Question

The promoter site and the terminator site for transcription are located at:

• A. 5' (upstream) end and 3' (downstream) end, respectively of the transcription unit
• B. 3' (downstream) end and 5' (upstream) end, respectively of the transcription unit
• C. the 5' (upstream) end
• D. the 3' (downstream) end

Answer 1

The correct option is A 5' (upstream) end and 3' (downstream) end, respectively of the transcription unit

Transcription unit:

Sequence of nucleotides in DNA that codes for a single RNA molecule is called a transcription unit. It consists of three regions - promoter, structural gene and terminator.


Promoter site:

Promoter is the DNA sequence where RNA polymerase binds to initiate transcription. With respect to the coding strand, the promoter is present upstream (5’ end) of the structural gene in the transcriptional unit.


Terminator site:

Terminator is the DNA sequence where transcription ends. With respect to the coding strand, the terminator is present downstream (3’ end) of the structural gene in the transcriptional unit.


Schematic representation of transcription unit:




Final answer: b. 5' (upstream) end and 3' (downstream) end, respectively of the transcription unit