Desire for DNA Flashcards
1
Q
Which way round is DNA?
A
right handed
2
Q
How is the building block of DNA made?
A
- RNR removes 2’OG from dNDPs
- Kinase phosphryaltes dNDPS to dNTPs
3
Q
What acts as the starting point for DNA sythesis?
A
an RNA primer that hybridises with a ssDNA template.
4
Q
How is DNA polymerase kept on the template strand?
A
by a β-clamp
5
Q
What two way are there to repair mismatch errors of DNA polymerase?
A
- Polymerase will back track and an exonuclease will cleave the error
- after synthesis DNA glycosylase will remove the mismatch base, endonucleases will recognise this and will remove a section of the DNA; this is then filled in by DNA polymerase and ligated by DNA lygase
6
Q
What is an Okazaki fragment?
A
- lagging DNA can only replicate from 5’ to 3’.
- so to act on it it must work in 1000bp Okazaki fragments
7
Q
What are the two ways of transcription inhibition in prokaryotes?
A
Rho-independent:
- as soon as the 3’UTR is produced it froms a hairpin that binds NusA blocking further Poll-II trascription.
Rho-dependent:
- Rho-utilisation site on 3’UTR binds Rho which moves upwards towards Poll-II to block transcription.
