eukaryotes have single origins of dna replication.
eukaryotes have single origins of dna replication.
eukaryotes have how many origins of dna replication?
single
bullet::::- eukaryotes often have multiple origins of replication on each linear chromosome that initiate at different times (replication timing), with up to 100,000 present in a single human cell. having many origins of replication helps to speed the duplication of their (usually) much larger store of genetic material. the segment of dna that is copied starting from each unique replication origin is called a replicon. the replicons range from 40 kb length, in yeast and "drosophila", to 300 kb in plants.
origin of replication
when the first archaeal genome, "methanococcus jannaschii", had been sequenced completely in 1996, it was found that the genes in the genome of "methanococcus jannaschii" involved in dna replication, transcription, and translation were more related to their counterparts in eukaryotes than to those in other prokaryotes. in 2001, the first genome sequence of "sulfolobus", "sulfolobus solfataricus" p2, was published. in p2's genome, the genes related to chromosome replication were likewise found to be more related to those in eukaryotes. these genes include dna polymerase, primase (including two subunits), mcm, cdc6/orc1, rpa, rpc, and pcna. in 2004, the origins of dna replication of "sulfolobus solfataricus" and "sulfolobus acidocaldarius" were identified. it showed that both species contained two origins in their genome. this was the first time that more than a single origin of dna replication had been shown to be used in a prokaryotic cell. the mechanism of dna replication in archaea is evolutionary conserved, and similar to that of eukaryotes. "sulfolobus" is now used as a model to study the molecular mechanisms of dna replication in archaea. and because the system of dna replication in archaea is much simpler than that in eukaryota, it was suggested that archaea could be used as a model to study the much more complex dna replication in eukaryota.
sulfolobus