Is the lac operon transcribed when lactose is present?
A) Yes, lactose binds to the repressor, allowing RNA polymerase to bind to the promoter and transcribe the operon.
B) Yes, lactose binds to RNA polymerase, allowing it to bind to the promoter and transcribe the operon.
C) No, lactose binds to the repressor, allowing it to bind to the two operators preventing transcription.
D) No, lactose has no effect on transcription of the lac operon.
E) No, lactose binds to the second operator, blocking transcription by RNA polymerase.

Question

Is the lac operon transcribed when lactose is present?
A) ​Yes, lactose binds to the repressor, allowing RNA polymerase to bind to the promoter and transcribe the operon.
B) ​Yes, lactose binds to RNA polymerase, allowing it to bind to the promoter and transcribe the operon.
C) ​No, lactose binds to the repressor, allowing it to bind to the two operators preventing transcription.
D) ​No, lactose has no effect on transcription of the lac operon.
E) ​No, lactose binds to the second operator, blocking transcription by RNA polymerase.

Quizplus · Accepted Answer

Lactose binds to the repressor of the lac operon, causing a conformational change in the protein that prevents it from binding to the two operators. This allows RNA polymerase to bind to the promoter and transcribe the operon, producing the necessary enzymes to metabolize lactose. Therefore, the lac operon is transcribed when lactose is present.

Is the Lac Operon Transcribed When Lactose Is Present