DNA polymerase III (not DNA polymerase) is an enzyme that works in association with other enzymes during the replication of a DNA molecule. DNA replication begins when the enz … yme, known as helicase unwinds a DNA strand.Helicase unwinds a DNA strand, thus, in the process, separating the two DNA templates. polymerase is an enzyme that catalyzes the conversion of free nucleotides into a single strand.   DNA polymerase differs from RNA polymerase in two major respects:   * … Like all enzymes, DNA polymerase is substrate-specific.