<P> The origin of replication (also called the replication origin) is a particular sequence in a genome at which replication is initiated . This can either involve the replication of DNA in living organisms such as prokaryotes and eukaryotes, or that of DNA or RNA in viruses, such as double - stranded RNA viruses . </P> <P> DNA replication may proceed from this point bidirectionally or unidirectionally . </P> <P> The specific structure of the origin of replication varies somewhat from species to species, but all share some common characteristics such as high AT content (repeats of adenine and thymine are easier to separate because their base stacking interactions are not as strong as those of guanine and cytosine). The origin of replication binds the pre-replication complex, a protein complex that recognizes, unwinds, and begins to copy DNA . </P>

Where does dna replication begin on a chromosome