Letter from the Author
Preface
1. Introduction to Genetics
Albinism among the Hopis
1.1 Genetics Is Important to Us Individually, to Society, and to the Study of Biology
The Role of Genetics in Biology
Genetic Diversity and Evolution
Divisions of Genetics
Model Genetic Organisms
1.2 Humans Have Been Using Genetics for Thousands of Years
The Early Use and Understanding of Heredity
The Rise of the Science of Genetics
The Future of Genetics
1.3 A Few Fundamental Concepts Are Important for the Start of Our Journey into Genetics
2. Chromosomes and Cellular Reproduction
The Blind Men’s Riddle
2.1 Prokaryotic and Eukaryotic Cells Differ in a Number of Genetic Characteristics
2.2 Cell Reproduction Requires the Copying of the Genetic Material, Separation of the Copies, and Cell Division
Prokaryotic Cell Reproduction
Eukaryotic Cell Reproduction
The Cell Cycle and Mitosis
Genetic Consequences of the Cell Cycle
CONNECTING CONCEPTS Counting Chromosomes and DNA Molecules
2.3 Sexual Reproduction Produces Genetic Variation Through the Process of Meiosis
Meiosis
Sources of Genetic Variation in Meiosis
CONNECTING CONCEPTS Mitosis and Meiosis Compared
The Separation of Sister Chromatids and Homologous Chromosomes
Meiosis in the Life Cycles of Animals and Plants
3. Basic Principles of Heredity
The Genetics of Red Hair
3.1 Gregor Mendel Discovered the Basic Principles of Heredity
Mendel’s Success
Genetic Terminology
3.2 Monohybrid Crosses Reveal the Principle of Segregation and the Concept of Dominance
What Monohybrid Crosses Reveal
CONNECTING CONCEPTS Relating Genetic Crosses to Meiosis
The Molecular Nature of Alleles
Predicting the Outcomes of Genetic Crosses
The Testcross
Genetic Symbols
CONNECTING CONCEPTS Ratios in Simple Crosses
3.3 Dihybrid Crosses Reveal the Principle of Independent Assortment
Dihybrid Crosses
The Principle of Independent Assortment
Relating the Principle of Independent Assortment to Meiosis
Applying Probability and the Branch Diagram to Dihybrid Crosses
The Dihybrid Testcross
3.4 Observed Ratios of Progeny May Deviate from Expected Ratios by Chance
The Chi-Square Goodness-of-Fit Test
3.5 Geneticists Often Use Pedigrees to Study the Inheritance of Human Characteristics
Symbols Used in Pedigrees
Analysis of Pedigrees
4. Extensions and Modifications of Basic Principles
The Odd Genetics of Left-Handed Snails
4.1 Sex Is Determined by a Number of Different Mechanisms
Chromosomal Sex-Determining Systems
Genic Sex Determination
Environmental Sex Determination
Sex Determination in Drosophila melanogaster
Sex Determination in Humans
4.2 Sex-Linked Characteristics Are Determined by Genes on the Sex Chromosomes
X-Linked White Eyes in Drosophila
MODEL GENETIC ORGANISM? The Fruit Fly Drosophila melanogaster
X-Linked Color Blindness in Humans
Symbols for X-Linked Genes
Dosage Compensation
Y-Linked Characteristics
CONNECTING CONCEPTS Recognizing Sex-Linked Inheritance
4.3 Additional Factors at a Single Locus Can Affect the Results of Genetic Crosses
Types of Dominance
Penetrance and Expressivity
Lethal Alleles
Multiple Alleles
4.4 Gene Interaction Takes Place When Genes at Multiple Loci Determine a Single Phenotype
Gene Interaction That Produces Novel Phenotypes
Gene Interaction with Epistasis
CONNECTING CONCEPTS Interpreting Phenotypic Ratios Produced by Gene Interaction
Complementation: Determining Whether Mutations Are at the Same Locus or at Different Loci
4.5 Sex Influences the Inheritance and Expression of Genes in a Variety of Ways
Sex-Influenced and Sex-Limited Characteristics
Cytoplasmic Inheritance
Genetic Maternal Effects
Genomic Imprinting
4.6 The Expression of a Genotype May Be Influenced by Environmental Effects
Environmental Effects on the Phenotype
The Inheritance of Continuous Characteristics
5. Linkage, Recombination, and Eukaryotic Gene Mapping
Linked Genes and Bald Heads
5.1 Linked Genes Do Not Assort Independently
5.2 Linked Genes Segregate Together, While Crossing Over Produces Recombination Between Them
Notation for Crosses with Linkage
Complete Linkage Compared with Independent Assortment
Crossing Over Between Linked Genes
Calculating Recombination Frequency
Coupling and Repulsion
CONNECTING CONCEPTS Relating Independent Assortment, Linkage, and Crossing Over
Predicting the Outcomes of Crosses with Linked Genes
Testing for Independent Assortment
Gene Mapping with Recombination Frequencies
Constructing a Genetic Map with Two-Point Testcrosses
5.3 A Three-Point Testcross Can Be Used to Map Three Linked Genes
Constructing a Genetic Map with a Three-Point Testcross
CONNECTING CONCEPTS Stepping Through the Three-Point Cross
Effects of Multiple Crossovers
Mapping with Molecular Markers
5.4 Genes Can Be Located with Genome-Wide Association Studies
6. Chromosome Variation
Building a Better Banana
6.1 Chromosome Mutations Include Rearrangements, Aneuploidy, and Polyploidy
Chromosome Morphology
Types of Chromosome Mutations
6.2 Chromosome Rearrangements Alter Chromosome Structure
Duplications
Deletions
Inversions
Translocations
Fragile Sites
Copy-Number Variations
6.3 Aneuploidy Is an Increase or Decrease in the Number of Individual Chromosomes
Types of Aneuploidy
Effects of Aneuploidy
Aneuploidy in Humans
6.4 Polyploidy Is the Presence of More Than Two Sets of Chromosomes
Autopolyploidy
Allopolyploidy
The Significance of Polyploidy
The Importance of Polyploidy in Evolution
7. Bacterial and Viral Genetic Systems
Life in a Bacterial World
7.1 The Genetic Analysis of Bacteria Requires Special Methods
Bacterial Diversity
Techniques for Studying Bacteria
The Bacterial Genome
Plasmids
7.2 Bacteria Exchange Genes through Conjugation, Transformation, and Transduction
Conjugation
Natural Gene Transfer and Antibiotic Resistance
Transformation
Bacterial Genome Sequences
MODEL GENETIC ORGANISM? The Bacterium Escherichia coli
7.3 Viruses Are Simple Replicating Systems Amenable to Genetic Analysis
Techniques for the Study of Bacteriophages
Transduction: Using Phages to Map Bacterial Genes
CONNECTING CONCEPTS Three Methods for Mapping Bacterial Genes
Gene Mapping in Phages
RNA Viruses
Human Immunodeficiency Virus and AIDS
Influenza
8. DNA: The Chemical Nature of the Gene
Arctic Treks and Ancient DNA
8.1 Genetic Material Possesses Several Key Characteristics
8.2 All Genetic Information Is Encoded in the Structure of DNA
Early Studies of DNA
DNA as the Source of Genetic Information
Watson and Crick’s Discovery of the Three-Dimensional Structure of DNA
8.3 DNA Consists of Two Complementary and Antiparallel Nucleotide Strands That Form a Double Helix
The Primary Structure of DNA
Secondary Structures of DNA
Genetic Implications of DNA Structure
8.4 Large Amounts of DNA Are Packed into a Cell
Supercoiling
The Bacterial Chromosome
Eukaryotic Chromosomes
8.5 Eukaryotic Chromosomes Possess Centromeres and Telomeres
Centromere Structure
Telomere Structure
8.6 Eukaryotic DNA Contains Several Classes of Sequence Variation
Types of DNA Sequences in Eukaryotes
Organization of Genetic Information in Eukaryotes
9. DNA Replication and Recombination
Topoisomerase, Replication, and Cancer
9.1 Genetic Information Must Be Accurately Copied Every Time a Cell Divides
9.2 All DNA Replication Takes Place in a Semiconservative Manner
Meselson and Stahl’s Experiment
Modes of Replication
Requirements of Replication
Direction of Replication
9.3 Bacterial Replication Requires a Large Number of Enzymes and Proteins
Initiation
Unwinding
Elongation
Termination
The Fidelity of DNA Replication
CONNECTING CONCEPTS The Basic Rules of Replication
9.4 Eukaryotic DNA Replication Is Similar to Bacterial Replication but Differs in Several Aspects
Eukaryotic Origins of Replication
The Licensing of DNA Replication
Eukaryotic DNA Polymerases
Replication at the Ends of Chromosomes
Replication in Archaea
9.5 Recombination Takes Place Through the Alignment, Breakage, and Repair of DNA Strands
10. From DNA to Proteins: Transcription and RNA Processing
Death Cap Poisoning
10.1 RNA, a Single Strand of Ribonucleotides, Participates in a Variety of Cellular Functions
An Early RNA World
The Structure of RNA
Classes of RNA
10.2 Transcription Is the Synthesis of an RNA Molecule from a DNA Template
The Template
The Substrate for Transcription
The Transcription Apparatus
10.3 Bacterial Transcription Consists of Initiation, Elongation, and Termination
CONNECTING CONCEPTS The Basic Rules of Transcription
10.4 Many Genes Have Complex Structures
Gene Organization
Introns
The Concept of the Gene Revisited
10.5 Many RNA Molecules Are Modified after Transcription in Eukaryotes
Messenger RNA Processing
CONNECTING CONCEPTS Eukaryotic Gene Structure and Pre-mRNA Processing
The Structure and Processing of Transfer RNA
The Structure and Processing of Ribosomal RNA
Small RNA Molecules and RNA Interference
Long Noncoding RNAs Regulate Gene Expression
MODEL GENETIC ORGANISM? The Nematode Worm Caenorhabditis elegans
11. From DNA to Proteins: Translation
Hutterites, Ribosomes, and Bowen–Conradi Syndrome
11.1 The Genetic Code Determines How the Nucleotide Sequence Specifies the Amino Acid Sequence of a Protein
The Structure and Function of Proteins
Breaking the Genetic Code
Characteristics of the Genetic Code
CONNECTING CONCEPTS Characteristics of the Genetic Code
11.2 Amino Acids Are Assembled into a Protein Through Translation
The Binding of Amino Acids to Transfer RNAs
The Initiation of Translation
CONNECTING CONCEPTS A Comparison of Bacterial and Eukaryotic Translation
11.3 Additional Properties of Translation and Proteins
Polyribosomes
Folding and Posttranslational Modifications of Proteins
Translation and Antibiotics
12. Control of Gene Expression
Operons and the Noisy Cell
12.1 The Regulation of Gene Expression Is Critical for All Organisms
Genes and Regulatory Elements
Levels of Gene Regulation
12.2 Operons Control Transcription in Bacterial Cells
Operon Structure
Negative and Positive Control: Inducible and Repressible Operons
The lac Operon of Escherichia coli
Mutations Affecting the lac Operon
Positive Control and Catabolite Repression
The trp Operon of E. coli
12.3 Gene Regulation in Eukaryotic Cells Takes Place at Multiple Levels
Changes in Chromatin Structure
Transcription Factors and Transcriptional Regulator Proteins
Gene Regulation by RNA Processing and Degradation
RNA Interference and Gene Regulation
Gene Regulation in the Course of Translation and Afterward
CONNECTING CONCEPTS A Comparison of Bacterial and Eukaryotic Gene Control
MODEL GENETIC ORGANISM? The Plant Arabidopsis thaliana
12.4 Epigenetic Effects Influence Gene Expression
Molecular Mechanisms of Epigenetic Changes
Epigenetic Effects
The Epigenome
13. Gene Mutations, Transposable Elements, and DNA Repair
A Fly Without a Heart
13.1 Mutations Are Inherited Alterations in the DNA Sequence
The Importance of Mutations
Categories of Mutations
Types of Gene Mutations
Phenotypic Effects of Mutations
Suppressor Mutations
Mutation Rates
13.2 Mutations May Be Caused by a Number of Different Factors
Spontaneous Replication Errors
Spontaneous Chemical Changes
Chemically Induced Mutations
Radiation
Detecting Mutations with the Ames Test
13.3 Transposable Elements Are Mobile DNA Sequences Capable of Inducing Mutations
General Characteristics of Transposable Elements
Transposition
The Mutagenic Effects of Transposition
Evolutionary Significance of Transposable Elements
13.4 A Number of Pathways Repair DNA
Types of DNA Repair
Genetic Diseases and Faulty DNA Repair
14. Molecular Genetic Analysis and Biotechnology
Helping the Blind to See
14.1 Molecular Techniques Are Used to Isolate, Recombine, and Amplify Genes
The Molecular Genetics Revolution
Working at the Molecular Level
Cutting and Joining DNA Fragments
Viewing DNA Fragments
Locating DNA Fragments with Southern Blotting and Probes
Cloning Genes
Amplifying DNA Fragments by Using the Polymerase Chain Reaction
14.2 Molecular Techniques Can Be Used to Find Genes of Interest
DNA Libraries
Positional Cloning
14.3 DNA Sequences Can Be Determined and Analyzed
Restriction Fragment Length Polymorphisms
DNA Sequencing
Next-Generation Sequencing Technologies
DNA Fingerprinting
14.4 Molecular Techniques Are Increasingly Used to Analyze Gene Function
Forward and Reverse Genetics
Transgenic Techniques
Knockout Mice
MODEL GENETIC ORGANISM? The Mouse Mus musculus
Silencing Genes by Using RNA Interference
14.5 Biotechnology Harnesses the Power of Molecular Genetics
Pharmaceutical Products
Specialized Bacteria
Agricultural Products
Genetic Testing
Gene Therapy
15. Genomics and Proteomics
Decoding the Waggle Dance: The Genome of the Honeybee
15.1 Structural Genomics Determines the DNA Sequences of Entire Genomes
Genetic Maps
Physical Maps
Sequencing an Entire Genome
The Human Genome Project
Single-Nucleotide Polymorphisms
Bioinformatics
Metagenomics
Synthetic Biology
15.2 Functional Genomics Determines the Function of Genes by Using Genome-Based Approaches
Predicting Function from Sequence
Gene Expression and Microarrays
15.3 Comparative Genomics Studies How Genomes Evolve
Prokaryotic Genomes
Eukaryotic Genomes
Comparative Drosophila Genomics
The Human Genome
15.4 Proteomics Analyzes the Complete Set of Proteins Found in a Cell
The Determination of Cellular Proteins
Protein Microarrays
Structural Proteomics
16. Cancer Genetics
Palladin and the Spread of Cancer
16.1 Cancer Is a Group of Diseases Characterized by Cell Proliferation
Tumor Formation
Cancer as a Genetic Disease
The Role of Environmental Factors in Cancer
16.2 Mutations in Several Types of Genes Contribute to Cancer
Oncogenes and Tumor-Suppressor Genes
Genes That Control the Cell Cycle
DNA-Repair Genes
Genes That Regulate Telomerase
Genes That Promote Vascularization and the Spread of Tumors
Epigenetic Changes Associated with Cancer
16.3 Colorectal Cancer Arises Through the Sequential Mutation of a Number of Genes
16.4 Changes in Chromosome Number and Structure Are Often Associated with Cancer
16.5 Viruses Are Associated with Some Cancers
17. Quantitative Genetics
Corn Oil and Quantitative Genetics
17.1 Many Quantitative Characteristics Are Influenced by Alleles at Multiple Loci
The Relation Between Genotype and Phenotype
Types of Quantitative Characteristics
Polygenic Inheritance
Kernel Color in Wheat
17.2 Statistical Methods Are Required for Analyzing Quantitative Characteristics
Distributions
The Mean
The Variance
Applying Statistics to the Study of a Polygenic Characteristic
17.3 Heritability Is Used to Estimate the Proportion of Variation in a Trait That Is Genetic
Phenotypic Variance
Types of Heritability
Calculating Heritability
The Limitations of Heritability
Locating Genes That Affect Quantitative Characteristics
17.4 Genetically Variable Traits Change in Response to Selection
Predicting the Response to Selection
Limits to Selection Response
18. Population and Evolutionary Genetics
Genetic Rescue of Bighorn Sheep
18.1 Genotypic and Allelic Frequencies Are Used to Describe the Gene Pool of a Population
Calculating Genotypic Frequencies
Calculating Allelic Frequencies
Models in Population Genetics
18.2 The Hardy–Weinberg Law Describes the Effect of Reproduction on Genotypic and Allelic Frequencies
Genotypic Frequencies at Hardy–Weinberg Equilibrium
Closer Examination of the Hardy–Weinberg Law
Implications of the Hardy–Weinberg Law
Testing for Hardy–Weinberg Proportions
Estimating Allelic Frequencies by Using the Hardy–Weinberg Law
Nonrandom Mating Alters Genotype Frequencies
18.3 Several Evolutionary Forces Can Cause Changes in Allelic Frequencies
Mutation
Migration
Genetic Drift
Natural Selection
CONNECTING CONCEPTS The General Effects of Forces That Change Allelic Frequencies
18.4 Evolution Occurs Through Genetic Change Within Populations
Biological Evolution
Evolution as a Two-Step Process
Types of Evolution
18.5 New Species Arise Through the Evolution of Reproductive Isolation
The Biological Species Concept
Reproductive Isolating Mechanisms
Modes of Speciation
18.6 The Evolutionary History of a Group of Organisms Can Be Reconstructed by Studying Changes in Homologous Characteristics
The Construction of Phylogenetic Trees
18.7 Patterns of Evolution Are Revealed by Changes at the Molecular Level
Rates of Molecular Evolution
The Molecular Clock
Evolution Through Changes in Gene Regulation
Genome Evolution
Glossary
Answers to Selected Questions and Problems
Index