PART I
The Molecular Design of Life
SECTION 1
Biochemistry Helps Us to Understand Our World 1
Chapter 1 Biochemistry and the Unity of Life 3
1.1 Living Systems Require a Limited Variety of Atoms
and Molecules 4
1.2 There Are Four Major Classes of Biomolecules 5
Proteins Are Highly Versatile Biomolecules 5
Nucleic Acids Are the Information Molecules of the Cell 6
Lipids Are a Storage Form of Fuel and Serve as a Barrier 6
Carbohydrates Are Fuels and Informational Molecules 7
1.3 The Central Dogma Describes the Basic Principles
of Biological Information Transfer 7
1.4 Membranes Define the Cell and Carry Out Cellular
Functions 8
Biochemical Functions Are Sequestered in Cellular
Compartments 11
Some Organelles Process and Sort Proteins and Exchange
Material with the Environment 12
Clinical Insight Defects in Organelle Function
May Lead to Disease 14
Chapter 2 Water, Weak Bonds, and the
Generation of Order Out of Chaos 17
2.1 Thermal Motions Power Biological Interactions 18
2.2 Biochemical Interactions Take Place
in an Aqueous Solution 18
2.3 Weak Interactions Are Important Biochemical
Properties 20
Electrostatic Interactions Are Between Electrical Charges 20
Hydrogen Bonds Form Between an Electronegative
Atom and Hydrogen 21
van der Waals Interactions Depend on Transient
Asymmetry in Electrical Charge 21
Weak Bonds Permit Repeated Interactions 22
2.4 Hydrophobic Molecules Cluster Together 22
Membrane Formation Is Powered by the
Hydrophobic Effect 23
Protein Folding Is Powered by the Hydrophobic Effect 24
Functional Groups Have Specific Chemical Properties 24
2.5 pH Is an Important Parameter of
Biochemical Systems 26
Water Ionizes to a Small Extent 26
An Acid Is a Proton Donor, Whereas a Base Is a
Proton Acceptor 27
Acids Have Differing Tendencies to Ionize 27
Buffers Resist Changes in pH 28
Buffers Are Crucial in Biological Systems 29
Making Buffers Is a Common Laboratory Practice 30
SECTION 2
Protein Composition and Structure 35
Chapter 3 Amino Acids 37
Two Different Ways of Depicting Biomolecules
Will Be Used 38
3.1 Proteins Are Built from a Repertoire of
20 Amino Acids 38
Most Amino Acids Exist in Two Mirror-Image Forms 38
All Amino Acids Have at Least Two Charged Groups 38
3.2 Amino Acids Contain a Wide Array of
Functional Groups 39
Hydrophobic Amino Acids Have Mainly
Hydrocarbon Side Chains 39
Polar Amino Acids Have Side Chains That Contain an
Electronegative Atom 41
Positively Charged Amino Acids Are Hydrophilic 42
Negatively Charged Amino Acids Have Acidic
Side Chains 43
The Ionizable Side Chains Enhance Reactivity and
Bonding 43
3.3 Essential Amino Acids Must Be Obtained from
the Diet 44
Clinical Insight Pathological Conditions Result
If Protein Intake Is Inadequate 44
Chapter 4 Protein Three-Dimensional
Structure 47
4.1 Primary Structure: Amino Acids Are Linked
by Peptide Bonds to Form Polypeptide Chains 48
Proteins Have Unique Amino Acid Sequences
Specified by Genes 49
Polypeptide Chains Are Flexible Yet Conformationally
Restricted 50
4.2 Secondary Structure: Polypeptide Chains
Can Fold into Regular Structures 52
The Alpha Helix Is a Coiled Structure Stabilized by
Intrachain Hydrogen Bonds 52
Beta Sheets Are Stabilized by Hydrogen Bonding
Between Polypeptide Strands 53
Polypeptide Chains Can Change Direction by
Making Reverse Turns and Loops 55
Fibrous Proteins Provide Structural Support for
Cells and Tissues 55
Clinical Insight Defects in Collagen Structure
Result in Pathological Conditions 57
4.3 Tertiary Structure: Water-Soluble Proteins Fold
into Compact Structures 57
Myoglobin Illustrates the Principles of Tertiary Structure 57
The Tertiary Structure of Many Proteins Can Be
Divided into Structural and Functional Units 59
4.4 Quaternary Structure: Multiple Polypeptide
Chains Can Assemble into a Single Protein 59
请点击此处下载
收藏
