Griffith's Experiment: Bacterial Transformation
This video explains Griffith's experiment to prove the existence of a "transformation principle" via experimentation with mice and two kinds of pneumonia bacteria. His work paved the way for Avery, McCarty and MacLeod to later prove the DNA is the molecule of heredity.
Chapters:
0:00-0:06 Introduction
0:06-0:40 S and R Strain of Streptococcus Pneumoniae
0:40-0:58 The Transformation Principle
0:58-1:24 Griffith's Experiment Structure
1:24-1:32 Live R Strain
1:32-1:40 Live S Strain
1:40-2:00 Heat Killed S Strain
2:00-2:30 Heat Killed S Strain, Live R Strain
2:30-2:55 Isolated S Strain
2:55-3:45 Conclusions, Connections to Avery, McCarty and MacLeod's Work
Details:
While observing the pneumococcus bacteria, Griffith noticed that sometimes the non-virulent R strain would revert into the virulent S strain. He theorized that a “transforming principle” was somehow transferred between the S strain and the R strain, causing the R strain to acquire dangerous properties.
To test his theory, he injected five different types of bacteria into groups of mice;
1) Live R strain
2) Live S Strain
3) Heat-Killed S strain
4) a COMBINATION of Heat-killed S strain AND live R-strain
5) S strain that had been isolated from mice in the fourth group.
The results Griffith’s famous experiment would confirm the presence of a “transforming principle”.
Predictably, the mice from group 1 survived, the mice from group 2 died, and the mice from group 3 survived. However, the mice in group 4 died. On their own, neither the heat killed S strain nor the live R strain should have been deadly, so Griffith concluded that the live R-strain had acquired some type of deadly component from the dead S-strain. He called this mystery component the “transformation principle”.
Griffith’s ground-breaking work proved that some organisms can acquire new properties from their environment and from one another, and that non-heritable exchange of genetic information is possible.
Useful Sources:
en.wikipedia.org/wiki/Griffit...
openstax.org/books/microbiolo...
APA Video Citation:
[BOGObiology]. (2021, May 24). Griffith's Experiment: Bacterial Transformation. [Video File]. Retrieved from • Hypertonic, Hypotonic ...
Пікірлер: 33
Can someone please give me some clarity on my question? How was the R (rough) strain able to get the genetic material DNA from the heat-killed S (smooth) strain in the 4th portion of the experiment? I am not understanding that part. Thank you!
@BOGObiology
2 жыл бұрын
Hey Miracle! We now know that they do this because of a process is called "bacterial transformation". When bacteria reproduce their offspring are clones with no genetic variation, which is not very useful for long-term survival. They usually get around the problem by slightly modifying their genome by swapping chunks of their DNA with other bacteria. Under the right conditions, they can also take in DNA from their environment and incorporate it into their own genome. We call this "transformation". Even though the S-strain bacteria had died, its DNA was still intact and the R-strain bacteria grabbed it and started using it. At the time, Griffith didn't know what the substance was, he just knew that the R strain bacteria acquired a something-or-other from the S-strain and thus "transformed" into S-strain bacteria as a result. Hope this helps! Love, BOGO
@i3ubogo599
2 жыл бұрын
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@humam_aldulaimi
2 жыл бұрын
Hereditary materials from the S strain bacterium was passed on into the R strain therefore transforming the R strain into a fatal deadly strain from the components it required from the S strain
@MOHAM3D_MOSTAFA
5 ай бұрын
What kind of them founded in mouses' blood after death? If we talk about group 4..it's argent👀
This 3 minute video beats the hell out of the 50 minute lecture I was supposed to learn this from
@BOGObiology
2 жыл бұрын
Haha that's the idea. It used to take me an entire class period to teach this content, and then another to teach avery, and then a third to teach hershey chase, but now I have videos for all 3 and I don't have to lecture, which is great because I hate lecturing. Please share with your classmates; I'm sure they'll appreciate it!
Griffith!!!!!!!!
@darken2935
6 ай бұрын
😂😂
Great work! This channel is trully amazing, love from Brazil❤❤
This was so useful, thank you for making this
Thank you. The video was simply clear and explanatory.
after so many videos finally cleared the concept
Hii. Could u pls do a section on the kidney especially glomerular filtration. I have a test ab it on Wednesday next week
Great work thanks for sharing.stay connected.
Hi. Could u pls do a video on glomerular filtration
Thank you very much ✌️❤️
thank you Doctor
Is S-strain & R-strain existed in mouses' blood after death(G4)
ty
Do make BOGOphysics and BOGOchemistry too.
Why didn't the genetic material from the heat killed s strain cause the mice to die, since the genetic material did survive after all?
@chubbycat8445
Жыл бұрын
It needs live cells to perform transcription and translation. But the cells are dead. Genetic material as it is can't do anything. It needs machinery.
U said tat dna is transferred from the live R strain to heat killed S strain .that's okie but R strain alredy has DNA in it why don't that cause dead when given individualy
@tigrantumanyan8545
Жыл бұрын
The R-strain isn't deadly on its own because it does not have a capsule around it (like the S-strain). And because it doesn't have a capsule around it, the organism's immune system can easily fight it off. On the other hand, the S-strain is deadly because the surrounding capsule protects the bacteria from the body's immune system and allows it to attack the organism.
@user-dy5jm9kk3r
Жыл бұрын
thats a non-virulent strain...its unable to produce disease
GRIFFIIIIITH!!!1!!!!
NOICE
@BOGObiology
2 жыл бұрын
Thanks! I had fun making this video!
yup still don't get it lol
grifiss
Bad video, hard explaination!