Exemplar Problems

Question:

How did Hershey and Chase differentiate between DNA and protein in their experiment while proving that DNA is the genetic material?

Answer:

Hershey and Chase used a bacteriophage (T2 phage) to differentiate between DNA and protein as the genetic material.

They labeled the DNA of the bacteriophage with radioactive phosphorus-32 {32P) and the protein coat with radioactive sulfur-35 {35S).

After allowing the labeled phages to infect E. coli bacteria, they found that only the radioactive phosphorus-32 entered the bacterial cells, indicating that DNA, not protein, was the genetic material.

This experiment demonstrated that DNA carries the genetic information because it was the DNA, labeled with (^{32})P, that was transmitted to the host bacteria and not the protein, which was labeled with {35}S.