During transcription holoenzyme RNA polymerase binds to a DNA sequence and the DNA assumes a saddle like structure at the point. What is the sequence called?
- TATA box
- GGTT box
- CAAT box
- AAAT box
Answer
(1) TATA box
Solution
The promoter is the DNA sequence where RNA polymerase binds to start transcription.
⇒ The core promoter element about 10 bp (prokaryotes, Pribnow box) or 25–30 bp (eukaryotes) upstream of the start site is the TATA box (TATAAT / TATAAAA).
⇒ When the holoenzyme binds here, the A=T rich region unwinds easily and the DNA bends into a saddle-like structure.
∴ The sequence is the TATA box.
Answer: (1)