Which one of the following events occurs when allolactose is not present in the E - VCE - SSCE Biology - Question 6 - 2018 - Paper 1

When allolactose is absent in the E. coli cell, it prevents the lac operon from being activated. In this scenario, the repressor protein LacI binds strongly to the operator, inhibiting transcription of the lacZ, lacY, and lacA genes. Molecule Q, which is a part of this regulatory mechanism, can bind to a specific section (Section X) to further prevent the transcription of these genes. This ensures that the enzymes necessary for lactose metabolism (encoded by lacZ, lacY, and lacA) are not produced when lactose is unavailable, effectively conserving resources.