Virus Structure

by Jason Amores Sumpter
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hi. In this video, we're going to talk about viruses, which are much, much, much, much, much smaller than your average cell. In fact, viruses are significantly smaller than even the smallest bacteria, and this is because viruses lack a lot of the necessary structures to sustain life that you'd find in cells. They don't have the machinery necessary to carry out metabolic processes or to process their genetic information through transcription and translation. Now, because of this, you could almost think of viruses as these vessels for genetic material, and the protective coating over that genetic material is called the Caps it. And this is really just a protein coat that covers the viral genome, and it is made up of little sub units we call caps Amir's so you can see in this image right here we have this virus, and it has a caps it. This blue structure made of all these little balls you see here. Each one of these little blue balls is a cap Samir now viruses. As I said, they're basically vessels for genetic information. But what kind of genetic information well, that actually can vary depending on the type of virus, so a virus could contain double stranded DNA, single stranded DNA, double stranded RNA. Believe it or not, that's not something we really encountered yet, and we probably won't really bring it up again. But it can happen, and they can also have single stranded RNA. And there's such a wide range of viruses and what they're all capable of, that we're really just gonna talk about generalities. Here, however, we are going to focus in on a particular class of virus called bacteria fage. And that's because these have been very heavily studied, and we have a lot of good information about how these particular types of viruses operate. Now what's defining about bacteria pages, or sometimes just called fage is for short is that their viruses that infect bacteria and they actually have some pretty complex caps is so this right here is a bacteria fage, and you can see that compared to its neighbor, this bacteria or this virus is struck. Capsized structure is much more intricate looking. In fact, that's because this caps it has to carry out a pretty specialized function that will get to a little later in lesson. But for now, just note that this protein coat encapsulates the viral genome right here. So that's our viral genome. And, well, there's a lot of other bells and whistles down here, and we'll get to what those do later. Now. Some viruses. Not all viruses, but some viruses have what's called a viral envelope, and this is an accessory structure, so it's not necessary for viruses. But some viruses have them frequently animal viruses, and these are member Enis structures that are often derived from the membrane of the viral host cell. So what that means is the virus will actually take a portion of the host membrane to form a viral envelope around itself. Now, in addition to these viral envelopes, viruses have important structures on their surface that you can see labeled here. We have thes glycoprotein and these, in addition to some other structures that I'm not going to mention define the viruses host range, which is the collection of hosts that a virus can enter and infect, and viruses identify their hosts based on these surface proteins that detect specific receptors on the host cell. So that's why I said these gallego proteins or other various protein structures on the surface of the virus will actually determine its host range. All right, now, let's flip the page