What is the small opening region of the $DNA$ helix where replication occurs called?

Escherichia coli is completely labeled with $N^{15}$ and then grown in an $N^{14}$ medium. What will be the nature of the two $DNA$ strands in the first generation of bacteria?

During the replication of a bacterial chromosome,$DNA$ synthesis starts from the origin of replication and proceeds in a.....

The process of $DNA$ replication is catalyzed by an enzyme called

The direction of $DNA$ replication is .........

Synthesis of $DNA$ takes place by