Prokaryotic Transcription Flashcards
1
Q
What is the Rpol holoenzyme?
A
sigma factor + RNA pol core enzyme
2
Q
Where does the sigma factor bind?
A
-35 promoter
then the core enzyme binds
3
Q
What does the -10 AT rich promoter do?
A
facilitates unwinding of DNA
4
Q
What is abortive synthesis?
A
synthesis of short transcripts under 10 nucleotides
5
Q
When does elongation phase begin?
A
Nucleotide sequence of over 10 is made, sigma factor released from polymerase
6
Q
How does Rpol move along the DNA template?
A
5’ to 3’ by a step mechanism
7
Q
What are the 2 forms of termination?
A
rho dependent
rho independent
8
Q
describe rho dependent termination
A
- rho protein follows Rpol enzyme
- At the end of gene Rpol stalls at a series of G nucleotides
- Rho collides with Rpol
- released mRNA from transcription bubble
9
Q
describe rho independent termination
A
- controlled by sequences in DNA
- at the end of gene, Rpol find GC rich region
- mRNA folds back in on itself
- forms termination hairpin
- followed by U’s which destabilises DNA from RNA
