What is meant by semi-conservative replication? How did Meselson and Stahl prove it experimentally?
An experiment was performed by Meselson and Stahl using E.coli to prove that DNA replication is semi-conservative in nature. They grew E.coli in a medium. Then heavy DNA was separated from normal (14N) by centrifugation in CsCl density gradient. The DNA extracted, after one generation of transfer from 15N medium to 14N medium, had an intermediate density. The extracted DNA, after two generations, consisted of equal amounts of light and hybrid DNA. Thus, it was proved that DNA replicates in a semiconservative manner.
