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Multiple Choice
How does the presence of lactose in the cell influence the transcription of the lac operon?
A
Lactose is converted into glucose, which then acts as an inducer for the lac operon.
B
Lactose directly binds to RNA polymerase, enhancing its ability to transcribe the operon.
C
Lactose acts as a co-repressor, enhancing the binding of the repressor to the operator and inhibiting transcription.
D
Lactose binds to the repressor, preventing it from binding to the operator, thus allowing transcription.
Verified step by step guidance
1
Understand the role of the lac operon: The lac operon is a set of genes responsible for the metabolism of lactose in bacterial cells. It is regulated by the presence or absence of lactose.
Identify the components involved: The lac operon includes the promoter, operator, and structural genes. The repressor protein binds to the operator to prevent transcription when lactose is absent.
Recognize the role of lactose: Lactose acts as an inducer by binding to the repressor protein. This binding changes the shape of the repressor, preventing it from attaching to the operator.
Explain the effect on transcription: When the repressor is unable to bind to the operator due to lactose binding, RNA polymerase can access the promoter and transcribe the operon genes.
Summarize the process: The presence of lactose in the cell leads to the inactivation of the repressor, allowing the transcription of genes necessary for lactose metabolism.