Question

Describe the Hershey and Chase experiment. Write the conclusion drawn by the scientists after their experiment.

Answer 1

Hint:The Hershey chase experiment was a pioneering point in genetics as it proved that our genetic material is DNA. It also corrected the ongoing belief among scientists that protein is the genetic material.

Complete answer:
Hershey and Chase’s experiment was carried out by Alfred Hershey and Martha Chase in 1952 that resulted in confirmation that DNA is the genetic material. They showed that when bacteriophages which are composed of DNA and proteins infect bacteria, their DNA enters the host cell, not the proteins. That proved that DNA is the genetic material, not the proteins.

Experiment: They began the experiment by culturing the viruses in two types of mediums-
-One set of virus named A was cultured in a medium if radioactive phosphorus
-The other set termed B was cultured in a radioactive sulfur medium.

Set A showed that it consists of radioactive DNA but not radioactive proteins as DNA is a phosphorus-based compound while protein is not. Set B was made of radioactive proteins but not radioactive DNA.

Then they took the E.coli bacteria as the host for bacteriophages and they removed the viral coats from the bacteria by a number of blending and centrifugation processes, allowing the viruses to infect the bacteria.

Conclusion: It was observed in the experiment that set A of viruses infected the E.coli and made them radioactive but the ones that were infected by set B turned out to be non-radioactive. It concluded that the viruses with radioactive DNA transferred its DNA to the bacteria but the radioactive proteins in set B viruses didn't get transferred. Hence it was proved that DNA is the genetic material.

Note:DNA was known to scientists since 1869, but due to its inert nature in the nucleus, it was assumed that its only role is to store phosphorus. The scientists of that time considered the proteins carried the information of inheritance. After the Hershey-Chase experiment, it was clear that DNA is the genetic material, not the proteins, and the hypothesis of proteins being genetic material was canceled.