Question

QUESTION 22

Upon removal of bacteriophage coats from infected bacterial cells, where was the label for the DNA?

A. in the cell pellet

B. in the supernatant

C. in bacteriophage coats

D. in both the cell pellet and supernatant

Answer 1

Upon removal of bacteriophage coats from infected bacterial cells, the label for the DNA was in the cell pellet.

Explanation :

Hershey and Chase have performed an experiment using bacteriophage and bacteial cells to proove that the DNA is the genetic material of the cell. They have used the T2 bacteriophage and inserted radioactive Phosphorus to the DNA of the bacteriophage virus and radioactive Sulfur to the protein coat of the T2 bacteriophage virus. They have cultured this virus and than these are used to infect the bacterial cells. When the bacterial cells were infected, than the bacteriophage coat was removed from the bacterial cells by centrifugation method and the cell pellet was prepared which contains the bacteriophage infected bacterial cells. When the cell pellet was tested traces of radioactive Phosphorus was found in that which was inserted to the DNA of the bacteriophage and they concluded from this experiment that DNA (of bacteriophage which was inserted with radioactive Phosphorus) which was present in the cell pellet is the genetic material.

Specifically because of the traces of radioactive phosphorus inserted to the DNA of the bacteriophage , the label of DNA from the cell pellet was found and they concluded that DNA is the genetic material of a cell.

N.B. : Cell pellet was containing bacteriophage infected bacterial cells.