Monday, 15 December 2014

DNA Replication

Initiation:
- Helicase unwinds double helix and breaks the hydrogen bonds
- Single strand bonding pairs keep the DNA separated and stabilized
- Gyrase relives tension between the two strands of DNA by cutting them
- RNA Primase signals polymerase II by putting primers to begin replication


Elongation:
- DNA opens up as replication forks
- DNA polymerase II adds nucleotide to 3' end
- 2 strands: lagging/leading
- Leading strand: RNA primes starts replication and DNA polymerase III replicates 5 to 3 towards the opening
- Lagging strand replicates the 5 to 3 template strand so it is replicating 3 to 5. Since DNA polymerase III only replicates 5 to 3 in segments okazaki fragments. RNA primes starts each segment with primer and DNA polymerase III continues until the end of the segment.


Termination:
- DNA Ligase joins okazaki fragments together
- DNA polymerase I proofreads the bases then replaces the RNA with DNA
- The two DNA molecules separate






No comments:

Post a Comment