Bio question from topscore

[jjw822]

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test 1 number 34.

question is which of the following best describes gene regulation and expression in an inducible system?

A. the repressor binds to the operator, forming a barrier that prevents gene from being transcribed.
B. the repressor is inactive until it combines with the corepressor allowing gene to be transcribed.
C. the inducer-repressor binds to the operator allowing genes to be transcribed.
D. the repressor-corepressor binds to the operator and represses enzyme synrhesis
E. regulation is tina constant state of transcription.

I know answers A. but i dont understand why D is wrong..

Any thought??

thanks

 

[DRHOYA]

This is a weird question. D is wrong, b/c we are talking about transcribing genes, not synthesizing enzymes.

In an inducible system, the repressor is contantly bound to the operator, preventing transcribing. Transcribing only happens when an inducer binds to the repressor, thus allowing transcribing. Thus, those produced proteins/genes are said to be "inducible". I think the wording is messed up on that question.

 

[jjw822]

but then wouldn't C will be correct too??
oh.... ok that is wrong because inducer-repressor doesnt bind to the operator.. right??

 

[osimsDDS]

test 1 number 34.

question is which of the following best describes gene regulation and expression in an inducible system?

A. the repressor binds to the operator, forming a barrier that prevents gene from being transcribed.
B. the repressor is inactive until it combines with the corepressor allowing gene to be transcribed.
C. the inducer-repressor binds to the operator allowing genes to be transcribed.
D. the repressor-corepressor binds to the operator and represses enzyme synrhesis
E. regulation is tina constant state of transcription.

I know answers A. but i dont understand why D is wrong..

Any thought??

thanks

D is wrong because it describes a repressible system, in a repressible system you have repressor-corepressor system that binds to the operator that represses or inhibits transcription of the gene

 

[osimsDDS]

but then wouldn't C will be correct too??
oh.... ok that is wrong because inducer-repressor doesnt bind to the operator.. right??

C is incorrect because when the inducer binds to the repressor it can not bind to the operator and therefore the transcription of the gene is induced, in an inducible system the system is not transcribing because the repressor is bound to the operator, ONLY when an inducer binds to the repressor does it block it from attaching to the operator and therefore RNA pol can transcribe the particular gene (ex/ lac...)

 

[jjw822]

ok thanks guys..///

i am really nervous right now i have dat this saturday....

 

[wkawk2416]

i just took test 1 damn

got 18 on bio and 20 on chem

and it is 3 am in the morning.

something wrong with this i bet