Question

Which is not true regarding the regulation of the lactose operon?

a. optimal expression of the lactose operon requires the activity of the activator protein cap
b. glucose levels affect lactose operon expression via the phenomenon of catabolite repression
c. expression of the lactose operon is constitutive because its expression is affected by cellular cyclic amp levels
d. expression is optimal when lactose is present and glucose is absent in the bacterium

Answer 1

The statement that is not true regarding the regulation of the lactose operon is that glucose levels do not affect lactose operon expression via catabolite repression. Therefore correct option is B

Step-by-step explanation:

Regarding the regulation of the lac operon, the statement that is not true is option B: glucose levels affect lactose operon expression via the phenomenon of catabolite repression.

In reality, glucose levels do affect lactose operon expression via catabolite repression. When glucose is present, catabolite repression occurs, leading to low levels of lactose operon expression. This happens because glucose inhibits the accumulation of cyclic AMP (cAMP), which is needed for the activation of the activator protein CAP that promotes the transcription of the lactose operon. Thus, when glucose is present, the lactose operon is repressed.

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