DNA+polymerase

=DNA polymerase=

**DNA polymerases** are a family of enzymes responsible for catalysing DNA-dependent DNA-synthesis, more simply known as DNA replication.

There are many types of polymerase, some described below.

In bacteria, there are three types of DNA polymerase: I, II and III.


 * **DNA polymerase I** fills the gaps between Okazaki fragments of the lagging strand, as well as removing the primer at the start of DNA replication and replacing it with nucleotides. DNA pol I also has a major gap-filling role in DNA repair.


 * **DNA polymerase II** is primarily involved in the SOS response to DNA damage


 * **DNA polymerase III** is the primary enzyme of DNA replication. Various subunits ( a, e , and q) ﻿form the core polymerase while other subunits prevent the enzyme from falling off its template.

In mammals, five types of DNA polymerase have been identified: a, b, g, d, and e. While g is found only in the mitochondria, where it is responsible for mitochondrial DNA (mtDNA) replication. The other polymerases have the following roles:


 * ** a : ** synthesis of lagging strand.
 * ** b : ** DNA repair.
 * ** d : ** synthesis of leading strand.
 * ** e : ** DNA repair.