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ENZYME: DNA-directed DNA polymerase
DNA RNA Protein
1. Semi-conservative2. Ordered and sequential3. Uses activated substrates4. Semi-discontinuous5. Accurate
1. Initiation2. Elongation3. Termination
A circular bacterial chromosome has a single origin of replication.
oriC : origin of replication of E. coli
1. Recognition of origin of replication by specific proteins
2. Formation of replication fork
INITIATION: Prokaryotic DNA Replication
Dna A – for identification of origin of replication
DNA Helicase – unwinds the DNA
Single strand DNA binding protein – prevents the reannealing of DNA
INITIATION: Prokaryotic DNA Replication
1. Both strands of the DNA double helix must be copied. DNA polymerase has only 5’ 3’ polymerase activity.
2. DNA polymerase cannot initiate DNA synthesis on a molecule that is entirely single-stranded.
ELONGATION: Prokaryotic DNA Replication
ELONGATION: Prokaryotic DNA Replication
1. Excision of RNA primers by DNA polymerase I
2. Filling up of the gaps by DNA polymerase I
3. Nick ligation
ELONGATION: Prokaryotic DNA Replication
DNA polymerase has DNA polymerase has proofreading abilityproofreading ability
DNA polymerase IIIDNA polymerase III3’ 5’ exonuclease activity
DNA polymerase IDNA polymerase I3’ 5’ exonuclease activity5’ 3’ exonuclease activity