Coupling site-specific recombination to extensive replication in a yeast plasmid. The yeast 2μ plasmid, a circular DNA, has two FRT sites (orange) on opposite sides of the circular DNA molecule and inverted relative to each other. FRT sites are targeted by the plasmid-encoded Flp recombinase. The recombination reaction inverts the DNA in the sequences of about one half of the plasmid relative to those of the other half. The inversion also changes the direction of one replication fork relative to the other. Inversion thus leads to a double rolling-circle replication that can produce multiple copies of the plasmid in one replication cycle, increasing the plasmid copy number in the cell.