Here's why:

* Origin of Replication: Prokaryotes have a single origin of replication (oriC) on their circular chromosome.

* Replication Forks: When replication begins, two replication forks are formed, moving in opposite directions around the circular chromosome.

* Bidirectional Nature: This movement of the forks in opposite directions leads to the bidirectional nature of DNA replication in prokaryotes.

The bidirectional nature of DNA replication ensures that the entire genome is replicated efficiently and quickly.