lac operon specific Flashcards

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1
Q

enzymes transcribed + translated from lac operon

A

permease and beta-galactosidase

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2
Q

when lactose is absent…lac operon is BLANK

A

repressed (no transcription or translation)

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3
Q

explain what happens with the lac operon when lactose is absent

A

when there is no lactose in the environment, the repressor protein unbinds from the repressor gene and binds to operator. since the operator sequence is downstream of the promoter, this physically blocks RNA polymerase from transcribing. no products are produced.

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4
Q

explain what happens with the lac operon when lactose is present

A

when lactose is present, it binds with the repressor protein which changes its shape (conformational change), barring the repressor from binding with the operator. nothing is blocking RNA polymerase so it can transcribe as normal. translation would then occur and the enzymes protease and beta-galactosidase are the products

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5
Q

when there IS BOTH glucose and lactose what is happening with the lac operon

A

CAP (repressor protein) not bound, LAC repressor not bound, operon is OFF

no activation or repression, overall very little activity

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6
Q

when there IS glucose but NO lactose, what is happening with the lac operon

A

CAP not bound, LAC repressor bound, operon is OFF

no activation but there is active represon, overall represon wins

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7
Q

when there is NO glucose and NO lactose, what is happening with the lac operon

A

CAP bound, LAC repressor bound, operon is OFF

there is activation and repression, overall repression wins

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8
Q

when there is NO glucose but there IS lactose, what is happening with the lac operon

A

CAP is bound, LAC repressor not bound, RNA polymerase bound, operon is ON

there is activation and no repression so transcription occurs

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9
Q

what is the repressor protein used in the lac operon

A

CAP

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