Who demonstrated the semi conservative replication of DNA?
Explain the experiment in detail. Ans30.Meselson and Stahl showed that the DNA replication is semiconservative, that is after the replication one of the DNA strands is of daughter generation and the other is of parental generation. They grew Escherichia coli in a medium containing nitrogen salts labelled with stable, heavy isotope 15N. 15N got incorporated into both strands of DNA and this DNA was heavier than the DNA obtained from E. coli grown in 14N medium. The heavier DNA could be separated from the lighter by centrifugation. E.Coli cells grown in 15N medium were transferred to 14N medium and the DNA was isolated after one generation-time when one bacterial cell has divided into two. This DNA had its density intermediate between that of 15N DNA and 14DNA. This was because, during one generation, new DNA molecules with parental 15N strand and a complementary 14N new strand were formed and this had an intermediate density between the DNA having 15N in both the strands and the DNA hav