Conjugation: F Plasmids

in this video, we're going to continue to talk about conjugation by focusing specifically on F plasma. It's and so conjugation actually requires the presence of a special type of plasmid called a conjugated plasma. And so a conjugated plasma as its name implies, is going to be a plasma that's capable of directing its own transfer to a recipient cell via conjugation. Now the best studied example of a conjugated plasma is actually the F plasma and the F. And F plasma actually stands for fertility. And so the F plasma or the fertility plasma again is the best studied example of a conjugated plasma, which means that the f plasma is capable of directing its own transfer to a recipient cell. And the F plasma or the fertility plasma was originally discovered, an E. Coli bacteria. And so this leads us to two main types of cells that we have listed down below. Uh F Plus cells are going to contain the entire F plasma. And so these are going to be donor cells. And so they will be able to donate the f plasma to recipient cells. And so these F plus cells that contain the entire F. Plasmid and our donor cells, they are going to be able to synthesize what's known as an F. Hillis and the f pitiless allows the F Plus cells to initiate conjugation. And so uh the second type of cell that's going to be important to note are the F minus cells and the F minus cells are going to be cells that do not contain the entire F plasma. And so because they do not contain the entire f plasma, these f minus cells are going to be recipient cells. And it's important to note that f minus cells, it is possible for them to contain a small portion of the f plasma. But again, they do not contain the entire F plasma, and because they do not contain the entire f plasma, this also means that F minus cells do not have an f pitiless. And so because they don't have an F palace F minus cells cannot initiate congregation, and so they can only serve as recipients uh and congregation. And so if we take a look at our image down below, we can get a better understanding of this. And so notice that here in this image we're focusing on the conjugated f plasma. And on the left we actually have an image that represents this f plasma. Okay, so this represents the F plasma. So this is going to be a D. N. A molecule circular, a small circular DNA molecule. And what you'll notice is that the F plasmid has a specific region right here, that's called the T. R. A region or the trial region. And this T. R. A region or the trial region contains genes that are required for conjugation, including genes that are going to create the F. Tell us. And you'll also notice that on this F plasma, there's another region here called the or ET region. And this or ET region is basically the region is going to serve as the origin of replication during conjugation. And so the F plasmid uh will be replicated and replication begins at this or ET region. And so this here is the F plasm. Once again F plus cells, as you see here in this image, are going to contain the entire F plasma. As you see right here, this is the F plasmid. And because F plus cells contain the entire F plasma, F plus cells, once again are going to be donor cells. And so they're able to donate f plasmid to a recipient cell. And because these F plus cells have the entire F plasma, they're also able to form an f pitiless. And this f pillows here is going to initiate conjugation and we'll be able to talk about how it initiates conjugation a little later in our course. Now, over here on the right, we're showing you an F minus cell and the f minus cell again, does not contain the entire F plasma, it could either not contain any of it at all, or it may only contain a small portion of the f plasma, but it does not contain the entire f plasma. So here, we're not showing it at all. And because it does not contain the entire f plasma, it does not have an F palace. And so f minus cells are not able to initiate congregation and they're going to serve as the recipient cell. And so the what we're going to learn is that the F. Plus cell will be the donor cell and it will be able to donate the F. Plasmid to an F minus recipient cell. And then the F minus recipient cell will be converted to an F. Plus cell. And so 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 year concludes our brief introduction to the F plasma and we'll be able to get some practice applying these concepts and learn more as we move forward in our course. So I'll see you all in our next video.

in this video, we're going to begin our lesson on the mechanism of F. Plasmid congregation and E. Coli. And so for the transfer of the F. Plasmid to occur from an F plus sell to an F minus sell. This actually involves a series of steps that we have numbered down below in this image. And so notice that this image is focusing on F. Plasmid conjugation. And in the very first step the donor cell which is the F. Plus cell is going to contain the entire F. Plasmid, allowing it to form an F. Phyllis. And so the donor F plus cell is able to initiate conjugation with a recipient cell which is the F minus cell. And so what you can see over here is we're saying that the F pitiless of the F. Plus donor cell is going to bind to a receptor on the outer membrane of the F minus recipient cell. And so that's exactly what we can see taking place right here where the uh F. Palace of the donor F plus cell is going to bind as you see here to the outer membrane of the F minus recipient cell. Then in step number two, what you're going to see is that the F palace is going to retract. And so when the f pillows retracts its shortened and therefore it pulls the cells closer together. And so you can see here that the F pillows is retracting represented by this backwards arrow. And the retraction of the pillows brings the two cells closer together as you see here and here and then uh the f plasma itself is actually going to be cut at the or ET region of the f plasma. And so here, what you can see is that the majority region is indicated in red and the plasma is being nicked or cut right at that or ET region. And so what can happen at this point in step three? Is that just a single strand of the f plasma is going to uh enter the F minus cell and then um that single strand is going to be used as a template to replicate, to replicate the F. Plasmid within the F minus cell. And so what you can see over here in this image is that the single strand of the f plasma is going to enter into the F minus cell. But as it's entering its being replicated. So you can see that the yellow border here corresponds with the yellow replicate that you see here. And so you can see that it is being replicated as it enters into the f minus cell. And so once the transfer of the entire f plasma is complete, then what happens is both the donor and the recipient cell are going to be F plus cells because they each have a full copy of the f plasma. And so you can see over here we have the donor F plus cell uh still retains its entire plasma and the recipient cell is now F plus because it contains the entire f Plasma that was transferred once again from the F plus L. Over to the F minus cell. And so this is a big takeaway of uh f. Plasmid congregation is that both cells at the end of congregation are going to be F. Plus, and this is going to be different as we talk about other types of congregation. So this is really important to keep in mind. And so this year concludes our brief introduction to the mechanism of F. Plasmid conjugation and E. Coli. And 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.