Final Answer:
Rolling circle replication is a model for leading strand synthesis. Thus, the correct answer is 1) Leading.
Step-by-step explanation:
Rolling circle replication represents a method of DNA replication that predominantly facilitates the synthesis of the leading strand in a replicating DNA molecule. In this mechanism, the process begins with the initiation of a single-strand nick in the DNA template, enabling the replication machinery to start copying the leading strand continuously.
The rolling circle model involves the formation of a circular DNA intermediate and the continuous unwinding of the template, allowing the leading strand synthesis to occur uninterrupted. As the replication machinery progresses along the circular template, it generates a long single-stranded DNA tail that eventually leads to the synthesis of multiple new copies of the DNA molecule.
This process contrasts with the lagging strand synthesis, which involves discontinuous DNA synthesis in short fragments known as Okazaki fragments. In rolling circle replication, the continuous synthesis of the leading strand ensures swift and efficient replication of DNA, making it a primary model for scenarios where a high rate of DNA replication is necessary, such as during viral genome replication or certain aspects of plasmid replication in bacteria.
Therefore, rolling circle replication primarily represents a model for the synthesis of the leading strand during DNA replication.
Thus, the correct answer is 1) Leading.