Question

Choose the incorrect statement of the following:

• A. Operator is the region of DNA where RNA polymerase binds and initiate transcription
• B. A group of closely placed structural genes and regulatory element is called promoter
• C. Process of turning genes on and off so that appropriate genes are expressed. This phenomenon is called gene regulation
• D. Heterogenous nucleus RNA present in nucleus which becomes mRNA is called hn RNA

Hint:

Promoter = Initiation site (Polymerase binds here).

Answer 1

The Correct Option is A

Step 1: The task.
We must spot the incorrect statement among four about gene expression.

Step 2: Check the operator claim.
The statement says the operator is where RNA polymerase binds to start transcription. That is wrong. The place where RNA polymerase binds is the promoter, not the operator.

Step 3: What the operator really does.
The operator is a small DNA region next to the promoter where a repressor protein can sit and act as a switch to block transcription.

Step 4: Check the other statements.
Gene regulation as turning genes on and off is correct. hnRNA as the heterogeneous nuclear RNA that matures into mRNA is correct.

Step 5: Note a small slip.
The statement calling a group of structural genes and a regulatory part a promoter is loosely worded, but the clearly and definitely wrong one is the operator statement, since the binding role really belongs to the promoter.

Step 6: Conclusion.
Therefore the correct answer is "Operator is the region of DNA where RNA polymerase binds and initiate transcription". \[ \boxed{\text{Operator statement is wrong}} \]