Question

When lactose is present:

Options

• transcription of lac y, lac z, and lac a genes occurs.

• repressor is unable to bind to the operator.

• repressor is able to bind to the operator.

• both transcription of lac y, lac z, and lac a genes occurs and repressor is unable to bind to the operator.

Answer 1

both transcription of lac y, lac z, and lac a genes occurs and repressor is unable to bind to the operator.

Explanation:

The lac operon is a regulatory system in bacteria like E. coli that ensures enzymes for lactose metabolism are only produced when necessary. When lactose is present, it is converted into its isomer, allolactose, which acts as an inducer by binding to the repressor protein. This binding causes a conformational change in the repressor, making it unable to bind to the operator. With the operator unblocked, RNA polymerase can proceed from the promoter to initiate the transcription of the structural genes lac Z, lac Y, and lac A, which code for the enzymes needed to digest lactose.