Question

a) What biological system did the Hershey Chase experiment use to determine that DNA was the genetic material? Why was this experiment an improvement on the Griffith experiment?

b) Which base pairing interaction is stronger? Why? What physical approach can we use to measure this interaction strength?

Answer 1

Ans a) The biological system that was used by Hershey and Chase for finding DNA as the genetic material was bacteria called E.Coli as well as bacteriophage T2. Their experiment helped in determining that the DNA is the genetic material which otherwise many researchers thought to be proteins. It was shown by them that bacteriophage consisting of DNA and protein, tend to infect bacteria and DNA was concluded as genetic material as it only enters the host cell and protein does not enter and remains outside. They used radioactive phosphorus 32 for labeling DNA in T2 phage and sulphur-35 to label protein and hence found that only phosphorus 32 label was found in host cell.

The Griffith Experiment suggested that bacteria has the ability to transfer its genetic information through transformation. The experiment by Hershey and Chase was an additional improvement because their experiment helped in showing and understanding the exact way how the process of transformation takes place and precisely how DNA enters the host.