Gene Expression and Regulation Prokaryotes Flashcards
Decribe positive regulation in prokaryotes.
Transcription and No transcription
Transcription: If activator is bound to the activator binding site, RNA pol will bind to promoter and enable transcription
No transcription: If there is no activator bound to the activator binding site, there is no transcription.
Decribe negative regulation in prokaryotes.
Transcription and No transcription
Transcription: RNA Pol binds to promoter region and enables transcription
No transcription: Repressor is bound to operator and blocks RNA pol
How do allosteric effectors affect regulatory proteins?
Activator vs Repressor proteins
Activator: Without effector, the activator will not bind to the activator binding site region
Repressor: Without the effector, the repressor will not bind to the operator region.
Where to repressors bind to?
The operator region
The lac operon is only transcribed in the presense of _
Lactose
How is transcription blocked when no lactose is present?
The repressor is bound to the operator site, blocking RNA pol
What does constitutive mean?
O^c
The repressor cannot bind to the gene so it is expressed
How does the repressor recognize the gene to repress?
The operator has a specific DNA sequence
How is the lac operon controlled?
Controlled by glucose levels
Is cAMP produced if the glucose is high?
No
When is cAMP produced?
When glucose level is low
(cell is hungry)
When can CAP bind to the promotor region to activate transcription?
It can bind to the promoter region after complexing with cAMP molecules.
How is AraC protein an activator?
AraC protein must be bound with its effector, arabinose. When AraC+arabinose and CAP-cAMP is bound to the araI (inducer region) it will activate transcription.
How is AraC protein a repressor?
AraC without effector can bind to the araO (operator region) and araI (inducer region) simultaneously.
The absence of the effector (arabinose) and CAP-CAMP results in this complex/conformation
Place holder for trp operon
