Essential Cell Biology 5th edition

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Contents
Specific Enzymes Couple tRNAs to the Correct Amino Acid 249
The mRNA Message Is Decoded on Ribosomes 249
The Ribosome Is a Ribozyme 252
Specific Codons in an mRNA Signal the Ribosome Where to Start and to Stop Protein
Synthesis 253
Proteins Are Produced on Polyribosomes 255
Inhibitors of Prokaryotic Protein Synthesis Are Used as Antibiotics 255
Controlled Protein Breakdown Helps Regulate the Amount of Each Protein in a Cell 256
There Are Many Steps Between DNA and Protein 257
RNA AND THE ORIGINS OF LIFE 259
Life Requires Autocatalysis 259
RNA Can Store Information and Catalyze Chemical Reactions 260
RNA Is Thought to Predate DNA in Evolution 261
ESSENTIAL CONCEPTS 262
QUESTIONS 264
CHAPTER 8
Control of Gene Expression 267
AN OVERVIEW OF GENE EXPRESSION 268
The Different Cell Types of a Multicellular Organism Contain the Same DNA 268
Different Cell Types Produce Different Sets of Proteins 269
A Cell Can Change the Expression of Its Genes in Response to External Signals 270
Gene Expression Can Be Regulated at Various Steps from DNA to RNA to Protein 270
HOW TRANSCRIPTION IS REGULATED 271
Transcription Regulators Bind to Regulatory DNA Sequences 271
Transcription Switches Allow Cells to Respond to Changes in Their Environment 273
Repressors Turn Genes Off and Activators Turn Them On 274
The Lac Operon Is Controlled by an Activator and a Repressor 275
Eukaryotic Transcription Regulators Control Gene Expression from a Distance 276
Eukaryotic Transcription Regulators Help Initiate Transcription
by Recruiting Chromatin-Modifying Proteins 276
The Arrangement of Chromosomes into Looped Domains Keeps Enhancers in Check 278
GENERATING SPECIALIZED CELL TYPES 278
Eukaryotic Genes Are Controlled by Combinations of Transcription Regulators 279
The Expression of Different Genes Can Be Coordinated by a Single Protein 279
Combinatorial Control Can Also Generate Different Cell Types 282
The Formation of an Entire Organ Can Be Triggered by a Single Transcription Regulator 284
Transcription Regulators Can Be Used to Experimentally Direct the Formation of Specific Cell
Types in Culture 285
Differentiated Cells Maintain Their Identity 286