Becker's World of the Cell

Cover
Title Page
Copyright
About The Authors
Detailed Contents
Preface
Acknowledgments
Chapter 1. A Preview of Cell Biology
1.1 The Cell Theory: A Brief History
Advances in Microscopy Allowed Detailed Studies of Cells
The Cell Theory Applies to All Organisms
1.2 The Emergence of Modern Cell Biology
The Cytological Strand Deals with Cellular Structure
The Biochemical Strand Concerns the Chemistry of Biological Structure and Function
The Genetic Strand Focuses on Information Flow
1.3 How Do We Know What We Know?
Biological “Facts” May Turn Out to Be Incorrect
Experiments Test Specific Hypotheses
Model Organisms Play a Key Role in Modern Cell Biology Research
Well-Designed Experiments Alter Only One Variable at a Time
Summary of Key Points
Problem Set
Key Technique: Using Immunofluorescence to Identify Specific Cell Components
Human Connections: The Immortal Cells of Henrietta Lacks
Chapter 2. The Chemistry of the Cell
2.1 The Importance of Carbon
Carbon-Containing Molecules Are Stable
Carbon-Containing Molecules Are Diverse
Carbon-Containing Molecules Can Form Stereoisomers
2.2 The Importance of Water
Water Molecules Are Polar
Water Molecules Are Cohesive
Water Has a High Temperature-Stabilizing Capacity
Water Is an Excellent Solvent
2.3 The Importance of Selectively Permeable Membranes
A Membrane Is a Lipid Bilayer with Proteins Embedded in It
Lipid Bilayers Are Selectively Permeable
2.4 The Importance of Synthesis by Polymerization
Macromolecules Are Critical for Cellular Form and Function
Cells Contain Three Different Kinds of Macromolecular Polymers
Macromolecules Are Synthesized by Stepwise Polymerization of Monomers
2.5 The Importance of Self-Assembly
Noncovalent Bonds and Interactions Are Important in the Folding of Macromolecules
Many Proteins Spontaneously Fold into Their Biologically Functional State
Molecular Chaperones Assist the Assembly of Some Proteins
Self-Assembly Also Occurs in Other Cellular Structures
The Tobacco Mosaic Virus Is a Case Study in Self-Assembly
Self-Assembly Has Limits
Hierarchical Assembly Provides Advantages for the Cell
Summary of Key Points
Problem Set
Key Technique: Determining the Chemical Fingerprint of a Cell Using Mass Spectrometry
Human Connections: Taking a Deeper Look: Magnetic Resonance Imaging (MRI)
Chapter 3. The Macromolecules of the Cell
3.1 Proteins
The Monomers Are Amino Acids
The Polymers Are Polypeptides and Proteins
Several Kinds of Bonds and Interactions Are Important in Protein Folding and Stability
Protein Structure Depends on Amino Acid Sequence and Interactions
3.2 Nucleic Acids
The Monomers Are Nucleotides
The Polymers Are DNA and RNA
A DNA Molecule Is a Double-Stranded Helix
3.3 Polysaccharides
The Monomers Are Monosaccharides
The Polymers Are Storage and Structural Polysaccharides
Polysaccharide Structure Depends on the Kinds of Glycosidic Bonds Involved
3.4 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
Problem Set
Human Connections: Aggregated Proteins and Alzheimer’s
Key Technique: Using X-Ray Crystallography to Determine Protein Structure
Chapter 4. Cells and Organelles
4.1 The Origins of the First Cells
Simple Organic Molecules May Have Formed Abiotically in the Young Earth
RNA May Have Been the First Informational Molecule
Liposomes May Have Defined the First Primitive Protocells
4.2 Basic Properties of Cells
The Three Domains of Life Are Bacteria, Archaea, and Eukaryotes
There Are Several Limitations on Cell Size
Bacteria, Archaea, and Eukaryotes Differ from Each Other in Many Ways
4.3 The Eukaryotic Cell in Overview: Structure and Function
The Plasma Membrane Defines Cell Boundaries and Retains Contents
The Nucleus Is the Information Center of the Eukaryotic Cell
Mitochondria and Chloroplasts Provide Energy for the Cell
The Endosymbiont Theory Proposes That Mitochondria and Chloroplasts Were Derived from Bacteria
The Endomembrane System Synthesizes Proteins for a Variety of Cellular Destinations
Other Organelles Also Have Specific Functions
Ribosomes Synthesize Proteins in the Cytoplasm
The Cytoskeleton Provides Structure to the Cytoplasm
The Extracellular Matrix and Cell Walls Are Outside the Plasma Membrane
4.4 Viruses, Viroids, and Prions: Agents That Invade Cells
A Virus Consists of a DNA or RNA Core Surrounded by a Protein Coat
Viroids Are Small, Circular RNA Molecules That Can Cause Plant Diseases
Prions Are Infectious Protein Molecules
Summary of Key Points
Problem Set
Human Connections: When Cellular “Breakdown” Breaks Down
Key Technique: Using Centrifugation to Isolate Organelles
Chapter 5. Bioenergetics: The Flow of Energy in the Cell
5.1 The Importance of Energy
Cells Need Energy to Perform Six Different Kinds of Work
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
5.2 Bioenergetics
Understanding Energy Flow Requires Knowledge of Systems, Heat, and Work
The First Law of Thermodynamics States That Energy Is Conserved
The Second Law of Thermodynamics States That Reactions Have Directionality
Entropy and Free Energy Are Two Means of Assessing Thermodynamic Spontaneity
5.3 Understanding ΔG and Keq
The Equilibrium Constant Keq Is a Measure of Directionality
ΔG Can Be Calculated Readily
The Standard Free Energy Change Is ΔG Measured Under Standard Conditions
Summing Up: The Meaning of ΔGʹ and ΔG°ʹ
Free Energy Change: Sample Calculations
Jumping Beans Provide a Useful Analogy for Bioenergetics
Life Requires Steady-State Reactions That Move Toward Equilibrium Without Ever Getting There
Summary of Key Points
Problem Set
Human Connections: The “Potential” of Food to Provide Energy
Key Technique: Measuring How Molecules Bind to One Another Using Isothermal Titration Calorimetry
Chapter 6. Enzymes: The Catalysts of Life
6.1 Activation Energy and the Metastable State
Before a Chemical Reaction Can Occur, the Activation Energy Barrier Must Be Overcome
The Metastable State Is a Result of the Activation Barrier
Catalysts Overcome the Activation Energy Barrier
6.2 Enzymes as Biological Catalysts
Most Enzymes Are Proteins
Substrate Binding, Activation, and Catalysis Occur at the Active Site
Ribozymes Are Catalytic RNA Molecules
6.3 Enzyme Kinetics
Monkeys and Peanuts Provide a Useful Analogy for Understanding Enzyme Kinetics
Most Enzymes Display Michaelis–Menten Kinetics
What Is the Meaning of V max and Km?
Why Are Km and Vmax Important to Cell Biologists?
The Double-Reciprocal Plot Is a Useful Means of Visualizing Kinetic Data
Enzyme Inhibitors Act Either Irreversibly or Reversibly
6.4 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 by the Addition or Removal of Chemical Groups
Summary of Key Points
Problem Set
Human Connections: Ace Inhibitors: Enzyme Activity as TheDifference Between Life and Death
Key Technique: Determining Km and Vmax Using Enzyme Assays
Chapter 7. Membranes: Their Structure, Function, and Chemistry
7.1 The Functions of Membranes
Membranes Define Boundaries and Serve as Permeability Barriers
Membranes Contain Specific Proteins and Therefore Have 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
7.2 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
7.3 Membrane Lipids: The “Fluid” Part of the Model
Membranes Contain Several Major Classes of Lipids
Fatty Acids Are Essential to Membrane Structure and Function
Thin-Layer Chromatography Is an Important Technique for Lipid Analysis
Membrane Asymmetry: Most Lipids Are Distributed Unequally Between the Two Monolayers
The Lipid Bilayer Is Fluid
Most Organisms Can Regulate Membrane Fluidity
Lipid Micro- or Nanodomains May Localize Molecules in Membranes
7.4 Membrane Proteins: The “Mosaic” Part of the Model
The Membrane Consists of a Mosaic of Proteins: Evidence from Freeze-Fracture Microscopy
Membranes Contain Integral, Peripheral, and Lipid-Anchored Proteins
Membrane Proteins Can Be Isolated and Analyzed
Determining the Three-Dimensional Structure of Membrane Proteins Is Becoming Easier
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 and Lipids Are Glycosylated
Membrane Proteins Vary in Their Mobility
The Erythrocyte Membrane Contains an Interconnected Network of Membrane-Associated Proteins
Summary of Key Points
Problem Set
Key Technique: Fluorescence Recovery After Photobleaching (FRAP)
Human Connections: It’s All in the Family
Chapter 8. Transport Across Membranes: Overcoming the Permeability Barrier
8.1 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
8.2 Simple Diffusion: Unassisted Movement Down the Gradient
Simple Diffusion Always Moves Solutes Toward Equilibrium
Osmosis Is the Simple Diffusion of Water Across a Selectively Permeable Membrane
Simple Diffusion Is Typically Limited to Small, Uncharged Molecules
The Rate of Simple Diffusion Is Directly Proportional to the Concentration Gradient
8.3 Facilitated Diffusion: Protein-Mediated Movement Down the Gradient
Carrier Proteins and Channel Proteins Facilitate 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
8.4 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
8.5 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
8.6 The Energetics of Transport
For Uncharged Solutes, the ΔG of Transport Depends Only on the Concentration Gradient
For Charged Solutes, the ΔG of Transport Depends on the Electrochemical Potential
Summary of Key Points
Problem Set
Key Technique: Expression of Heterologous Membrane Proteins in Frog Oocytes
Human Connections: Membrane Transport, Cystic Fibrosis, and the Prospects for Gene Therapy
Chapter 9. Chemotrophic Energy Metabolism: Glycolysis and Fermentation
9.1 Metabolic Pathways
9.2 ATP: The Primary Energy Molecule in Cells
ATP Contains Two Energy-Rich Phosphoanhydride Bonds
ATP Hydrolysis Is Exergonic Due to Several Factors
ATP Is Extremely Important in Cellular Energy Metabolism
9.3 Chemotrophic Energy Metabolism
Biological Oxidations Usually Involve the Removal of Both Electrons and Protons and Are Exergonic
Coenzymes Such as NAD+ Serve 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
9.4 Glycolysis: ATP Generation Without the Involvement of Oxygen
Glycolysis Generates ATP by Catabolizing Glucose to Pyruvate
9.5 Fermentation
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 Efficiently as ATP
Cancer Cells Ferment Glucose to Lactate Even in the Presence of Oxygen
9.6 Alternative Substrates for Glycolysis
Other Sugars and Glycerol Are Also Catabolized by the Glycolytic Pathway
Polysaccharides Are Cleaved to Form Sugar Phosphates That Also Enter the Glycolytic Pathway
9.7 Gluconeogenesis
9.8 The Regulation of Glycolysis and Gluconeogenesis
Key Enzymes in the Glycolytic and Gluconeogenic Pathways Are Subject to Allosteric Regulation
Fructose-2,6-Bisphosphate Is an Important Regulator of Glycolysis and Gluconeogenesis
Glycolytic Enzymes May Have Functions Beyond Glycolysis
Summary of Key Points
Problem Set
Key Technique: Using Isotopic Labeling to Determine the Fate of Atoms in a Metabolic Pathway
Human Connections: What Happens to the Sugar?
Chapter 10. Chemotrophic Energy Metabolism: Aerobic Respiration
10.1 Cellular Respiration: Maximizing ATP Yields
Aerobic Respiration Yields Much More Energy than Fermentation Does
Respiration Includes Glycolysis, Pyruvate Oxidation, the Citric Acid Cycle, Electron Transport, and ATP Synthesis
10.2 The Mitochondrion: Where the Action Takes Place
Mitochondria Are Often Present Where the ATP Needs Are Greatest
Mitochondria Can Adopt Complex Shapes and Vary in Number in Different Cell Types
The Outer and Inner Membranes Define Two Separate Mitochondrial Compartments and Three Regions
Many Mitochondrial Proteins Originate in the Cytosol
Mitochondrial Functions Occur in or on Specific Membranes and Compartments
In Bacteria, Respiratory Functions Are Localized to the Plasma Membrane and the Cytoplasm
10.3 The Citric Acid Cycle: Oxidation in the Round
Pyruvate Is Converted to Acetyl Coenzyme A by Oxidative Decarboxylation
The Citric Acid Cycle Begins with the Entry of Two Carbons from Acetyl CoA
Two Oxidative Decarboxylations Then Form NADH and Release CO2
Direct Generation of GTP (or ATP) Occurs at One Step in the Citric Acid Cycle
The Final Oxidative Reactions of the Citric Acid Cycle Generate FADH2 and NADH
Summing Up: The Products of the Citric Acid Cycle Are CO2 , ATP, NADH, and FADH2
Several Citric Acid Cycle Enzymes Are Subject to Allosteric Regulation
The Citric Acid Cycle Also Plays a Central Role in the Catabolism of Fats and Proteins
The Citric Acid Cycle Serves as a Source of Precursors for Anabolic Pathways
The Glyoxylate Cycle Converts Acetyl CoA to Carbohydrates in Plants
10.4 Electron Transport: Electron Flow from Coenzymes to Oxygen
The Electron Transport Chain Conveys Electrons from Reduced Coenzymes to Oxygen
The Electron Transport Chain Consists of Five Kinds of Carriers
The Electron Carriers Function in a Sequence Determined by Their Reduction Potentials
Most of the Carriers Are Organized into Four Large Respiratory Complexes
The Respiratory Complexes Move Freely Within the Inner Membrane
10.5 The Electrochemical Proton Gradient: Key to Energy Coupling
Electron Transport and ATP Synthesis Are Coupled Events
Coenzyme Oxidation Pumps Enough Protons to Form Three ATP Moleculesper NADH and Two ATP Molecules per FADH2
The Chemiosmotic Model Is Affirmed by an Impressive Array of Evidence
10.6 ATP Synthesis: Putting It All Together
F1 Particles Have ATP Synthase Activity
Proton Translocation Through Fo Drives ATP Synthesis by F1
ATP Synthesis by FoF1 Involves Physical Rotation of the Gamma Subunit
10.7 Aerobic Respiration: Summing It All Up
The Actual ATP Yield per Glucose during Aerobic Respiration Is Influencedby Several Factors
Aerobic Respiration: A Remarkable Process
Summary of Key Points
Problem Set
Key Technique: Visualizing Cellular Structures with Three-Dimensional Electron Microscopy
Human Connections: A Diet Worth Dying For?
Chapter 11. Phototrophic Energy Metabolism: Photosynthesis
11.1 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 Organelle in Eukaryotic Cells
Chloroplasts Are Composed of Three Membrane Systems
11.2 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
11.3 Photosynthetic Energy Transduction II: NADPH Synthesis
Photosystem II Transfers Electrons from Water to a Plastoquinone
The Cytochrome b6/f Complex Transfers Electrons from a Plastoquinol to Plastocyanin
Photosystem I Transfers Electrons from Plastocyanin to Ferredoxin
Ferredoxin-NADP+ Reductase Catalyzes the Reduction of NADP+
11.4 Photosynthetic Energy Transduction III: ATP Synthesis
A Chloroplast ATP Synthase 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
Bacteria Use a Photosynthetic Reaction Center and Electron Transport System Similar to Those in Plants
11.5 Photosynthetic Carbon Assimilation I: The Calvin Cycle
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
11.6 Regulation of the Calvin Cycle
The Calvin Cycle Is Highly Regulated to Ensure Maximum Efficiency
Rubisco Activase Regulates Carbon Fixation by Rubisco
11.7 Photosynthetic Carbon Assimilation II: Carbohydrate Synthesis
Glucose-1-Phosphate Is Synthesized from Triose Phosphates
Biosynthesis of Sucrose Occurs in the Cytosol
Biosynthesis of Starch Occurs in the Chloroplast Stroma
Photosynthesis Also Produces Reduced Nitrogen and Sulfur Compounds
11.8 Rubisco’s Oxygenase Activity Decreases Photosynthetic Efficiency
The Glycolate Pathway Returns Reduced Carbon from Phosphoglycolate to the Calvin Cycle
C4 Plants Minimize Photorespiration by Confining Rubisco to CellsContaining High Concentrations of CO2
CAM Plants Minimize Photorespiration and Water Loss by Opening Their Stomata Only at Night
Summary of Key Points
Problem Set
Key Technique: Determining Absorption and Action Spectra via Spectrophotometry
Human Connections: How Do Plants Put On Sunscreen?
Chapter 12. The Endomembrane System and Protein Sorting
12.1 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
12.2 The Golgi Apparatus
The Golgi Apparatus Consists of a Series of Membrane-Bounded Cisternae
Two Models Account for the Flow of Lipids and Proteins Through the Golgi Apparatus
12.3 Roles of the ER and Golgi Apparatus in Protein Processing
Protein Folding and Quality Control Take Place Within the ER
Initial Glycosylation Occurs in the ER
Further Glycosylation Occurs in the Golgi Apparatus
12.4 Roles of the ER and Golgi Apparatus In Protein Trafficking
Cotranslational Import Allows Some Polypeptides to Enter the ER as They Are Being Synthesized
The Signal Recognition Particle (SRP) Attaches the Ribosome-mRNA-PolypeptideComplex to the ER Membrane
Proteins Released into the ER Lumen Are Routed to the Golgi Apparatus, Secretory Vesicles, Lysosomes, or Back to the ER
Stop-Transfer Sequences Mediate the Insertion of Integral Membrane Proteins
Posttranslational Import Is an Alternative Mechanism for Import into the ER Lumen
12.5 Exocytosis and Endocytosis: Transporting Material Across the Plasma Membrane
Secretory Pathways Transport Molecules to the Exterior of the Cell
Exocytosis Releases Intracellular Molecules Outside the Cell
Endocytosis Imports Extracellular Molecules by Forming Vesicles from the Plasma Membrane
12.6 Coated Vesicles in Cellular Transport Processes
Clathrin-Coated Vesicles Are Surrounded by Lattices Composed of Clathrin and Adaptor Protein
The Assembly of Clathrin Coats Drives the Formation of Vesicles from the Plasma Membrane and TGN
COPI- and COPII-Coated Vesicles Travel Between the ER and Golgi Apparatus Cisternae
SNARE Proteins Mediate Fusion Between Vesicles and Target Membranes
12.7 Lysosomes and Cellular Digestion
Lysosomes Isolate Digestive Enzymes from the Rest of the Cell
Lysosomes Develop from Endosomes
Lysosomal Enzymes Are Important for Several Different Digestive Processes
Lysosomal Storage Diseases Are Usually Characterized by the Accumulation of Indigestible Material
The Plant Vacuole: A Multifunctional Digestive Organelle
12.8 Peroxisomes
Most Peroxisomal Functions Are Linked to Hydrogen Peroxide Metabolism
Plant Cells Contain Types of Peroxisomes Not Found in Animal Cells
Peroxisome Biogenesis Can Occur by Division of Preexisting Peroxisomes or by Vesicle Fusion
Summary of Key Points
Problem Set
Key Technique: Visualizing Vesicles at the Cell Surface Using Total Internal Reflection (TIRF) Microscopy
Human Connections: A Bad Case of the Munchies? (Autophagy In Inflammatory Bowel Disease)
Chapter 13. Cytoskeletal Systems
13.1 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 Dynamically Assembled and Disassembled
13.2 Microtubules
Two Types of Microtubules Are Responsible for Many Functions in the Cell
Tubulin Heterodimers 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 Plus Ends of Microtubules
Drugs Can Affect the Assembly and Stability of Microtubules
GTP Hydrolysis Contributes to the Dynamic Instability of Microtubules
Microtubules Originate from Microtubule-Organizing Centers Within the Cell
MTOCs Organize and Polarize Microtubules Within Cells
Microtubule Stability Is Tightly Regulated in Cells by a Variety of Microtubule-Binding Proteins
13.3 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 Microfilaments
Cells Can Dynamically Assemble Actin into a Variety of Structures
Actin-Binding Proteins Regulate the Polymerization, Length, and Organization of Microfilaments
Proteins That Link Actin to Membranes
Phospholipids and Rho Family GTPases Regulate Where and When Actin-Based Structures Assemble
13.4 Intermediate 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
Problem Set
Key Technique: Studying the Dynamic Cytoskeleton
Human Connections: When Actin Kills
Chapter 14. Cellular Movement: Motility and Contractility
14.1 Microtubule-Based Movement Inside Cells: Kinesins and Dyneins
Motor Proteins Move Cargoes Along MTs During Axonal Transport
Classic Kinesins Move Toward the Plus Ends of Microtubules
Kinesins Are a Large Family of Proteins
Dyneins Are Found in Axonemes and the Cytosol
Microtubule Motors Direct Vesicle Transport and Shape the Endomem-brane System
14.2 Microtubule-Based Cell Motility: Cilia And Flagella
Cilia and Flagella Are Common Motile Appendages of Eukaryotic Cells
Cilia and Flagella Consist of an Axoneme Connected to a Basal Body
Doublet Sliding Within the Axoneme Causes Cilia and Flagella to Bend
14.3 Microfilament-Based Movement Inside Cells: 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
14.4 Microfilament-Based Motility: Muscle Cells In Action
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 Cells Involves Electrical Coupling
Smooth Muscle Is More Similar to Nonmuscle Cells than to Skeletal Muscle
14.5 Microfilament-Based Motility In Nonmuscle Cells
Cell Migration via Lamellipodia 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 Actin
Actin-Based Motors Move Components Within the Cytosol of Some Cells
Summary of Key Points
Problem Set
Key Technique: Watching Motors Too Small to See
Human Connections: Dyneins Help Us Tell Left From Right
Chapter 15. Beyond the Cell: Cell Adhesions, Cell Junctions, and Extracellular Structures
15.1 Cell-Cell Junctions
Adhesive Junctions Link Adjoining Cells
Transient Cell-Cell Adhesions Are Important for Many Cellular Events
Tight Junctions Prevent the Movement of Molecules Across Cell Layers
Gap Junctions Allow Direct Electrical and Chemical Communication Between Cells
15.2 The Extracellular Matrix of Animal Cells
Collagens Are Responsible for the Strength of the Extracellular Matrix
Elastins Impart Elasticity and Flexibility to the Extracellular Matrix
Collagen and Elastin Fibers Are Embedded in a Matrix of Proteoglycans
Free Hyaluronate Lubricates Joints and Facilitates Cell Migration
Adhesive Glycoproteins Anchor Cells to the Extracellular Matrix
Fibronectins Bind Cells to the ECM and Foster Cellular Movement
Laminins Bind Cells to the Basal Lamina
Integrins Are Cell Surface Receptors That Bind ECM Components
The Dystrophin/Dystroglycan Complex Stabilizes Attachments of Muscle Cells to the ECM
15.3 The Plant Cell Surface
Cell Walls Provide a Structural Framework and Serve as a Permeability Barrier
The Plant Cell Wall Is a Network of Cellulose Microfibrils, Polysaccharides, and Glycoproteins
Cell Walls Are Synthesized in Several Discrete Stages
Plasmodesmata Permit Direct Cell-Cell Communication Through the Cell Wall
Summary of Key Points
Problem Set
Human Connections: The Costly Effects of Weak Adhesion
Key Technique: Building an ECM from Scratch
Chapter 16. The Structural Basis of Cellular Information: DNA, Chromosomes, and the Nucleus
16.1 Chemical Nature of the Genetic Material
The Discovery of DNA Led to Conflicting Proposals Concerning the Chemical Nature of Genes
Avery, MacLeod, and McCarty Showed That DNA Is the Genetic Material of Bacteria
Hershey and Chase Showed That DNA Is the Genetic Material of Viruses
RNA Is the Genetic Material in Some Viruses
16.2 DNA Structure
Chargaff ’s Rules Reveal That A = T and G = C
Watson and Crick Discovered That DNA Is a Double Helix
DNA Can Be Interconverted Between Relaxed and Supercoiled Forms
The Two Strands of a DNA Double Helix Can Be Denatured and Renatured
16.3 DNA Packaging
Bacteria Package DNA in Bacterial Chromosomes and Plasmids
Eukaryotes Package DNA in Chromatin and Chromosomes
Nucleosomes Are the Basic Unit of Chromatin Structure
A Histone Octamer Forms the Nucleosome Core
Nucleosomes Are Packed Together to Form Chromatin Fibers and Chromosomes
Changes in Histones and Chromatin Remodeling Proteins Can Alter Chromatin Packing
Chromosomal DNA Contains Euchromatin and Heterochromatin
Some Heterochromatin Plays a Structural Role in Chromosomes
Chromosomes Can Be Identified by Unique Banding Patterns
Eukaryotic Chromosomes Contain Large Amounts of Repeated DNA Sequences
Eukaryotes Package Some of Their DNA in Mitochondria and Chloroplasts
16.4 The Nucleus
A Double-Membrane Nuclear Envelope Surrounds the Nucleus
Molecules Enter and Exit the Nucleus Through Nuclear Pores
The Nucleus Is Mechanically Integrated with the Rest of the Cell
Chromatin Is Located Within the Nucleus in a Nonrandom Fashion
The Nucleolus Is Involved in Ribosome Formation
Summary of Key Points
Problem Set
Key Technique: FISHing for Specific Sequences
Human Connections: Lamins and Premature Aging
Chapter 17. DNA Replication, Repair, and Recombination
17.1 DNA Replication
DNA Synthesis Occurs During S Phase
DNA Replication Is Semiconservative
DNA Replication Is Usually Bidirectional
Replication Initiates at Specialized DNA Elements
DNA Polymerases Catalyze the Elongation of DNA Chains
DNA Is Synthesized as Discontinuous Segments That Are Joined Together by DNA Ligase
In Bacteria, Proofreading Is Performed by the 3'→5' Exonuclease Activity of DNA Polymerase
RNA Primers Initiate DNA Replication
The DNA Double Helix Must Be Locally Unwound During Replication
DNA Unwinding and DNA Synthesis Are Coordinated on Both Strands via the Replisome
Eukaryotes Disassemble and Reassemble Nucleosomes as Replication Proceeds
Telomeres Solve the DNA End-Replication Problem
17.2 DNA Damage and Repair
Mutations Can Occur Spontaneously During Replication
Mutagens Can Induce Mutations
DNA Repair Systems Correct Many Kinds of DNA Damage
17.3 Homologous Recombination and Mobile Genetic Elements
Homologous Recombination Is Initiated by Double-Strand Breaks in DNA
Transposons Are Mobile Genetic Elements
Transposons Differ Based on Their Autonomy and Mechanism of Movement
Bacterial DNA-Only Transposons Can Be Composite or Noncomposite
Eukaryotes Also Have DNA-Only Transposons
Retrotransposons
Summary of Key Points
Problem Set
Human Connections: Children of The Moon
Key Technique: CRISPR/Cas9 Genome Editing
Chapter 18. Gene Expression: I. Transcription
18.1 The Directional Flow of Genetic Information
Transcription and Translation Involve Many of the Same Components in Prokaryotes and Eukaryotes
Where Transcription and Translation Occur Differs in Prokaryotes and Eukaryotes
In Some Cases RNA Is Reversed Transcribed into DNA
18.2 Mechanisms of Transcription
Transcription Involves Four Stages: RNA Polymerase Binding, Initiation, Elongation, and Termination
Bacterial Transcription Involves ˜ Factor Binding, Initiation, Elongation, and Termination
Transcription in Eukaryotic Cells Has Additional Complexity Compared with Prokaryotes
RNA Polymerases I, II, and III Carry Out Transcription in the Eukaryotic Nucleus
Three Classes of Promoters Are Found in Eukaryotic Nuclear Genes, One for Each Type of RNA Polymerase
General Transcription Factors Are Involved in the Transcription of All Nuclear Genes
Elongation, Termination, and RNA Cleavage Are Involved in Completing Eukaryotic RNA Synthesis
18.3 RNA Processing and Turnover
The Nucleolus Is Involved in Ribosome Formation
Ribosomal RNA Processing Involves Cleavage of Multiple rRNAs from a Common Precursor
Transfer RNA Processing Involves Removal, Addition, and Chemical Modification of Nucleotides
Messenger RNA Processing in Eukaryotes Involves Capping, Addition of Poly(A), and Removal of Introns
Spliceosomes Remove Introns from Pre-mRNA
Some Introns Are Self-Splicing
The Existence of Introns Permits Alternative Splicing and Exon Shuffling
Cells Localize Nuclear RNAs in Several Types of Processing Centers
Nucleic Acid Editing Allows Sequences to Be Altered
The C-Terminal Domain of RNA Polymerase II Coordinates RNA Processing
Nuclear Export of Mature mRNA
Most mRNA Molecules Have a Relatively Short Life Span
The Abundance of mRNA Allows Amplification of Genetic Information
Summary of Key Points
Problem Set
Key Technique: Hunting for DNA-Protein Interactions
Human Connections: Death by Fungus (Amanita PhalloidesPoisoning)
Chapter 19. Gene Expression: II. The Genetic Code and Protein Synthesis
19.1 The Genetic Code
The Genetic Code Is a Triplet Code
The Genetic Code Is Degenerate and Nonoverlapping
Messenger RNA Guides the Synthesis of Polypeptide Chains
The Codon Dictionary Was Established Using Synthetic RNA Polymers and Triplets
Of the 64 Possible Codons in Messenger RNA, 61 Encode Amino Acids
The Genetic Code Is (Nearly) Universal
Codon Usage Bias
19.2 Translation: The Cast of Characters
Ribosomes Carry Out Polypeptide Synthesis
Transfer RNA Molecules Bring Amino Acids to the Ribosome
Aminoacyl-tRNA Synthetases Link Amino Acids to the Correct Transfer RNAs
Messenger RNA Brings Polypeptide Coding Information to the Ribosome
Protein Factors Are Required for Translational Initiation, Elongation, and Termination
19.3 The Mechanism of Translation
Translational Initiation Requires Initiation Factors, Ribosomal Subunits, mRNA, and Initiator tRNA
Chain Elongation Involves Cycles of Aminoacyl tRNA Binding, Peptide Bond Formation, and Translocation
Most mRNAs Are Read by Many Ribosomes Simultaneously
Termination of Polypeptide Synthesis Is Triggered by Release Factors That Recognize Stop Codons
Polypeptide Folding Is Facilitated by Molecular Chaperones
Protein Synthesis Typically Utilizes a Substantial Fraction of a Cell’s Energy Budget
A Summary of Translation
19.4 Mutations and Translation
Suppressor tRNAs Overcome the Effects of Some Mutations
Nonsense-Mediated Decay and Nonstop Decay Promote the Destruction of Defective mRNAs
19.5 Posttranslational Processing
Summary of Key Points
Problem Set
Human Connections: To Catch a Killer: The Problem of Antibiotic Resistance In Bacteria
Key Technique: Protein Localization Using Fluorescent Fusion Proteins
Chapter 20. The Regulation of Gene Expression
20.1 Bacterial Gene Regulation
Catabolic and Anabolic Pathways Are Regulated Through Induction and Repression, Respectively
The Genes Involved in Lactose Catabolism Are Organized into an Inducible Operon
The lac Operon Is Negatively Regulated by the lac Repressor
Studies of Mutant Bacteria Revealed How the lac Operon Is Organized
Catabolite Activator Protein (CAP) Positively Regulates the lac Operon
The lac Operon Is an Example of the Dual Control of Gene Expression
The Structure of the lac Repressor/Operator Complex Confirms the Operon Model
The Genes Involved in Tryptophan Synthesis Are Organized into a Repressible Operon
Sigma Factors Determine Which Sets of Genes Can Be Expressed
Attenuation Allows Transcription to Be Regulated After the Initiation Step
Riboswitches Allow Transcription and Translation to Be Controlled by Small-Molecule Interactions with RNA
The CRISPR/Cas System Protects Bacteria Against Viral Infection
20.2 Eukaryotic Gene Regulation: Genomic Control
Multicellular Eukaryotes Are Composed of Numerous Specialized Cell Types
Eukaryotic Gene Expression Is Regulated at Five Main Levels
The Cells of a Multicellular Organism Usually Contain the Same Set of Genes
Gene Amplification and Deletion Can Alter the Genome
DNA Rearrangements Can Alter the Genome
Chromatin Decondensation Is Involved in Genomic Control
DNA Methylation Is Associated with Inactive Regions of the Genome
20.3 Eukaryotic Gene Regulation: Transcriptional Control
Different Sets of Genes Are Transcribed in Different Cell Types
Proximal Control Elements Lie Close to the Promoter
Enhancers and Silencers Are DNA Elements Located at Variable Distances from the Promoter
Coactivators Mediate the Interaction Between Regulatory Transcription Factors and the RNA Polymerase Complex
Multiple DNA Control Elements and Transcription Factors Act in Combination
DNA-Binding and Activation Domains of Regulatory Transcription Factors Are Functionally Separable
Several Common Types of Transcription Factors Bind to DNA and Activate Transcription
DNA Response Elements Coordinate the Expression of Nonadjacent Genes
Steroid Hormone Receptors Act as Transcription Factors That Bind to Hormone Response Elements
CREBs and STATs Are Examples of Transcription Factors Activated by Phosphorylation
The Heat Shock Response Element Coordinates Stress Responses
Homeotic Genes Encode Transcription Factors That Regulate Embryonic Development
20.4 Eukaryotic Gene Regulation: Posttranscriptional Control
Control of RNA Processing and Nuclear Export Follows Transcription
Translation Rates Can Be Controlled by Initiation Factors and Translational Repressors
Translation Can Also Be Controlled by Regulation of mRNA Degradation
RNA Interference Utilizes Small RNAs to Silence Gene Expression
MicroRNAs Produced by Normal Cellular Genes Silence the Translation of mRNAs
Piwi-Interacting RNAs Are Small Regulatory RNAs That Protect the Germline of Eukaryotes
Long Noncoding RNAs Play a Variety of Roles in Eukaryotic Gene Regulation
Posttranslational Control Involves Modifications of Protein Structure, Function, and Degradation
Ubiquitin Targets Proteins for Degradation by Proteasomes
A Summary of Eukaryotic Gene Regulation
Summary of Key Points
Problem Set
Human Connections: The Epigenome: Methylation and Disease
Key Technique: Gene Knockdown via RNAi
Chapter 21. Molecular Biology Techniques for Cell Biology
21.1 Analyzing, Manipulating, and Cloning DNA
PCR Is Widely Used to Clone Genes
Restriction Endonucleases Cleave DNA Molecules at Specific Sites
Gel Electrophoresis Allows DNA to Be Separated by Size
Restriction Mapping Can Characterize DNA
Southern Blotting Identifies Specific DNAs from a Mixture
Restriction Enzymes Allow Production of Recombinant DNA
DNA Cloning Can Use Bacterial Cloning Vectors
Genomic and cDNA Libraries Are Both Useful for DNA Cloning
21.2 Sequencing and Analyzing Genomes
Rapid Procedures Exist for DNA Sequencing
Whole Genomes Can Be Sequenced
Comparative Genomics Allows Comparison of Genomes and Genes Within Them
The Field of Bioinformatics Helps Decipher Genomes
Tiny Differences in Genome Sequence Distinguish People from One Another
21.3 Analyzing RNA and Proteins
Several Techniques Allow Detection of mRNAs in Time and Space
The Transcription of Thousands of Genes Can Be Assessed Simultaneously
Proteins Can Be Studied Using Electrophoresis
Antibodies Can Be Used to Study Specific Proteins
Proteins Can Be Isolated by Size, Charge, or Affinity
Proteins Can Be Identified from Complex Mixtures Using Mass Spectrometry
Protein Function Can Be Studied Using Molecular Biology Techniques
Protein-Protein Interactions Can Be Studied in a Variety of Ways
21.4 Analyzing and Manipulating Gene Function
Transgenic Organisms Carry Foreign Genes That Are Passed on to Subsequent Generations
Transcriptional Reporters Are Useful for Studying Regulation of Gene Expression
The Role of Specific Genes Can Be Assessed By Identifying Mutations and by Knockdown
Genetic Engineering Can Produce Valuable Proteins That Are Otherwise Difficult to Obtain
Food Crops Can Be Genetically Modified
Gene Therapies Are Being Developed for the Treatment of Human Diseases
Summary of Key Points
Problem Set
Key Technique: The Polymerase Chain Reaction (PCR)
Human Connections: More Than Your Fingertips: Identifying Genetic “Fingerprints”
Chapter 22. Signal Transduction Mechanisms: I. Electrical and Synaptic Signaling in Neurons
22.1 Neurons and Membrane Potential
Neurons Are Specially Adapted to Transmit Electrical Signals
Neurons Undergo Changes in Membrane Potential
Neurons Display Electrical Excitability
Resting Membrane Potential Depends on Ion Concentrations and Selective Membrane Permeability
The Nernst Equation Describes the Relationship Between Membrane Potential and Ion Concentration
Steady-State Ion Concentrations Affect Resting Membrane Potential
The Goldman Equation Describes the Combined Effects of Ions on Membrane Potential
22.2 Electrical Excitability and the Action Potential
Patch Clamping and Molecular Biological Techniques Allow Study of Single Ion Channels
Specific Domains of Voltage-Gated Channels Act as Sensors and Inactivators
Action Potentials Propagate Electrical Signals Along an Axon
Action 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 Losing Strength
The Myelin Sheath Acts Like an Electrical Insulator Surrounding the Axon
22.3 Synaptic Transmission and Signal Integration
Neurotransmitters Relay Signals Across Nerve Synapses
Elevated Calcium Levels Stimulate Secretion of Neurotransmitters from Presynaptic Neurons
Secretion of Neurotransmitters Involves the Docking and Fusion of Vesicles with the Plasma Membrane
Neurotransmitters Are Detected by Specific Receptors on Postsynaptic Neurons
Neurotransmitters Must Be Inactivated Shortly After Their Release
Postsynaptic Potentials Integrate Signals from Multiple Neurons
Summary of Key Points
Problem Set
Key Technique: Patch Clamping
Human Connections: The Toxic Price of the Fountain of Youth
Chapter 23. Signal Transduction Mechanisms: II. Messengers and Receptors
23.1 Chemical Signals and Cellular Receptors
Chemical Signaling Involves Several Key Components
Receptor Binding Involves Quantitative Interactions Between Ligands and Their Receptors
Cells Can Amplify Signals Once They Are Received
Cell-Cell Signals Act Through a Limited Number of Receptors and Signal Transduction Pathways
23.2 G Protein–Coupled Receptors
G Protein–Coupled Receptors Act via Hydrolysis of GTP
Cyclic AMP Is a Second Messenger Whose Production Is Regulated by Some G Proteins
Disruption of G Protein Signaling Causes Human Disease
Many G Proteins Act Through Inositol Trisphosphate and Diacylglycerol
The Release of Calcium Ions Is a Key Event in Many Signaling Processes
23.3 Enzyme-Coupled 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
The Key Steps in RTK Signaling Can Be Dissected Using Mutants
Receptor Tyrosine Kinases Activate a Variety of Other Signaling Pathways
Other Growth Factors Transduce Their Signals via Receptor Serine-Threonine Kinases
Other Enzyme-Coupled Receptors Families
23.4 Putting It All Together: Signal Integration
Scaffolding Complexes Can Facilitate Cell Signaling
Different Signaling Pathways Are Integrated Through Crosstalk
23.5 Hormones and Other Long-Range Signals
Hormones Can Be Classified by Their Chemical Properties
The Endocrine System Controls Multiple Signaling Pathways to Regulate Glucose Levels
Steroid Hormones Bind Hormones in the Cytosol and Carry Them into the Nucleus
Gases Can Act as Cell Signals
Summary of Key Points
Problem Set
Key Technique: Calcium Indicators and Ionophores
Human Connections: The Gas That Prevents a Heart Attack
Chapter 24. The Cell Cycle and Mitosis
24.1 Overview of the Cell Cycle
24.2 Nuclear and Cell Division
Mitosis Is Subdivided into Prophase, Prometaphase, Metaphase, Anaphase, and Telophase
The Mitotic Spindle Is Responsible for Chromosome Movements During Mitosis
Cytokinesis Divides the Cytoplasm
Bacteria and Eukaryotic Organelles Divide in a Different Manner from Eukaryotic Cells
24.3 Regulation of the Cell Cycle
Cell Cycle Length Varies Among Different Cell Types
Cell Cycle Progression Is Controlled at Several Key Transition Points
Cell Fusion Experiments and Cell Cycle Mutants Identified Molecules That Control the Cell Cycle
The Cell Cycle Is Controlled by Cyclin-Dependent Kinases (Cdks)
Cdk-Cyclin Complexes Are Tightly Regulated
The Anaphase-Promoting Complex Allows Exit from Mitosis
Checkpoint Pathways Monitor Key Steps in the Cell Cycle
24.4 Growth Factors and Cell Proliferation
Stimulatory Growth Factors Activate the Ras Pathway
Stimulatory Growth Factors Can Also Activate the PI 3-Kinase–Akt Pathway
Inhibitory Growth Factors Act Through Cdk Inhibitors
Putting It All Together: The Cell Cycle Regulation Machine
24.5 Apoptosis
Apoptosis Is Triggered by Death Signals or Withdrawal of Survival Factors
Summary of Key Points
Problem Set
Key Technique: Measuring Cells Millions at a Time
Human Connections: What do Ethnobotany and Cancer Have in Common?
Chapter 25. Sexual Reproduction, Meiosis, and Genetic Recombination
25.1 Sexual Reproduction
Sexual Reproduction Produces Genetic Variety
Gametes Are Haploid Cells Specialized for Sexual Reproduction
25.2 Meiosis
The Life Cycles of Sexual Organisms Have Diploid and Haploid Phases
Meiosis Converts One Diploid Cell into Four Haploid Cells
Meiosis I Produces Two Haploid Cells That Have Chromosomes Composed of Sister Chromatids
Meiosis II Resembles a Mitotic Division
Defects in Meiosis Lead to Nondisjunction
Sperm and Egg Cells Are Generated by Meiosis Accompanied by Cell Differentiation
Meiotic Maturation of Oocytes Is Tightly Regulated
25.3 Genetic Variability: Segregation and Assortment of Alleles
Meiosis Generates Genetic Diversity
Information Specifying Recessive Traits Can Be Present Without Being Displayed
Alleles of Each Gene Segregate from Each Other During Gamete Formation
Alleles of Each Gene Segregate Independently of the Alleles of Other Genes
Chromosome Behavior Explains the Laws of Segregation and Independent Assortment
The DNA Molecules of Homologous Chromosomes Have Similar Base Sequences
25.4 Genetic Variability: Recombination and Crossing Over
Chromosomes Contain Groups of Linked Genes That Are Usually Inherited Together
Homologous Chromosomes Exchange Segments During Crossing Over
Gene Locations Can Be Mapped by Measuring Recombination Frequencies
25.5 Genetic Recombination in Bacteria and Viruses
Co-infection of Bacterial Cells with Related Bacteriophages Can Lead to Genetic Recombination
Recombination in Bacteria Can Occur via Transformation or Transduction
Conjugation Is a Modified Sexual Activity That Facilitates Genetic Recombination in Bacteria
25.6 Mechanisms of Homologous Recombination
DNA Breakage and Exchange Underlie Homologous Recombination Between Chromosomes
The Synaptonemal Complex Facilitates Homologous Recombination During Meiosis
Homologous Recombination Between Chromosomes Relies on High-Fidelity DNA Repair
Summary of Key Points
Problem Set
Human Connections: When Meiosis Goes Awry
Key Technique: Using Mendel’s Rules to Predict Human Disease
Chapter 26. Cancer Cells
26.1 How Cancers Arise
Tumors Arise When the Balance Between Cell Division and Cell Differentiation or Death Is Disrupted
Cancer Cell Proliferation Is Anchorage Independent and Insensitive to Population Density
Cancer Cells Are Immortalized by Mechanisms That Maintain Telomere Length
Defects in Signaling Pathways, Cell Cycle Controls, and Apoptosis Contribute to Cancer
Cancer Arises Through a Multistep Process Involving Initiation, Promotion, and Tumor Progression
26.2 How Cancers Spread
Angiogenesis Is Required for Tumors to Grow Beyond a Few Millimeters in Diameter
Blood Vessel Growth Is Controlled by a Balance Between Angiogenesis Activators and Inhibitors
Cancer Cells Spread by Invasion and Metastasis
Changes in Cell Adhesion, Motility, and Protease Production Promote Metastasis
Relatively Few Cancer Cells Survive the Voyage Through the Bloodstream
Blood Flow and Organ-Specific Factors Determine Sites of Metastasis
The Immune System Influences the Growth and Spread of Cancer Cells
The Tumor Microenvironment Influences Tumor Growth, Invasion, and Metastasis
26.3 What Causes Cancer?
Epidemiological Data Have Allowed Many Causes of Cancer to Be Identified
Errors in DNA Replication or Repair Explain Many Cancers
Inborn Errors Explain Some Cancers
Many Chemicals Can Cause Cancer, Often After Metabolic Activation in the Liver
DNA Mutations Triggered by Chemical Carcinogens Lead to Cancer
Ionizing and Ultraviolet Radiation Also Cause DNA Mutations That Lead to Cancer
Viruses and Other Infectious Agents Trigger the Development of Some Cancers
26.4 Oncogenes and Tumor Suppressor Genes
Oncogenes Are Genes Whose Products Can Trigger the Development of Cancer
Proto-oncogenes Are Converted into Oncogenes by Several Distinct Mechanisms
Most Oncogenes Encode Components of Growth-Signaling Pathways
Tumor Suppressor Genes Are Genes Whose Loss or Inactivation Can Lead to Cancer
The RB Tumor Suppressor Gene Was Discovered by Studying Families with Hereditary Retinoblastoma
The p53 Tumor Suppressor Gene Is the Most Frequently Mutated Gene in Human Cancers
The APC Tumor Suppressor Gene Encodes a Protein That Inhibits the Wnt Signaling Pathway
Inactivation of Some Tumor Suppressor Genes Leads to Genetic Instability
Cancers Develop by the Stepwise Accumulation of Mutations Involving Oncogenes and Tumor Suppressor Genes
Epigenetic Changes in Gene Expression Influence the Properties of Cancer Cells
Summing Up: Carcinogenesis and the Hallmarks of Cancer
26.5 Diagnosis, Screening, and Treatment
Cancer Is Diagnosed by Microscopic and Molecular Examination of Tissue Specimens
Screening Techniques for Early Detection Can Prevent Cancer Deaths
Surgery, Radiation, and Chemotherapy Are Standard Treatments for Cancer
Molecular Targeting Can Attack Cancer Cells More Specifically Than Chemotherapy
Using the Immune System to Target Cancer Cells
Cancer Treatments Can Be Tailored to Individual Patients
Summary of Key Points
Problem Set
Human Connections: Molecular Sleuthing in Cancer Diagnosis
Key Technique: Targeting Molecules in the Fight Against Cancer
Appendix Visualizing Cells And Molecules
Answer Key To Concept Check And Key Technique Questions
Glossary
Photo, Illustration, And Text Credits
Index
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