Griffith Experiment Flashcards
What did the Griffith experiment lay the foundation for?
Identifying DNA as the genetic material
What did the Griffith experiment demonstrate?
That transformation had occurred during the experiment
What organism was used?
Streptococcus pneumoniae
The s-strain was…
Smooth
Had capsule
Virulent
The r- strain was…
Rough
Had no capsule
Avirulent
Produced lymphocytes
Heat killed virulence cells were found to ____________________
Transform avirulent cells to virulent cells
Transformed cells could _____________________
Pass virulence to their descendants as a heritable trait
Describe Griffith’s first experiment
Placed virulent s-strain on agar resulting in symmetrical, smooth shaped colonies
Observed that all a were covered with a capsule material
Injected mice with live s-strain
The mouse died
What was the conclusion his first experiment?
The capsules restricted the mouse’s ability to recognize the bacteria and was unable to create antibodies
Describe Griffith’s second experiment
Grew r-strain on agar which grew as rough, irregular colonies
Observed colonies did not have capsule surrounding the cells
Injected r-strain into mice
The mice lived!
What was the conclusion of his second experiment?
Proteins on the bacteria without capsule could be recognized and attacked by the immune system to form antibodies
Why did Griffith perform his third experiment?
He wanted to know if the bacteria needed to be alive
Describe Griffith’s third experiment
Grew s-strain on agar
Heat-inactivated the bacteria
Introduced heat-killed bacteria into the mouse
The mouse lived!
What was the conclusion of Griffith’s third experiment?
You must have live cells to kill the host
Describe Griffith’s fourth experiment
Took heat-killed s-strain and mixed with live r-strain
Introduced mixture to the mice
The mice died
Then he isolated live s-strain and live r-strains from the dead mouse
