Question

Who proved that DNA is basic genetic material?

Answer 1

Hint: DNA stands for Deoxyribonucleic Acid. It is a molecule that contains and carries the genetic material from parents to the offsprings. It is double-stranded. It is chemically less sensitive and structurally more stable than RNA.

Complete answer:
In 1952, Alfred Hershey and Martha Chase conducted an experiment on bacteriophage to prove that DNA is the basic genetic material.

Procedure:
1. Some bacteriophage viruses were grown on a medium that contained radioactive phosphorus (32P) and a few in another medium with radioactive sulphur (35S).
2. Viruses grown within the presence of radioactive phosphorus (32P) contained radioactive DNA.
3. Similar viruses grown within the presence of radioactive sulphur (35S) contained radioactive protein.
4. Both the radioactive virus forms were allowed to infect E. coli separately.
5. Soon after infection, the bacterial cells were gently agitated in the blender to get rid of viral coats from the bacteria.
6. The culture was also centrifuged to separate the viral particle from the bacterial cell.

Observations and Conclusions:
1. Only radioactive 32P was found to be associated with the bacterial cell, whereas radioactive 35S was only found in the surrounding medium and not within the bacterial cell.
2. This indicates that only DNA and no protein coat entered the bacterial cell.
3. This proves that DNA is that the genetic material that is passed from virus to bacteria and not protein.
4. From the above experiment, Harshey and Chase proved that DNA is the genetic material.

Thus Harshey and Chase proved that DNA is the genetic material.

Note: Genetic material should be ready to generate its own replicas by the method of replication and may undergo slow and gradual changes called mutations which may result in evolution.
DNA is formed from 2 polynucleotide chains which have a basic unit called nucleotides. Nitrogenous bases existing in DNA are Adenine, Guanine, Thiamine, Cytosine.