The lac operon is known to have an additional level of control just so that the operon would remain inactive in the presence of glucose even in the presence of lactose. This is known as catabolite repression. If both lactose and glucose are present, β-galactosidase would not be synthesized unless all glucose has been consumed.
What is the likely state of the lac operon in conditions in which glucose is very low and lactose is plentiful?
A. The CAP protein is bound to the CAP site, and allolactose is bound to the repressor.
B. The polycistronic mRNAs are not translated.
C. Transcription of the LacZ gene is high but transcription of the LazY gene is low.
D. The CAP protein is bound to the CAP site, and the repressor is bound to the operator.