In this video, we're going to begin our lesson on the mechanism of F plasmid conjugation in E. coli. For the transfer of the F plasmid to occur from an F+ cell to an F- cell, this actually involves a series of steps that we have numbered down below in this image. Notice that this image is focusing on F plasmid conjugation. In the very first step, the donor cell, which is the F+ cell, contains the entire F plasmid allowing it to form an F pilus. The donor F+ cell is able to initiate conjugation with a recipient cell, which is the F- cell.

What you can see over here is that the F pilus of the F+ donor cell is going to bind to a receptor on the outer membrane of the F- recipient cell. That's exactly what we can see taking place, where the F pilus of the donor F+ cell binds, as you see here, to the outer membrane of the F- recipient cell. Then in step number 2, you're going to see that the F pilus retracts. When the F pilus retracts, it shortens and therefore pulls the cells closer together. You can see here that the F pilus is retracting, represented by this backward arrow, and the retraction of the pilus brings the two cells closer together, as you see here and here.

Then, the F plasmid itself is actually going to be cut at the oriT region of the F plasmid. Here, you can see that the oriT region is indicated in red and the plasmid is being nicked or cut right at that oriT region. What can happen at this point in step 3 is that just a single strand of the F plasmid is going to enter the F- cell. That single strand is going to be used as a template to replicate the F plasmid within the F- cell. You can see over here in this image that the single strand of the F plasmid is going to enter into the F- cell, and as it's entering, it's being replicated.

You can see that the yellow border here corresponds with the yellow replicate that you see here. It is being replicated as it enters into the F- cell. Once the transfer of the entire F plasmid is complete, then what happens is both the donor and the recipient cell are going to be F+ cells because they each have a full copy of the F plasmid. You can see over here that the donor F+ cell still retains its entire plasmid, and the recipient cell is now F+ because it contains the entire F plasmid that was transferred once again from the F+ cell over to the F- cell. This is a big takeaway of F plasmid conjugation, that both cells at the end of conjugation are going to be F+.

This is going to be different as we talk about other types of conjugation. This is really important to keep in mind. This here concludes our brief introduction to the mechanism of F plasmid conjugation in E. coli. Once again, we'll be able to get some practice applying these concepts and learn about other types of conjugation as we move forward in our course.

So I'll see you all in our next video.