Question

Write properties of genetic material. Explain with a diagram, the experiment of Alfred Hershey and Marthachase that DNA is a genetic material.

Answer 1

The properties of the genetic material should be

• The genetic material should be present in every cell.
  
• It must contain all the biologically useful information in a stable form.
  
• It should be able to store information in the coded form for the control of biological functions of the cells, and also to express its information.
  
• It should show diversity corresponding to the variety existing in the organisms.
• It should also be capable of variations, i.e., recombination and mutation. Further, such variations must be stable and inheritable.
  

The genetic material should be able to generate its own kind and also new kinds of molecules.

• It should be capable of differential expression so that the various parts of an organism may acquire specific form, structure and functions in-spite of having the same genetic material.
  

Hershey and chase used differential labels (35-sulphur and 32-phosphorous) to label proteins and nucleotides of bacteriophages. Using these differentially labeled bacteriophages, Hershey and Chase were able to prove that the radioactivity status of progeny virus particles produced is dependent on the nucleic acid and not protein. Thus, DNA was proved to be the genetic material. They were awarded a Nobel prize for providing conclusive evidence that DNA is the genetic material.