The proof for semiconservative mode of DNA replication was first provided by

Options

A. Watson and Crick
B. George Gamow
C. Matthew Meselson and Franklin Stahl
D. Hershey and Chase

Explanation

To answer the question about who first provided proof for the semiconservative mode of DNA replication, we can follow these steps:

1. **Understand the Concept**: The semiconservative model of DNA replication suggests that each strand of the original DNA molecule serves as a template for the formation of a new complementary strand. This means that when DNA replicates, each new double helix consists of one old (parental) strand and one newly synthesized strand.

2. **Identify Key Experiments**: The question asks for the scientist(s) who first provided proof for this model. Historical context is important here. The semiconservative model was proposed by Watson and Crick based on the structure of DNA, but they did not conduct the experiments to prove it.

3. **Focus on the Correct Scientists**: The correct answer to the question is Matthew Meselson and Franklin Stahl. They conducted a pivotal experiment in 1958 using E. coli bacteria to demonstrate that DNA replication is semiconservative. They used isotopes of nitrogen to label the DNA and analyzed the results through density gradient centrifugation.

4. **Eliminate Other Options**:
- Watson and Crick proposed the double helix structure of DNA but did not provide experimental proof for the semiconservative replication.
- George Gamow was a physicist known for his work in cosmology and did not contribute to DNA replication studies.
- Hershey and Chase conducted experiments that demonstrated that DNA is the genetic material, but they did not focus on the mechanism of DNA replication.

5. **Conclude**: Therefore, the first proof for the semiconservative mode of DNA replication was provided by Matthew Meselson and Franklin Stahl.

**Final Answer**: Matthew Meselson and Franklin Stahl.

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