Question

Conventionally the -10 ($5'$-TATAAT) and -35 ($5'$-TTGACA) regions are denoted in

• A. On the same strand which is used a template strand of DNA
• B. On the same strand which is used a coding strand of DNA
• C. On the same strand which is used a sense strand of DNA
• D. On the same strand which is used a coding strand of DNA downstream to the +1 site

Hint:

The RNA transcript matches the sequence and direction of the coding strand (with U instead of T), which is why promoter and gene sequences are conventionally written using the coding strand sequence.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Bacterial promoters contain conserved sequence elements located upstream of the transcription start site ($+1$). These elements (such as the -10 Pribnow box and the -35 box) are recognized by the $\sigma$ subunit of RNA polymerase.

Step 2: Detailed Explanation:
- DNA is double-stranded, consisting of a template strand (used by RNA polymerase to synthesize RNA) and a coding (non-template) strand.
- By convention, all DNA sequences, including promoter motifs, regulatory elements, and gene sequences, are written in the $5' \rightarrow 3'$ direction.
- This direction matches the sequence of the transcribed RNA molecule.
- Therefore, promoter consensus sequences like the -10 ($5'$-TATAAT-$3'$) and -35 ($5'$-TTGACA-$3'$) regions are written as they appear on the coding strand of the DNA.

Step 3: Final Answer:
These promoter regions are denoted on the coding strand of DNA.