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BIOL 2320_Microbiology for Non-Science Majors - 2320_10_19_23_CH13 Pt 2
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00:03 Yeah, good. Let's see. and testing, testing, testing.
00:23 , there we go. Testing. . All right, folks. Uh
00:27 . So, uh today we're gonna on with the viruses like life cycles
00:35 uh on animal viruses. Uh But obviously that this stuff we uh began
00:42 about this week. Unit three is on the exam, of course.
00:45 uh that starts tomorrow. Uh There's , no canvas clues, there's no
00:50 or anything due on Monday. So need to worry about that. Um
00:56 , uh let's see. OK. I think that's pretty much it.
00:59 11 thing OK. So big big is going on Saturday, right?
01:05 he's aware of what's going on. realize a quarter of a third,
01:10 probably more don't really care. And get that that's fine. But those
01:14 you that do care a little right? So, um who,
01:19 , who, who, who are playing? Um So I went to
01:25 of H OK. It's a graduate . OK? But not the same
01:30 as being a part of the undergrad body. When you're a grad student
01:33 in, you're in, especially for in, you know, one of
01:37 science majors you're doing research or focus your, your circles of the grad
01:42 , you know, in, in building. So you don't really get
01:44 same thing as being an undergraduate. my undergraduate experience of course was not
01:49 U of H OK. It was . OK. So bye.
02:05 so I, I knew I was it. I knew I was gonna
02:08 food, so I was prepared for . They really, I really got
02:13 in my 11 30 class. uh, so, yeah,
02:21 so, um, so, it's gonna, I'm, so I'll
02:26 there so don't throw any rocks at , so I'm there. Ok.
02:31 . Uh, my, um, and daughter-in-law also went to UT.
02:36 we're, we're all going, we're, we're sitting in,
02:40 I think we're still sitting on UBA but kind of up in a corner
02:43 somewhere. So, anyway, I mean, ii, I
02:49 I hope it's a competitive game, know, that, uh, close
02:53 , those are more exciting than But, uh, um, we'll
02:58 , you know, who knows any given, well, used to
03:01 it's the same, any given Sunday any, any given Saturday, anything's
03:05 . All right. And, and, uh, so we'll
03:09 So, uh, all right, on to, I guess less fun
03:14 . So let's, uh, start little bit of recap. Ok.
03:21 , yeah, a little bit of recap from last time. So talking
03:24 viruses, right? Um The Monday uh Tuesday was basically, here's what
03:30 virus is, here's how we describe to find them. So remember,
03:34 know, the structure. So recall we, we don't, we don't
03:39 to them as cells there, these um at, at all viruses
03:44 can define as having like this protein covering that has some kind of RN
03:50 or DNA genome. You know, viruses have that. Uh But then
03:54 can be other variations, an right? A uh what we call
03:59 envelope virus. Uh If it doesn't the envelope, it's a naked
04:04 Um But remember the naked virus itself has that, that protein code and
04:10 . OK? Uh Of course, be virus proteins sticking out, you
04:15 , on the surface, there'll be inside as well. Uh So remember
04:19 that they, they can't metabolize, can't give a glucose and say,
04:23 , carry out the causes doesn't OK. So they um rely on
04:28 host for most of their functions. . And um so speaking of
04:34 so we went through a kind of basic life cycle. So we're gonna
04:39 um especially today, let's talk about viruses variations in each of these
04:44 But you know, all of them to, you know, uh have
04:48 genome come inside the cell, be , transcribe it, translate into proteins
04:54 symbol, put genomes in uh they and infect more cells. So that's
05:00 , that's a process for every right? But there is kind of
05:04 on the virus type, there's kind little variations here and there.
05:08 And then we'll point those out as go through this today. OK.
05:11 remember it all begins or ends right , recognition. So just think of
05:18 lock and key, right? Can get into the door? Right?
05:20 it have the lock that fits to in? And that of course,
05:24 all about molecules on the surface recognition and that that begins the infection
05:31 OK. So um uh let's see ? So then there is, so
05:36 went through the uh bacterial virus life . OK. So these terms laic
05:45 um uh is still are are used for animal viruses. So a lighting
05:50 in general is one that basically does infects cell makes for particles kills host
05:58 then infect more. That's kind of mode, that's the mode of a
06:01 virus. They also refer to it a, as a virulent uh
06:07 Um the with the page. So that word page is only for bacterial
06:14 . OK. And so uh they that kind of structure that almost looks
06:19 something uh from outer space, This um capsule portion, but then
06:24 has these other parts to it that with um binding to the cell.
06:29 But you know, like all they uh attach that specific receptors come
06:35 the cell. Uh But with bacterial , remember, uh it's generally only
06:41 genome comes in. We don't see else, right? Which is why
06:46 just see uh all of this is remain outside the cell, only the
06:51 is entering. Ok. That's very for, for bacterial viruses to do
06:56 . We'll, we're gonna see variations that when we look at animal
07:00 OK? The uh degrading the DNA the host. So then it can
07:05 use those. So we can chop up into nucleotide, it can then
07:09 those for itself when it replicates. so of course, then synthesizing um
07:16 proteins, putting stuff together assembly um then exit. OK. And so
07:23 uh we also have the other cycle is this lysogenic cycle. OK.
07:29 of that as kind of a, dormant stage if you will.
07:34 So the stage enters this one. these types of here back up for
07:39 types of here, we call that this are what are called t
07:46 So T two T four T 68 cetera, OK. The ones that
07:52 the lysogenic types really the main example use is lambda. It's called lambda
07:57 Greek letter lambda. OK. And this is one that has the lighting
08:03 like we see up here as part its um life cycle. OK?
08:10 it has the misogyny. So this the formation of a prophage,
08:14 So you hear prophage like you think , OK. Um Now, animal
08:21 have a, have a very similar uh state as well. And
08:26 and we refer to animal viruses that that as forming a provirus,
08:31 So, provirus, animal viruses, , bacteria, viruses. OK.
08:37 so the um and so what happens the page genome enters the host
08:43 OK. And so basically, uh no harm to the cell, the
08:48 , it continue, can continue on like it normally would. But what
08:53 is eventually every generation of cells that are all carrying a copy of that
09:02 . OK. So, right. then you can imagine what happens when
09:13 cell, the virus decides it's time get out of there. Let's let's
09:25 . So, um and you when they, when they undergo the
09:30 cycle, it's not like they all it at one time, they're not
09:33 in sync with each other, but very quickly. Uh they do um
09:40 go to the lighting cycle, produce of page and then go to infect
09:43 cells. OK. So um so the key here is the the the
09:49 trigger for do I stay in do I go to light cycle is
09:55 a stress thing. Things that stress host cell. OK. Uh Radiation
10:02 the lab you induce this by just temperature OK. But any kind of
10:07 , uh lack of nutrients is another . So these can all be things
10:11 will enable the cell to go. ? Um The, the, the
10:16 inside to go, OK. I'm get out of here before the,
10:20 these whole cells begin to die and so that I can make sure I'm
10:24 new viral particles. OK? And um the uh so it's really about
10:32 so, and so the virus inside is synthesizing a few proteins while it's
10:39 the state and those proteins have to of monitor the state of the
10:43 There's different things. Uh a host produces uh that it can notice.
10:50 without going into details, um uh can kind of monitor the energy
10:55 So maybe A TP ad P levels kind of really changing dramatically. That's
11:01 indicator that the cell maybe isn't too . And so it can then use
11:06 to then say, OK, let's out and go into lighting cycle.
11:11 . So um are there any questions that light cycle? Less a genic
11:18 ? OK. They also call this like like um light light page has
11:24 the name virulently agentic types have the alternate name uh temperate temp, temperate
11:31 . You can kind of go one two ways basically. OK. Um
11:37 . So let's look at um so , we're gonna continue on with life
11:44 but into uh animal virus life OK. So it's gonna get a
11:49 more, slightly more complicated uh but in the, let's look at this
11:54 here. So we're gonna focus on viruses. So you can kind of
12:01 um by the nature of the animal , this particular characteristic of it can
12:07 of tell us, tell us where , what it might likely likely do
12:12 terms of its life cycle. This particular feature tells us that.
12:19 . And so, you know, a animal virus is uh infecting a
12:25 cell, eukaryotic cells are more right? They have organelles and this
12:29 that and so that, that's kind why it makes the viruses that infect
12:34 their cycle a little more complicated compared a bacterial virus. OK. Um
12:46 . Let's count down from 10. . Yeah, the type and form
13:02 its genome is correct. OK. , and, and the reason for
13:08 is um in the UK at the options are you can go to
13:15 nucleus or it can stay just in cytoplasm outside the nucleus. That's kind
13:21 the two choices typically made by an virus and which way it goes depends
13:27 its genome type. OK. RN versus DNA. OK. So,
13:35 and so this is kind of a basic uh process for an animal
13:40 . Uh The one term you see that's different from what we just saw
13:43 the bacterial virus is this process called coding. OK. That's because the
13:51 animal virus can, the cape comes into the uh se and so we
13:59 to get rid of that uncode So the genome is released. And
14:03 this is a term you see only with uh animal viruses because of the
14:07 they infect the cell. OK. Chronic infection. This is actually uh
14:14 to um uh virus, animal viruses can form a provirus. They can
14:21 the uh insert themselves in the host . OK? And when they do
14:26 , it sets up a situation where may be infected with it. One
14:30 these and, and not even know . OK. And it's not until
14:35 enough, maybe produces itself at at a low level, it accumulates
14:40 then you have enough there to kind detect it in a, in a
14:44 test, for example. OK. that can lead to a chronic
14:48 So chronic basically means long term, term uh acute. So it's acute
14:53 chronic is the difference there. So a cute versus chronic acute infection basically
15:02 in over the course of a week 10 days. OK. Chronic infection
15:07 over months or longer. OK. So, and, and it can
15:12 because that virus persists in the body that kind of inserted into the chromosome
15:18 . OK. So um so in at this encoding process, right?
15:25 like with any viral life cycle that with attachment, right? Recognize
15:29 let's uh uh bind and then various to enter. OK. So this
15:37 gives you some examples here. So so when co so in in the
15:42 is basically a besic, OK. many viruses like this will use existing
15:51 that cells use to take in certain . So, so for example,
15:56 cells take in cholesterol very much the way they'll bind to a receptor.
16:04 . And then they will um uh binding induces this kind of pinching or
16:14 engulfing of the cell. Right. , binding to the receptors in uses
16:19 it completely closes off and forms the . We call it an endo
16:25 And so now uh but but of , it's not cholesterol being taken
16:28 it's this virus being taken. So can use the lysosomes to remember right
16:35 cells have various organelles, right lysosome one of those, it's one of
16:40 digestive organelles. So it uh it fuses with those and that helps to
16:46 apart cap capsule. OK. And release the genome in the process.
16:53 . Uh As you see here. And so like hepatitis C, for
16:59 , is, is an RN A virus and basically RN A viruses will
17:03 their thing, their life cycle outside nucleus. OK. So once this
17:08 happened, then it can pretty much initiate its life cycle. OK.
17:13 is just showing a similar an actual micrograph, same thing or is a
17:18 attaching, there's the endo zone Um And so we call it receptor
17:28 because it's all initiated by buying into receptors. OK. That's what initiates
17:33 process. Um Oh, sorry, up here. Um OK. So
17:40 process here on coding forming a right? I need to receptor form
17:45 vesicle but the process doesn't end or sorry, begin until we get to
17:52 nucleus. OK. So this is for DNA viruses. OK. That's
17:58 adenovirus is. And so DNA viruses the rule of thumb is rodent
18:06 OK? And there is a reason that. All right. Uh we'll
18:10 about that in a second. So so again, un coding at the
18:14 or encoding at the nucleus. Again, depending on what's the viral
18:20 DNA. Um AR OK. Take pen to work here. OK.
18:30 Going come on and RN A DNA RN A OK. Going two different
18:40 that um all right. So let's at this one. So this is
18:46 what we call membrane fusion. So generally it happens with um enveloped
18:54 . OK. So um the membrane of the virus kind of melds with
19:02 membrane of the host. OK. in doing so, the capsule is
19:06 released again, it's always specific, ? There's always gonna be this specific
19:12 . OK? But in this the the envelope of the virus is
19:16 kind of fusing with the membrane of host. OK. And then caps
19:21 is released. Genome is uncoated. ? Um So, and here's an
19:27 of that here and you can't really it so well, but the remnants
19:32 the envelope are kind of here and rest of it comes into the
19:35 OK. Um So this again is RN A virus. So it doesn't
19:42 to go to the nucleus. So is common for another mechanism for an
19:46 A virus. Besides, so we the endo zone formation or we can
19:51 the fusion at the membrane surface. . Um OK. All right.
19:59 why do, why are uh DNA DNA viruses? Why do they typically
20:06 to go to the nucleus? So think of what does a DNA
20:13 use to copy its genome in a , right. So where is that
20:23 to be found in the hotel OK. So we, we call
20:30 cell cycle and uh what is it phases of mitosis? Right.
20:38 you know, in s phase, chromosomes are being copied in the
20:42 right? Because that's where the DNA is at. And so that's what
20:47 the DNA animal virus to go there well. That's where it'll find the
20:52 , it needs to copy itself, ? It's genome. And so um
20:58 that, but you know, like said, there's gonna be variations here
21:02 there the gene, that's the general . But you do have some DNA
21:06 that do have their own DNA right? But most DNA viruses don't
21:13 that and they are required to go the nucleus to get it.
21:17 Rely on the host for it. . Um So OK, so that
21:23 is kind of, that's how they get in to a host cell in
21:26 own formation. Fusion, go to nucleus. OK? Um Now we
21:34 uh exit, for example, exit kind of what's showing there's different variations
21:39 . Um It can simply just um the cell. So that's one
21:45 OK. It could do this what's budding. OK. So basically what's
21:51 in is the these red things or proteins. OK. And so um
22:00 you recall functions of various organelles and carry out the uh goji, the
22:08 is kind of where protein synthesis occurs the plastic reticulum. Um the
22:13 so kind of proteins that are made sent to the goji and the goji
22:18 of sorts them out to say, , you go, here you go
22:23 kind of a trafficking routing station for . OK. Do they go to
22:29 surface? Do they stay in the or what happened? OK. And
22:33 the virus uses that too. And so it'll, that's how prot
22:39 proteins get sent to the surface OK. And so um so when
22:46 exit, right? So here's your , right? So when it begins
22:49 exit as it, it pinches off the membrane. And so, so
22:55 engulf it as it goes out. now it has acquired an envelope.
23:01 ? And that's a typical scenario for enveloped virus. That's how they,
23:07 how they acquire this envelope. And so this can happen, this
23:12 thing. They also, I I think also they use this synonymously
23:16 the word shedding virus, OK? an animal shedding hair, right?
23:24 So the the rate at which this can be low, right? It
23:30 be a handful of viruses per cell coming out this way. OK?
23:36 or it can be a much higher . OK? It varies. And
23:41 if it, so if it's coming at a low rate, typically,
23:45 the whole cell is OK. It's not as well as it would
23:50 if it didn't have this going but it's enough for it to still
23:54 , right? So you have to that the virus inside there and using
23:59 to replicate itself takes a toll on hotel, right? Because it's using
24:04 resources and energy, right? So how much of that it can take
24:09 be still be alive? OK. Depends on how much the virus is
24:16 using it. OK. So if only replicating at a low rate,
24:21 whole c can, can kind of along, so to speak.
24:24 It's still viable and can replicate also slower. OK. Uh But it
24:30 be at a very fast rate and just overwhelms the cell and it
24:35 OK. But if the virus in meantime has produced lots of viral
24:40 OK. So there can be a , right? In terms of how
24:44 it's affecting the host. OK. Any questions about that, that make
24:50 sense? Yeah. OK. So , so general rule be viruses uh
24:59 to nucleus to replicate their DNA. So with be viruses, it gets
25:05 little complicated because they have stuff going in the nucleus, just copying their
25:10 . So remember being that you carry transcription occurs in the nucleus translation outside
25:17 , right? And so if you're virus and you're replicating well, and
25:21 , and you're a DNA virus in nucleus, then you have to follow
25:25 same rule. OK. So uh viral proteins will be made synthesize outside
25:32 nucleus, come back in into the and assemble in the nucleus and exit
25:38 nucleus and then exit the cell. they kind of got stuff going every
25:42 way. But and, and it's because that's how, that's how the
25:48 cell works. Transcription of the nucleus here. And so that's, that's
25:54 it happens that way. OK. Or viruses maybe not so complicated because
25:59 that because everything can occur outside OK. And like I said,
26:05 kind of exceptions uh even for these . So actually the flu virus is
26:10 RN A virus, but it actually go to the nucleus. So it's
26:15 of those outliers that goes to the , not, not to get DNA
26:20 , it doesn't need that, but just, it's just part of,
26:22 evolved to have that as part of life cycle. OK. So,
26:27 I said, you see exceptions here there. So, but most of
26:30 are, are for the most part , for most types, but like
26:34 said, there can be exceptions here there. OK. Um Now,
26:42 , take a look at this And uh so does anybody have any
26:47 on anything so far? OK. . Uh Let me get this out
26:53 the way. So, in reference our new viruses, so you're gonna
26:59 um plus ARNI viruses minus RNA um retroviruses. Um And so there
27:09 be variations here. OK? In of what their template, their
27:15 uh their genome is used for. . It was OK. Let's uh
27:44 down from 10. OK. Uh , if you answered all the
28:06 OK. You are correct. All . So, um so for
28:13 that's the plus RN A viruses, ? Uh MRN A synthesis, that's
28:21 minus RN A virus, you a that's retrovirus. OK. So this
28:33 back uh as, as we, get into, we'll first talk a
28:37 bit about DNA viruses but RN A is where it gets a little bit
28:41 . Ok. So that's why I previously I said, remember the whole
28:46 minus relationship. So, remember that to DNA, right? Um,
28:53 , DNA RN A, right? , R and A R and
29:00 So it's just, it's just the, um, a feature of
29:07 acid is, it's really what it's about. Ok. There's nothing more
29:12 than that. simply just this. talking about DNA uh well, stay
29:23 Arne you AC GC, right? base pairing. This is all it
29:32 . And so one of these strands a plus strand, the, the
29:38 strand is the minus strand. the one we call the plus is
29:43 one that will contain the information to , right? For protein.
29:49 And um of course, if it's let me just make this, just
29:56 this all DNA here. Got it you erase that. OK? And
30:05 that. OK? So just make T, right? So one of
30:11 two DNA strands, the plus tells , oh, this is the one
30:14 the coding information for the gene. this is the complementary strand.
30:18 So remember that if we want to a copy of this, right?
30:24 a copy of that, we have make what we, what we copy
30:29 this strand, right? We copy minus strand because that will give us
30:36 ? Uh A TGCG. All They will give us the, they'll
30:43 us that right. So if you to make a copy of this copy
30:49 strand, because complimentary strand is which is identical. OK. So
30:55 in a nutshell is what the plus plus thing is all about.
30:59 So when we talk, start talking life cycles of these viruses, these
31:07 guys, OK, this guy and guy, OK. It's having to
31:14 this relationship. OK. Yes, would be the, the easiest thing
31:19 the world if we could just copy strand directly into that. Of
31:29 that's the easy thing to do. ? But it doesn't work that way
31:33 nucleic acids don't, don't work that . OK? So can't do
31:39 OK. So we have to go this and make that. OK.
31:46 um so when we start talking about and plus RN A viruses and how
31:51 replicate trying to, oh, copy to get that, copy this,
31:57 get that et cetera, right? , uh just a warning. All
32:01 . So warning. So when you there, you'll see why uh it
32:05 to be that way. It's not there aren't any viruses and they're just
32:09 to mess with us. OK? is simply the language of nucleic A
32:14 it's how they work. OK. um so we'll get there in a
32:20 . OK. Any questions, I . OK. All right.
32:28 OK, so we just, we saw this in the question.
32:31 Do you know of a DNA Um It, it's us,
32:35 you look at that first one, just what we do, right?
32:38 got DNA. What's, what's our do is a template for transcription,
32:42 ? Make Mrnas. And uh of , we can copy it when our
32:47 by, right? We copy it make DNA strands, right?
32:50 do you know RN A virus? just learn, right? 12 and
32:56 , right? So the retrovirus is out uh is, is the,
33:01 kind of the weirdo here because um an R A virus that it's,
33:07 uh genome is to make a DNA of its RN A. OK.
33:12 that's because it is one that does , oh I don't have it on
33:18 slide anyway. It's one, it's that integrates into the host chromosome.
33:24 . So if you're R virus that to the host, but you better
33:29 somewhere to make DNA because that's what trying to get into. You're trying
33:34 meld with a DNA chromosome. So if you RN A,
33:38 you gotta have a way to do . OK. And that's, and
33:41 what it does, it has a enzyme. OK. So um all
33:48 . So we just talked about, , do this real. Wow.
33:53 . That was good. All Hold on back. There we
33:58 OK. Um All right DNA So, uh right. So,
34:05 viruses are gonna go to the nucleus the most part, get their DNA
34:10 copy their genome. OK. And uh so non retroviral RN A.
34:18 we have to make that distinction, ? Because retrovirus viruses or RN A
34:25 , but theirs is to make right? So we, we specify
34:30 in this way, non retroviral RN viruses. So we have a special
34:34 . OK. So viral enzyme because one, the RN A ply we
34:42 OK? Is one and the one other eukaryotes have. OK. Um
34:51 one that is what we call a DNA dependent RN A polymerase. So
34:59 is Dr VP, right? That's we've got. OK. DNA dependent
35:09 right. That's what we use to we carry out transcription, copy our
35:12 to RN A, that's what we're . OK? We don't, we
35:18 copy RNAs into RNAs. No, carry out, does that?
35:23 It's not, you don't need OK. But an R A virus
35:28 need to do that. So it's , that's why it's a virus specific
35:34 . A an arm virus isn't gonna , is not gonna find this
35:39 this enzyme and it's host. So a strictly viral enzyme. OK?
35:47 Now let me erase that. So again, depending on the how
35:53 type uh its GM can be used translation or for, to make a
36:02 a template for translation. So we're look at both those life cycles here
36:06 . OK. So again, the is its own kind of thing.
36:10 , it goes through a DNA So RT stands for this reverse transcript
36:16 , right? Again, a viral , right? So we got two
36:20 specific enzymes. We're talking about reverse and um this RDRP. OK.
36:30 A dependent RN A lyme, both enzymes. OK. So um
36:38 The and so again, copies aren't DNA. But you know if
36:44 if you're gonna make copies of you're gonna replicate, you're gonna have
36:49 get out of that mode and copy RN A, right? Because
36:54 that's the kind of virus it right? And the protein. So
36:58 going to have to have a cycle it does that if it's going to
37:01 itself. So we'll look at that in a sec. OK. So
37:06 is a DNA virus, right? um let's see, attachment. So
37:13 always begins with attachment, right? specific host. Um It's gonna uncoat
37:19 the nucleus like most DNA viruses will down here and then begin to transcribe
37:28 , the current in the nucleus. then these have to exit because translation
37:33 out here, right? And so have, you see V proteins being
37:38 outside the nucleus and then returning to nucleus. So you have stuff going
37:42 outside this assembled with the material comes inside, then you begin to assemble
37:49 particles in the nucleus and they exit then exit the cell. OK?
37:55 , activity is going on in the , outside the nucleus back in the
38:00 . Yada yada. OK. So nature of a of most DNA
38:06 that's how, how they work. . So um step wise,
38:12 copy genome transcribe outside the nucleus, , translate whose proteins return to the
38:20 , right to assemble. OK. then exit. So it's back and
38:27 , back and forth. OK? obviously the end result, you're forming
38:31 viral particles as a result. Now, um we don't talk about
38:37 here. Um We'll talk about it the retrovirus in terms of integrating to
38:43 chromosome. OK. That's part of life cycle. But DNA viruses,
38:48 of those do the same thing. For example, herpes virus is a
38:53 virus uh that integrates into the host . So we can have a period
38:59 uh it's simply just sits in the and nothing else is going on.
39:04 of this is going on just sitting the chromosome. OK. And uh
39:09 so can divide. Um And so remember that's what we call a
39:13 OK. And so the, and may realize um the effects of a
39:20 a fever blister, right is to a herpes virus. And those things
39:24 to erupt right form uh when you're stress or something like that. And
39:30 that's, that's actually then that stress what triggers this, that's the cell
39:36 of coming out of its hibernation, to speak, or the virus,
39:39 me, coming out of its hibernation then beginning to replicate and, and
39:44 , and make more viruses and the you see from that is kind of
39:48 and it's sore, but that's actually virus waking up, so to
39:52 And now going through its cycle, typical for a herpes that causes blisters
39:57 things like that. Um the uh virus which causes cervical cancer. Um
40:04 the type, that's a deia virus also inserts itself into the host
40:10 And uh what we call cancer causing are oncogenic viruses. OK? And
40:21 happen to insert themselves in a normal gene and by inserting themselves, the
40:28 function is disrupted and so uh that lead to different types of cancers.
40:35 . So, I think roughly uh viruses cause something like 10% of
40:42 OK. Um And Papilloma virus is of those certain leukemias um uh et
40:50 . So, uh but those that cause cancer are types that can do
40:55 integrate into the host chromosome and just themselves in the, in the wrong
40:59 , so to speak. So it leads to a cancer itself.
41:04 . Um OK. Any, all . So let's look at this
41:12 All right. So it's gonna lead into RN A virus life cycle.
41:16 , back to the plus minus kind of OK. So this is
41:21 a highet minus or any virus. it's just, it's 10 nucleotides.
41:29 , OK. Which one below is likely its genome, right? So
41:36 gotta remember uh what's the difference between plus and a minus strand? How's
41:43 plus strand differentiated from minus strain? really the, the gist of this
41:50 ? OK. So what is most its genome down to two choices?
42:16 . Yeah. OK. Mhm. . OK. Mhm. OK.
42:56 down from 15, 14. OK. All right. OK.
43:23 picked C? You pick CCCCC? you c, you pick C why
43:31 you pick C and of course, sorry, what? You thought?
43:53 ? Yeah, you p I but eliminated B because of what I'm
43:58 Yeah. Right. It's got, . So DNA has thymine, not
44:02 A, right? So that's why is out, right? So you
44:05 C because uh OK. So I you're probably, did you see something
44:17 in here that gave you a clue here? Right? So I think
44:25 on the right track. All So you did anybody else pick C
44:30 you pick Cy? Yes, The dark code on, right?
44:37 the um so if it's a minus genome, uh so it wouldn't,
44:46 let me back up. So do think who picked a, anybody pick
44:52 , so why did you pick Right. Because which of those strands
45:01 be one that you could actually translate that one, right? So that's
45:07 the genome, genome of a So what would this be the genome
45:16 a minus or plus stran plus? . So this would be this could
45:21 a plus RN a virus genome, ? That would be DNA. So
45:27 would be the one that would be a minus strand. OK. So
45:31 is correct. OK. OK. let's look here, look at the
45:38 here. OK? So that's right? Sense, right? Because
45:46 got those guys there. OK. remember, so the plus trans always
45:52 the coding information, right? So with what we've got here, the
45:58 , there's really no a UG there we can see that there's any kind
46:01 coding information in that one. So why um the ann that,
46:07 that's your best pick for antisense OK. So again, it's
46:12 you know, this isn't um it have anything to do with the fact
46:16 we're talking about RN A viruses. just that it's nucleic acid thing,
46:21 ? Is what it is. And um the plus strand always contains the
46:25 information that the minus strand would We'd have to copy the minus into
46:30 plus to get that coding information. . So um any questions about
46:38 OK. So when we get we're about to uh so right
46:44 you see right here. So we that we copy that minus and now
46:54 got a plus, right? And is already a plus. OK.
47:00 , um and it's because we've got now. OK. So um all
47:09 . So let's look at these So the best way to really think
47:15 this, let me see if yeah, so look at uh what's
47:22 in. So this is the virus infecting. OK. So it's already
47:27 the encoding process, right? We the genome, right? So it's
47:32 the cell. So now what Well, um you start with
47:38 this is what's infecting and you this is what you're going to end
47:45 , right? So lots of, mean, for simplicity's sake, I
47:50 drew four here but think of that more but um uh you gotta make
47:56 lots of protein, right? Captured different, there's lots of protein,
48:00 ? And then copies of genomes, ? So we have to make this
48:05 in between, right? And so this is what's this, what it
48:08 infecting, right? Then we have make a lot of stuff to
48:13 make these end products here, These virus particles. So um how
48:18 we do that because we have to that because yes, this one plus
48:24 A strand can be directly translated sure into protein. But it's not gonna
48:31 enough, you need more quantities of , especially the fact the fact that
48:37 gotta make lots of copies, Imagine that there's I don't know,
48:42 at number 50 viruses here. And so you know, we need
48:47 copies of this right? One coming is enough. All right. So
48:53 is the route you go. If a plus RN A virus, you
48:57 , you have your viral enzyme you make lots of minus copies right
49:04 . These you go. OK. do that again? It's the language
49:08 DNA. It's the way or of acids plus, if you have plus
49:13 , you have to go, even you wanna make lots of plus
49:17 you got to go this route. just it's complementary base pairing,
49:21 And so uh so the first step copy that plus genome into lots of
49:26 and then copy those into lots of strands. OK? So now we've
49:32 the genomes to stuff in. But of course, we are um also
49:39 me get this out of the way , right? We have to then
49:44 course, uh translate right. Translate into proteins, right? Make the
49:51 and then stuff the genomes inside right? And, and again,
49:58 I said, it would be super if all you had to do,
50:02 all you could do was directly go to that, copy the plus into
50:08 plus. You can't, we just over this, right? It doesn't
50:12 that way. You have to go route. OK? Because if you
50:20 a plus strand, you're only making complementary strand, not the identical copy
50:23 it, right? So that's why have to go this, that's why
50:28 has to be this way. So similarly with um minus ARNI
50:35 Oh Wrong, wait, sorry, here. OK. So again,
50:39 or virus. So um these uh , end product, right? These
50:45 all gonna have a minus genome in , right? So you know that
50:50 one virus affecting, that's not gonna enough. We're gonna make copies of
50:54 , right? And we know that can't copy a minus to minus.
50:58 got to go this route. So we copy this in lots of
51:02 forms. OK? But then, that remember the plus is a translatable
51:07 , right? That allows us to the protein, OK? And then
51:12 , copy the plus strands to make genomes, right? So stuff those
51:16 here, right? So, um that's, I mean, yeah,
51:21 could be a lot easier. You just copy a plus to a plus
51:24 a minus to a minus and be with it, right? But the
51:28 about the minus or virus is it has to go through to make these
51:34 strands because that's, that's the one tr the only way to make proteins
51:46 to make it into a plus OK? If you're a minus or
51:57 virus, you gotta go to the then to the Mius. Well,
52:01 have to go to m you just from, you know, plus Mius
52:03 to plus, right? Because your are here going to suffer from
52:07 Ok? And these are, these be made into, translated into
52:11 right? So, you know, uh if you're plus virus, you're
52:16 plus minus plus, if you're minus , you're going minus plus minus.
52:20 . So just remember that. Um And again, it's, I
52:26 I'm beating a dead horse here, it's, it's just the way nucleic
52:29 work. It's not because these RN viruses are, are doing this to
52:35 us. It's just they're following the of nuclear gasses, right?
52:40 any questions about that? Yeah. right. So let's look at
52:47 I'm not crazy about this textbook but it's basically just showing you the
52:53 the routes here. So the, top one is a plus RN A
53:08 uh copied the plus transit, it translate. We just saw it on
53:12 previous slide um Similarly with the uh RN viruses in the middle. So
53:20 , uh my recommendation is refer to these two slides. OK? I
53:29 it's illustrates it better uh down So the double stranded R virus,
53:36 thing, OK? You have to uh if you're double stranded,
53:40 You've got, obviously you have one these and you have one of the
53:45 strands, right, as its So you got to copy both strands
53:50 make to make the intact genome, ? And so um and again,
53:56 gonna have to use this same. . Right. Is going to be
54:09 these three RN A virus types, plus single stranded, minus single stranded
54:16 the double strand, right? They're gonna have that same end.
54:20 The um OK. So the right? That one's different,
54:26 No, no RN A dependent RN prelim is required, right? Uh
54:33 transcript case, that's its enzyme. . So um so with this,
54:41 one, right, its first step to um transcribe that or reverse
54:50 I guess they call it uh And so you can see right
54:53 right? The, the the the acid relationship, right? This is
54:58 , that's RN A. But yet copying that plus into a minus
55:02 right? So it, it's irrelevant you're talking Rnarnarn A DNA,
55:07 DNA, that's things that relationship is same. OK. So, uh
55:13 what it then does from this it has to be double stranded because
55:18 it's going to insert itself into the chromosome, that's, that's double stranded
55:24 . So it actually uses a host prelimerase to make the complementary strand,
55:29 ? So there again, right, a minus into a plus. Right
55:33 , we have the double stranded DNA then uh it could, it could
55:40 insert itself into the host. Uh uh At the same time while
55:45 sitting in the host OK. It use host RN a climes to copy
55:52 into transcripts, right? Plus RN translate into proteins, assemble package into
56:00 particles, right? Do all that do its retrovirus thing. OK.
56:08 , um yes, we're not having see a plus RN A to minus
56:12 A to plus RN A or but we're still saying the plus minus
56:15 , right? Whether it's RN A to DNA plus RN to minus
56:20 the um plus minus DNA, one those is transcribed into a, a
56:25 strand that C into a plus. it's, it's all around you,
56:28 ? You can't escape it. but again, it's just complimentary based
56:32 in relationship to each one. So let's look at this cycle here
56:37 this context. So, um so is the example here for retrovirus and
56:43 it has a, it has a , very, so remember that term
56:48 um tissue specificity. So it's very just infects this one cell type.
56:54 talk about these guys probably in a of weeks. Um T helper cells
56:59 part of your adaptive immune system. uh the, the particular ones they
57:05 are a T cell type that kind controls the whole adaptive immune response.
57:11 , remember your adaptive immunity is what , that's one function of it.
57:16 . There's others. Um And so infect those cells and the uh reverse
57:23 is part of the enzyme that's in in the virus as it enters the
57:28 and begins to copy into DNA and eventually into uh double stranded DNA and
57:36 inserting into the nucleus in into the in the nucleus. OK. So
57:41 thing with retrovirus is it can So remember there's what we call a
57:45 , it integrates. So what it do is um so what we call
57:52 state means it kind of just hangs in that provirus state. OK?
57:59 so it can just be that doing . But of course, the cells
58:04 , right? So the cell divides um uh the t the T helper
58:10 divides, you know, more and and more. And so, of
58:13 , that provirus then accumulates, of . But um uh so in that
58:21 , it's kind of persisting and this go on for months years.
58:26 And so at some point, it begin then to uh initiate replication of
58:32 . OK? While staying in this state. OK? And so,
58:38 that's unlike it's very different from G me with the lambda phage,
58:44 Lambda page would just pop out and go into a lighting cycle and kill
58:48 cell, right? That's not what doing. It's staying in this provirus
58:53 and simultaneously directing replication of the OK? And it can do this
59:00 a low, low rate. So of the provirus produces viruses at a
59:06 rate. OK. In the the cell continues to divide.
59:11 And so again, this state can for months and years. Ok.
59:16 it's not until you accumulate enough viruses through the body or becomes detectable.
59:24 ? That's when one, it, becomes HIV positive when they reach a
59:29 that's detectable. OK. And um, you know, it's left
59:35 , obviously, uh then the replication begins to increase in terms of rate
59:42 . Um, cell is overwhelmed and . Uh You can imagine if
59:48 if you're losing uh a, an immune system, cell type that's
59:54 for kind of guiding the whole a a new response. You're really,
60:00 um severely damaging your immune response that . And so we all know,
60:05 sure that people with HIV, they die necessarily from the viral infection
60:12 They die from things like pneumonia or a flu or common cold because they
60:17 have the immune response to fight And so they succumb to that
60:22 So, um and so budding is of the things they do. All
60:27 , that's how they acquire the OK. These are envelope viruses.
60:32 And so targets for um therapy are the reverse transcriptase. Um this
60:41 So there's one called a ZT, been around for a long time.
60:47 It's specific for binding to that enzyme not uh and inhibiting it inhibiting the
60:54 function. Uh But I think nowadays give like a uh people with
60:59 get like, I think a AAA of like nine or 10, 12
61:04 drugs at once. A ZT is among them. But, um,
61:09 , you know, nowadays, it is a very treatable disease if
61:14 have access to the drugs. So, uh, back in the
61:19 , of course, it was not way. And so, uh,
61:23 it's still in parts of the world HIV is epidemic, right? Parts
61:28 Africa and elsewhere. And that's for the other reasons because they don't
61:33 access to the drugs. So that's a whole other conversation, but
61:38 , it's still a um still certainly persistent disease around the world.
61:44 Um But as I said, very uh if you can have access.
61:49 uh any questions about Mr Laws that OK. So this, this is
61:58 a recap, let's see if we've got the plus minus thing down
62:02 . OK. So we got an A virus for the plus. So
62:06 time it's got a plus string, plus genome. OK. So it's
62:11 um you would first have to transcribe into a minus anti, then translate
62:20 this minus antisense into viral proteins. or false. So what?
62:30 sorry. Yes, of course. we go. Let me open it
62:33 . That might help 007. 214. Good. When, so
63:07 a heads up. Um The, next um the last two things that
63:14 part of the viral life cycle section vids and freons. So, thyroids
63:23 prions are not viruses. Ok. we got three groups. We have
63:28 , vids and prions. So they don't, they're not interchangeable.
63:33 . So just remember that. OK. The OK. All
63:52 Bad. Yeah, it's, it's it is false. OK. So
63:59 we're gonna do that, then do and then translate, right?
64:08 as written up there, that's OK. So, um, and
64:14 a good place to stop folks. we'll, we'll do the last two
64:17 on uh Tuesday. OK. See all and we talk
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