Audio Transcript Auto-generated
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Today we will be discussing Griffith's experiment.
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It is the first known demonstration of bacterial transformation and
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was performed in 1928 by the British bacteriologist Frederick Griffith.
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The experiment was with pneumococcal strains of streptococcus pneumoniae, which
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causes pneumococcal infections.
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He performed this experiment on what's Griffith used two different
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strains of bacteria on the Nice to see how the
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viral strains would impact them.
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He also created another type of strange.
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So there were three main strains in his experiment that
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he should be familiar with.
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The first one is the S or smooth strain, which
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is known to be deadly environment.
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This is due to the policy Ackroyd outer coating.
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The R or rough strain is a nonviolent strain due
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to the lack of the Polish soccer I coded.
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Then, in his lab, he created the heat killed s
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strain, which is no longer violent due to the police
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asteroid coding not being effective anymore.
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He started this experiment with mice and for his first
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round, he injected it with the R string, which proved
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to show that it was nonviolent because the mouse survived
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for the second mouse, he injected it with the S
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strain which was known to be violent.
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Therefore, the not stopped for the third one, he injected
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it with the heat killed s strength and to his
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sleeve. He saw that the mouse survived.
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This is due to the bacterial strain no longer being
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effective at creating the infection.
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Then for the fourth mouse, he injected with the heat
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killed s strain and the normal our string and to
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his surprise, the Mount stock.
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So both Griffith and probably you are asking the same
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question. Why did the mouse die when injected with the
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heat, killed s strain and are strained when both previous
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experiments show that the mask slip before I move on
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to the next step.
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Take a look at the different experiments he performed and
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see if you can create an answer.
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So what happened in his experiment?
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When the mice were injected with both the heat killed
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s train and the R strain, the mice still developed
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pneumonia and died After a closer look at the blood.
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Griffith found that there was live bacteria still that was
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normally found in the viral and estranged.
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Essentially, there was still a viral and bacterial information from
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the S string even after it had been heat killed
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and made the policy Ackroyd outer coating ineffective only with
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the presence of the R strain, the viral bacteria was
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able to succeed at infecting and killing the mouse.
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The conclusions drawn from this experiment is that the heat
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killed estrange bacteria somehow combined with the R strain to
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become a violent strain of bacteria.
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This suggested genetic transformation.
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Excuse me.
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Information may be transferred between cells.
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So here in this image we see that the heat
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killed s strength has transferred some genetic information to the
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R strain, which created a viral in bacteria strength and
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ultimately killed the host.
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This suggested the concept of genetic transformation or also known
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as the transforming factor Griffith's experiment has allowed for future
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research. You'll learn in future videos and lessons that his
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findings allowed for transformation principle to be more research.
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And for the next 15 years, more scientists were allowed
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to explore this and the other experience