Question

A promoter in a transcription unit is a DNA sequence ________.

• A. which appears in processed RNA
• B. that provides a binding site for RNA polymerase
• C. which terminates the transcription process
• D. that provides the binding site for DNA polymerase

Hint:

A transcription unit has a promoter, a structural gene and a terminator. Recall which enzyme attaches to the promoter.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
A transcription unit has three regions: the promoter, the structural gene and the terminator.

Step 2: Role of the promoter
The promoter lies upstream of the structural gene. RNA polymerase recognises and binds to it, which fixes the start point and the template strand.

Step 3: Why the other options fail
The promoter is not part of the processed RNA, the terminator stops transcription, and DNA polymerase is an enzyme of replication.

Final Answer:
The promoter is the DNA sequence that provides the binding site for RNA polymerase. \[ \boxed{\text{(B) }\text{that provides a binding site for RNA polymerase}} \]