Frederick Griffith (1879 - 1941) was a British medical officer. In 1928, in what is today known as Griffith's experiment, he discovered a transforming principle, which is today known as DNA. 1879 (MDCCCLXXIX) was a common year starting on Wednesday (see link for calendar). ... For the movie, see 1941 (film). ... Year 1928 (MCMXXVIII) was a leap year starting on Sunday (link will display full calendar). ... Griffiths experiment was conducted in 1928 by Frederick Griffith which was one of the first experiments suggesting that bacteria are capable of transferring genetic information, otherwise known as the “transforming principle”, which was later discovered to be DNA. Griffith used two strains of Pneumococcus (which infects mice), a S... Griffiths experiment was conducted in 1928 by Frederick Griffith which was one of the first experiments suggesting that bacteria are capable of transferring genetic information, otherwise known as the “transforming principle”, which was later discovered to be DNA. Griffith used two strains of Pneumococcus (which infects mice... The structure of part of a DNA double helix Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living organisms. ...

Griffith was 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 pneumoniae 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) did have a polysaccharide capsule and was deadly when injected, causing pneumonia and killing the mice in a day or two. When the S strain was heated to inactivate it and then injected into mice, it produced no ill effects in the subjects. However, when dead S coupled with live R was injected into the mouse, the mouse died. After isolating bacteria from the blood of the mice, Griffith discovered that the normally nonpathogenic R bacteria had acquired polysaccharide capsules. The bacteria isolated from the mice infected with the mixture of live R and heat inactived S were all of the S strain, and maintained this phenotype over many generations. Griffith hypothesized that some "transforming principle" from the heat inactivated S strain converted the R strain to the virulent S strain. It wasn't until several years later that Griffith's "transforming principle" was identified as DNA. Pneumonia is an illness of the lungs and respiratory system in which the alveoli (microscopic air-filled sacs of the lung responsible for absorbing oxygen from the atmosphere) become inflamed and flooded with fluid. ... An epidemic is generally a widespread disease that affects many individuals in a population. ... Combatants Allied Powers: Russian Empire France British Empire Italy United States Central Powers: Austria-Hungary German Empire Ottoman Empire Bulgaria Commanders Nicholas II Aleksei Brusilov Georges Clemenceau Joseph Joffre Ferdinand Foch Robert Nivelle Herbert Henry Asquith Sir Douglas Haig Sir John Jellicoe Victor Emmanuel III Luigi Cadorna Armando Diaz Woodrow...

Griffith was killed at work along with longtime friend and bacteriologist William M. Scott in London as a result of an air raid. He died holding a page that included formulas that seemed to be a breakthrough, however they were too random to be interpreted. Today the paper has remained in a preservation lab so that one day somebody can make sense of it and hopefully discover something that Griffith wasn't able to complete.

He was the uncle of John Stanley Griffith, a winner of the Royal Society's Faraday Medal.