Describe the Meselson-Stahl experiment (7)

2 radioactive isotopes of N were used during replication (15N and 14N) DNA molecules were first incorporated with 15N and then replicated in the presence of the 14N (nitrogen makes up DNA and can be either 15N or 14N) DNA samples were separated to see the composition of DNA in replicated molecules 1st division: DNA molecules had both 15N and 14N = disproves conservative 2nd division: Some molecules only had 14N = disproves dispersive = supports the semi conservative model