RNA synthesis and DNA transcription in Prokaryotes Flashcards
What does the ability of RNA to form complex structures allow it to do?
Have structural and catalytic roles
How many subunits form RNA polymerase?
5
Where does transcription initiation occur?
At a promoter
How does RNA polymerase bind to the DNA?
Binds to sigma factors which are bound to promoters
Where do sigma factors bind?
On the -35 region and the Pribnow box
Where is the pribnow box positioned relative to the start of the RNA?
-10 bases away
What affects the binding of sigma factors?
How close the sequences are to the consensus sequences
What makes the -10 region easy to open up?
It is rich in T’s and A’s
Does RNA polymerase require a 3’ OH group?
No
What is the function of the -35 region?
It is the RNA polymerase recognition site
What type of molecule is rho?
Protein
Describe how rho-dependent transcription termination occurs
- Rho binds to rut sites on the RNA transcript
- Using ATP, rho moves along RNA polymerase
- Rho catches up with RNA polymerase and pulls the RNA out of RNA polymerase
- RNA polymerase falls off the DNA
Describe how rho-independent transcription termination occurs
- A run of A’s on the DNA forms a run of U’s on the RNA transcript which causes the RNA polymerase to slow down
- This gives time for a hairpin structure to form within the RNA transcript
- This hairpin structure pulls the transcript off the RNA polymerase
What are the requirements for RNA polymerase?
- All 4 NTPs
- Mg2+
- A 3’ hydroxyl to attach incoming NTP
- Requires a promoter and a sigma subunit for initation
Does RNA polymerase require a primer?
No
