DNA Polymerase is an enzyme which promotes or catalyzes the joining of deoxyribonucleotide units (Phosphodiester bond formation) to form a DNA strand. It is essentially involved in DNA replication and DNA repair. During DNA replication, DNA polymerase requires the presence of a template DNA strand which it copies and synthesizes a new DNA strand. The newly synthesized DNA strand is complementary to the template strand. The catalytic activity of joining the deoxyribonucleotide requires four precursors which are the deoxynucleoside 5' triphosphates dATP, dGTP, dCTP and dTTP. Magnesium ions are also required for the catalytic activity.
The DNA polymerase adds nucleotides to the 3' end of the primer.