In E.coli, during lactose metabolism repressor binds to:
In E.coli, during lactose metabolism repressor binds to:
regulator gene
operator gene
structural gene
promoter gene
Solution
The repressor can bind to a short sequence of the lac gene, called operator. When repressor binds to that sequence it physically blocks access by RNA polymerase to the DNA. As a result, as long as it is bound no lac $m$ RNA can be initiated.
Related Theory
The regulatory gene codes for a regulatory protein. The lac repressor, encoded by the lac gene, is the regulatory protein of the lac operon.