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To analyze:
The inducibility of a gene that is mediated by activator and repressor in response to change in environmental conditions, with the help of suitable diagram.
Introduction:
An operon is a stretch of DNA which consists of a cluster of functionally related genes. It contains an operator, promoter, and related genes. It is present only in prokaryotes. It was first characterized in E. coli. Operon can be inducible or repressible.
Inducible operon: In presence of substrate, transcription of structural gene occurs, and in
absence of substrate, the operator region is occupied by the repressor so, RNA polymerase is unable to bind at promoter region, and transcription cannot be initiated. In inducible operon, transcription in inhibited in absence of the substrate.
Repressible operon: In repressible operon, the substrate acts as a co-repressor that facilitates the conformational change in the repressor of the operon and transcription is inhibited in absence of co-repressor. The conformation of original repressor does not allow it to bind to the operator region of the operon. Thus, the operator region is free and RNA polymerase can bind at the promoter region, and transcription of genes can be initiated.
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Chapter 13 Solutions
Genetic Analysis: An Integrated Approach (3rd Edition)
- Compare and contrast how activators, coactivators, repressors,TFIID, and mediator play a role in gene regulation.arrow_forwardExplain the single transcription factor can be both an activator and a repressorarrow_forwardExplain how small effector molecules affect the function of activators and repressors.arrow_forward
- Describe the steps involved in the Direct Gene activation system. Give an example of a hormone that uses this mechanism in the bodyarrow_forwardCompare and contrast the role of promoter and operators with enhancers and repressors.arrow_forwardGive typing answer with explanation and conclusion In eukaryotes, repressors can function by: Select one: binding to the regulatory promoter blocking DNA polymerase binding binding to the polyA tail blocking ribosome bindingarrow_forward
- Explain the Structures of repressors?arrow_forwardExplain how a gene knockdown reagent, such as RNAi or a morpholino, could interfere with expression of a gene without affecting the rate of transcription of the target gene.arrow_forwardWhy is regulating transcription the main way that cells control gene expression? A. Because transcription is the last step in gene expression, stopping here ensures that the cell has a stockpile of proteins to prepare them from all unexpected environmental changes. B. Because transcription involves interactions with DNA, preventing transcription reduces the changes of mutation in the cell’s genome. C. Because transcription is the first step in gene expression, stopping at transcription reduces the amount of energy and resources used by producing unnecessary gene products. D. Because transcription is the shortest step in gene expression, preventing transcription has little effect on the rate of protein production.arrow_forward
- Define repressors?arrow_forwardWhat role does an operator sequence serve in bacterial gene expression regulation? Describe one change in bacterial cells that can cause a repressor protein to go from inactive to active or from active to inactive.arrow_forwardWhat type of control generally involves binding of a repressor protein to a regulatory DNA sequence? (one or two word answer only, please)arrow_forward
Biology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage Learning