The unequivocal proof that DNA is the genetic material came from the experiments of -

Options

A. Hershey and chases (1952)
B. Frederic Griffith (1928)
C. Watson and Crick
D. Meselson and Stal (1958)

Answer

To solve the question regarding the unequivocal proof that DNA is the genetic material, we will analyze the contributions of the scientists mentioned in the options provided.

### Step-by-Step Solution:

1. **Identify the Scientists and Their Contributions**:
- **Hershey and Chase**: Conducted experiments in 1952 using bacteriophages to demonstrate that DNA is the genetic material.
- **Frederick Griffith**: Known for his transformation experiments with Streptococcus pneumoniae, but he did not identify DNA as the genetic material.
- **Watson and Crick**: Proposed the double helical structure of DNA but did not conduct experiments to prove that DNA is the genetic material.
- **Meselson and Stahl**: Conducted experiments that demonstrated the semi-conservative replication of DNA but did not prove that DNA is the genetic material.

2. **Analyze Hershey and Chase's Experiment**:
- They used radioactive isotopes to label DNA and proteins in bacteriophages.
- After allowing the labeled bacteriophages to infect bacteria, they found that only the DNA entered the bacterial cells, not the protein.
- This provided strong evidence that DNA, not protein, is the genetic material responsible for heredity.

3. **Conclusion**:
- Based on the experiments and findings, the unequivocal proof that DNA is the genetic material came from the experiments of **Hershey and Chase**.

### Final Answer:
The unequivocal proof that DNA is the genetic material came from the experiments of **Hershey and Chase**.

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