Final answer:
A mutated LacI protein that cannot bind to the lac operator would lead to unregulated, constant transcription of the lac operon, as the repressor could no longer inhibit transcription.
Step-by-step explanation:
If the LacI protein is mutated and cannot bind the lac operator sequences at all, transcription of the lac operon will occur unregulated. Normally, the LacI protein acts as a repressor, binding to the operator sequence and preventing transcription when lactose is absent. In this mutated scenario, because the repressor can no longer bind to the operator, RNA polymerase is free to bind to the promoter and transcribe the genes of the operon, leading to the constant production of enzymes necessary for lactose metabolism, even if lactose is not present.