The Steps and Proteins involved in DNA Replication (Prokaryotic and Eukaryotic)

It is now well established that DNA Replication occurs semi conservatively, copying each strand of DNA separately, to produce two new DNA double helices. Each is composed of an old(Parent) strand and a newly synthesized one.

Meselson and Stahl in 1958 and J.Cairns in 1963 experimentally verified that the DNA of E.coli replicates semi conservative manner. J.H.Taylor confirmed semi conservative replication of DNA in Vicia faba chromosomes in 1963.

The Steps and Proteins involved in DNA Replication (Prokaryotic and Eukaryotic)

Steps	Prokaryotic cells	Eukaryotic cells
Unwinding of DNA double helix at replication origins(s)	Helicase (Requires ATP)	Helicase (Requires ATP)
Stabilization of unbound template strands	Single strand binding protein (SSB)	Single strand binding protein (SSB)
Synthesis of DNA leading strand lagging strand (Okazaki fragment)	DNA polymerase III DNA polymerase III	DNA polymerase delta DNA polymerase alpha
Removal of RNA primers	DNA polymerase I( 5’-exonuclease)	Unknown
Replacement of RNA with DNA	DNA polymerase I	Unknown
Joining of okazaki fragments	DNA ligase I (Requires NAD)	DNA ligase I (Requires ATP)
Removal of supercoils ahead of advancing replication forks	Topoisomerase II (DNA gyrase) (Inhibited by nalidixic acid, norfloxacin)	Topoisomerase II (Inhibited by etoposide, teniposide
Synthesis of telomers	Not required	Telomerase