Step 4: Ligation of Okazaki fragments

The fifth enzyme that has a final role in completing replication is DNA ligase (shown in Fig. 13f). This enzyme will seal the sugar phosphate bond between the last replacement nucleotide added by DNA pol I and the first nucleotide that was added after priming by DNA pol III. With this bond sealing work, the replication process is complete.

The two double stranded DNA molecules that get made will have identical sequences unless rare mistakes happen as the enzymes conduct their work.