DNA replication will begin at a specific area of the molecule called the origin of replication. The origin of replication denotes the area of active replication called the replication fork. In order to understand how complex eukaryotic organisms replication DNA, scientist first studied replication in prokaryotic modles, like E.coli. A number of enzymes are needed for replication to proceed once the replication fork is established . Helicase separates the strand of the double helix and single stranded binding.