Griffith's experiment

Griffiths experiment that was conducted in 1928 by Frederick Griffith, was the first evidence of transformation in a bacterium, which is the transfer of genetic information among bacteria.

He experimented with this bacterium Streptococcus pneumoniae which causes pneumonia in mice. This bacterium comes in two variants: as "S- cells " (smooth, smooth), can form the slime capsules and therefore appear smooth under the light microscope and are pathogenic. The " R-form " (rough, rough), however, lost the ability to capsule formation, appears rough and is non-pathogenic, as it is recognized by the immune system of the mouse due to the lack of protection capsule.

The Griffith experiment now consists of the following four steps:

This proved that a transformation had taken place: the ability of slime capsule formation is transmitted from the dead S cells to the living R cells.

1944 Oswald Avery and his colleagues showed that the transformation to a transfer of deoxyribonucleic acid ( DNA) is based. This was an important step towards the realization that DNA is the carrier of genetic information in general.