Origin of replication is the site on the DNA strand, both genomic and extrachromosomal, which is recognised by the DNA polymerase for the initiation of replication. It is also the site where the unwinding of DNA occurs to facilitate replication. The stretch of DNA replication from one origin in one single go is known as a replicon. The eukaryotic DNA has only one replicon thus has only one origin of replication whereas the eukaryotic DNA is a multiple replicon system consisting of multiple recognisable origins of replication.