THE MOLECULAR BASIS OF INHERITANCE
GENE MUTATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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In the lac operon model, the genes within the operon will be activated if ____
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Lactose is present in the cell
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Lactose is absent in the cell
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Explanation:
Detailed explanation-1: -The genes are expressed only when lactose is present and glucose is absent. The operon is turned on and off in response to the glucose and lactose levels: catabolite activator protein and lac repressor. The lac repressor blocks the transcription of the operon. In the presence of lactose, it stops acting as a repressor.
Detailed explanation-2: -When lactose is present, the lac repressor loses its DNA-binding ability. This clears the way for RNA polymerase to bind to the promoter and transcribe the lac operon.
Detailed explanation-3: -The Lactose operon expresses as long as the Lactose is present. When all lactose is converted into glucose and galactose, the reaction stops.
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