Question

DNA was proved to be genetic material through experiment of

• A. Transduction
• B. Transformation
• C. Viral infection of Tobacco
• D. Both A and B

Answer 1

Answer: (D)

Both A and B

Alfred D. Hershey and Martha Chase used radioactive phosphorus (32P) and radioactive sulfur (35S) and showed that when bacteriophage T2 infects its host cell i.e., Escherichia coli, the phosphorus-containing DNA of the viral particle and not the sulfur-containing protein of the viral coat, enters the host cell and serves the genetic information for viral replication. Since the transfer of genetic material from one strain to other via viral particles is termed as transduction. They infected E. coli not tobacco plants with the virus. Transformation is the transfer of genetic material from one bacterial strain to other 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. S-type, which was capsulated and produced a smooth colony on a synthetic medium.

R-type, which was non-capsulated and produced rough colony on a synthetic medium. At the end of the experiment, Griffith announced that there was a change in the type of bacterium because of a phenomenon other than mutation, which he called transformation.

So, the correct answer is option D.