ALFRED HERSHEY AND MARTHA CHASE

Scientists Names:
Alfred Hershey & Martha Chase

PROTEIN VS DNA: WHICH IS THE GENETIC MATERIAL?

For several years scientists believed that proteins carried Genetic information. That was until Hershey and Chase provided solid evidence through their scientific investigations.

THE HERSHEY AND CHASE EXPERIMENT

The experiment involved the use of T2 bacteriophage and radioisotopes to track the transfer of proteins and DNA between the virus and the host. The bacteria were placed into 2 separate bacteria cultures. One contained the radioisotope 35 Sulphur and the other isotope 32 Phosphorous.

T2 Bacteriohage Virus 

The sulfur radioisotope synthesized the protein coat of the cultured T2 bacteriophage. Only proteins specificically the amino acids: cysteine and methionine contain sulfur and therefore will extract sulfur from the environment to create these amino acids R group. The viruses were then exposed to bacteria and infected them. The bacteriophage injected their DNA into the host leaving the protein coat of the virus outside the host. As a result the offspring of the bacteriophage inside the host did not contain the sulfur radioisotope.

In the case of the bacteriophage that was cultured in a medium containing the phosphorous radioisotope, the DNA of the bacteriophage contained the phosphorous radioisotope (This is because during mitosis, the DNA synthesized used nutrients from the provided bacteria culture, Since DNA has a phosphorous backbone it utilized the phosphorous from the culture medium to create its DNA).
The T2 bacteriophage virus that infected the bacteria injected their DNA into the host, which then reproduced offspring that contained DNA with the phosphorous radioisotope. This proved that the parent viruses transferred their DNA to their offspring and not their protein. There are other scientists that utilized different methods of determining that DNA was in fact thegenetic hereditary material. Another example would be