Question

Why were radioactive sulfur and phosphorous used to label bacteriophage in Hershey and Chase's experiments?

Short answer

A series of studies carried out by Martha Chase and Alfred Hershey proved that DNA is an organism's genetic material. They did this by cultivating bacteriophages in two different media, one having radioactive sulphur (35 S), and the other containing radioactive phosphorus, which was used to label the DNA core. They could then permit the infection of bacterial cells by these radiolabeled bacteriophages.

Step-by-step solution

Introduction

A series of studies carried out by Martha Chase and Alfred Hershey proved that DNA is an organism's genetic material. The bacteriophage virus, which has a protein coat and nucleic acid that holds the genetic material, was used in the experiment. The bacteriophage targets bacteria like E. coli in its attacks. When a phage infects bacteria, it attaches to the cell's surface, injects its DNA inside the bacterial cell, and leaves the virus's protein coat outside the bacterial cell.

The explanation for the answer.

They did this by cultivating bacteriophages in two different media, one having radioactive sulphur (35 S), which is present in some amino acids and was used to label the bacteriophage's protein coat, and the other containing radioactive phosphorus, which was used to label the DNA core. They could then permit the infection of bacterial cells by these radiolabeled bacteriophages. After the daughter phage particles had multiplied within the bacterial cells, if radioactive phosphorus 32 P was discovered, it could be deduced that DNA is the genetic material conveyed; if radioactive sulphur was discovered, it could be deduced that protein is the genetic material communicated.