Практика Shadowing: Antibiotics: Cell Wall Synthesis Inhibitors: Part 1 - Изучайте разговорный английский по видео

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Alright engineers, in this video we're going to talk about antibiotics.
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Alright, so the way we're going to do this is we're going to go through multiple different types of antibiotics.
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We're not going to cover all of them.
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It would just be impossible to cover all of them and all their different effects and mechanisms of action.
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We're going to start off by looking at antibiotics that are affecting the cell wall.
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So let's go ahead and start there.
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So if you look here, now bacteria, if we're talking about gram positive or gram negative bacteria, we'll make a video on this,
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but gram negative and gram positive bacteria really just differ and they're overall, like if I were to have, let's say I take for example here,
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I take two bacterial cells, just real quickly.
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Let's say here's a bacteria and here's a bacteria.
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Let's say this is gram negative and let's say that this is gram positive.
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The real big difference between gram negative and gram positive is that when you look at gram negative bacteria, they have a very thin peptidoglycan layer.
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So their peptidoglycan layer that we're going to talk about that is very thin.
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And another thing is that they have a cell membrane, an outer cell membrane surrounding that peptidoglycan layer.
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And they have little porins inside of it, right?
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So little porins.
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A gram positive bacteria is the exact opposite.
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It has a very very thick peptidoglycan layer, a very thick peptidoglycan layer.
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Okay and that is going to be our gram positive.
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So when we're looking at gram positive
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and gram negative bacteria
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it really is important to kind of have a basic idea of what their overall cell wall looks like
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and overall cell structure is consisting of.
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Okay so again one more time gram negative has a very thin peptidoglycan layer but has an outer cell membrane.
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And it also has what's called lipopolysaccharides with lipid A and lipopolysaccharides and stuff like that that are the toxins.
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And then over here, gram -positive bacteria just has a very thick peptidoglycan layer, but no outer cell membrane.
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Okay, so now that we know that, let's go ahead and dig into antibiotics.
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So the first antibiotics that we're going to talk about here, we're going to talk about the beta -lactams.
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Okay, so we're going to focus here on our beta -lactams.
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Now what is a beta -lactam?
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Now just really really quickly it has a specific structure.
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So if you look at a beta -lactam usually you have a five ring structure here
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and then you have a little four ring structure right here
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and then you have a little carbonyl and then you have this little nitrogen group here.
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So it's kind of like a cyclic amide.
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This right here is the beta -lactam, this component here, this is the beta -lactam.
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So these beta -lactam antibiotics usually have this beta -lactam ring which is incorporated into it.
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The beta -lactams we're going to focus on here, we're going to focus specifically on the penicillins.
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So we'll talk about penicillin, specifically like penicillin G, and then we're going to talk about amoxicillin,
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so amoxicillin, and then we're going to talk about cephalosporins.
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And we'll talk about all the generations of cephalosporins okay before I do
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that let's take a look at the overall cell wall structure
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again just a little bit more in depth zooming in on
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that peptidoglycan layer
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if we look in the peptidoglycan layer what is a peptidoglycan
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you see these blue structures right here those blue structures are specific derivatives of carbohydrates like glucose
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so what do I mean they're made up of structures which is called NAM and NAG.
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So they're just derivatives of glucose.
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NAM, NAM, stands for N -acetylmuramic acid.
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NAG stands for N -acetylglucosamine.
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All these are, these blue structures here, they're just derivatives of our carbohydrates, like glucose.
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Okay?
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Now coming up off of these carbohydrate residues you see this like a violet structure coming up out of this
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that right there is like peptide bonds actually a pentapeptide
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and then across from
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that again you're gonna have another what would this be this would be another anacetylmuramic acid
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and this could be another anacetylglucosamine
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these black proteins are coming downwards from this part too this is another pentapeptide
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and if you look there this little orange structure that's the cross link between them that's the peptide bond between them
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So this is the basic structure of our peptidoglycine layer in a zoomed look.
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You see this little orange guy just kind of sitting down?
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That's our penicillin binding protein.
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So that little red structure right there, which is actually going to be sitting down there on the cell membrane,
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is going to be the penicillin binding protein.
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So what is this guy here called?
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He's called the penicillin binding protein.
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Okay, he's a pretty important structure here because he's really what a lot of these actual beta -lactams are binding onto.
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Alright, next thing.
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If you look here, these brown scissors, those are little autolytic enzymes.
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We're going to talk about them.
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And then these little C -like orange enzymes there, they're called beta -lactamases.
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Okay, so this little orange structure up here, this orange structure here is called beta -lactamase.
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and then these little brown structures there are actually going to be called autolytic enzymes.
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Okay now that we've done that let's go over these antibiotics here.
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All right penicillin first.
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So penicillin it's it is able to treat in general gram -positive and gram -negative bacteria.
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However However, over the past years,
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certain bacteria have become resistant to penicillin.
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Okay?
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How have they become resistant to penicillin?
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Okay.
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This beta -lactamase, there's a specific part of its name, beta -lactamase.
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So it's an enzyme, right?
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So look what it can actually do.
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I'm going to draw that beta -lactam ring over here.
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And it's got that double bond right there with the NH and then it's got that little five -membered ring there.
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This is our penicillin.
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If we give someone penicillin who already has bacteria that are very resistant to the penicillin, what do I mean?
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Maybe they have plasmids that allow for them to produce this enzyme called beta -lactamase.
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What will the beta -lactamase do?
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Boom.
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It'll break the beta -lactam ring.
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If it cuts the beta -lactam ring, this penicillin is not going to be able to bind to this penicillin binding protein and mediate its effects.
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So because of this would be rendered ineffective.
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So that is the importance as a certain bacteria become resistant by developing these beta -lactamases.
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So really it's more effective now just being able to treat gram -positive bacteria with a little bit of gram -negative coverage.
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So what type of bacteria is it able to cover?
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It can cover streptococcal, okay that's the main one.
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It can cover streptococcal bacteria.
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So any type of streptococcal bacteria.
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It was able to develop in the past treat staphylococcal bacteria but again they've developed resistance also.
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So streptococcal bacteria it's also able to treat syphilis.
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So just a little bit on the penicillin.
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So what is penicillin actually do?
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How does it mediate these effects that it can actually kill these bacteria because it's bactericidal meaning it can kill the bacteria.
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So let's say here here's the penicillin.
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What the penicillin does is it comes in and it binds on to this penicillin binding protein.
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So let's say that we draw that here.
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Here's the penicillin and he binds on to this penicillin binding protein.
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When he binds to the penicillin binding protein he stimulates the penicillin binding protein
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and what this penicillin binding protein does is it takes its hand
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and it comes up there and it stimulates these brown enzymes.
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So then what does it do?
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It comes up here and stimulates these autolytic enzymes.
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If these autolytic enzymes are activated, what are they gonna do?
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They're gonna start cutting up these bonds, these peptide bonds, these glycosidic bonds, and it's gonna start altering the overall structure of the cell wall.
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That's one thing that happens.
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Second thing that happens, there's a lot of other enzymes here.
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There is other enzymes that actually link these peptide bonds together between these little pentapeptides, so you're having different types of transpeptidase enzymes,
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whenever the penicillin binding protein is stimulated, he inhibits the transpeptidases from cross -linking these pentapeptides.
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And if these are no longer cross -linked, the cell wall starts becoming disrupted.
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Now, when the cell wall is disrupted, it allows for water to start leaking into the bacterial cells.
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And when water leaks into the bacteria cell eventually can cause the cell to lice.
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That is the way penicillin works.
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So again one more time because all the rest of them are gonna do the same thing.
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So once we know penicillin we know what these functions are too.
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So one more time what does penicillin do?
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Penicillin comes in binds onto the penicillin binding protein, stimulates him.
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When he becomes stimulated he stimulates these autolytic enzymes who start cleaving and breaking up the cell wall.
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Then he also inhibits, let's say that I draw this enzyme out here I'm just gonna draw some little dude out here.
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Here's this little dude and he's got his hand in this bond right there.
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Okay these are transpeptidase enzymes.
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What are these transpeptidase enzymes doing?
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They're helping to link these actual pentapeptides.
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He will inhibit these transpeptidase enzymes.
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So now they can no longer cross -link these little peptide chains and because that the cell wall will be disrupted.
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Once it's disrupted water can leak in.
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When water leaks in to cell lysis.
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Okay so we're set there.
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Amoxicillin, same mechanism of action.
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Cephalosporin, same mechanism of action.
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But now, Amoxicillin, he is very, very susceptible to these beta -lactamases.
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Very, very susceptible.
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So when you give someone Amoxicillin, you usually want to give it to them with clavulonic acid.
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Clavulonic acid.
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Why do you want to give that?
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Because clavulonic acid is a beta -lactamase inhibitor.
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So if you give them clavulonic acid, what is it going to do?
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It's going to inhibit the beta -lactamase enzyme.
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If the beta -lactamase is inhibited, now this amoxicillin is going to have more available to start exhibiting this effect.
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Okay, so that's the job of clavulonic acid.
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What can amoxicillin treat?
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It can treat a lot of different things.
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So amoxicillin is good at being able to treat urinary tract infections.
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He's good at being able to treat respiratory tract infections.
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He's also good at being able to treat meningitis.
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and he can also treat infections that are caused by salmonella too.
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So he can also treat infections caused by salmonella, and he's also really good at being able to treat middle ear infections, otitis media too.
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So otitis media, middle ear infections, right?
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Okay, so that is going to be the amoxicillin.
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So he's good at being able to treat urinary tract infections, respiratory tract infections, meningitis, salmonella, otitis media, okay?
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Cephalosporins, mechanism of action, same thing, activates the penicillin binding proteins and exerts all those effects.
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Cephalosporins though are very interesting.
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Okay, so there's four generations of cephalosporins, right?
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So let's go ahead and go over those real quickly.
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So they're first generation, so we could say first generation.
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So first generation is actually going to be, we could take for example, Cephalexin.
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So Cephalexin is one example here of a first generation Cephalosporum.
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Then we could take for example a second generation.
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Now a second generation would be like Cephiroxine.
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Okay and then we could take for example a third generation Cephalosporum.
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So a third generation Cephalosporum could be like ceftriaxone.
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And then there's even fourth generation.
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So fourth generation would be like cefepine.
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So fourth generation would be like cefepine.
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Now why am I mentioning this?
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Well the reason why is cephalosporins, the first and second generation,
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are really only good at being able to treat mainly gram positive bacteria.
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So these are really only good at being able to treat gram positive bacteria.
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Okay whereas what's happened over the years is that the ceftriaxone
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and the sepapine have actually had a little bit more ability to treat more of the gram negative bacteria.
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Okay so again first generation could be like cefalexan
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and second generation could be like cefiroxan but But the big takeaway is these aren't really used anymore, but they're good to treat gram -positive.
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Third generation, fourth generation have a little bit more gram -negative coverage.
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So like ceftriaxone and cefepine.
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Okay, so what would be the coverage?
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So for example, let's say that I used cefalexan and cefiroxine.
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They really only have gram -positive coverage.
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So what would I really use these guys for?
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I would probably use these guys for more of your Staphylococcus aureus and Streptococcus pyogenes.
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So even Streptococcus pyogenes.
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Okay?
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Now if we use Ceftriaxone and Cefepime, they can treat Gram -negative.
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So what could I use that for?
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I could use that to treat, they have a lot of things that they could treat.
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Pseudomonas is a really big one.
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They can treat Pseudomonas, so like Pseudomonas aeruginosa.
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They can treat certain types of bacteria that cause meningitis.
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They're also pretty good at being able to treat infections caused by Klebsiella.
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So Klebsiella, which is very common bacteria that can cause pneumonia.
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So pneumonia, this is actually a bacteria that can cause pneumonia.
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More commonly, it can cause other infections, but more commonly pneumonia.
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and even other different types of enterobacteria.
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So even different types of enterobacteria.
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All right.
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So that's our cephalosporins.
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There is other beta -lactams and different types of penicillin derivatives that I could have mentioned, like Piptazo.
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I could even have mentioned carbopanems.
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You know, Piptazo can treat pseudomonas.
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Carbopanems are actually good at being able to treat very, very...
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problematic abdominal infections so they can treat that too.
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Alright but that's pretty much going to cover our beta -lactam
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so quick review and then we're gonna move on to the next ones.
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Really?
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Here we go.
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Penicillins.
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What do they actually do?
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They're gonna come down here, bind onto the penicillin binding proteins, then what?
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Activate the autolytic enzymes which are gonna cut up some of the cell wall structures, disrupting the cell wall.
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Also penicillin binding proteins are going to inhibit these enzymes which are called transpeptidases.
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So if you inhibit them they can't cross -link these actual peptide chains.
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Cell walls disrupted.
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What happens as a result?
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Water leaks in and then eventually causes the cell to lice and kills the cell.
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So these are bactericidal, meaning they kill the bacteria.
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What could be certain types of beta -lactams?
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Penicillin, amoxicillin, cephalosporins, right?
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And I could even include carbapandums or pipericillin with tazobactam like piptazo.
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But again, what is penicillin treating?
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Gram positive and gram negative, mainly streptococcal because there's staphylococcal bacteria become resistant.
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He can also treat syphilis.
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What about amoxicillin?
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He's very very sensitive to the beta -lactamases who cleave the beta -lactam rings.
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So in order to make them effective, what do you give them with?
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Calavulonic acid.
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What can they treat?
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UTIs, respiratory tract infections, bacteria that cause meningitis, salmonella, otitis media.
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Okay, and then cephalosporins we said there are four main generations.
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There is five.
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Fifth I said can treat MRSA.
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First generation and second generation are mainly for gram -positive.
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First generation could be like cephalexin, second generation could be like cefiroxime, so they can treat staphylococcus aureus and streptococcus pyogenes.
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Okay, and then third and fourth generation are more for the gram -negative coverage, and so those third generations would be like ceftriaxone
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and cefepime, right? what can they treat like Pseudomonas aeruginosa meningitis Klebsiella
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which can cause pneumonia as well as enterobacteria okay what other kind of drugs affect the cell wall
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because there is other drugs besides these ones very very powerful one
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we have to mention this one this very very powerful one is actually called it's a glycopeptide
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so let's actually put that down
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so let's actually this is actually a group under the glycopeptides so what glycopeptides Glycopeptide is this.
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This glycopeptide is very very strong.
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This is called vancomycin.
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And vancomycin is actually really good at being able to treat MRSA.
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What is MRSA?
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MRSA stands for Methicillin Resistant Staphylococcus Aureus.
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Now Methicillin is an antibiotic but they don't really use that anymore.
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okay but certain bacteria have become resistant right to penicillins
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or methicillin so you have to get vanco because
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that can kill the MRSA okay
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now vanco is actually really good mainly at being able to treat gram -positive bacteria okay
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so like MRSA and C diff so Clostridium difficile colitis
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so it's good at being able to treat C diff
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so C diff is the one that makes you pee out your butthole all right
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so it's really nasty one really really infectious diarrhea
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and it also can treat certain types of bacteria
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which are like resistant resistant coagulase
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so coagulase negative now remember I'm saying negative resistant coagulase negative bacteria okay
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and this is vanco
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so vanco is a pretty powerful antibiotic
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now what is vancomycin do he does something different he has the overall same effect as these beta -lactams
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but different mechanism of action what exactly is he doing?
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Vanko is very very interesting so you know
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that every protein usually has what's called a carboxy terminus
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and then it has an amino terminus right and then really
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if I were to show this peptide bond correctly
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it's really what's linking this part together right here's what's interesting let's say I take Vanko if I give someone vanco,
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look what it's doing.
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It's binding onto this carboxyl end.
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When it binds onto the carboxyl end, this can't form a peptide bond.
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So now what happens is vancomycin binds onto the carboxyl end of these actual peptide chains.
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And if it blocks onto it, it hysterically hinders that peptide bond formation.
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So now if you can't form a peptide bond, this cell wall is disrupted.
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If the cell wall is disrupted what happens?
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Water flows in.
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As water flows in what happens?
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The cell lysis.
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So this is a bacteriocidal antibiotic.
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Okay so one more time.
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What is vanco doing?
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It's binding onto the carboxyl end of these peptide chains.
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As it binds onto the carboxyl end it sterically hinders this amine group from being able to form a peptide bond.
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And as a result the cell wall is disrupted, water enters in and the cell lysis.
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So it's a bacteriocidal antibiotic.
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Okay, so we've covered our glycopeptides.
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Now let's go over here
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and let's cover a very weird type of bacteria that's not for gram positive or gram negative bacteria.
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Okay, so this one that I'm going to talk about is mainly important for being able to treat tuberculosis.
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Okay, so it's mainly used to treat tuberculosis.
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So caused by the mycobacterium.
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Now mycobacterium don't have a cell wall that's made up of peptidoglycans.
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They are made up of these little orange structures.
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You know what these orange structures are called?
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They're called mycolic acid.
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So, and you see this enzyme right here, this blue enzyme?
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This blue enzyme is called a mycolic acid synthetase or synthase.
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It's called isoniazid.
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and again what is this antibiotic do this antibiotic is mainly treating tuberculosis caused by the mycobacterium
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so what it does is it has a specific point where it actually here let's say here's the isoniazid
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it's actually going to come in and inhibit this mycolic acid synthase
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or synthetase enzyme
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if this enzyme is inhibited can it synthesize the mycolic acids to make up the cell wall no
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and if it can't synthesize this mycolic acid the cell wall integrity is altered.
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If the cell wall's integrity is altered, can that cell survive?
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No. Water might flush into it and cause the bacteria to die.
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So again, isoniazid is used to treat tuberculosis caused by the mycobacterium.
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Its cell walls consisting of these mycolic acid residues.
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What happens is if you give isoniazid, it inhibits the mycolic acid synthetase or synthase enzyme, which then can no longer synthesize mycolic acid.
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If it can't synthesize mycolic acid, the cell walls integrity is altered and then what happens the bacterial cell dies.
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Okay all right guys so that pretty much covers on this part the antibiotics
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that are treating for specifically the cell wall synthesis and structure.
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In the next video we're going to talk about the antibiotics that are mainly used to target the folic acid pathway.

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Этот урок разговорной практики построен на видео «Antibiotics: Cell Wall Synthesis Inhibitors: Part 1». Чаще всего повторяются слова: penicillin, cell, bacteria, treat, gram. В этом видео 320 предложений и 3467 слов для шедоуинга. Речь длится 22:08. Говорящий говорит в естественном темпе, около 157 слов в минуту, близком к повседневной речи. Только 76% слов входят в 3000 самых частых слов английского языка, поэтому лексика сложная.

Ключевая лексика этого видео

15 слов из видео, которые стоит выучить, с произношением и значением:

СловоПроизношениеЗначение
gram существительное/ˈɡɹæm/грамм
beta существительное/ˈbeɪtə/бе́та
enzyme существительное/ˈɛn.zaɪm/ферме́нт, энзи́м
acid существительное/ˈæsɪd/кислота́, кисля́тина
antibiotic существительное/ˌæn.taɪ.baɪˈɑ.tɪk/антибио́тик
infection существительное/ɪnˈfɛkʃən/инфе́кция, зараже́ние
layer существительное/ˈleɪ̯ɚ/слой, пласт
stimulate глагол/ˈstɪm.jəˌleɪt/стимули́ровать
mechanism существительное/ˈmɛk.ə.nɪ.zəm/механи́зм
leak существительное/liːk/течь, проте́чка
membrane существительное/ˈmɛm.bɹeɪn/мембра́на
pneumonia существительное/njuˈməʊniə/пневмони́я, воспале́ние лёгких
tract существительное/tɹækt/уча́сток
alter глагол/ˈɔl.təɹ/изменя́ть, измени́ть
derivative существительное/dɪˈɹɪvətɪv/произво́дное

Фразовые глаголы, которые вы услышите

СловоПроизношениеЗначение
come up глаголподнима́ться, подня́ться
go ahead глагол/ˌɡoʊ əˈhɛd/дава́й, приступа́йте
go over глаголхорошо́ принима́ться
cut up глаголразрезать
sit down глаголсади́ться, сесть
come down глаголспуска́ться, спусти́ться
make up глагол/ˌmeɪk ˈʌp/составля́ть, соста́вить

Фразы, которые стоит повторять

Короткие законченные фразы из видео, которые пригодятся в повседневном разговоре:

  • We're not going to cover all of them.
  • Let's say here's a bacteria and here's a bacteria.
  • You see this little orange guy just kind of sitting down?
  • Why do you want to give that?
  • You know what these orange structures are called?

Грамматика в этом видео

Конструкции, которые говорящий использует чаще всего, с точными словами из видео:

КонструкцияВ видео
Пассивный залог be + причастие прошедшего времени — важно, что происходит, а не кто это делаетis incorporated · is called · be called
Present Perfect have/has + причастие прошедшего времени — прошлое действие, важное сейчасwe've done · have become · have they become
Придаточные определительные who / which + предложение — уточнение о человеке или предметеring which is · structures which is · there, which is

Произношение, на которое стоит обратить внимание

Говорящий использует 61 сокращённых и редуцированных форм, например we're, they're, gonna. Произносите их коротко, так, как слышите.

  • Звуки «th»: thin /ˈθɪn/, thick /θɪk/, synthesis /ˈsɪnθəsɪs/, pathway /ˈpæθˌweɪ/, synthesize /ˈsɪnθəsaɪz/
  • Звуки «sh» и «zh»: infection /ɪnˈfɛkʃən/, infectious /ɪnˈfɛk.ʃəs/, flush /ˈflʌʃ/
  • Длинные слова — следите за ударением: antibiotic /ˌæn.taɪ.baɪˈɑ.tɪk/, mechanism /ˈmɛk.ə.nɪ.zəm/, derivative /dɪˈɹɪvətɪv/, tuberculosis /tʃuːˌbɜː(ɹ)kjʊˈləʊsɪs/, integrity /ɪnˈtɛɡɹəti/

Звуки, трудные для русскоязычных:

  • /w/ — губы округлены, это не /v/: whereas /(h)wɛɹˈæz/, pathway /ˈpæθˌweɪ/, downwards /ˈdaʊnwɚdz/, takeaway /ˈteɪkəweɪ/
  • /h/ — лёгкий выдох, а не русское «х»: whereas /(h)wɛɹˈæz/, inhibit /ɪnˈhɪbɪt/, carbohydrate /kɑɹboʊˈhaɪdɹeɪt/, hinder /ˈhɪndɚ/, inhibitor /ɪnˈhɪbɪtɚ/
  • Звонкие согласные в конце слова — не оглушайте их: bind /ˈbaɪ̯nd/, acid /ˈæsɪd/, derivative /dɪˈɹɪvətɪv/, glucose /ˈɡluː.kəʊz/, sensitive /ˈsɛn.sɪt.ɪv/

Как заниматься с этим видео

  1. Прослушайте всё видео один раз молча и выпишите незнакомые слова.
  2. Начните со скорости 0,75×, повторяйте предложение за предложением и вернитесь к обычной скорости, когда станет легко.
  3. Запишите себя и сравните с оригиналом, обращая внимание на такие слова, как gram, beta, enzyme.

Что такое техника Shadowing?

Shadowing — это научно обоснованная техника изучения языка, изначально разработанная для подготовки профессиональных переводчиков и популяризированная полиглотом доктором Александром Аргуэльесом. Метод прост, но эффективен: вы слушаете аудио на английском от носителей языка и немедленно повторяете вслух — как тень, следующая за говорящим с задержкой в 1–2 секунды. В отличие от пассивного прослушивания или грамматических упражнений, Shadowing заставляет мозг и мышцы рта одновременно обрабатывать и воспроизводить реальные речевые паттерны. Исследования показывают, что это значительно улучшает точность произношения, интонацию, ритм, связную речь, понимание на слух и беглость речи — что делает его одним из самых эффективных методов для подготовки к IELTS Speaking и реального общения на английском.

Техника шедоуинга: читать полное пошаговое руководство →