Final answer:
In addition to bacterial cell extracts, an in vitro replication system for plasmid DNA requires nucleotides, RNA primers, ATP, enzymes like helicase, single-stranded binding proteins, DNA polymerase, DNA ligase, and topoisomerases to ensure complete and efficient DNA replication.
Step-by-step explanation:
To set up an in vitro replication system for a plasmid with a single origin of replication and a single replication termination site, in addition to the bacterial cell extracts containing necessary proteins for DNA replication, other materials are indeed required. These additional materials, crucial for facilitating the replication process, include a source of nucleotides, RNA primers, ATP for energy, and possibly other cofactors and enzymes.
Enzymes such as helicase are needed to unwind the DNA helix, while single-stranded binding proteins stabilize the open DNA strands. Primase is necessary to synthesize RNA primers that provide a starting point for DNA synthesis since DNA polymerases can only add new nucleotides to an existing strand. Additionally, the replicative DNA polymerase (such as DNA polymerase III in bacteria) is essential to add nucleotides to the growing DNA strand.
Once DNA replication is initiated, the process includes leading and lagging strand synthesis, where the lagging strand is made in Okazaki fragments. This also requires DNA ligase to join the Okazaki fragments together. After the replication is complete, the plasmids are usually supercoiled, and enzymes like topoisomerase IV and DNA gyrase, a form of topoisomerase II, may be needed to manage DNA topological issues such as supercoiling and concatenation of the replicated DNA molecules.
Altogether, to ensure efficient replication of the plasmid DNA in vitro, it is essential to provide all the biochemical and structural components needed for the replication machinery to perform its task.