Editase molecules move slowly along the newly paired strands, checking the base-pairings between the original and the newly formed complement to assure their accuracy. Any incorrectly paired nucleotides are cut away from the new strand and replaced by the correct nucleotides. Editase enzymes work slowly to locate and correct the base pairing. Estimates of the rate of remaining errors place the rate of copy errors that escape correction at about one in a billion. Finally, a fourth DNA polymerase enzyme, called ligase , the 'linking enzyme' joins the separate segments of the lag strand into a single strand.
Replication is complete.