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:

APA Video Citation:

[Empress]

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!

[LimeyLassen]

This 3 minute video beats the hell out of the 50 minute lecture I was supposed to learn this from

[DanielleFreeman-imyj]

I learn better when someone explains a topic to me. Thank you! your video was very helpful!

[patobanana]

Great work! This channel is trully amazing, love from Brazil❤❤

[anilazahid]

after so many videos finally cleared the concept

[JohnsonOluwabusayo]

Thank you.
The video was simply clear and explanatory.

[themanofsowses]

This was so useful, thank you for making this

[CookCravings]

Great work thanks for sharing.stay connected.

[zahrahmohamed]

Hii. Could u pls do a section on the kidney especially glomerular filtration. I have a test ab it on Wednesday next week

[zahrahmohamed]

Hi. Could u pls do a video on glomerular filtration

[MOHAMD_MOSTAFA]

Is S-strain & R-strain existed in mouses' blood after death(G4)

[mumbaikar]

Do make BOGOphysics and BOGOchemistry too.

[JoanneDsouza-gdvq]

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?

[parnikanika]

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