Molecular Koch's Postulates - Video Tutorials & Practice Problems
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Intro to Molecular Koch's Postulates
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In this video, we're going to begin our lesson on molecular cokes postulates. And so what's important to note here is that in 1988, Stanley Falcao, a scientist proposed a revised set of cokes postulates which are known today as molecular cokes postulates. And molecular cokes postulates as its name implies, is used to identify the molecular cause of a pathogens virulent factors and recall that virulent factors are the specific traits of an organism that allow it to cause disease, that allow it to be pathogenic. And so therefore molecular cokes postulates can be used to explain why some microbial strains are pathogenic, based on their virulence factors while other microbial strains are not pathogenic. And so, if we take a look at our image down below, notice that we're showing you molecular cokes postulates, and specifically, we're showing you uh falcao over here and he's saying that these postulates uh use molecular techniques and so he'll call them molecular cokes postulates. And again, they can be used to identify the specific virulent factors that allow a microbial strain to cause disease. And so we'll get to talk more details about the specific molecular cokes postulates in our next lesson video. So, I'll see you all there
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The 3 Molecular Koch's Postulates
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So there are actually three molecular cokes postulates that are used to identify the virulent factors in a pathogenic microbe. And so down below, we're going to take a look at the three molecular cokes postulates in this image. And so the first of the postulates states that the suspected virulent factor gene or the jeans product must be found in every pathogenic strain of the microbe and then it must be absent in the non pathogenic strains of the microbe. And so, if we take a look at our image down below notice, on the left hand side, we're showing you the pathogenic strain of a specific bacteria. And this pathogenic strain of the bacteria notice contains the virulent factor gene or the suspected virulence factor gene. And therefore it's going to have the suspected virulence factor genes product as well. On its surface. These surface proteins are these little reddish triangles here and so this one because it is the pathogenic strain of the bacteria, it is going to be able to cause the disease. Now notice on the right, we're showing you the non pathogenic strain of the bacteria which is lacking the virulent factor gene or the suspected virulence factor gene and it is lacking the suspected virulence factor genes product. Now the second of the molecular Kochs postulate states that mutating the suspected virulence factor gene must either remove or reduce the pathogens virulent or in other words mutating the suspected variance factor gene must remove or reduce the pathogens ability to cause disease. And so notice that we're taking the pathogenic strain of the bacteria and here we have the suspected virulence factor gene. And we are going to mutate that suspected virulent factor gene. And so you can see the mutation over here on the right hand side. And so now we have a mutated version. And so this mutation must again either remove or reduce the pathogens virulent to create a non pathogenic strain of the bacteria which is what we're showing you here. And so that would be a good sign that this gene right here is indeed a virulence factor. Now the third of the molecular codes postulate states that reversing that same exact mutation must restore or increase the pathogens variance. And so if we start with the mutated non pathogenic strain of the bacteria, if we take this mutation and we reverse the mutation so that it goes back to its original form uh then it must again create the pathogenic strain of the bacteria. And so if all three of these molecular cokes postulates are stated, then the suspected virulence factor would we would conclude that it is indeed a virulent factor that contributes to the pathogens ability to cause disease. And so this here concludes our brief lesson on the three molecular cokes postulates and we'll be able to get some practice applying these concepts as we move forward. So I'll see you on our next video
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Problem
Problem
Which of the following answers is not a reason why Dr. Falkow developed molecular Koch's postulates?
A
Koch's original postulates possessed many limitations.
B
Genetic technology and microbial studies have vastly improved and grown since Dr. Koch's research.
C
Pathogenic microbes cannot be cultured on laboratory medium.
D
Molecular Koch's postulates allow a more detailed investigation into how pathogens cause disease.
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Problem
Problem
Virulence factors include which of the following answers?
A
Toxins found in the outer-membrane of certain species of bacteria.
B
Bacterial capsules that allow the bacterium to evade phagocytosis by immune cells.
C
Proteins on the surface of a virus that allows the virus to bind to the host cell's surface.
D
A and B only.
E
All of the above.
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Problem
Problem
Which of the following answers describes virulence factors of a pathogen?
A
Traits of a pathogen that allow it to successfully reproduce outside of a host.
B
Traits of a pathogen that allow it to successfully cause symptoms in its host.
C
Traits of a pathogen that allow it to successfully colonize within its host.
