Classic Experiment—Hershey–Chase Conclusion What overall conclusion emerged from the Hershey–Chase bacteriophage experiment using 32P and 35S labeling?

Introduction / Context:The Hershey–Chase experiment (1952) used T2 bacteriophages labeled with radioactive isotopes to determine whether DNA or protein is the genetic material. This landmark study complemented Avery–MacLeod–McCarty’s work and helped establish DNA as the carrier of hereditary information.

Given Data / Assumptions:

• Phage protein shells were labeled with 35S (sulfur in methionine/cysteine).
• Phage DNA was labeled with 32P (phosphate in nucleotides).
• After infection and blender treatment, radioactivity was tracked between pellet (cells) and supernatant (ghosts).

Concept / Approach:If DNA is genetic, it should enter bacteria and be found in progeny phage. If protein is genetic, labeled protein should enter cells. Observations showed 32P (DNA) inside cells and in progeny, while 35S (protein) largely remained with phage coats outside the cells.

Step-by-Step Solution:

Verification / Alternative check:Progeny phage produced from infected bacteria carried 32P labeling, confirming DNA transmission across generations.

Why Other Options Are Wrong:

• Proteins as genetic material: contradicted by labeling results.
• A=T ratio statement: Chargaff’s rule, not the experiment’s main conclusion.
• “Phage DNA identical to bacterial DNA”: not the question addressed.
• Protein entering while DNA stays outside: opposite of observed outcome.

Common Pitfalls:Confusing the roles of 32P and 35S; misinterpreting pellet vs supernatant radioactivity.

Final Answer:DNA was responsible for heredity