Mutation effect on expression of proteins of the lac operon | Homework Help

1. If E. coli cells are grown in medium in which lactose is the only available carbon source, which of the following events will occur with respect to the lac operon?
A. RNA polymerase will be blocked from binding to the promoter.
B. The lac repressor will bind to the operator sequence.
C. Three distinct mRNAs will be synthesized, encoding the structural genes (lacZ, lacY, lacA).
D. Cyclic AMP (cAMP) concentrations will be low.
E. The catabolite activator protein (CAP) will stimulate transcription.
2. A mutation occurs in the lac repressor protein such that it can no longer bind to allolactose. What effect will this mutation have on expression of proteins of the lac operon in the presence of lactose?
A. It will have no effect since lactose shuts off the operon.
B. It will decrease expression of the lac operon proteins.
C. It will increase the expression of lac operon proteins.
D. It will increase the expression of lac operon proteins, but only when lactose is present.
E. It will have no effect since the operon is modulated by the CAP protein