DNA Polymerase (pol III) is needed for DNA synthesis. It adds the DNA nucleotides in the 5' to 3' direction to build the complementary strand of DNA.

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Initiation of DNA replication requires many proteins to interact with DNA to begin replication. Prokaryotes have a single DNA sequence to begin DNA replication. 
Important terms in prokaryotic initiation:
- Origin of replication
- Topoisomerase II
- DNA Polymerase III

Initation of DNA Replication in Prokaryotes

Elongation of DNA replication requires adding the DNA bases of the elongating strands. The primers introduced in initiation are also removed. 
Key terms in prokaryotic elongation:
- DNA Polymerase I

Elongation of DNA Replication in Prokaryotes

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Bacterial DNA is often supercoiled, or twisted onto itself. Topoisomerase II relaxes the DNA so that it is more accessible to other proteins needed for replication. 
Topoisomerase II is also called DNA gyrase.

Topoisomerase II

The origin of replication is the DNA nucleotide sequence where DNA replication initiates. In  *E. coli*, this is called *oriC*. Proteins bind to the origin of replication to initiate DNA replication in bacteria. It is typically an Adenine-Thymine rich sequence. Because the origin of replication is an A-T rich region, this aids in separating the DNA strands because they contain one less hydrogen bond compared to G-C base pair hydrogen bonding interactions.

Origin of Replication

DNA Polymerase III 

DNA Polymerase I (pol I) removes the RNA primers that are present on the lagging strand and synthesizes the small gaps of the lagging strand during DNA replication.
Pol I also has an important role in synthesizing new nucleotides after mutated DNA base pairs have been removed by the nucleotide excision repair.

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