Final answer:
The discontinuous replication of DNA in vivo occurs on the lagging strand where DNA is synthesized in short segments known as Okazaki fragments. DNA ligase is responsible for connecting these fragments to form a continuous DNA strand.
Step-by-step explanation:
The discontinuous aspect of DNA replication in vivo refers to the way in which the new strand of DNA, the lagging strand, is synthesized in short segments known as Okazaki fragments. The enzyme responsible for this process is DNA polymerase because it can only synthesize DNA in the 5' to 3' direction, which necessitates the synthesis of Okazaki fragments on the lagging strand. These fragments are eventually joined together into a continuous strand by the enzyme DNA ligase, which connects the pieces by forming phosphodiester bonds between them.