Question

The unequivocal proof of DNA as the genetic material came from the studies on a
A. Bacterium
B. Fungus
C. Viroid
D. Bacterial virus

Answer 1

The genetic material is a medium through which instructions are passed in generations. To prove this Hershey and Chase experimented on Bacteriophages.

Complete step by step answer: In 1952, Alfred Hershey and Martha Chase did an experiment that proved that information from one organism to another in a generation is passed through DNA.
Hershey and Chase performed an experiment involving Bacteriophages.
-Bacteriophages or bacterial viruses are those that infect or eat bacteria. They infect bacteria by passing over their genetic material into bacterial cells. This genetic material having all information encoded over it enters the bacterial genome and hijack’s it. After having control over bacterial genetic material it assists it to make proteins required to form more Bacteriophages. Once, Bacteriophage progeny is formed, the bacterial cell is lysed or gets killed.
-This was observed by Hershey and Chase. They grew some Bacteriophages in radioactive phosphorus and these bacterial viruses contained radioactive DNA. While another Bacteriophage culture grown over radioactive sulfur contained radioactive protein coat only. After this, they infected two E.coli bacterial cultures separately. Once the infection was done both the infected cultures were centrifuged separately to remove viral coats from bacteria. The infected bacterial cells and surrounding media having viral coats were differentiated.

It was observed that Bacteriophages with radioactive phosphorus were found in association with bacterial cells. But those with radioactive sulfur were found only in the surrounding medium. Thus, they concluded that it is the DNA that entered the bacterial cell and not the protein coat of the virus.
Therefore, the right answer is option D, i.e., Hershey and Chase employed Bacterial viruses to prove that it is the DNA that acts as genetic material for an organism.

Note: DNA or Deoxyribonucleic acid is a nucleic acid that has information encoded over it in form of bases. These bases form the framework for the production of various proteins and enzymes required by cells. Also, these codes assist in the determination of phenotypic characteristics for an organism.