Griffith's experiment was a series of biological experiments by Frederick Griffith (Frederick Griffith) using Streptococcus pneumoniae and mice in 1928. The results show that the genetic information of a bacterium can change as a result of the transformation (or transformation) effect.
Non-toxic rough type (left) toxic smooth type (right)
Experiment
The experiment was based on the use of two different strains of Streptococcus pneumoniae (infected mice), one type iii-s (smooth, toxic), and the other ii-r (coarse, non-toxic). The iii-s type has a capsule composed of polysaccharides, which can protect itself against the host's immune system, thus causing the host to die. Ii-r does not have this structure, so it is not immune from the attack of the immunity system. The experiment is divided into four different steps and processing methods, as shown in the following table:
| |
|
|
| Ii-r (rough type) |
Non-pod film |
Survive |
| Iii-s (Smooth type) |
There is a pod film |
Death |
| Dead Iii-s. |
|
Survive |
| Dead Iii-s + Live Ii-r |
|
Death |
In one of the treatments (at the bottom of the table), Griffith kills the bacteria from the iii-s strains at high temperatures and mixes them with the live ii-r strains. Experimental results show that this combination can kill the host mice, and from these dead mice, can isolate the caller iii-s strains and the ii-r strains. Griffiths therefore concluded that a transformation factor contained in the iii-s strains of the Ii-r strain (
Transforming Principle"Transformation" has become a deadly iii-s. Later studies by others showed that the transformation factor was iii-s DNA (discovered by Oswald Avery). Although Iii-s is dead, DNA is still preserved during heating, so when the iii-s remains mixed with the living Ii-r, Ii-r receives the DNA from iii-s, resulting in a gene capable of producing a polysaccharide capsule that prevents the host's immune system from killing and causing the host to die. Another: In the high school biology compulsory 2 Avery experiment was carried out in the medium, and Griffith is a mouse as the experimental material.2 See Also
Hirsch-Chase Experiment3 References
Avery, MacLeod, and McCarty. Studies on the Chemical Nature of the substance inducing transformation of pneumococcal types:induction of transformation By a desoxyribonucleic Acid fraction Isolated from pneumococcus Type iii. Journal of experimental Medicine. 1944,
-(1): 137-58. (References the original experiment by Griffith. Original Articleand 35th Anniversary reprintavailable.
)Daniel Hartl and Elizabeth Jones. Genetics:analysis of Genes and Genomes, 6th edition. Jones & Bartlett. 2005.854 pages. ISBN 0-7637-1511-5.4 External links
In Fes
Griffith experiment Griffith ' s experiment
