Rolling
Circle
Model - According to one model suggested by earlier work, the first rounds of RF replication are by the conventional semiconservative method in which the growing point moves around the circular genome from origin to terminus.
Each, strand of the duplex serves as a template for the synthesis of a complementary strand. The rolling circle mechanism operates in the final rounds of replication to generate ssDNA molecules.
Dressler and Wolfson (1970) have, however, suggested that the rolling circle mechanism operates for RF replication as well as for ssDNA production. They showed that a (+) strand label follows a (-) strand label into RFI supercoils after a delay of about 20 seconds.
This would happen if the supercoil is derived from the tail of a rolling circle, rather than from semiconservative replication around the circle. Thus all parental RF replication would take place by the rolling circle mechanism.
