Prokaryotic Gene Regulation via Operons exam Flashcards
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Terms in this set (26)
Operon
A set of prokaryotic genes controlled by a single promoter.
What is the role of the promoter in an operon?
It is a DNA sequence where RNA polymerase binds to initiate transcription.
Operator
A DNA sequence in an operon where regulatory proteins bind to influence transcription.
What happens when a repressor binds to the operator?
It blocks RNA polymerase from binding to the promoter, preventing transcription.
Inducible Operon
An operon that is normally off but can be turned on by an inducer.
What is an inducer?
A molecule that inactivates a repressor, allowing transcription to proceed.
Repressible Operon
An operon that is normally on but can be turned off by a corepressor.
What is a corepressor?
A molecule that activates a repressor, turning off transcription.
Regulatory Protein
Proteins that bind to the operator to either block or promote RNA polymerase binding.
What is the function of an activator in gene regulation?
It promotes RNA polymerase binding, stimulating transcription.
Lac Operon
An example of an inducible operon that is activated in the presence of lactose.
Trp Operon
An example of a repressible operon that is turned off in the presence of tryptophan.
What is the effect of an active repressor on an inducible operon?
It keeps the operon turned off by blocking transcription.
What happens to a repressible operon in the absence of a corepressor?
The operon remains on, allowing transcription to occur.
Positive Gene Regulation
A mechanism where genes are turned on, often involving activators.
Negative Gene Regulation
A mechanism where genes are turned off, often involving repressors.
What is the outcome when an inducer inactivates a repressor?
Transcription is turned on, allowing gene expression.
Metabolic Adaptability
The ability of prokaryotes to change their metabolic pathways in response to environmental changes.
What is the significance of the operator in an operon?
It is the binding site for regulatory proteins that control transcription.
What does an inactive repressor indicate in a repressible operon?
The operon is on, allowing transcription to proceed.
What is the function of the regulatory gene in an operon?
It codes for the regulatory protein that controls the operon's transcription.
What happens when a corepressor binds to a repressor?
It activates the repressor, turning off transcription.
What is the effect of an active repressor on a repressible operon?
It turns off the operon by blocking transcription.
What is the role of the promoter in gene regulation?
It is the site where RNA polymerase binds to start transcription.
What is the function of the operator in an operon?
It regulates transcription by binding regulatory proteins.
What is the outcome when an inducer is absent in an inducible operon?
The operon remains off, preventing transcription.