When E. coli is grown in a culture medium and lactose is added as the sole carbon source, it acts as an inducer for the lac operon. Which of the following represents the immediate molecular event that occurs after lactose enters the bacterial cell?

Step-by-step solution

Lactose acts as an inducer in the lac operon. When lactose enters the E. coli cell, it binds to the repressor protein (which is synthesized constitutively by the i gene). This binding induces a conformational change in the repressor, rendering it inactive. The inactivated repressor can no longer bind to the operator region, allowing RNA polymerase access to the promoter to transcribe the structural genes. Lactose does not bind to the operator or RNA polymerase, and the i gene continues to synthesize the repressor p