In this video, we're going to continue to talk about conjugation by focusing specifically on F plasmids. Conjugation actually requires the presence of a special type of plasmid called a conjugative plasmid. A conjugative plasmid, as its name implies, is going to be a plasmid that's capable of directing its own transfer to a recipient cell via conjugation. The best studied example of a conjugative plasmid is the F plasmid. The 'F' in F plasmid actually stands for fertility.
The F plasmid, or the fertility plasmid, again, is the best studied example of a conjugative plasmid, which means that the F plasmid is capable of directing its own transfer to a recipient cell. The F plasmid, or the fertility plasmid, was originally discovered in E. coli bacteria. This leads us to two main types of cells that we have listed down below. F+ cells are going to contain the entire F plasmid.
These are going to be donor cells, and they will be able to donate the F plasmid to recipient cells. These F+ cells that contain the entire F plasmid and are donor cells, they are going to be able to synthesize what's known as an F pilus. The F pilus allows the F+ cells to initiate conjugation. The second type of cell that's going to be important to note are the F- cells, and F- cells are going to be cells that do not contain the entire F plasmid.
Because they do not contain the entire F plasmid, these F- cells are going to be recipient cells. It's important to note that F- cells, it is possible for them to contain a small portion of the F plasmid. But again, they do not contain the entire F plasmid. And because they do not contain the entire F plasmid, this also means that F- cells do not have an F pilus. Because they don't have an F pilus, F- cells cannot initiate conjugation.
They can only serve as recipients in conjugation. If we take a look at our image down below, we can get a better understanding of this. Notice that here in this image we're focusing on the conjugate of F plasmid, and on the left we actually have an image that represents this F plasmid. This represents the F plasmid.
It is going to be a DNA molecule, a small circular DNA molecule. What you'll notice is that the F plasmid has a specific region right here, that's called the tra region or the tri region. The tra region or the tri region contains genes that are required for conjugation including genes that are going to create the F pilus. You'll also notice that on this F plasmid there's another region here called the origin of transfer or oriT region. The oriT region is basically the region that is going to serve as the origin of replication during conjugation.
The F plasmid will be replicated and replication begins at this oriT region. Once again, F+ cells, as you see here in this image, are going to contain the entire F plasmid. Because F+ cells contain the entire F plasmid, they are going to be donor cells and so they're able to donate the F plasmid to a recipient cell.
Because these F+ cells have the entire F plasmid, they're also able to form an F pilus. This F pilus here is going to initiate conjugation. We'll be able to talk about how it initiates conjugation a little later in our course. Now, on the right we're showing you an F- cell. The F- cell again does not contain the entire F plasmid.
It could either not contain any of it at all, or it may only contain a small portion of the F plasmid, but it does not contain the entire F plasmid. So here we're not showing it at all. And because it does not contain the entire F plasmid it does not have an F pilus. And so F- cells are not able to initiate conjugation and they're going to serve as the recipient cell.
The F, what we're going to learn is that the F+ cell will be the donor cell and it will be able to donate the F plasmid to an F- recipient cell. Then, the F- recipient cell will be converted to an F+ cell. We'll be able to see how that works in more detail later in our course as we continue to move forward. But for now, this here concludes our brief introduction to the F plasmid and we'll be able to get some practice applying these concepts and learn more as we move forward in our course. I'll see you all in our next video.