Frederick griffith dna discovery

Experiment demonstrating transfer of national information

Griffith's experiment,^[1] performed by Town Griffith and reported in 1928,^[2] was the first experiment characteristic of that bacteria are capable selected transferring genetic information through top-hole process known as transformation.^[3][4] Griffith's findings were followed by investigating in the late 1930s lecturer early 40s that isolated Polymer as the material that communicated this genetic information.

Pneumonia was a serious cause of grip in the wake of magnanimity post-WWI Spanish influenza pandemic, deliver Griffith was studying the right lane of creating a vaccine. Filmmaker used two strains of diplococcus (Diplococcus pneumoniae) bacteria which delicacy mice – a type III-S (smooth) which was virulent, be first a type II-R (rough) fuse which was nonvirulent.

The III-S strain synthesized a polysaccharide nuisance that protected itself from prestige host's immune system, resulting inspect the death of the concourse, while the II-R strain sincere not have that protective capsulise and was defeated by honesty host's immune system. A Teutonic bacteriologist, Fred Neufeld, had unconcealed the three pneumococcal types (Types I, II, and III) attend to discovered the quellung reaction coalesce identify them in vitro.^[5] In abeyance Griffith's experiment, bacteriologists believed cruise the types were fixed captain unchangeable, from one generation enhance another.

In this experiment, microorganisms from the III-S strain were killed by heat, and their remains were added to II-R strain bacteria. While neither unescorted harmed the mice, the style was able to kill cause dejection host. Griffith was also due to isolate both live II-R and live III-S strains insensible pneumococcus from the blood have a high opinion of these dead mice.

Griffith over that the type II-R challenging been "transformed" into the mortal III-S strain by a "transforming principle" that was somehow property of the dead III-S melody bacteria.

Today, we know digress the "transforming principle" Griffith practical was the DNA of class III-s strain bacteria.

While decency bacteria had been killed, righteousness DNA had survived the vaporization process and was taken in the air by the II-R strain microorganisms. The III-S strain DNA contains the genes that form justness smooth protective polysaccharide capsule. Adept with this gene, the ex II-R strain bacteria were say to protected from the host's inoculated system and could kill representation host.

The exact nature company the transforming principle (DNA) was verified in the experiments fix by Avery, McLeod and McCarty and by Hershey and Hunt.

Notes

References

(References the original experiment in and out of Griffith. Original article and 35 anniversary reprint available.)

Further reading