Biochemistry-Stryer-5th-Edition
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published by W. H. Freeman and Company
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ISBN-10: 0716746840
About the authors
JEREMY M. BERG has been Professor and Director (Department Chairperson) of Biophysics and Biophysical
Chemistry at Johns Hopkins University School of Medicine since 1990. He received his B.S. and M.S. degrees in
Chemistry from Stanford (where he learned X-ray crystallography with Keith Hodgson and Lubert Stryer) and his Ph.D.
in Chemistry from Harvard with Richard Holm. He then completed a postdoctoral fellowship with Carl Pabo. Professor
Berg is recipient of the American Chemical Society Award in Pure Chemistry (1994), the Eli Lilly Award for
Fundamental Research in Biological Chemistry (1995), the Maryland Outstanding Young Scientist of the Year (1995),
and the Harrison Howe Award (1997). While at Johns Hopkins, he has received the W. Barry Wood Teaching Award
(selected by medical students), the Graduate Student Teaching Award, and the Professor's Teaching Award for the
Preclinical Sciences. He is co-author, with Stephen Lippard, of the text Principles of Bioinorganic Chemistry.
JOHN L. TYMOCZKO is the Towsley Professor of Biology at Carleton College, where he has taught since 1976. He
currently teaches Biochemistry, Biochemistry Laboratory, Oncogenes and the Molecular Biology of Cancer, and
Exercise Biochemistry and co-teaches an introductory course, Bioenergetics and Genetics. Professor Tymoczko received
his B.A. from the University of Chicago in 1970 and his Ph.D. in Biochemistry from the University of Chicago with
Shutsung Liao at the Ben May Institute for Cancer Research. He followed that with a post-doctoral position with
Hewson Swift of the Department of Biology at the University of Chicago. Professor Tymoczko's research has focused on
steroid receptors, ribonucleoprotein particles, and proteolytic processing enzymes.
LUBERT STRYER is currently Winzer Professor in the School of Medicine and Professor of Neurobiology at Stanford
University, where he has been on the faculty since 1976. He received his M.D. from Harvard Medical School. Professor
Stryer has received many awards for his research, including the Eli Lilly Award for Fundamental Research in Biological
Chemistry (1970) and the Distinguished Inventors Award of the Intellectual Property Owners' Association. He was
elected to the National Academy of Sciences in 1984. Professor Stryer was formerly the President and Scientific Director
of the Affymax Research Institute. He is a founder and a member of the Scientific Advisory Board of Senomyx, a
company that is using biochemical knowledge to develop new and improved flavor and fragrance molecules for use in
consumer products. The publication of the first edition of his text Biochemistry in 1975 transformed the teaching of
biochemistry.
Preface
For more than 25 years, and through four editions, Stryer's Biochemistry has laid out this beautiful subject in an
exceptionally appealing and lucid manner. The engaging writing style and attractive design have made the text a pleasure
for our students to read and study throughout our years of teaching. Thus, we were delighted to be given the opportunity
to participate in the revision of this book. The task has been exciting and somewhat daunting, doubly so because of the
dramatic changes that are transforming the field of biochemistry as we move into the twenty-first century. Biochemistry
is rapidly progressing from a science performed almost entirely at the laboratory bench to one that may be explored
through computers. The recently developed ability to determine entire genomic sequences has provided the data needed
to accomplish massive comparisons of derived protein sequences, the results of which may be used to formulate and test
hypotheses about biochemical function. The power of these new methods is explained by the impact of evolution: many
molecules and biochemical pathways have been generated by duplicating and modifying existing ones. Our challenge in
writing the fifth edition of Biochemistry has been to introduce this philosophical shift in biochemistry while maintaining
the clear and inviting style that has distinguished the preceding four editions.Figure 9.44
A New Molecular Evolutionary Perspective
How should these evolution-based insights affect the teaching of biochemistry? Often macromolecules with a common
evolutionary origin play diverse biological roles yet have many structural and mechanistic features in common. An
example is a protein family containing macromolecules that are crucial to moving muscle, to transmitting the
information that adrenaline is present in the bloodstream, and to driving the formation of chains of amino acids. The key
features of such a protein family, presented to the student once in detail, become a model that the student can apply each
time that a new member of the family is encountered. The student is then able to focus on how these features, observed
in a new context, have been adapted to support other biochemical processes. Throughout the text, a stylized tree icon is
positioned at the start of discussions focused primarily on protein homologies and evolutionary origins.
Two New Chapters.
To enable students to grasp the power of these insights, two completely new chapters have been added. The first,
"Biochemical Evolution" (Chapter 2), is a brief tour from the origin of life to the development of multicellular
organisms. On one level, this chapter provides an introduction to biochemical molecules and pathways and their cellular
context. On another level, it attempts to deepen student understanding by examining how these molecules and pathways
arose in response to key biological challenges. In addition, the evolutionary perspective of Chapter 2 makes some
apparently peculiar aspects of biochemistry more reasonable to students. For example, the presence of ribonucleotide
fragments in biochemical cofactors can be accounted for by the likely occurrence of an early world based largely on
RNA. The second new chapter, "Exploring Evolution" (Chapter 7), develops the conceptual basis for the comparison of
protein and nucleic acid sequences. This chapter parallels "Exploring Proteins" (Chapter 4) and "Exploring
Genes" (Chapter 6), which have thoughtfully examined experimental techniques in earlier editions. Its goal is to enable
students to use the vast information available in sequence and structural databases in a critical and effective manner.
Organization of the Text.
The evolutionary approach influences the organization of the text, which is divided into four major parts. As it did in the
preceding edition, Part I introduces the language of biochemistry and the structures of the most important classes of
biological molecules. The remaining three parts correspond to three major evolutionary challenges namely, the
interconversion of different forms of energy, molecular reproduction, and the adaptation of cells and organisms to
changing environments. This arrangement parallels the evolutionary path outlined in Chapter 2 and naturally flows from
the simple to the more complex.
PART I, the molecular design of life, introduces the most important classes of biological macromolecules, including
proteins, nucleic acids, carbohydrates, and lipids, and presents the basic concepts of catalysis and enzyme action. Here
are two examples of how an evolutionary perspective has shaped the material in these chapters:
Chapter 9 , on catalytic strategies, examines four classes of enzymes that have evolved to meet specific
challenges: promoting a fundamentally slow chemical reaction, maximizing the absolute rate of a reaction,
catalyzing a reaction at one site but not at many alternative sites, and preventing a deleterious side reaction. In
each case, the text considers the role of evolution in fine-tuning the key property.
Chapter 13 , on membrane channels and pumps, includes the first detailed three-dimensional structures of an ion
channel and an ion pump. Because most other important channels and pumps are evolutionarily related to these
proteins, these two structures provide powerful frameworks for examining the molecular basis of the action of
these classes of molecules, so important for the functioning of the nervous and other systems.
PART II, transducing and storing energy, examines pathways for the interconversion of different forms of
energy.
Chapter 15, on signal transduction, looks at how DNA fragments encoding relatively simple protein
modules, rather than entire proteins, have been mixed and matched in the course of evolution to generate the
wiring that defines signal-transduction pathways. The bulk of Part II discusses pathways for the generation of
ATP and other energy-storing molecules. These pathways have been organized into groups that share common
enzymes. The component reactions can be examined once and their use in different biological contexts illustrated
while these reactions are fresh in the students' minds.
Chapter 16 covers both glycolysis and gluconeogenesis. These pathways are, in some ways, the reverse of each
other, and a core of enzymes common to both pathways catalyze many of the steps in the center of the pathways.
Covering the pathways together makes it easy to illustrate how free energy enters to drive the overall process
either in the direction of glucose degradation or in the direction of glucose synthesis.
Chapter 17, on the citric acid cycle, ties together through evolutionary insights the pyruvate dehydrogenase
complex, which feeds molecules into the citric acid cycle, and the a-ketoglutarate dehydrogenase complex, which
catalyzes one of the key steps in the cycle itself.Figure 15.34
l Oxidative phosphorylation, in Chapter 18 , is immediately followed in Chapter 19 by the light reactions of
photosynthesis to emphasize the many common chemical features of these pathways.
l The discussion of the light reactions of photosynthesis in Chapter 19 leads naturally into a discussion of the dark
reactions that is, the components of the Calvin cycle in Chapter 20 . This pathway is naturally linked to the
pentose phosphate pathway, also covered in Chapter 20 , because in both pathways common enzymes
interconvert three-, four-, five-, six-, and seven-carbon sugars.
PART III, synthesizing the molecules of life, focuses on the synthesis of biological macromolecules and their
components.
Chapter 24, on the biosynthesis of amino acids, is linked to the preceding chapter on amino acid degradation by a
family of enzymes that transfer amino groups to and from the carbon frameworks of amino acids.
Chapter 25 covers the biosynthesis of nucleotides, including the role of amino acids as biosynthetic precursors. A
key evolutionary insight emphasized here is that many of the enzymes in these pathways are members of the same
family and catalyze analogous chemical reactions. The focus on enzymes and reactions common to these
biosynthetic pathways allows students to understand the logic of the pathways, rather than having to memorize a
set of seemingly unrelated reactions.
Chapters 27, 28, and 29 cover DNA replication, recombination, and repair; RNA synthesis and splicing; and
protein synthesis. Evolutionary connections between prokaryotic systems and eukaryotic systems reveal how the
basic biochemical processes have been adapted to function in more-complex biological systems. The recently
elucidated structure of the ribosome gives students a glimpse into a possible early RNA world, in which nucleic
acids, rather than proteins, played almost all the major roles in catalyzing important pathways.
PART IV, responding to environmental changes, looks at how cells sense and adapt to changes in their environments.
Part IV examines, in turn, sensory systems, the immune system, and molecular motors and the cytoskeleton. These
chapters illustrate how signaling and response processes, introduced earlier in the text, are integrated in multicellular
organisms to generate powerful biochemical systems for detecting and responding to environmental changes. Again, the
adaptation of proteins to new roles is key to these discussions.
I. The Molecular Design of Life
1. Prelude: Biochemistry and the Genomic Revolution
1.1. DNA Illustrates the Relation between Form and Function
1.2. Biochemical Unity Underlies Biological Diversity
1.3. Chemical Bonds in Biochemistry
1.4. Biochemistry and Human Biology
Appendix: Depicting Molecular Structures
2. Biochemical Evolution
2.1. Key Organic Molecules Are Used by Living Systems
2.2. Evolution Requires Reproduction, Variation, and Selective Pressure
2.3. Energy Transformations Are Necessary to Sustain Living Systems
2.4. Cells Can Respond to Changes in Their Environments
Summary
Problems
Selected Readings
3. Protein Structure and Function
3.1. Proteins Are Built from a Repertoire of 20 Amino Acids
3.2. Primary Structure: Amino Acids Are Linked by Peptide Bonds to Form Polypeptide
Chains
3.3. Secondary Structure: Polypeptide Chains Can Fold Into Regular Structures Such as the
Alpha Helix, the Beta Sheet, and Turns and Loops
3.4. Tertiary Structure: Water-Soluble Proteins Fold Into Compact Structures with Nonpolar
Cores
3.5. Quaternary Structure: Polypeptide Chains Can Assemble Into Multisubunit Structures
3.6. The Amino Acid Sequence of a Protein Determines Its Three-Dimensional Structure
Summary
Appendix: Acid-Base Concepts
Problems
Selected Readings
4. Exploring Proteins
4.1. The Purification of Proteins Is an Essential First Step in Understanding Their Function
4.2. Amino Acid Sequences Can Be Determined by Automated Edman Degradation
4.3. Immunology Provides Important Techniques with Which to Investigate Proteins
4.4. Peptides Can Be Synthesized by Automated Solid-Phase Methods
4.5. Three-Dimensional Protein Structure Can Be Determined by NMR Spectroscopy and XRay
Crystallography
Summary
Problems
Selected Readings
5. DNA, RNA, and the Flow of Genetic Information
5.1. A Nucleic Acid Consists of Four Kinds of Bases Linked to a Sugar-Phosphate Backbone
5.2. A Pair of Nucleic Acid Chains with Complementary Sequences Can Form a Double-
Helical Structure
5.3. DNA Is Replicated by Polymerases that Take Instructions from Templates
5.4. Gene Expression Is the Transformation of DNA Information Into Functional Molecules
5.5. Amino Acids Are Encoded by Groups of Three Bases Starting from a Fixed Point
5.6. Most Eukaryotic Genes Are Mosaics of Introns and Exons
Summary
Problems
Selected Readings
6. Exploring Genes
6.1. The Basic Tools of Gene Exploration
6.2. Recombinant DNA Technology Has Revolutionized All Aspects of Biology
6.3. Manipulating the Genes of Eukaryotes
6.4. Novel Proteins Can Be Engineered by Site-Specific Mutagenesis
Summary
Problems
Selected Reading
7. Exploring Evolution
7.1. Homologs Are Descended from a Common Ancestor
7.2. Statistical Analysis of Sequence Alignments Can Detect Homology
7.3. Examination of Three-Dimensional Structure Enhances Our Understanding of
Evolutionary Relationships
7.4. Evolutionary Trees Can Be Constructed on the Basis of Sequence Information
7.5. Modern Techniques Make the Experimental Exploration of Evolution Possible
Summary
Problems
Selected Readings
8. Enzymes: Basic Concepts and Kinetics
8.1. Enzymes Are Powerful and Highly Specific Catalysts
8.2. Free Energy Is a Useful Thermodynamic Function for Understanding Enzymes
8.3. Enzymes Accelerate Reactions by Facilitating the Formation of the Transition State
8.4. The Michaelis-Menten Model Accounts for the Kinetic Properties of Many Enzymes
8.5. Enzymes Can Be Inhibited by Specific Molecules
8.6. Vitamins Are Often Precursors to Coenzymes
Summary
Appendix: Vmax and KM Can Be Determined by Double-Reciprocal Plots
Problems
Selected Readings
9. Catalytic Strategies
9.1. Proteases: Facilitating a Difficult Reaction
9.2. Making a Fast Reaction Faster: Carbonic Anhydrases
9.3. Restriction Enzymes: Performing Highly Specific DNA-Cleavage Reactions
9.4. Nucleoside Monophosphate Kinases: Catalyzing Phosphoryl Group Exchange between
Nucleotides Without Promoting Hydrolysis
Summary
Problems
Selected Readings
10. Regulatory Strategies: Enzymes and Hemoglobin
10.1. Aspartate Transcarbamoylase Is Allosterically Inhibited by the End Product of Its
Pathway
10.2. Hemoglobin Transports Oxygen Efficiently by Binding Oxygen Cooperatively
10.3. Isozymes Provide a Means of Regulation Specific to Distinct Tissues and
Developmental Stages
10.4. Covalent Modification Is a Means of Regulating Enzyme Activity
10.5. Many Enzymes Are Activated by Specific Proteolytic Cleavage
Summary
Problems
Selected Readings
11. Carbohydrates
11.1. Monosaccharides Are Aldehydes or Ketones with Multiple Hydroxyl Groups
11.2. Complex Carbohydrates Are Formed by Linkage of Monosaccharides
11.3. Carbohydrates Can Be Attached to Proteins to Form Glycoproteins
11.4. Lectins Are Specific Carbohydrate-Binding Proteins
Summary
Problems
Selected Readings
12. Lipids and Cell Membranes
12.1. Many Common Features Underlie the Diversity of Biological Membranes
12.2. Fatty Acids Are Key Constituents of Lipids
12.3. There Are Three Common Types of Membrane Lipids
12.4. Phospholipids and Glycolipids Readily Form Bimolecular Sheets in Aqueous Media
12.5. Proteins Carry Out Most Membrane Processes
12.6. Lipids and Many Membrane Proteins Diffuse Rapidly in the Plane of the Membrane
12.7. Eukaryotic Cells Contain Compartments Bounded by Internal Membranes
Summary
Problems
Selected Readings
13. Membrane Channels and Pumps
13.1. The Transport of Molecules Across a Membrane May Be Active or Passive
13.2. A Family of Membrane Proteins Uses ATP Hydrolysis to Pump Ions Across
Membranes
13.3. Multidrug Resistance and Cystic Fibrosis Highlight a Family of Membrane Proteins
with ATP-Binding Cassette Domains
13.4. Secondary Transporters Use One Concentration Gradient to Power the Formation of
Another
13.5. Specific Channels Can Rapidly Transport Ions Across Membranes
13.6. Gap Junctions Allow Ions and Small Molecules to Flow between Communicating Cells
Summary
Problems
Selected Readings
II. Transducing and Storing Energy
14. Metabolism: Basic Concepts and Design
14.1. Metabolism Is Composed of Many Coupled, Interconnecting Reactions
14.2. The Oxidation of Carbon Fuels Is an Important Source of Cellular Energy
14.3. Metabolic Pathways Contain Many Recurring Motifs
Summary
Problems
Selected Readings
15. Signal-Transduction Pathways: An Introduction to Information Metabolism
15.1. Seven-Transmembrane-Helix Receptors Change Conformation in Response to Ligand
Binding and Activate G Proteins
15.2. The Hydrolysis of Phosphatidyl Inositol Bisphosphate by Phospholipase C Generates
Two Messengers
15.3. Calcium Ion Is a Ubiquitous Cytosolic Messenger
15.4. Some Receptors Dimerize in Response to Ligand Binding and Signal by Crossphosphorylation
15.5. Defects in Signaling Pathways Can Lead to Cancer and Other Diseases
15.6. Recurring Features of Signal-Transduction Pathways Reveal Evolutionary Relationships
Summary
Problems
Selected Readings
16. Glycolysis and Gluconeogenesis
16.1. Glycolysis Is an Energy-Conversion Pathway in Many Organisms
16.2. The Glycolytic Pathway Is Tightly Controlled
16.3. Glucose Can Be Synthesized from Noncarbohydrate Precursors
16.4. Gluconeogenesis and Glycolysis Are Reciprocally Regulated
Summary
Problems
Selected Readings
17. The Citric Acid Cycle
17.1. The Citric Acid Cycle Oxidizes Two-Carbon Units
17.2. Entry to the Citric Acid Cycle and Metabolism Through It Are Controlled
17.3. The Citric Acid Cycle Is a Source of Biosynthetic Precursors
17.4. The Glyoxylate Cycle Enables Plants and Bacteria to Grow on Acetate
Summary
Problems
Selected Readings
18. Oxidative Phosphorylation
18.1. Oxidative Phosphorylation in Eukaryotes Takes Place in Mitochondria
18.2. Oxidative Phosphorylation Depends on Electron Transfer
18.3. The Respiratory Chain Consists of Four Complexes: Three Proton Pumps and a
Physical Link to the Citric Acid Cycle
18.4. A Proton Gradient Powers the Synthesis of ATP
18.5. Many Shuttles Allow Movement Across the Mitochondrial Membranes
18.6. The Regulation of Cellular Respiration Is Governed Primarily by the Need for ATP
Summary
Problems
Selected Readings
19. The Light Reactions of Photosynthesis
19.1. Photosynthesis Takes Place in Chloroplasts
19.2. Light Absorption by Chlorophyll Induces Electron Transfer
19.3. Two Photosystems Generate a Proton Gradient and NADPH in Oxygenic
Photosynthesis
19.4. A Proton Gradient Across the Thylakoid Membrane Drives ATP Synthesis
19.5. Accessory Pigments Funnel Energy Into Reaction Centers
19.6. The Ability to Convert Light Into Chemical Energy Is Ancient
Summary
Problems
Selected Readings
20. The Calvin Cycle and the Pentose Phosphate Pathway
20.1. The Calvin Cycle Synthesizes Hexoses from Carbon Dioxide and Water
20.2. The Activity of the Calvin Cycle Depends on Environmental Conditions
20.3 the Pentose Phosphate Pathway Generates NADPH and Synthesizes Five-Carbon Sugars
20.4. The Metabolism of Glucose 6-Phosphate by the Pentose Phosphate Pathway Is
Coordinated with Glycolysis
20.5. Glucose 6-Phosphate Dehydrogenase Plays a Key Role in Protection Against Reactive
Oxygen Species
Summary
Problems
Selected Readings
21. Glycogen Metabolism
21.1. Glycogen Breakdown Requires the Interplay of Several Enzymes
21.2. Phosphorylase Is Regulated by Allosteric Interactions and Reversible Phosphorylation
21.3. Epinephrine and Glucagon Signal the Need for Glycogen Breakdown
21.4. Glycogen Is Synthesized and Degraded by Different Pathways
21.5. Glycogen Breakdown and Synthesis Are Reciprocally Regulated
Summary
Problems
Selected Readings
22. Fatty Acid Metabolism
22.1. Triacylglycerols Are Highly Concentrated Energy Stores
22.2. The Utilization of Fatty Acids as Fuel Requires Three Stages of Processing
22.3. Certain Fatty Acids Require Additional Steps for Degradation
22.4. Fatty Acids Are Synthesized and Degraded by Different Pathways
22.5. Acetyl Coenzyme A Carboxylase Plays a Key Role in Controlling Fatty Acid
Metabolism
22.6. Elongation and Unsaturation of Fatty Acids Are Accomplished by Accessory Enzyme
Systems
Summary
Problems
Selected Readings
23. Protein Turnover and Amino Acid Catabolism
23.1. Proteins Are Degraded to Amino Acids
23.2. Protein Turnover Is Tightly Regulated
23.3. The First Step in Amino Acid Degradation Is the Removal of Nitrogen
23.4. Ammonium Ion Is Converted Into Urea in Most Terrestrial Vertebrates
23.5. Carbon Atoms of Degraded Amino Acids Emerge as Major Metabolic Intermediates
23.6. Inborn Errors of Metabolism Can Disrupt Amino Acid Degradation
Summary
Problems
Selected Readings
III. Synthesizing the Molecules of Life
24. The Biosynthesis of Amino Acids
24.1. Nitrogen Fixation: Microorganisms Use ATP and a Powerful Reductant to Reduce
Atmospheric Nitrogen to Ammonia
24.2. Amino Acids Are Made from Intermediates of the Citric Acid Cycle and Other Major
Pathways
24.3. Amino Acid Biosynthesis Is Regulated by Feedback Inhibition
24.4. Amino Acids Are Precursors of Many Biomolecules
Summary
Problems
Selected Readings
25. Nucleotide Biosynthesis
25.1. In de Novo Synthesis, the Pyrimidine Ring Is Assembled from Bicarbonate, Aspartate,
and Glutamine
25.2. Purine Bases Can Be Synthesized de Novo or Recycled by Salvage Pathways
25.3. Deoxyribonucleotides Synthesized by the Reduction of Ribonucleotides Through a
Radical Mechanism
25.4. Key Steps in Nucleotide Biosynthesis Are Regulated by Feedback Inhibition
25.5. NAD+, FAD, and Coenzyme A Are Formed from ATP
25.6. Disruptions in Nucleotide Metabolism Can Cause Pathological Conditions
Summary
Problems
Selected Readings
26. The Biosynthesis of Membrane Lipids and Steroids
26.1. Phosphatidate Is a Common Intermediate in the Synthesis of Phospholipids and
Triacylglycerols
26.2. Cholesterol Is Synthesized from Acetyl Coenzyme A in Three Stages
26.3. The Complex Regulation of Cholesterol Biosynthesis Takes Place at Several Levels
26.4. Important Derivatives of Cholesterol Include Bile Salts and Steroid Hormones
Summary
Problems
Selected Readings
27. DNA Replication, Recombination, and Repair
27.1. DNA Can Assume a Variety of Structural Forms
27.2. DNA Polymerases Require a Template and a Primer
27.3. Double-Stranded DNA Can Wrap Around Itself to Form Supercoiled Structures
27.4. DNA Replication of Both Strands Proceeds Rapidly from Specific Start Sites
27.5. Double-Stranded DNA Molecules with Similar Sequences Sometimes Recombine
27.6. Mutations Involve Changes in the Base Sequence of DNA
Summary
Problems
Selected Readings
28. RNA Synthesis and Splicing
28.1. Transcription Is Catalyzed by RNA Polymerase
28.2. Eukaryotic Transcription and Translation Are Separated in Space and Time
28.3. The Transcription Products of All Three Eukaryotic Polymerases Are Processed
28.4. The Discovery of Catalytic RNA Was Revealing in Regard to Both Mechanism and
Evolution
Summary
Problems
Selected Readings
29. Protein Synthesis
29.1. Protein Synthesis Requires the Translation of Nucleotide Sequences Into Amino Acid
Sequences
29.2. Aminoacyl-Transfer RNA Synthetases Read the Genetic Code
29.3. A Ribosome Is a Ribonucleoprotein Particle (70S) Made of a Small (30S) and a Large
(50S) Subunit
29.4. Protein Factors Play Key Roles in Protein Synthesis
29.5. Eukaryotic Protein Synthesis Differs from Prokaryotic Protein Synthesis Primarily in
Translation Initiation
Summary
Problems
Selected Readings
30. The Integration of Metabolism
30.1. Metabolism Consist of Highly Interconnected Pathways
30.2. Each Organ Has a Unique Metabolic Profile
30.3. Food Intake and Starvation Induce Metabolic Changes
30.4. Fuel Choice During Exercise Is Determined by Intensity and Duration of Activity
30.5. Ethanol Alters Energy Metabolism in the Liver
Summary
Problems
Selected Readings
31. The Control of Gene Expression
31.1. Prokaryotic DNA-Binding Proteins Bind Specifically to Regulatory Sites in Operons
31.2. The Greater Complexity of Eukaryotic Genomes Requires Elaborate Mechanisms for
Gene Regulation
31.3. Transcriptional Activation and Repression Are Mediated by Protein-Protein Interactions
31.4. Gene Expression Can Be Controlled at Posttranscriptional Levels
Summary
Problems
Selected Readings
IV. Responding to Environmental Changes
32. Sensory Systems
32.1. A Wide Variety of Organic Compounds Are Detected by Olfaction
32.2. Taste Is a Combination of Senses that Function by Different Mechanisms
32.3. Photoreceptor Molecules in the Eye Detect Visible Light
32.4. Hearing Depends on the Speedy Detection of Mechanical Stimuli
32.5. Touch Includes the Sensing of Pressure, Temperature, and Other Factors
Summary
Problems
Selected Readings
33. The Immune System
33.1. Antibodies Possess Distinct Antigen-Binding and Effector Units
33.2. The Immunoglobulin Fold Consists of a Beta-Sandwich Framework with Hypervariable
Loops
33.3. Antibodies Bind Specific Molecules Through Their Hypervariable Loops
33.4. Diversity Is Generated by Gene Rearrangements
33.5. Major-Histocompatibility-Complex Proteins Present Peptide Antigens on Cell Surfaces
for Recognition by T-Cell Receptors
33.6. Immune Responses Against Self-Antigens Are Suppressed
Summary
Problems
Selected Readings
34. Molecular Motors
34.1. Most Molecular-Motor Proteins Are Members of the P-Loop NTPase Superfamily
34.2. Myosins Move Along Actin Filaments
34.3. Kinesin and Dynein Move Along Microtubules
34.4. A Rotary Motor Drives Bacterial Motion
Summary
