Final answer:
One replication bubble is needed per origin of replication, containing two replication forks for synthesizing both the leading and lagging strands, with the lagging strand comprising multiple Okazaki fragments.
Step-by-step explanation:
For replicating both the leading and lagging strands during DNA replication, only one replication bubble is needed at each origin of replication. Within each replication bubble, there are two replication forks that move away from the origin in opposite directions. The leading strand is synthesized continuously in the direction of the replication fork from a single primer. In contrast, the lagging strand is synthesized discontinuously in the direction away from the replication fork, in short stretches known as Okazaki fragments, each requiring a separate primer. Therefore, even though the lagging strand is synthesized in fragments, the overall process of DNA duplication at the origin of replication requires just one replication bubble.