Transcription factor, promoter, and operon concepts that control gene expression, tested at the introductory genetics level.
30 cards · basic cards · AI-written, checked twice. Edit anything.
- What is an operon?
- A cluster of genes in bacteria transcribed together as a single mRNA and controlled by a shared promoter and operator
- What DNA sequence does RNA polymerase bind to in order to initiate transcription?
- The promoter
- What DNA sequence in an operon serves as the binding site for a repressor protein, controlling access to the promoter?
- The operator
- In the lac operon, what molecule acts as the inducer that binds the repressor and allows transcription to proceed?
- Allolactose
- What type of operon is the lac operon, based on how it responds to its regulatory molecule?
- An inducible operon (normally off, turned on in the presence of lactose)
- What type of operon is the trp (tryptophan) operon, based on how it responds to its regulatory molecule?
- A repressible operon (normally on, turned off in the presence of tryptophan)
- What molecule acts as a corepressor in the trp operon, binding the repressor protein to shut down transcription?
- Tryptophan itself
- What additional regulatory mechanism in the trp operon causes transcription to terminate prematurely when tryptophan levels are already high?
- Attenuation
- What term describes global regulation of the lac operon by glucose availability, mediated by cAMP and the CAP protein?
- Catabolite repression
- What happens to cAMP levels in a bacterial cell when glucose is abundant, and how does this affect the lac operon?
- cAMP levels fall, reducing CAP-cAMP binding to the promoter and decreasing lac operon transcription even if lactose is present
- What term describes a protein that binds DNA to increase the rate of transcription of a target gene?
- An activator (transcriptional activator)
- What term describes a protein that binds DNA to decrease or block transcription of a target gene?
- A repressor
- What is a transcription factor, in general terms?
- A protein that binds specific DNA sequences to help regulate the transcription of a gene
- What DNA regulatory element can increase transcription of a gene even when located far from the promoter, in either orientation?
- An enhancer
- What DNA regulatory element decreases transcription of a gene, functioning as the opposite of an enhancer?
- A silencer
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