Polymerase

…enzymes that facilitate the polymerization of new DNA or RNA against an existing DNA or RNA template in the processes of replication and transcription. It “reads” an intact DNA strand as a template and uses it to synthesize the new strand.

Helicase

…a “motor protein” that separates strands of a DNA double helix or a self-annealed RNA molecule using the energy from ATP hydrolysis by breaking hydrogen bonds between annealed nucleotide bases.

Ligase

…catalyses the joining of two large molecules by forming a new chemical bond.

DNA primase

…synthesizes a short RNA segment (called a primer) complementary to a DNA template and is of key importance for replication because no known DNA polymerases can initiate the synthesis of a DNA strand without an initial RNA or DNA primer.

Topoisomerase

…unwinds and winds the DNA, for protein synthesis and DNA replication. They cut the DNA, and at the end of the process connect it again.