Gene regulation in repressible systems.

[Lazerous]

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Which of the following best describes gene regulation and expression in a repressible system?

A. The repressor binds to the operator, forming a barrier that prevents the genes from being transcribed

B. The repressor is inactive until it combines with a corepressor allowing genes to be transcribed

C. The repressor co repressor binds with the operator and represses enzyme synthesis

D. In a constant state fo transcription without a corepressor

E. Both C & D

This is from topscore test 2 question 34. I chose E since that seemed to be the best answer and it is in fact the correct answer.

BUT, isn't A also correct?

 

[jjw822]

Which of the following best describes gene regulation and expression in a repressible system?

A. The repressor binds to the operator, forming a barrier that prevents the genes from being transcribed

B. The repressor is inactive until it combines with a corepressor allowing genes to be transcribed

C. The repressor co repressor binds with the operator and represses enzyme synthesis

D. In a constant state fo transcription without a corepressor

E. Both C & D

This is from topscore test 2 question 34. I chose E since that seemed to be the best answer and it is in fact the correct answer.

BUT, isn't A also correct?

It is E not A because A is describing inducible system

 

[Lazerous]

It is E not A because A is describing inducible system

Aah, I knew I was over looking something simple.

Thanks!

 

[doc3232]

A is incorrect because they said it forms a barrier...it doesn't form any sort of barrier. Kind of awkward question...🙂

 

[doc3232]

It is E not A because A is describing inducible system

??? How is that inducible?

 

[Lazerous]

A is incorrect because they said it forms a barrier...it doesn't form any sort of barrier. Kind of awkward question...🙂

Of course it forms some type of barrier. How else, then, would an inducible system prevent transcription. It doesn't have to be a great wall of china type of barrier, just a theoretical form of one.

 

[Lazerous]

??? How is that inducible?

You have Cliff's AP right?

Turn to page 118 and read up on the lac operon.

 

[klpennin]

A is wrong because the repressor must be bound with the co-repressor in order to block transcrition of the gene.

 

[jjw822]

A is wrong because the repressor must be bound with the co-repressor in order to block transcrition of the gene.

NOPE!! you are talking about repressor system. ONLY in repressor system you need corepressor which binds to repressor to make it active.

In INDUCIBLE system, repressor is bound to operon at any given time until inducer binds to repressor to make it inactive.

 

[klpennin]

I was talking about the original question, which is talking about a repressible system, not an inducable system