The Hershey-Chase experiment used which system to show that DNA is the genetic material?

• A. Bacteriophages
• B. Bacteria
• C. Yeast
• D. Plant cells

Answer: (A)

Genetic material is the molecule that actually enters the host cell and directs the production of new viral particles. Hershey-Chase used bacteriophages because these viruses are simple systems that infect bacteria and deliver their genetic material into the bacterial cell, making it easy to track what gets inside.

In the experiment, the phage’s DNA was labeled with radioactive phosphorus, while the phage’s proteins were labeled with radioactive sulfur. After allowing infection, they used a method to separate the phage coats from the infected bacterial cells. The radioactivity ended up inside the bacterial cells only with the phosphorus label, meaning DNA entered the cells and directed the production of new phages. The sulfur-labeled proteins stayed with the outside coats and did not enter the cells. This clearly showed that DNA is the genetic material, not protein.

Other systems like bacteria, yeast, or plant cells aren’t used in this specific approach because they don’t provide the same clean, direct separation of genetic material from proteins during a straightforward infection and replication process.