DNA polymerases need a pre-existing DNA or RNA chain end (a primer) onto which to add each nucleotide. For this reason, the lagging strand polymerase requires the action of a DNA primase enzyme ...

During DNA replication, the unwinding of strands leaves a single strand vulnerable ... and causes the polymerase to pause (Figures 3 and 4a). For example, a DNA base can be chemically modified ...

The process begins by unzipping DNA's ladder-like structure, resulting in two strands called the leading and lagging strands ... that forces the leading strand polymerase to let go of the new ...