Question

Which scientist experimentally demonstrated that DNA replication is semiconservative in nature using \(^ {15}N\) and \(^ {14}N\) isotopes?

• A. Watson and Crick
• B. Meselson and Stahl
• C. Hershey and Chase
• D. Griffith

Hint:

Meselson and Stahl experiment is called: \[ \boxed{\text{The most beautiful experiment in biology}} \] It proved semiconservative DNA replication using nitrogen isotopes.

Answer 1

The Correct Option is B

Concept: Semiconservative replication means:
• each daughter DNA molecule contains
• one parental strand
• one newly synthesized strand This was experimentally verified by Meselson and Stahl.

Step 1: Understanding the experiment. Meselson and Stahl grew E.coli in medium containing: \[ ^{15}N \] which produced heavy DNA. The bacteria were then shifted to: \[ ^{14}N \] medium.

Step 2: Observation after generations. After one generation:
• intermediate density DNA was obtained After second generation:
• one light band
• one intermediate band These observations supported semiconservative replication. Final Answer: \[ \boxed{(B)\ \text{Meselson and Stahl}} \]