Frederick Griffith

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Frederick Griffith (1877 - 1941) was a British medical officer. 1928. In what is today known as Griffith's experiment, he discovered a transforming principle, which is today known as DNA.

Griffith was, in fact, trying to make a vaccine to prevent pneumonia infections in the epidemics after World War I. Griffith was trying to make a vaccine using two strains of the Streptococcus pneumonia bacterium. The rough strain (R strain) did not cause pneumonia when injected into mice and was not covered with a polysaccharide capsule. The smooth strain (S strain) was deadly when injected, causing pneumonia and killing the mice in a day or two and does have a polysacchride capsule. When the S strain was heated to kill it and then injected into mice, it produced no ill effects in the subjects. However, when dead S coupled with live R were injected into the mouse, the mouse died. After examining the blood of the mice, Griffith discovered that the normally healthy R bacteria had acquired polysaccharide capsules. The dead genes of the smooth strand, transferred their DNA to the rough strand. The rough strand thus gained the instructions to produce a smooth and deadly coat. Since the genes that were transferred were dead, it is evident that the rough strand only became deadly because of the DNA it gained. This is the first known example of bacterial transformation.

Griffith was killed at his home in London as a result of an air raid.

He was the uncle of John Stanley Griffith, a winner of the Royal Society's Faraday Medal. Template:Geneticist-stub de:Frederick Griffith pl:Frederick Griffith hu:Frederick Griffith