Introduction to Bacterial Plasmids

in this video, we're going to begin our introduction to bacterial plasmids. And so plasmids are really just small molecules of circular double stranded DNA that can be replicated independently of the cells chromosome. Now these plasmids, they typically contain genes that are not required for survival of the cell. And so if the cell loses a plasmid in many cases, the cell will still be able to survive. Now that being said, some plasmas do have genes that provide key features for survival, for example, antibiotic resistance. But for the most part, plasmas do not have genes required for survival. Now the plasmids are going to be replicated by the cell's DNA proliferates, which is the enzyme that performs DNA replication. Now curing is actually a process where the cell loses its plasma and when the cell loses its plasma, this can actually be something that happens spontaneously or naturally, or it's something that can be induced chemically by a scientist. And so if we take a look at our image down below, we can get a better understanding of plasma curing with chemical induction. And so notice on the left hand side over here we're showing you a bacterial cell and notice that the bacterial cell has its own chromosomal DNA here in red. But notice that over here in green, there's a circular, a small circular double stranded DNA molecule that we call a plasma. And once again, this plasma does not typically contain genes that are required for survival. And so through plasmid curing, which can be induced chemically chemical induction will allow the cell to lose its plasma. And so you can see that the plasma is being lost here being removed. And so over here we have the cell which no longer has that plasma. And notice the cells saying that's okay, I don't really need it. And so once again, in most cases, these plasmas do not have genes that are required for survival. However, in some scenarios, they can have genes that provide key features such as antibiotic resistance. But for now, this year concludes our brief introduction to bacterial plasmids, and we'll be able to apply these concepts here as we move forward. So I'll see you all in our next video.

in this video we're going to introduce episodes OEMs. And so an episode is really just a special type of plasmid that has this unique ability to be able to integrate into the bacterial cells chromosome. And so this integrated D. N. A. Is actually going to be replicated along with the bacterial chromosome all DNA. And so it can be inherited by the daughter cells as well in this fashion. And so if we take a look at our image down below, we can take a look at how episodes are plasmas that can integrate into a bacterial chromosome. And so notice over here on the far left what we're showing you is a bacterial cell. You can see the bacterial chromosome is here in red and over here in green. What we have is this specialist plasmid called the episode own. And so the episode has the ability to integrate. And so notice that through integration the episode is now embedded within the chromosome DNA. So we have our integrated episode um here and so now that the episode has been integrated, it will be replicated along with the bacterial chromosome itself, and so through binary fission, the two daughter cells that result are each going to have a copy of the bacterial chromosome with the episode um uh integrated into that position. And so this year concludes our brief introduction to episodes and we'll be able to get some practice applying these concepts as we move forward. So I'll see you all in our next video.