The fact that DNA is genetic material came from the experiments usingbacteria and viruses.
The first series of experiments were performed by a British bacteriologist F. Griffith in 1928, using the bacterium Diplococcus pneumoniae which causes pneumonia in mammals.Griffith noticed that this bacterium had two types of strains.
When S-type of bacteria was injected into healthy mice, the mice developed pneumonia and died. So S-type was named as virulent.
If heatkilled S-type of bacteria were injected into healthy mice, they did not cause disease and the mice remained healthy.
When heat killed S-type of bacteria were mixed with R-type living bacteria and themixture injected into healthy mice, the mice developed pneumonia and died.
When bacteria were isolated from the dead mice, they were of living S-type and R-type.
Griffith announced that it wasbecause of a phenomenon other than mutation, which he called transformation.
Avery, McCarthy, and MacCleod’s Experiment
The three men purified the “transforming principle”. They extracted Streptococcuspneumonia S bacteria nucleoid purified DNA, proteins and other materials and mixed R bacteria with these different materials, and only those mixed with DNA were transformed into S bacteria. Fortheir experiments they used a test tube instead of mice.
This experiment strongly implied that DNA is the “transforming factor” and not the proteins and other materials.
Keywords:Transmitting, Storing, Copying, Information, DNA
Role Of DNA |
DNA carries the genetic information that is copied when a cell divides. The way with which nucleotides are ordered.
DNA firstneeds to be transcribed into RNA, though, and then replicated to form a new molecule. DNA has a unique, right-handed, double-helical structure which allows it to store much genetic information....