Final answer:
Bacteria utilize the origin of replication (orT) for initiating binary fission on their chromosomal DNA which proceeds bidirectionally, and in rolling circle replication of plasmids, orT is engaged after initial strand displacement to synthesize the complementary strand.
Step-by-step explanation:
In bacteria, origin of replication (orT) is the specific sequence where DNA replication begins. Bacteria use this site somewhat differently depending on whether the DNA in question is part of the bacterial chromosome or a plasmid. The binary fission process in bacteria primarily replicates the bacterial chromosome, which starts at a single origin of replication, and proceeds bidirectionally.
However, when referring to plasmid replication, orT signifies the single-stranded origin used during rolling circle replication. In this case, orT is operational after the initial nicking at the double-stranded origin (dso), and subsequent displacement of a DNA strand. This leaves a single-stranded DNA, where replication ensues at the orT to create a double-stranded plasmid again, thus completing the replication process.