Griffith's Experiment

Griffith's Experiment

(1928)

1. Griffith injected a mouse with the S-smoot strain, but the mouse dead.

S-smoot strain:

- Secrete a capsule.

- Produce smooth colonies.

- Virulent: produce disease.

R-rough strain:

- Produce colonies with a rough.

- Unable to secret a capsule.

- Avirulent: Not produce disease.

2. Griffith injected a mouse with a R-rough and the mouse survived.

3. Griffith heated the "S" strain to extreme temperatures that ended up killing the virulent strains, and were injected to the mouse. It survived.

4. Griffith injected a mouse with a healt killed "S" strain and "R" strain, but the mouse didn't survive, because the "R" strain mutated in the capsule of "S" strain.

Live Bacteria "S"

Live Bacteria "R"

Heat killed "S" strain

Heat killed "S" strain + "R" strain