrane Potential Depends on Differing Concentrations of ions Inside and Outside the Neuron
The Nernst Equation Describes the Relationship Between Membrane Potential and Ion Concentration
Steady State Concentrations of Common tons Affect Resting Membrane Potential
The Goldman Equation Describes the Combined Effects of Ions on Membrane Potential
Electrical Excitability
Ion Channels Act Like Gates for the Movement of tons Through the Membrane
Patch Clamping and Molecular Biological Techniques Allow the Activity of Single Ion Channels to Be Monitored
Specific Domains of Voltage-Gated Channels Act as Sensors and Inactivators
TheAction Potential
Action Potentials Propagate Electrical Signals Along an Axon
A,tion Potentials Involve Rapid Changes in the Membrane Potential of the Axon
Action Potentials Result from the Rapid Movement of Ions Through Axonal Membrane Channels
Action Potentials Are Propagated Along the Axon Without Loalng Strength
The Myelin Sheath Acts Like an Electrical Insulator Surrounding the Axon
Synaptic Transrnission
Neurotransmitters Relay Signals Across Nerve Synapses
Elevated Calcium Levels Stimulate Secretion of Neurotransmitters from Presynaptic Neurons
Secretion of Neurotransmitters Requires the Docking and Fusion of Vesicles with the Plasma Membrane
Neurotransmgters Are Detected by Specific Receptors on Postsypaptic Neurons
Neurotransmitters Must Be Inactivated Shortly After Their Release
Integration and Processing of Nerve Signals
Neurons Can Integrate Signals from Other Neurons Through Both Temporal and Spatial Summation
Neurons Can Integrate Both Excitatory and Inhibitory Signals from Other Neurons
Summary of Key Points
Making Connections
Problem Set
Suggested Reading
Box 13A Human Applications:Poisoned Arrows.Snake Bites,and Nerve Gases
14 Signal Transduction Mechanisms:II,Messengers and Receptors
Chemical Signals and Cellular Receptors
Different Types of Chemical Signals Can Be Received by Cells
Receptor Binding Involves Specific Interactions Between Ligands and Their Receptors
Receptor Binding Activates a Sequence of Signal Transduction Events Within the Cell
G Protein-Linked Receptors
Seven Membrane Spanning Receptors Act via G Proteins
Cyclic AMP Is a Second Messenger Whose Production is Regulated by Some G Proteins
Disruption of G Protein Signaling Causes Several Human Diseases
Many G Proteins Use lnositol Trisphosphate and Diacylglycerol as Second Messengers
The Release of Calcium Ions Is a Key Event in Many Signaling Processes
Nitric Oxide Couples G Protein Linked Receptor Stimulation in Endothelial Cells to Relaxation of Smooth Muscle ells in Blood Vessels
The βγ Subunits of G Proteins Can Also Transduce Signals
Protein Kinase-Associated Receptors
Growth Factors Often Bind Protein Kinase Associated Receptors
Receptor Tyrosine Kinases Aggregate and Undergo Autophosphorylation
Receptor Tyrosine Kinases Initiate a Signal Transduction Cascade Involving Ras and MAP Kinase
Receptor Tyrosine Kinases Activate a Variety of Other Signaling Pathways
Scaffolding Complexes Can Facilitate Cell Signaling
Dominant Negative Mutant Receptors Are Important Tools for Studying Receptor Function
Other Growth Factors Transduce Their Signals via Receptor SerineThreonine Kinases
Disruption of Growth Factor Signaling Can Lead to Cancer
Growth Factor Receptor Pathways Share Common Themes
Hormonal Signaling
Hormones Can Be Classified by the Distance They Travel and by Their Chemical ProperBes
Control of Glucose Metabolism Is a Good Example of Endocrine Regulation
Insulin Affects Several Signaling Pathways to Regulate Resting Glucose Levels
Cell Signals and Apoptosis
Apoptosis Is Triggered by Death Signals or Withdrawal of Surival Factors
Summary of Key Points
Making Connections
Problem Set
Suggested Reading
Box 14A Experimental Techniques:Using Genetic Model Systems to Study Cell Signaling
15 Cytoskeletal Systems
Major Structural Elements of the Cytoskeleton
Eukaryotes Have Three Basic Types of Cytoskeletal Elements
Bacteria Have Cytoskeletal Systems That Are Structurally Similar to Those in Eukaryotes
The Cytoskeleton Is Dypamicallg Assembled and Disassembled
Microtubules
Two Types of Microtubules Are Responsible for Many Functions in the Cell
Tubufin Heterndimers Are the Protein Building Blocks of Microtubules
Microtubules Can Form as Singlets,Doublets,or Triplets
Microtubules Form by the Addition of Tubulin Dimers at Their Ends
Addition of Tubulin Dimers Occurs More Quickly at the Flus Ends of Microtubules
Dr ugs Can Affect the Assembly o f Microtubules
GTP Hydrolysis Contributes to the Dynamic Instability of Microtubules
Microtubifies Originate from Microtubule Organizing Centers Within the Cell
MTOCs Organize and Polarize the Mierot ubules Within Cells
Microtubule Stability Is Tightly Regulated in CelLs by a Variety of Microtubile-Binding Proteins
Microfilaments
Actin Is the Protein Building Block of Microfilaments
Different Types of Actin Are Found in Cells
G-Actin Monomers Polymerize into F Actin Microfilaments
Specific Drugs Affect Polymerization of Microflaments
Ceils Can Dynamically Assemble Actin into a Variety of Structures
AcBn Binding Proteins Regulate the Polymerization,Length,and Organization of Microfilaments
Cell Signagng Regulates Where and When Actin Based Structures Assemble
Interediate Filaments
Intermediate Filament Proteins Are Tissue Specific
Intermediate Filaments Assemble from Fibrous Subunits
Intermediate Filaments Confer Mechanical Strength on Tissues
The Cytoskeleton Is a Mechanically Integrated Structure
Summary of Key Points
Making Connections
Problem Set
Suggested Reading
Box 15A Human Applications:Infectious Microorganisms Can Move Within Ceils Using Actin "Tails"
16 Cellular Movement:Motility and Contractility
Motile Systems
Intracellular Microtubule-Based Movement:Kinesin and Dynein
MT Motor Proteins Move OrganeUes Along Microt ubules DuringAxonal Transport
Motor Proteins Move Along Microtubules by Hydrolyzing ATP
Kinesins Are a Large Family of Proteins with Varying Structures and Functions
Dyneins Can Be Grouped into Two Major Classes:Axonemal and Cytoplasmic Dyneins
Microtubule Motors Are Involved in Shaping the Endomembrane System and Vesicle Transport
Microtubule-Based Motility:Cilia and Flagella
Cilia and Flagella Are Common Motile Appendages of Eukaryotic Cegs
Cilia and Flagella Consist of an Axoneme Connected to a Basal Body
Microtubule Sliding Within the Axoneme Causes Cilia and Flagega to Bend
Actin-Based Cell Movernent:The Myosins
Myosins Are a Large Family of Actin Based Motors with Diverse Roles in Cell Motility
Many Myosins Move Along Actin Filaments in Short Steps
Filament-Based Movement in Muscle
Skeletal Muscle Cells Contain Thin and Thick Filaments
Sarcomeres Contain Ordered Arrays of Actin,Myosin,and Accessory Proteins
The Sliding Filament Model Explains Muscle Contraction
Cross Bridges Hold Filaments Together,and ATP Powers Their Movement
The Regulation of Muscle Contraction Depends on Calcium
The Coordinated Contraction of Cardiac Muscle Ceils Involves Electrical Coupling
Smooth Muscle Is More Similar to Nonmuscle Cells than to Skeletal Muscle
Actin-Based Motility in Nonmusde Cells
Cell Migration via Lamegipodia Involves Cycles of Protrusion,Attachment,Translocation,and Detachment
Chemotaxis Is a Directional Movement in Response to a Graded Chemical Stimulus
Amoeboid Movement Involves Cycles of Gelation and Solation of the Aciln Cytoskeleton
Aciln-Based Motors Move Components Within the Cytoplasm of Some Cells
Summarty of Key Points
Making Connections
Problem Set
Suggested Reading
Box 16A Human Applications:Cytoskeletaf Motor Proteins and Human Disease
17 Beyond the Cell:Cell Adhesions,Cell Junctions,and Extracellular Structures
Cell-Cell Recognition and Adhesion
Transmemhrane Proteins Mediate Cell Cell Adhesion
Carhohyd rate Groups Are Important in Cell-Cell Recognition and Adhesion
Cell-Cell Junctions
Adhesive Junctions Link Adjoining Ceils to Each Other
Tight Junctions Prevent the Movement of Molecules Across Cell Layers
Gap Junctions Allow Direct Electrical and Chemical Communication Between Cells
The Extracellular Matrix of Animal Ceils
Collagens Are Responsible for the Strength of the Extracellular Matrix
A Precursor Called Procoilagen Forms Many Types of Tissue-Specific Collagens
Elastins Impart Elasticity and Flexibility to the Extraceilular Matrix
Collagen and Elastin Fibers Are Embedded in a Matrix of Proteoglycans
Free Hyaluronate Lubricates Joints and Facilitates Cell Migration
Adhesive Glycoprateins Anchor Cegs to the Ext racel
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