שכפול בפרוקריוטים

In prokaryotes, such as E. coli, DNA replication of the circular, double–stranded genome begins at the origin of replication called OriC.

Initiator proteins bind to OriC and initiate DNA separation. Then, a helicase is loaded onto each strand to unwind the DNA further and form a replication bubble.

The unwound DNA is stabilized by single-strand DNA binding proteins or SSBs.

The replication bubble now has two replication forks on either side that proceed bidirectionally.

At each fork, the multi-protein replication machinery, including DNA polymerases, simultaneously synthesize the leading strand and the lagging strand.

As the unwinding continues, the DNA ahead of the fork becomes overwound and supercoiled, creating a torsional strain.

Type one topoisomerase enzymes help relieve this stress by creating a nick to allow the other strand to pass through and then ligating the DNA back.

As the replication continues along the genome, the two forks meet at the termination or ter sites where DNA replication completes.

The resulting daughter DNA molecules are composed of one parental strand and one newly synthesized strand following the semi-conservative model of DNA replication.