Question

The transformation experiments on Pneumococcus showed that

• A. DNA can duplicate itself
• B. RNA is the genetic material
• C. DNA is the genetic material
• D. None of the above

Answer 1

The correct option is C DNA is the genetic material

Griffith experiment was conducted to prove that DNA is the genetic material which carries the character and it is transformed from one cell to the other. Two strains of pneumococcus (Streptococcus pneumoniae ) bacteria which infect mice, a type III-S (smooth) and type II-R (rough) strain. The III-S strain covers itself with a polysaccharide capsule that protects it from the host's immune system, resulting in the death of the host, while the II-R strain doesn't have that protective capsule which protects the immune system of the host.In this experiment, bacteria from the III-S strain were killed by heat, and their remains were added to II-R strain bacteria. While neither alone harmed the mice, the combination was able to kill its host. Griffith was also able to isolate both live II-R and live III-S strains of pneumococcus from the blood of these dead mice. Griffith concluded that the type II-R had been "transformed" into the lethal III-S strain by a "transforming principle" that was somehow part of the dead III-S strain bacteria.

It was the Avery–MacLeod–McCarty experiment that finally proved that the transforming principle is DNA,