Assertion (A): Regulation of lac operon by re | vedclass

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(A) The $lac$ operon is a classic example of an inducible operon that is regulated by both negative and positive control mechanisms.Negative regulatio

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

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(A) The $lac$ operon is a classic example of an inducible operon that is regulated by both negative and positive control mechanisms.Negative regulation occurs because a repressor protein,encoded by the $i$ gene,binds to the operator region $(O)$ of the operon.When the repressor is bound to the operator,it physically blocks the $	ext{RNA}$ polymerase from binding to the promoter or moving forward to transcribe the structural genes.Since the presence of the repressor protein inhibits transcription,this mechanism is termed 'negative regulation'.Therefore,both the assertion and the reason are true,and the reason correctly explains why the regulation is called negative.

Column-$I$	Column-$II$
$(i)$ Operator site	$(a)$ Codes for enzyme (protein)
$(ii)$ Promoter site	$(b)$ Codes for repressor
$(iii)$ Structural gene	$(c)$ Binding site for $RNA$ polymerase
$(iv)$ Regulator gene	$(d)$ Binding site for repressor

Assertion $(A):$ Regulation of $lac$ operon by repressor is referred to as negative regulation.
Reason $(R):$ Repressor protein binds to the operator region and prevents $\text{RNA}$ polymerase from transcribing the operon.

Similar Questions

Match Column-$I$ with Column-$II$:

Column-$I$ Column-$II$

$(i)$ Operator site $(a)$ Codes for enzyme (protein)

$(ii)$ Promoter site $(b)$ Codes for repressor

$(iii)$ Structural gene $(c)$ Binding site for $RNA$ polymerase

$(iv)$ Regulator gene $(d)$ Binding site for repressor

Which of the following is the substrate for $\beta$-galactosidase?

The structural unit of a gene is .....

Identify the $INCORRECT$ statement with reference to the regulation of gene expression.

Identify the $INCORRECT$ statement from the following with reference to lac operon.

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Assertion $(A):$ Regulation of $lac$ operon by repressor is referred to as negative regulation.Reason $(R):$ Repressor protein binds to the operator region and prevents $\text{RNA}$ polymerase from transcribing the operon.