Well, basically, certain types of cells contain special plasmids known as the fertility factor or the F factor. And these are plasmids that code for special types of proteins that build something called the sex Pillus. Now, the sex Pillus is basically the cytoplasmic bridge that connects one cell to another cell and allows one cell to transfer genetic information to a different cell, as we'll see in just a moment. So a cell that contains this fertility factor, the F factor, is called our F plus, or the donor cell. While the cell that does not contain the F factor, our fertility factor, is known as our recipient or F minus. So, to initiate the process of conjugation, the donor cell must actually use its F plasmid or f factor to actually replicate or to actually produce the proteins that build our sex Pillus.