VideoPoints

• ••• • •• • ••••• • •
BIOL 2320_Microbiology for Non-Science Majors - 10_06_22_Lecture
Help Tour
© Distribution of this video is restricted by its owner
Transcript ×
Auto highlight
Font-size
00:06 Oh thank you. Mhm. Ok , let's go and get started.
00:55 is annoying but it will disappear in than a minute. Okay, I
01:03 so. Let me just do this . We got there we go.
01:14 that will disappear shortly. So um uh let's see. So I sent
01:23 email this morning. So I think already aware of these announcements. Um
01:32 . Go away. Go away. I see. I don't get
01:44 Alright, hold on, let's All right. Oh thank you.
01:57 . Alright. Um Alright blackboard Do monday open tomorrow basically covering stuff
02:06 week. Chapter eight part one We'll talk about today mastering. So
02:12 of those is due on monday. So schedule schedule opens I guess basically
02:20 tonight. Okay, so in eight I guess. So uh for exam
02:27 exam two is 20 21st. 22nd this month. Okay. Um so
02:35 couple weeks away so we'll finish up we'll finish up um this section Units
02:48 um but we still have until the . We have a little bit of
02:52 over on that day but don't expect much. Chapter 12 is relatively
02:57 I'm not covering everything in there. kind of overview of some of the
03:02 of more larger I guess types you encounter in health care of those I
03:10 I mentioned last time bungle diseases maybe you might encounter. Um But again
03:17 depends on kind of where you end in the world. Some of these
03:21 kinds of diseases are are more common other parts of the world in
03:25 but specifically talking about protozoan diseases, like that, malaria for example,
03:32 others. So anyway, so it's relatively kind of really quick overview
03:37 those types but but certainly with the couple of lectures, we'll talk about
03:43 . Okay. Which I'm sure we're familiar with one virus in particular.
03:49 most of them we want to be friend, not our friend, our
03:54 , Covid. Okay, so we'll about the nature of viruses today is
03:58 kind of definition, what are they the variations of them? So there's
04:05 kind of thing and kind of the of a life cycle. But we're
04:09 this more specifics um as we go to next week. So, but
04:15 need that. I just want to up this last bit of just to
04:22 of what we talked about on Tuesday of the horizontal gene transfer. So
04:28 to put that in perspective again, went through this kind of diagram where
04:32 big, big circle of blue circle the coli it could be it could
04:39 any species really right, but we're on microbes. It could be another
04:43 type, What have you that they define a species by all the genes
04:49 and all the members of that species be homo sapiens, for example.
04:54 , and there will be a collection all the genes that are known in
04:58 species only Anyone given species in that group is going to have a subset
05:06 those genes. Okay so E coli average is about 4 48 100 of
05:12 10,000 genes that are known to be E. Coli. And then a
05:17 then well not that small subset but E coli eyes. Okay we'll have
05:23 in common. It's basically what defines E. Coli. But uh typically
05:28 be things like involved in critical functions DNA replication protein synthesis. These are
05:36 all the coal I do they're gonna genes that are gonna be specific for
05:39 . Okay that they all share. so the point of this is that
05:46 you might think that okay because you bacteria divide by binary fission. Everybody
05:52 the same and we know that they're right that they do acquire variation through
05:57 that we talked about and through horizontal transfers. Right So these mechanisms of
06:04 cells in the population could can can with each other. Okay and so
06:13 went through the mechanisms uh last time . Conjugation trans deduction transposition. So
06:21 know you should have you know be to spot which one is which okay
06:26 do have a fairly distinctive features, they could take a D.
06:31 A congregation to be involving a Certainly cell to cell contact. Right
06:37 unique to it, transaction virus. the is the connection there transposition?
06:45 A transpose on. Okay that contains transpose ace to kind of help cut
06:52 kind of cut and paste function if will. Okay um so so and
06:59 remembering that with all these mechanisms right this piece of DNA coming into the
07:06 right? Either through transformation conjugation. duck sh in right? That that
07:13 . N. A. We'll have somehow combined recombined right with the
07:20 If it's a plasma it can stay out here by itself but we know
07:25 that also it can also integrate. so really the main thing is about
07:31 part two. Chapter eight. Okay with that mind this next thing is
07:36 not a clicker question. Just kind a let's see what we can do
07:39 with this. Okay so again just identifying the four types and whether the
07:45 for the four types for and they're be more than one answer here.
07:48 for conjugation what would fit with anybody throw something at it throw something
07:56 me? He got seven choices. one? Come on. Three
08:03 Yes. Three. Anything else? yes correct. Okay um transformation and
08:21 . There is a term that relates transformation to um Anything else?
08:33 Yes of course. OK um Trans sh in. Yeah of course one
08:40 . Um for transposition five. Yeah . Anything else? Yeah 4.
08:54 and five and actually five you can with all these they can be a
09:00 recombination can be a feature of all four of these things. Okay,
09:05 again, just you should be familiar kind of the basics of how you
09:09 identify each one. What's unique to of thing? Okay. Um any
09:14 about any of those processes? Alright. So let's look At
09:23 So we're gonna switch to 13. talk about viruses. Okay, for
09:26 next couple of lectures here. So as I mentioned, so we're gonna
09:31 gonna you should be able to say word virus that. Okay, here's
09:35 it is. The basic definition here some here's the here's the basic
09:40 there's a basic feature that defines all which will learn shortly. There's gonna
09:45 variations that can be that we'll see that. Um You should know the
09:51 life cycle. Okay. We'll go that. There'll be specifics for certain
09:57 and we'll go through that as Um No where to host ranges.
10:03 classification and kind of just very very terms and the we start in terms
10:09 life cycles. So the viral life can be somewhat complicated. And so
10:16 why we typically always start with the bacterial viruses because they're gonna be
10:21 Okay. And so a bacterial viruses simpler, relatively speaking in terms of
10:29 life cycle than an even entry into cell. Remember virus needs a host
10:34 course, which I'm sure we all . And so that the entry process
10:39 a bacterium and the life cycle of bacteria viruses generally simpler than than an
10:44 virus. Anybody know why would be very reason why it would be not
10:50 a complicated thing. And a bacterium to eukaryotic cell small. True.
10:57 the what's the basic difference between one your cells and the bacterial cell?
11:01 cell is a carry out. So goes with the complication of the cell
11:07 . Right? So you carry out organelles like a nucleus and in a
11:12 particular um golgi apparatus. All this in there. Right. And viruses
11:18 those things animal viruses. And so can be they can be in different
11:23 and in the animal cell depending on kind of virus they are. So
11:26 that reason, because the cell it is complicated. More so than the
11:32 . The viral cycle can be a bit more complicated. So that's how
11:36 start with the bacterial viruses first. that reason. Okay, so um
11:44 let's start here with this question. . And this is a clicker question
11:49 open it up. So which of following is false concerning viruses. This
11:55 of goes really to the features of virus and there are some features common
12:01 all viral types. Um so things uh some features like an envelope.
12:15 and so forth. Okay. Okay, counting down from 10
12:48 Okay, pause for any stragglers. right, counting down from three.
13:03 . Um, yeah, they are a a cell. Nor are they
13:09 precarious cell. Okay, so that's one of the more defining features.
13:14 that Okay? Um, we always the term a cellular to describe the
13:21 . Okay. And so certainly the basic all viruses have this um
13:28 They have a genome of course, they're surrounded by a protein coat.
13:31 all have that. But then there's be lots of variations beyond that.
13:35 that protein coat is what's called a . Okay. The uh, I
13:42 I should say state this now. you kind of get it in your
13:46 because we'll talk about this next Is there's also something called a viral
13:51 . A prion. Okay. And in this same they're always lumped together
13:57 viruses. Okay. But these are considered viruses. Okay. And
14:07 when you get to this part of notes, it says the same
14:09 But I figured I'd just start getting your head now. So they're not
14:14 , viruses have a particular structure to . Right. These are their infectious
14:19 in the prime. But they're just very viral is basically just a piece
14:24 RNA. And that's it. Viral is a protein and that's all there
14:29 to it. Okay, So you the structures of the virus, but
14:33 though they're very simple, they still infectious. I think it can cause
14:37 . But we'll talk about those I just want to point that out
14:41 . So certainly they're tiny. Um in terms of size and because
14:46 small, right, they're going to a genome that's going to be relatively
14:51 as well. But it can be or DNA single strand of double stranded
14:56 variations. Um and an envelope. an envelope is what they may
15:01 Envelopes are generally features of animal Not bacteria viruses. Okay, uh
15:07 talk about that as well. so um so let's look at kind
15:12 comparing these types. So here our of bacterial cells and viruses.
15:21 So you can you have a bit a quasi viral type. So by
15:29 I mean a parasites and viruses are because they need a host.
15:33 So you do have bacterial types in category that um have I mean they're
15:40 bacterial cells, there's no doubt but actually have a lot of functions they
15:44 do on their own. So actually life cycle actually involves living inside of
15:48 cell. Okay. And rocket CIA types uh you particularly get those through
15:55 bite of a tick. Okay. but they're the type that will infect
16:00 and kind of that's kind of their . They hang out in there and
16:02 where they grow. Um So those can't for that reason they can't have
16:07 similarities to a virus. Okay, course you can see here certainly that
16:12 are parasites. Right. Um, plans for membrane. There's no such
16:19 as boundary vision. Okay. they can pass through filters that would
16:27 stop a bacterium of course, reach small size. Um, their metabolism
16:34 really no energetic metabolism in the Okay. Um, ribosomes are typically
16:41 as well. Right? Uh, to be antibiotics. No.
16:45 You can't There's antibiotics don't work on virus. Right? Because really because
16:49 don't have the components of the cell because antibiotics target particular processes in a
16:55 like protein synthesis and identification. And virus doesn't have that internally.
17:01 so, but there can be antiviral that work against viral specific things,
17:08 antibiotics don't. Okay, um, on this is something we'll talk about
17:15 the context of your innate immune You have a defense that involves interferon
17:22 will stop a viral infection. so, um, so speaking of
17:28 filters, right, being able to through those that's actually how they were
17:33 . Okay, that's what we see Janowski and beiring. So they were
17:39 at this tobacco mosaic. What? looking at the this disease that in
17:45 plants. Okay. Um, and normal plants, of course they
17:51 You're usually looking green leaves. Tobacco do because these ones have that kind
17:55 appearance. Okay. And they can't and they die. Okay.
18:03 um, so at this time it like 18 nineties, I want to
18:07 early 19 hundreds. So the germ was well known by this time.
18:13 so it became they thought, okay this plant disease must be due to
18:18 sort of microbe. Okay, let's cokes postulates to figure this out.
18:23 ? So instead of using a rabbit or model, they used obviously the
18:28 . And so they basically took the leaves, took a disease one,
18:34 it up, okay. And made like a paste out of it and
18:37 um paste, then ran it through filter and then they have filters in
18:42 time that could stop the cells that bacterial sized. So I thought,
18:47 , easy enough, we'll put it a filter, it'll stick on top
18:50 the filter and that's that's where we'll a micro they did that and applied
18:55 to a normal leaf and a normal never became diseased. It was just
19:00 normal. And they go, what's this about? I guess somebody
19:04 ideas to say, okay well let's what went through the filter infiltrate and
19:09 there something in there maybe? And they did that then they found the
19:16 , the plant became diseased. And they said, okay this is something
19:19 weird because it's super small. They even aware of things. Microbes that
19:24 be that small. And so that's kind of led to discovery of
19:28 that's actual virus here. And it on the small end in terms of
19:33 sizes 20 nanometers 200.2 microns. That is the lower end size.
19:40 really we're dealing with something small even by virus standards. And so um
19:48 But at this time they didn't have capabilities to to see these things.
19:52 came like 30 years later the electron was discovered. But nonetheless, so
19:59 viruses and of course they can span ranges as mentioned. Um as big
20:05 Ebola. We don't talk about it . But there's been virus is discovered
20:09 the last five years that are approaching are over a micron. They're called
20:16 viruses. And uh there they are that affect different types of like amoebas
20:22 things. They're not super prevalent but are they are supersized. Okay.
20:28 again most most of what we know terms of viruses fits in this
20:32 Okay. And then they have different , what we call helical. Uh
20:36 gonna have like these geometric shapes like um as we'll see. So but
20:43 course the thing is that they um a cell. They take it
20:47 They don't have a lot of functions their own. So they have to
20:50 a cell and take it over and make it a virus factory.
20:55 So what they do and so um long and when I studied the notice
21:01 college and learning about viruses. uh was I never heard of a virus
21:07 didn't do anything, they had let's say good purpose. Okay,
21:11 all over disease causing all this bad . But In the last 10,
21:17 , 20 years that has changed. viruses do have are ecologically important.
21:24 they can control populations of species in environment when you do that, you
21:30 kind of minimize the effect of having dominant species where it's really only one
21:35 predominates and get more diversity and viruses have found to be very important in
21:41 that. Okay, so the point not all viruses are bad. They
21:46 have an important role in the but certainly you are familiar with viruses
21:53 mostly disease causing. Okay, so and almost everything on earth can be
22:01 has has has a virus that infects . Right? So be it an
22:06 , be it algae or proto zones animals? Of course plants they all
22:13 likely can succumb to a viral type specific for them. Okay, so
22:18 are pretty well distributed. Um here's the next question. So this
22:23 of goes into the the uh life and what kind of what needs to
22:32 first in order for that to This is really the probably one of
22:36 most important things from the perspective of virus, what it needs to
22:40 Okay, and while you're answering So this term very in.
22:48 You see, variant virus, I those interchangeably. They don't they don't
22:53 anything different to me. Right. if you see that term it's just
22:57 virus. Okay, Berrien virus, thing. So basically these are all
23:25 elements of viral life cycle or can okay, but there is an order
23:33 it. Okay, let's count down . Yeah, it is gonna be
23:47 for sure. Okay, so we're the host. Okay, so um
23:55 where it begins or ends for the . Okay. And so those you've
23:59 seen I'm sure you've all seen pictures of coronavirus and it has those little
24:04 things all over the surface. It's those things that it recognizes on
24:09 of your cells and then been able infect. Okay. If your cells
24:14 have those then it wouldn't be able infect. Okay. And so certainly
24:21 this is gonna be a feature of viral life cycle translation of proteins.
24:27 replication of genome. Uh this one for all viruses. Right. Obviously
24:33 bacterial viruses. That's not the There's no nucleus. Right. But
24:37 many it is. Um so um we look at uh definition.
24:45 as mentioned already a Sailor is the we use right there. We have
24:49 features that we associate with most Okay. Um can divide on their
24:54 can produce proteins on their own can replicate on their own a metabolism.
25:03 things you don't associate with viruses. . So hence the term a
25:06 So they require a host. Obligate it's a requirement. So obligate
25:11 Okay. The caps it is the covering. Okay so all viruses the
25:17 basic have that protein covering that covers genome. And the genome can be
25:23 . D. N. A single double stranded. Okay. So if
25:27 look at a basic viral life So as we go through this this
25:35 I pointed out asterisks where there can variations. Okay. And the way
25:40 best um I think uh comprehend this to look at what's what's infecting the
25:49 . And we have host proteins on surface of some sort and that's and
25:54 viral proteins on the surface of its . They recognize each other kind of
25:59 , lock and key kind of a . Okay. And so it'll have
26:04 use certain parts of the host uh . Okay. And so what I've
26:12 to risk those what can vary. some viruses need those. Some don't
26:17 carry it with them and some So some viruses are more deficient in
26:22 of what they have and other viruses it varies by viral species.
26:28 But certainly ribosomes, the other machinery protein synthesis, ribosomes, tr.
26:33 . A. S. Nuclear Those are all gonna be needed.
26:37 . They don't they don't bring those them. Okay. Again they don't
26:40 a metabolism. So as as they're the hosts, remember? They're they're
26:45 stuff from the host. So that they're taking their stopping that host of
26:50 . Right? That host certainly wouldn't as happy and as as functional um
26:58 having that virus inside doing what it's to it. Okay. So the
27:01 is certainly suffering, right? It's parasitic relationship. The host isn't is
27:05 benefiting from that of course. So takes a toll on in terms of
27:09 that toll on the cell is growing . Not like like not like a
27:15 would perhaps probably dying likely gonna die or later. If not sooner.
27:22 , so there is a consequence of . Okay. In terms of the
27:26 . And so um now the so of basic cycle. So viral genome
27:35 uh and that can differ whether it's bacteria virus, bacteria viruses generally only
27:42 genome matters. Everything else stays Okay. For animal viruses, the
27:48 thing can come into the cell. . Um Now, once the genome
27:53 in the cell it can begin to copies. So what you have to
27:57 is, right, this is what's in. Okay. And then what
28:01 gonna have are a bunch of they're gonna exit the cell eventually.
28:08 . And if you're going to do , okay, You're gonna have to
28:13 lots of virus babies. Right, gonna exit the cell. Well then
28:19 have to number one make a genome goes in each one. Right,
28:24 our genome. Right? We have this thing. The little boxes I
28:32 around these genomes. That's the Right? That's this. That's
28:36 Make lots of protein. You need make our proteins. You need to
28:39 copies of genome. You need to it all together. Right. And
28:44 that takes quantities of material. Because one's coming in and then a
28:51 a bunch of them are coming Okay. So that means a lot
28:54 stuff is going to be going on the cell to make that happen.
28:57 . One of the stuff doesn't make of genome. Okay. The now
29:01 happens to that genome? If it's packaged packaged into a virus capsule,
29:07 it may some virus life cycle is okay, I'm not gonna do that
29:11 . I'm gonna stick out and put in the host chromosome. Okay.
29:16 that's what it does. So things herpes virus does that. It uh
29:22 you've ever had experienced fever blisters, ? Where all of a sudden it
29:25 out, that's a herpes virus that's this genome into that cell. And
29:32 you haven't noticed anything. Right? you have those fever blisters that's actually
29:37 virus coming out of the chromosome and viral copies now? And what can
29:42 can trigger that can be stress stress one of the triggers for that.
29:46 that manifests itself is like a fever . Okay. One example HIV is
29:52 one that does this. Okay so just different different viruses have different strategies
29:57 that's one is to integrate into the and while it's doing that the host
30:02 completely fine and it just grows and whatever is going on with it.
30:07 . But while that host cell is right of course it's making copies of
30:13 viral genome as well. So viruses getting more and more in terms of
30:19 cell divides. So we'll talk about couple of those life seconds but that
30:23 a strategy. Okay so eventually even it does that it's gonna have to
30:29 our particles if it wants to perpetuate we have to go and make
30:34 Okay so what's happening here then is the cell is taking the virus will
30:41 it over then and use it to copies or make viral particles. So
30:47 making it a replication factory basically. what they call inter sailor replication
30:53 And so again what's this involved? and translate viral genes and proteins then
31:00 these units put genomes in right and exit and then go on to infect
31:07 cells. Okay so that ultimately is will happen here. Okay and it
31:15 be immediate. It could go to route very quickly and overwhelmed to sell
31:23 and kill it or it may go way hang out for a while then
31:30 this. Okay. Or it may do that at a slow rate.
31:34 it can span the spectrum. It crank out viruses very quickly. It
31:38 just do them slowly. You cannot it at all and hang out in
31:43 cell. Uh So again all depends the viral type. Okay. Um
31:49 you know if it does have the of just sitting the chromosome doing
31:53 you don't even know you're infected, . Until this begins to happen.
31:59 , so again it's a lot of here depending on and the virus
32:04 Okay. Um Okay so and well we revisit this whole virus life cycle
32:12 we look at specific ones. But kind of the basics. Okay,
32:18 in terms of structure, right, already know we have a protein structure
32:21 that. The captain uh can shape vary, you can have these 20
32:27 um geometric structures, uh some can kind of fila mentis or helical,
32:33 call it like you see here Ebola that type? Um The genome of
32:37 can vary. DNA RNA single double the envelope. Okay, so if
32:43 have an envelope then you have a around your caps it right. That
32:50 be an envelope. Okay. That comes from when it exits the
32:57 Okay, so you'll have a Okay and here is the viral particle
33:03 assembled. Okay. And when it it will do this that and here's
33:14 viral particle so it kind of pinches , so to speak. So as
33:19 exits. It does that and eventually it has that the host membrane
33:27 So that's where the envelope comes from from the host cell membrane itself.
33:31 . As it exits and it can it can direct synthesis viral proteins,
33:42 role proteins that can assemble and be into the membrane. And so when
33:49 exits then it has its viral proteins . Okay, um and that's important
33:58 course for recognition finding the right host binding to it. Right. So
34:05 uh that's a process that envelope viruses go through. Okay. Now as
34:11 said before, it's your animal viruses will do this. Not your bacterial
34:15 types, but animal viruses will do . Okay. And uh we see
34:21 there. And so the the let's here. So a naked virus,
34:31 one that doesn't have an envelope. . And so flu virus has an
34:37 . Um This is one that wouldn't could be a virus which is
34:41 D. N. A. Type D. N. A virus.
34:43 guess the simple herpes virus is one like that. So it doesn't have
34:46 envelope but it can it doesn't mean not infectious because it certainly is.
34:52 . So the envelope is just a . Some have some don't. Okay
34:57 and uh naked virus would not have envelope. Okay, those glycoprotein spikes
35:03 knobby things, those are typically for recognition of the host infected. Um
35:12 can be other certainly other proteins sticking there with different functions to.
35:17 flu virus has has types of surface that summer for entry and some of
35:24 exit of the cell actually. So can it can it can have different
35:27 . Okay um now the complex viruses kind of like the name implies you
35:36 kind of a typical structure we just right, that caption structure but then
35:41 have additional parts to the thing. , so you can see the different
35:46 shown here below. That's what we complex viruses. Right. And so
35:52 is typical for bacterial virus, this of structure. Okay, so down
35:57 these parts are really about the So we recognize the host cell surface
36:05 through these tail fibers they call Right? Because it's gonna sit on
36:09 surface of the cell. Okay. then this part what they call the
36:14 will actually compress. Okay, that's . Like a spring. It kind
36:19 squeezes down and that actually shoots the genome D. N. A.
36:26 the that's held in the captain is into the cell cytoplasm. That's typical
36:33 a bacterial virus. Okay, because all that goes in the cell is
36:38 genome. All this stuff stays outside cell. And basically it's just an
36:45 shell. And they call those things . Really? That's what you see
36:49 here. Right. So this one has its genome in its caps it
36:56 this one looks like it's yeah it's . So you can see how part
36:58 it is still in the capsule and in this little sheath area and it's
37:03 of it's here. So it's in process of going into self the one
37:07 the middle. That's a ghost. nothing in the captured the genomes already
37:11 itself. That's that's typical for viral bacterial virus type in china. Um
37:19 again don't don't worry about the variant mean the same thing. Okay,
37:25 uh infectivity. Right. So the is what it's all about for the
37:30 to be able to recognize a particular cell type and effect. If it's
37:34 there it won't. And that's where range comes in. So there's host
37:39 and then there's um then there is book says it calls it something
37:47 Yeah. So there's actually a term . You don't need to worry about
37:52 because your book doesn't use it. the term is called trope is um
37:57 , so you have tissue specificity and have host range. Okay, similar
38:05 different. Okay, so host range rabies is a perfect example,
38:11 Because we all know we all know can affect humans, dogs,
38:16 bats, um squirrels. All kinds different mammals. Right? So it
38:22 a wide host range. It can all those different animals. Okay.
38:28 HIV narrow right? It infects um humans and it also has a narrow
38:37 specificity. So when you talk about specificity now you're going from you're not
38:43 about how many different hosts can It's how many different cell types within
38:49 host can infect. Okay so a virus, okay it actually has um
38:58 very broad host range. Many different but a very narrow um tissue
39:04 Okay because it only affects nerve Okay um so a Ebola has relatively
39:16 host range um but it can affect different cell types in the body.
39:22 . And that's really what Gives it how tells you about how I gives
39:29 this lethal itty. It's so So if you get infected by Ebola
39:34 best you have a 50% chance of right upwards of 90% mortality. So
39:41 times out of 10 your life you it. Okay because it can affect
39:45 cell types in the body. People that die from Ebola or it's
39:49 type of viral disease called a hemorrhagic virus they call it because it can
39:55 basically your body the fluid just come of you right because they can infect
39:59 cells that make blood vessels and cause to start leaking. It can infect
40:04 different types of epithelial cells in different types and so that explains why it's
40:11 deadly. Okay um a narrow tissue . So as mentioned, maybe virus
40:18 nerve cells. Um nerve cells of central nervous system. Uh cold
40:25 respiratory tissues. Um HIV HIV very . So it affects only one specific
40:32 type and that's what we call t cells. We'll talk about those
40:36 But so again host range. How different um Always equate if you if
40:46 confused. Just think of rabies. . In fact many different animal
40:49 That's the broad host range. But then when you go to tissue
40:54 in a squirrel, how many cell can rabies? In fact? Well
40:58 nerve cells. So narrow tissue Okay um Any questions on that?
41:07 so genome so just mentioned this um is you know, genome size of
41:14 varies by size of the virus. so something like polio virus, uh
41:21 pox, you may have heard that . Those are kind of on the
41:25 end. So you know they'll have 10 times more genes than something that's
41:31 . Like the tobacco mosaic virus. was like 20.2 microns. So that
41:38 will limit things. The so what the virus specific genes? Well,
41:45 that are involved in being able to a host cell, there's gonna be
41:49 genes. The captured proteins are gonna viral genes. Of course. Okay
41:54 there are certainly going to be all viruses don't carry a lot of stuff
41:57 them. There will be certain Things have to viral genes, they have
42:03 code for proteins will have to make a virus proteins and you can see
42:07 here these different protein types okay that part of the Zika virus and you
42:13 if you want to give an average is probably about average size 10-11,000 nucleotides
42:20 represents not a lot of genes. this is just an example of something
42:24 don't you don't need to memorize this . Okay, this is just an
42:27 of of viral genes and that they they have proteins that are virus specific
42:34 they have to have to carry out infection their life cycle. Okay.
42:38 very common that viruses really even bacterial , infectious organisms disease causing microbes,
42:48 or bacterial, there's kind of a element to when they express their genes
42:54 some genes are involved in getting in into the host and then there's genes
42:59 in kind of setting up the infection then some that come later. So
43:02 very common to refer to especially viral as being early or late, early
43:08 late for that reason because there's different of the life cycle that occur at
43:13 times. Um The uh okay here's I just do this in here just
43:19 show you just to reiterate this point infectivity. Okay and they have a
43:26 narrow uh tissue specificity. So these um receptors that will be in your
43:32 the ravioli of course is where you oxygen. So those cells are in
43:37 lungs obviously and exchange auction with the . And so they actually affect these
43:43 of recognize these particular proteins on those and that's where they bind to.
43:50 . And so that goes to the of how covid can cause you know
43:56 a pneumonia like effects. Okay um with respiratory system breathing and build up
44:04 like that. Okay. Um I threw this term in here. I
44:09 expect you to know this but um used to seeing maybe longer you study
44:16 and what not to look at this . You think that your typical virus
44:21 with a caps ID. Okay. here's the genome. Okay. That
44:28 what all viruses would look like. and there's a variation that involves
44:36 Okay, so what can happen is said this structure it can have have
44:45 . So the genome okay, is self gets coded with protein.
44:58 I think so. I'm not gonna the whole thing out but that we
45:03 a new clio cleo capsule. Did . Right, So in essence the
45:13 for this kind of virus is one just simply coast the genome. It's
45:18 its own thing out here. Like a box covering it. It's
45:23 intimately associated with the genome. And that's a variation. Okay, when
45:32 if you see the term nuclear caps that's what we're talking about and that's
45:36 coronavirus has. So here here is genome. It's almost like an intestine
45:43 way they drew it. But I know if you can see there is
45:47 a very thin blue line that goes the thin blue line is the actual
45:54 the more blobby reddish. That's the protein covering it. Right? So
45:59 is basically then the capital structure for and it's surrounded by an envelope.
46:04 so you see that in in not viruses that that's what they look
46:10 They're they're caps it is basically kind protein stuck all along the genome covering
46:16 . Okay so you you do see variation. Okay. Um so flu
46:24 is um unique and bring that up whereas most genomes um viruses have are
46:34 linear segment of DNA. Or Um The flu virus has what's called
46:44 segmented Genome. So the the chromosome broken up into pieces. Right?
46:53 flu virus eight segments. Okay. so those eight segments. So one
46:58 the things is when a virus infects know I mentioned earlier that one virus
47:03 in and several come out but you you can have viruses of the same
47:09 infecting the same cell um flu virus affect. Um and if you have
47:17 to virus to flu viruses infecting at same time they can exchange these
47:23 Okay they can recombine and exchange And viruses coming out of that cell
47:29 be combinations of these. Okay and flu virus has its origins in aquatic
47:37 , initially things like ducks and wild birds that then went to domestic
47:44 like also ducks and geese and Okay. And then uh then to
47:52 swine pigs. Okay. And so remnants of those various hosts are found
48:00 the genome. And here they have coded. So you see like the
48:03 ones, domestic ducks, yellow wild birds, domestic poultry red.
48:09 . And so you see the combinations . Okay and uh of course you
48:14 mix it in with swine as And so these rearrangements occur and that's
48:20 these ancient end numbers come from. these are on the surface this will
48:26 be things here proteins uh green are h blue at the ends. So
48:32 you have a whatever during flu season always one that kind of predominates and
48:37 give it like an agent and end which relates to the type of agent
48:43 proteins they have. These can change season to season because of this recombination
48:47 can occur in these viruses. Um in generally viruses and this is an
48:55 viruses. RNA viruses are really um are made when they're copying their genome
49:03 they're not fixed. So they're very notorious for having lots of mistakes in
49:07 nucleotide sequence and that can lead to that occur especially in the flu
49:13 And so we all know a flu . You get one season will not
49:16 the next season because because they evolve they change for this reason. Okay
49:21 um and all viruses do. But done some reading on this D.
49:26 . A viruses don't tend to be as careless let's say in terms of
49:31 so many mistakes. So making mistakes replication is not uncommon. But we
49:38 very rigorous ways to fix those So we our ability to let a
49:44 go on changes very rare. But as you go to other species
49:52 not so much. And so the because they're parasites, they don't really
49:57 that system in them. So why they? So they tend to have
50:01 rates of mutation for that reason. . They can't go really nearly and
50:05 everything up because then it just won't function. But it can certainly make
50:11 . And some of those stick and of those enabled uh to change how
50:16 looks to the body. Right? changing this these these things that's what
50:20 body sees, right? And if change it up then your body doesn't
50:24 it and that's how it can go . Escape and cause disease.
50:29 Nature of the virus. Okay. and so and that's what we make
50:36 are the parts we use really when make vaccines is to use these.
50:42 . And that will you inject the and they produce antibodies to these parts
50:48 the virus is constantly changing. And know that's how the effectiveness of the
50:52 can vary because we may not have the right construct in the beginning.
50:57 maybe the vaccine is only maybe 10% or something. So that that varies
51:02 season to season how effective the flu is. Okay. So because you
51:08 always predict exactly what the virus will from year to year anyway. So
51:16 always comes back to like what's what's the outside here because that's what it
51:20 and how it gets into the host . Okay. Um so in terms
51:26 virus structure, it's just a right? So just a recap of
51:31 structure. Um so we defined it a sailor. I didn't list
51:37 but there's there's other features here, course requires a host, no metabolism
51:43 . Uh Captain type. Right? it can be that geometric shape or
51:49 can be like a filament or a shape. Okay, genome type of
51:55 , DNA RNA can be naked or , right naked envelope. Other things
52:04 viruses, like a protein spikes, virus specific proteins here. So the
52:10 . Okay, um now uh any at this point? So as we
52:19 , we're gonna leave yet. But we'll end with um bacterial viral
52:25 But let's look at this question Okay this is about you can of
52:32 they do classify viruses. Okay. you probably think having just gone through
52:36 structure you can probably think of. here's how we can compare viruses looking
52:41 X. Y. And Z. there's gonna be some things you simply
52:45 use any time. So which one these could not be used as a
53:13 to identify a virus? All Let's count down. three.
53:30 Yeah you couldn't use fermentation right? it's not like you can't grow them
53:35 a Petri dish. You could affect um you can't um give it glucose
53:41 hope it will inspire or anything like . Right. So you wouldn't use
53:44 . But certainly A C. And E. Are all plausible things
53:50 can do to identify the virus. . What is typically done? So
53:55 taxonomic system uh in place basically uses genome type. Okay and um presence
54:06 of an envelope. Okay so um do not do not memorize this
54:12 Okay uh I just put up there for you know just to show you
54:16 different types of viruses and really the in you know many of the human
54:23 caused by viruses fall in to this which is the RNA viruses. Okay
54:28 everything from coronavirus of course uh two virus to flu virus mumps and measles
54:37 lots of them fall into this RNA category. Okay. But certainly there's
54:43 in in these other groups for But it tends to be a real
54:47 of human disease causing viruses in that that in these two groups. Okay
54:54 so let's look at um viral life . So we did go through this
55:02 . Okay the basics so we're gonna a little bit more specifics in terms
55:07 uh we'll start with bacterial uh virus cycles. And so just remembering recognition
55:15 uh genome copying the genome getting into cell, copying transcribe, translate,
55:22 proteins and assemble making virus. So is what's going to have to happen
55:26 not immediately at some point depending on virus type. Okay so uh the
55:35 entry. So we'll see that animal have a different variation here. Um
55:42 there's a process called uncoated. That's we use to describe how animal viruses
55:47 into the cell uh senses an So obviously taking over the host and
55:52 making it a factory to make new . Ok and then exit and
55:58 So and and there's different ways this happen right? It can they can
56:04 the cell and just lice the They can come out at a lower
56:08 and the host cell is functioning and . Um It can come out and
56:15 out with an envelope. So there's different mechanisms here. Okay. Different
56:21 depending on the virus type. Okay let's look at this question. So
56:26 is where we're gonna start with in of life cycles. Um bacteria
56:32 And so the word fage. so fage is um when you see
56:40 it only refers to bacterial viruses. wouldn't call a human virus. A
56:45 infects human cells. Age pages only the context of bacterial cells.
56:52 the long name is bacterial fade. we just use safe age for
56:57 Okay. And so um the term it has a specific definition,
57:05 Or features that go with that? so let's see how we do
57:48 Okay. Alright. Now from Right. Yes, if you
58:13 B you are correct. Okay. be the one that does that is
58:20 less a genic type. We'll talk both lighting and estrogenic here in a
58:26 . So this is a license genic that can do the let's integrate into
58:31 host chromosome 11 page basically it's endgame in fact make viral particles kill
58:37 get out and infect more cells. kind of their mode of operation.
58:42 the lice A genic fage have have as part of the cycle. But
58:46 also have the let's be dormant for while part of the cycle. But
58:51 other features. So um of course is typical for any kind of viral
58:55 cycle is to copy genome right Make viral proteins. Uh make copies
59:01 genome and assemble viruses. Uh but page that this is true only the
59:08 enters everything else stays out external. , so let's look at these two
59:15 . So the light uh I'm Uh Yeah, page these. Um
59:21 the term so that when you like lice, a genic fage temperate.
59:28 . So there's two those two So virulent means if you're temperate,
59:32 start with the temperate you can go of two ways. Right? Um
59:37 can be angry. Right then. that licensing goes into the lifting
59:42 Right? Or you can just kind chill and hang out. All
59:45 So the license in the temperate that's what they can do. Go
59:49 way or the other. Okay, virulent page or landing page. It's
59:54 mode. Okay. In fact, make viruses kill cell. Okay.
60:00 so whatever type you are you're gonna doing this here on the right.
60:05 attached to host and then have your enter. And so you note that
60:12 the genome is entering. Um this that part. All that other stuff
60:18 staying outside the cell. Okay. for bacterial virus. So um so
60:26 less hygienic cycle temperate phages form the . So that prophet. Is that
60:33 where it integrates its genome into the chromosome that's forming a profane in animal
60:38 . Because animal cells will do this well. And we use the term
60:42 virus for those types of pro virus reserved for animal viruses. Pro fage
60:47 course for bacterial viruses. Okay but if it does this process of pro
60:55 it will at some point have to viruses if it's going to perpetuate
61:01 Right and to do that it has go into the lighting cycle. So
61:06 genic fage has the lighting cycle as of its process. Okay the page
61:15 not have a profane part to its . It only has one mode.
61:20 and so we'll see that here. so um these are what we call
61:28 face that duties are called T even like T two T four T six
61:35 names of bacterial viruses that do Okay and so yeah we start with
61:41 there's attachment and then there's penetration. and so the genome enters in this
61:49 here. Okay um part of the is to actually break up the host
61:56 as you see here. Okay it recycle those parts. Right Remember you
62:01 up the D. N. It's gonna it's going to become
62:05 And of course the virus will use to make its own genome. Okay
62:10 so decorating host DNA synthesis right synthesized DNA. Now from bacterial viruses most
62:18 these if not all our D. . A viruses. Right you get
62:23 variations of RNA DNA et cetera and viruses for bacteria viruses they're generally just
62:28 . N. A viruses. Okay Okay so again synthesis so attachment penetration
62:36 bio synthesis. Now we're making the parts here. Right and then we're
62:41 to assemble mature First create the first fragments and then we create more mature
62:49 parts of the virus and then assemble . Um here. Okay so this
62:55 what we're putting together here and making bacterial virus all the different parts packaging
63:01 . N. A. Okay and really slice of the life of the
63:05 . So they'll they'll have this enzyme listeners. I'm design breaks apart peptidoglycan
63:11 wall. Okay and so um so point so created. Okay so they
63:17 to that in a little cycle. what that basically is is the period
63:22 here from from once the genome has the cell right to kind of
63:31 Alright we haven't yet formed intact particles so we're kind of to that point
63:38 not yet. And they call that eclipse. So it's a point where
63:40 kind of basically assembling everything synthesizing and the viral particles but we haven't yet
63:47 an intact particle yet. So the after that point infection is what's called
63:52 period. Okay so like I said is kind of demarcation here that line
63:58 kind of there so this part here worth pointing out here that recall
64:07 Alright back in the previous chapter. generalized transaction. Is this this is
64:16 it happens. Okay so these fragments you see of the host DNA can
64:22 packaged incorrectly into the heads here. and so that's that's how you get
64:30 transaction. So basically theoretically any any of the D. N.
64:34 In this host can be packaged in . And now it's part of this
64:39 can infect other cells and carry that D. N. A. To
64:42 cell transaction. Right? That's that's this fits in here. Okay.
64:48 That's like cycle. So that's what uh And you know in e.
64:53 culture uh Um you can it can very cloudy right? You have a
64:59 suspension of bacterial cells. You can a drop of fate and effects
65:04 Coli as a live virus. And 30 minutes basically the whole thing becomes
65:10 like water because it's basically infected killed it broken out and infect more
65:17 . And it happens very rapidly It happens at an exponential rate and
65:22 soon they're all wiped out. And it happens for letting virus faget happens
65:28 quick. Um So with misogyny so light. Exactly you see here this
65:37 all it is for a lot of for less. A genic virus it
65:41 have this. Okay But it has other part of the cycle as
65:46 Okay so the type of virus that this is called lambda lambda fage um
65:53 one that infects the choline. And it has when it infects.
65:59 So we still have the same recognition attachment and the you know enters when
66:05 does it actually circular rises like Okay. And then it can
66:11 All right. And so this this the lice a genic cycle or
66:17 Okay. And so uh as this and the host cell is unaffected.
66:25 . And is basically free to just and eat food and grow and what
66:31 you. Right. And so it . And so success successive generations of
66:36 are inheriting the chromosome plus that pro so shown by the dark blob here
66:43 the genome. Right? So all members of the next generations are getting
66:48 copy of that page genome. so it's more or less like a
66:51 time bomb almost. Okay. And what determines whether it stays in
66:57 So ginny or then exits? And goes into lighting cycle depends on
67:05 factors. So in this pro fade . Okay, it's actually synthesizing directing
67:13 of viral proteins whose job is a of sense what's going on inside the
67:19 . Okay. What's the energy state the cell? There are certain molecules
67:23 the cell that that can tell the what's the energy state? So the
67:29 state equates the health. Right. um there's certain indicator molecules in the
67:34 you can look for to determine Okay, so so that's what determines
67:39 or less hygienic cycle in You don't to know this but really the thing
67:44 that tells it to go one way the other is the the um nutritional
67:52 nutrients. Okay so if you have nutrients that means that the uh the
68:07 the cells themselves the whole cells will quite happy. But the nutrients don't
68:11 and grow and grow and grow. compared to a situation where they're
68:16 Okay and there's not a lot of . Okay that's kind of the queue
68:20 the virus. So if the virus let's go to like cycle okay it
68:25 typically be because there is abundant nutrients the cells are growing like crazy
68:31 Because when the cells here break out viruses I'm sorry fate break out.
68:38 what's the more likely scenario or they'll a host if the host cells are
68:46 growing and multiplying like crazy or they're likely to find a host when the
68:52 are happily growing. Right? Because there's the chances are so so remember
68:59 when um the life cycle happens it's happening to every single infected host
69:07 Okay there's a rate at which it and so not all of them are
69:11 . Right? So you have a of e coli a proportion that will
69:15 infected like this but some won't. so if they're happily growing that's lots
69:21 host potential hosts. So that's typically Q. Two let's go and light
69:26 because of course the virus wants to itself and so that's that's how it
69:30 best do it, right. If starving, there might not be a
69:34 of host cells around. So the of it breaks out nobody to
69:39 What am I going to do? . So that's kind of that's what
69:42 virus is doing inside the cell, of sensing that. Okay. Many
69:48 about that. Right? Alright. what I wanted to cover today,
69:53 . So we'll see you Tuesday, the weather.
-
+