Question

In Hershey and Chase experiment, some viruses grew on medium that contained:

• A. ³⁵S,³²P
• B. ³⁶S,³⁴P
• C. ³²S,³⁶P
• D. ³⁴S,³⁶P

Answer 1

The Correct Option is A

In the Hershey and Chase experiment, radioactive isotopes were used to label different components of the bacteriophage, a virus that infects bacteria. The two isotopes used were ³⁵S and ³²P. These isotopes were crucial in determining the nature of genetic material. 

• ³⁵S (Sulfur-35): This isotope was used to label proteins. Sulfur is found in the amino acids cysteine and methionine, which are components of proteins, but not in nucleic acids.
• ³²P (Phosphorus-32): This isotope was used to label DNA. Phosphorus is a key component of the phosphate backbone of nucleic acids, but not a constituent of amino acids and proteins.

The experiment involved growing bacteriophages in a medium that contained either ³⁵S or ³²P, allowing them to incorporate the radioactive isotopes into their structure.

When these radioactively-labeled bacteriophages infected bacteria, Hershey and Chase were able to demonstrate that phosphorus (associated with DNA) entered the bacterial cells while sulfur (associated with proteins) did not. This provided strong evidence that DNA, not protein, was the material responsible for heredity.

Answer 2

In the Hershey and Chase experiment (1952), the researchers used radioactively labeled isotopes to distinguish between the two components of a virus—its protein coat and its DNA. They grew viruses in mediums containing:

• 35S (Sulfur isotope) to label the protein coat of the virus because sulfur is present in proteins (specifically in methionine and cysteine).
• 32P (Phosphorus isotope) to label the DNA because phosphorus is found in DNA but not in proteins.

The experiment involved infecting bacteria with these labeled viruses and observing whether the DNA or protein entered the bacterial cells. This experiment provided strong evidence that DNA, not protein, is the genetic material that is transferred into bacterial cells during infection.