What did Hershey and Chase demonstrate about the hereditary material in bacteriophages?

What did Hershey and Chase demonstrate about the hereditary material in bacteriophages?

• A. Proteins carry the hereditary information.
• B. RNA carries the hereditary information.
• C. DNA is the hereditary material in bacteriophages, not the protein coat.
• D. Carbohydrates carry hereditary information.

Answer: (C)

The key idea demonstrated is that DNA carries genetic information in bacteriophages. Hershey and Chase used two labeling strategies with the T2 phage: one set labeled the protein coat with radioactive sulfur and another set labeled the DNA with radioactive phosphorus. After allowing infection, they used a blender to separate the empty protein coats from the infected bacterial cells and then measured where the radioactivity ended up. The signal from the labeled DNA (phosphorus) was found inside the cells and in the progeny phages, while the signal from the labeled proteins (sulfur) remained with the outside protein coats and did not direct replication. This shows that the material responsible for heredity—what directs phage production inside the cell—is DNA, not the protein coat. The experiment provides no support for carbohydrates carrying information, and it did not show RNA as the hereditary material in this system.

The key idea demonstrated is that DNA carries genetic information in bacteriophages. Hershey and Chase used two labeling strategies with the T2 phage: one set labeled the protein coat with radioactive sulfur and another set labeled the DNA with radioactive phosphorus. After allowing infection, they used a blender to separate the empty protein coats from the infected bacterial cells and then measured where the radioactivity ended up. The signal from the labeled DNA (phosphorus) was found inside the cells and in the progeny phages, while the signal from the labeled proteins (sulfur) remained with the outside protein coats and did not direct replication. This shows that the material responsible for heredity—what directs phage production inside the cell—is DNA, not the protein coat. The experiment provides no support for carbohydrates carrying information, and it did not show RNA as the hereditary material in this system.