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MESELSON AND STHAL EXPERIMENT

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Meselson and Stahl’s Experiment

Meselson and Stahl’s Experiment was an experimental proof for semiconservative DNA replication. In 1958, Matthew Meselson and Franklin Stahl conducted an experiment on E.coli which divides in 20 minutes, to study the replication of DNA.

Experiment

15N (heavy) and 14N (normal) are two isotopes of nitrogen which can be distinguished based on their densities by centrifugation in cesium chloride (CsCl). Meselson and Stahl cultured E.coli in a medium constituting 15NH4Cl over many generations. As a result, 15N was integrated into the bacterial DNA. Later, they revised the 15NH4Cl medium to normal 14NH4Cl. At a regular interval of time, they took the sample and checked for the density of DNA.

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