Question

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

Answer 1

Hint: This experiment was to prove that DNA is the genetic material and is a factor of heredity that is responsible for carrying the genetic information from one generation to another since it is present inside the nucleus.

Complete step by step answer:
Earlier it was believed that the genetic information is carried through proteins. But later Hershey and Chase demonstrated their experiment based on the conclusion that the genetic material of the body is the DNA. They have done their experiment in bacteriophages that were composed of proteins and DNA. They observed that while injecting the bacteria most of the DNA of bacteriophage entered the host cell but the proteins do not enter completely. This proves that DNA is the genetic material.

Hershey and Chase added Sulfur-35 radioactive elements in the bacteriophages and isotopes in the culture medium where bacteria were kept for four hours. Then after some time, the bacteria were infected by bacteriophages resulting in the formation of the offsprings having radioactive isotopes. It was done by radioactive phosphorus isotopes also. The radioactive progenies formed were then injected in the unlabeled bacteria where it was observed that the outer coat of the bacteriophage that was made up of protein was left outside but the genetic material that was DNA moved inside. The bacteriophage was then started from bacteria through agitation and centrifugation to release their protein coats. The bacteria were then broken down to release their progenies and was found that those progenies that were labeled by radioactive phosphorus were found to be labeled while those that were labeled by radioactive phosphorus were not labeled.
They concluded that genetic material is DNA, not protein as the protein coat remains outside only the DNA enters the host cell. They observed that no protein was responsible for their growth, only DNA was responsible. The radioactive materials that entered the cell were all due to the DNA.

Note: In 1952, Alfred Hershey and Martha Chase performed an experiment that was named Hershey and Chase experiment. In 1969, Hershey even got the Nobel Prize in Physiology and Medicine. The DNA was first thought to be a genetic material by Aver - MacLeod - MacCarty experiment in 1944. The confirmation that DNA was a genetic material came by Watson and Crick in 1953.