Hershey-Chase experiment successfully proved DNA to be genetic material. The correct sequence of steps followed in this experiment is

Options

A. Blending, Infection, Centrifugation
B. Centrifugation, Infection, Blending
C. Infection, Centrifugation, Blending
D. Infection, Blending, Centrifugation.

Answer

### Step-by-Step Solution:

1. **Infection of Bacteria**: The Hershey-Chase experiment began with the infection of bacterial cells using a bacteriophage (a virus that infects bacteria). The bacteriophage was labeled with radioactive phosphorus to trace the DNA and sulfur to trace the protein coat.

2. **Blending**: After the bacteriophage had infected the bacterial cells, the mixture was blended. This step was crucial as it helped to separate the viral protein coat from the bacterial cells, allowing for the analysis of what had entered the bacterial cells.

3. **Centrifugation**: The blended mixture was then subjected to centrifugation. This process separated the heavier bacterial cells from the lighter viral protein coats. The bacterial cells formed a pellet at the bottom of the centrifuge tube, while the viral protein coats remained in the supernatant.

4. **Analysis of Radioactivity**: Finally, the radioactivity of both the pellet (bacterial cells) and the supernatant (viral protein coats) was measured. The results showed that only the bacterial cells contained radioactive phosphorus, indicating that DNA had entered the bacterial cells, while the protein coat remained outside. This demonstrated that DNA, not protein, is the genetic material.

### Final Sequence:
1. Infection of bacteria with labeled bacteriophage.
2. Blending to separate the viral protein coat from the bacterial cells.
3. Centrifugation to separate the bacterial cells from the viral protein coats.
4. Analysis of radioactivity to determine the genetic material.