The hershey and chase experiments involved the preparation of two different types of radioactively labeled phage. which of the following best explains why two preparations were required? a. the bacteriophage used in the experiments was a t2 phage. b. it was necessary that each of the two phage components, dna and protein, be identifiable upon recovery at the end of the experiment. c. each scientist had his own method for labeling phage, so each conducted the same experiment using a different isotope. d. establishing the identity of the genetic material required observation of two phage generations.
B. It was necessary that each of the two phage components, DNA and protein, be identifiable upon recovery at the end of the experiment.
Hershey and Martha Chase used radiolabeled the DNA of some of the bacteriophage cells with phosphorus (32P). They radiolabeled the sulfur (35S) of the coat protein in the second batch of the phage cells. They infected some of the bacterial cells with phage having radiolabeled DNA while the other E. coli cells were infected with the phage carrying radiolabeled coat protein. This allowed the clear identification of the radiolabelled molecule (DNA or protein) present in the host cell.
They observed that the E. coli cells infected with phage having radiolabeled DNA exhibited the radioactivity while the other batch of the host cell did not show it.
The correct answer is B.It was necessary that each of the two phage components, DNA and protein, be identifiable upon recovery at the end of the experiment
Hershey and chase in his experiment lebelled the T₂ bacteriophage with radioactive sulfur and radioactive phosphorus separately. Then they infect E.coli with T₂phage and separated phage from bacteria by centrifugation.
Because DNA contains phosphorus not protein, cells infected with phage containing radioactive phosphorous showed radioactivity bacause DNA enters the cell not protein confirming DNA is the genetic material and radioactive sulfur was found in supernatant.
It was necessary that each of the two phage components, DNA and protein also , be identifiable while recovery at the end of the experiment.
Because it was concluded that the those component associated with bacteria by the end of the experiment must be the genetic material, it was critical that the those component be identifiable as either DNA or protein. If it is not identifiable, then Hershey and Chase were not be able to define the genetic material.