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25 Cards in this Set

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  • Back
What happens when glucose and lactose are present in the medium?
What did Jacob and Monod do?
1)Elucidated principles of gene expression.
2)Operon model(Lac operon)
3)Catabolite repression.
What is an operon?
A series of genes whose expression is controlled by some common regulatory elements and will yield a polycistronic mRNA as a product.
monocistronic:_ mRNA and _ protein
polycistronic: _ mRNA and _ proteins.
1, many
What is found in the lac operon?
promoter and operator
What is a promoter
it is where RNA pol will bind to initiate transcription.
What is a operator?
A DNA sequence bound by a regulatory protein that can block transcription.
What is the regulatory protein called that is associated with blocking transcription?
The repressor.
What is Lac Z?
beta galactosidase--> cleaves glucose and galtose.
Lac Y does is what?
Lactose permease--> transport protein.
Lac A does is what?
Lactose transacetylase--> function unclear.
The repressor is ___ from the operator when lactose binds to it.
Because Repression is leaky we observe ??
Very low levels of transcription even with the repressor on the operator.
What is an example of negative regulation?
When lactose binds to the repressor and it falls off and allows from transciption of the lac operon/
What role does lactose play in this?
An inducer
Maimal transcription of the lac operon requires an ??
Catabolite activator protein
(CAP) can interact with the activator region only when it binds to _____
cycliv AMP(cAMP)
CA{ and cAMP can bind to the activator region and this promotes ??
RNA pol binding to the promoter.
Transcription occurs when??
RNA binds to the promoter and the repressor falls off.
In the biphasic growth curve what is occuring?
1)glucose is used first bc in most bacteria it is the preffered carbon source.
2)In the presence of glucose and alternate carbon source(lactose) wont be used.
3)This prevention of usage of the secondary carbon source is called catabolit repression.
What would happen to the lac operon if cRMP was provided to the cell in unlimiting amounts in the presence of glucose?
1)RNA pol would bind to the promoter of the operon.
2)Lac Repressor would interact with the operator their is no lactose to make it fall off.
When toxins and antibiotics come into the cell they increase the acitvator proteins which then do what?
stimulate transciption of efflux pump encoding genes.
What is an example that causes transcription activation of efflux pump gene expression?
If you take aspirin with anitbiotics will ___ the effect of antibiotic
reduce (more antibiotic resistant)