The following four short movies are an artist's depiction of the cellular machinery during DNA Replication.
The helicase is in blue, the polymerase is purple, and the ligase is green.
All three proteins are attached in a complex which the DNA helix is fed into.
Notice that after the helicase unwinds the DNA double helix, one strand is fed directly to one polymerase/ligase pair for continuous synthesis of the leading strand. The other strand is fed to a polymerase/ligase pair in short segments for discontinuous synthesis of the lagging strand.