Final answer:
Okazaki fragments on the lagging strand of DNA are ligated together by the enzyme DNA ligase, which ensures continuous double-stranded DNA after replication.
Step-by-step explanation:
Eventually replication bubbles meet and the Okazaki fragments are ligated together. As DNA replication progresses, multiple replication forks are formed, and the DNA is synthesized in segments. On the leading strand, DNA is synthesized continuously, but on the lagging strand, it is synthesized in short stretches known as Okazaki fragments. These fragments are eventually joined together to form a continuous DNA strand. The joining process is facilitated by the enzyme DNA ligase, which seals the nicks between the fragments through the formation of phosphodiester bonds. This process is crucial for the replication of the lagging strand, ensuring that the DNA molecule is a continuous double-stranded helix.