Question

Assertion (A): Regulation of lac operon by a repressor is referred to as negative regulation.

Reason (R): Lac operon is under the control of positive regulation as well.

Options

• Both A and R are true and R is the correct explanation of A.

• Both A and R are true but R is not the correct explanation of A.

• A is true but R is false.

• A is false but R is true.

Answer 1

Both A and R are true and R is the correct explanation of A.

Explanation:-

An operon is a group of genes that are all controlled in the same way. It consists of structural genes (which normally code for enzymes), regulatory genes (which code for activators or repressors, for example), and regulatory sites (such as promoters and operators).

The operon's response when no regulatory protein is present determines the type of regulation.

The lac operon's inducer–repressor control is an example of negative control, in which expression is generally suppressed.

The CAP- cAMP system, on the other hand, is an example of positive control, as the lac operon requires the presence of an activating signal to be expressed.