Textbook Question
Is attenuation the product of an allosteric effect? Is attenuation the result of a transcriptional or a translational activity? Explain your answers.
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Ch. 12 - Regulation of Gene Expression in Bacteria and Bacteriophage
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172
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Table of contents
- Ch. 1 - The Molecular Basis of Heredity, Variation, and Evolution64
- Ch. 2 - Transmission Genetics144
- Ch. 3 - Cell Division and Chromosome Heredity81
- Ch. 4 - Gene Interaction87
- Ch. 5 - Genetic Linkage and Mapping in Eukaryotes103
- Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages73
- Ch. 7 - DNA Structure and Replication71
- Ch. 8 - Molecular Biology of Transcription and RNA Processing79
- Ch. 9 - The Molecular Biology of Translation110
- Ch. 10 - Eukaryotic Chromosome Abnormalities and Molecular Organization100
- Ch. 11 - Gene Mutation, DNA Repair, and Homologous Recombination86
- Ch. 12 - Regulation of Gene Expression in Bacteria and Bacteriophage90
- Ch. 13 - Regulation of Gene Expression in Eukaryotes38
- Ch. 14 - Analysis of Gene Function via Forward Genetics and Reverse Genetics72
- Ch. 15 - Recombinant DNA Technology and Its Applications69
- Ch. 16 - Genomics: Genetics from a Whole-Genome Perspective49
- Ch. 17 - Organelle Inheritance and the Evolution of Organelle Genomes27
- Ch. 18 - Developmental Genetics43
- Ch. 19 - Genetic Analysis of Quantitative Traits66
- Ch. 20 - Population Genetics and Evolution at the Population, Species, and Molecular Levels105
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
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Sanders 3rd EditionCh. 12 - Regulation of Gene Expression in Bacteria and BacteriophageProblem 9
Sanders 3rd EditionCh. 12 - Regulation of Gene Expression in Bacteria and BacteriophageProblem 9Chapter 12, Problem 9
What role does cAMP play in transcription of lac operon genes? What role does CAP play in transcription of lac operon genes?
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Understand the lac operon: The lac operon is a set of genes in E. coli that are involved in the metabolism of lactose. It is regulated by the presence or absence of lactose and glucose in the environment.
Explain the role of cAMP: Cyclic AMP (cAMP) is a signaling molecule that accumulates in the cell when glucose levels are low. It acts as a signal to indicate that the cell needs to utilize alternative energy sources, such as lactose.
Describe the interaction between cAMP and CAP: cAMP binds to the Catabolite Activator Protein (CAP), forming a cAMP-CAP complex. This complex is essential for the activation of the lac operon.
Explain the role of CAP: CAP, when bound to cAMP, binds to a specific site near the promoter of the lac operon. This binding enhances the ability of RNA polymerase to attach to the promoter, thereby increasing the transcription of the lac operon genes.
Summarize the relationship: In summary, cAMP signals low glucose levels, and the cAMP-CAP complex facilitates the transcription of the lac operon genes by enhancing RNA polymerase binding. This ensures that the cell can metabolize lactose when glucose is scarce.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
cAMP (cyclic Adenosine Monophosphate)
cAMP is a secondary messenger important in cellular signaling. In the context of the lac operon, cAMP levels increase when glucose is scarce, leading to the activation of the transcription of genes responsible for lactose metabolism. It binds to the CAP protein, facilitating the recruitment of RNA polymerase to the promoter region of the lac operon.
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06:55
Lac Operon Regulation
CAP (Catabolite Activator Protein)
CAP is a transcriptional activator that enhances the expression of the lac operon in the presence of cAMP. When cAMP binds to CAP, the complex binds to the promoter region of the lac operon, promoting the binding of RNA polymerase and thus increasing transcription of the operon genes. This mechanism ensures that the cell efficiently utilizes available energy sources.
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05:05Proteins
lac Operon
The lac operon is a set of genes in E. coli that are involved in the metabolism of lactose. It consists of three structural genes (lacZ, lacY, and lacA) and is regulated by the presence of lactose and glucose. The operon is an example of gene regulation, where the presence of lactose induces transcription, while glucose availability inhibits it through catabolite repression.
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04:27Lac Operon Overview
Related Practice
Textbook Question
The trpL region contains four repeated DNA sequences that lead to the formation of stem-loop structures in mRNA. What are these stem-loop structures, and how do they affect transcription of the structural genes of the trp operon?
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Textbook Question
The CAP binding site in the lac promoter is the location of positive regulation of gene expression for the operon. Identify what binds at this site to produce positive regulation, under what circumstances binding occurs, and how binding exerts a positive effect.
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Textbook Question
How would a cap⁻ mutation that produces an inactive CAP protein affect transcriptional control of the lac operon?
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Textbook Question
Explain the circumstances under which attenuation of operon gene expression is advantageous to a bacterial organism. Would you expect attenuation to be found in a single-celled eukaryote? In a multicelled eukaryote?
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Textbook Question
Consider the transcription of genes of the lac operon under two conditions: (1) when both glucose and lactose are present and (2) when glucose is absent and lactose is present. Describe the comparative levels of transcription of lac operon genes under these conditions, and explain the molecular basis for the difference.
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