How Does An F Plasmid Transfer?

First of all, the donor cell (which can be Hfr, F+, or F') must directly touch the F- recipient cell by means of the F pilus.  The F pilus is like a long tendril that connects the two cells... like a needle.  Later, this connection takes place via the conjugation bridge.

Next, one strand of the F plasmid is nicked by a special endonuclease that has been encoded by an F-plasmid.  This occurs at the origin of transfer (which we shall refer to as the Ori T).  Then this strand travels across the conjugation tube. :-)

As the strand moves across from the donor cell to the recipient cell, complementary DNA synthesis takes place on both strands.  This is also known as rolling circle DNA replication.

Finally, the DNA transfer across the conjugation bridge (aka conjugation tube) is terminated and the DNA synthesis is completed in both recipient and donor cells.  Ligase then closes the circular DNA molecules and everything turns out better than expected. :)