What do you mean semi-conservative nature of DNA replication? Who proved it & how?
The semiconservative nature of DNA replication suggested that during replication two strands would separate & each acts as a template for the synthesis of a new complementary strand so, that after complete replication, each DNA molecule would have one parental & one newly synthesized strand thus, half the information is conserved over a generation. Mathew Messselson& Franklin Stahl have performed an experiment using Escherichia coli to prove that DNA replication is semiconservative. They grew E.coli in a medium containing 15NH4Cl until 15N was incorporated in the two strands of newly synthesized DNA this heavy DNA can be separated from normal DNA lay centrifugation in CsCl density gradient. Then they transferred the cells into a medium with normal X14NH4Cl & took samples at various time intervals & extracted DNA & centrifuged them to measure their densities. The DNA is extracted from the cells after one generation to transfer from X15N medium to X14N
