Concept explainers
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.
Want to see the full answer?
Check out a sample textbook solutionChapter 13 Solutions
Genetic Analysis: An Integrated Approach (3rd Edition)
- Explain 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_forwardWhat is the role of a substrate that controls a repressible operon? a. increase the production of inactive repressor proteins b. bind to the repressor protein and activate it c. bind to the repressor protein and deactivate it d. bind to the promoter region and decrease the affinity of RNA polymerase for the promoterarrow_forward
- Describe the steps involved in the Direct Gene activation system. Give an example of a hormone that uses this mechanism in the bodyarrow_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_forwardCompare and contrast the role of promoter and operators with enhancers and repressors.arrow_forward
- E. coli are grown on a medium containing lactose. Once glucose is added to the medium, the bacteria stop fermenting lactose. Which of the following BEST explains the observed effect? A. Cellular levels of cAMP are lowB.Glucose is bound to the promoter C. Repressor protein is bound to the operator D. Repressor protein is bound to the promoterarrow_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_forwardDefine repressors?arrow_forward
- Human Anatomy & Physiology (11th Edition)BiologyISBN:9780134580999Author:Elaine N. Marieb, Katja N. HoehnPublisher:PEARSONBiology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStaxAnatomy & PhysiologyBiologyISBN:9781259398629Author:McKinley, Michael P., O'loughlin, Valerie Dean, Bidle, Theresa StouterPublisher:Mcgraw Hill Education,
- Molecular Biology of the Cell (Sixth Edition)BiologyISBN:9780815344322Author:Bruce Alberts, Alexander D. Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter WalterPublisher:W. W. Norton & CompanyLaboratory Manual For Human Anatomy & PhysiologyBiologyISBN:9781260159363Author:Martin, Terry R., Prentice-craver, CynthiaPublisher:McGraw-Hill Publishing Co.Inquiry Into Life (16th Edition)BiologyISBN:9781260231700Author:Sylvia S. Mader, Michael WindelspechtPublisher:McGraw Hill Education