In the Meselson-Stahl experiment, the dispersive model of DNA replication was ruled out by which observation?
A) All of the DNA at the end of the second generation was of intermediate density.
B) All of the DNA at the end of the second generation was heavy.
C) There were three bands of DNA at the end of the second generation, all with different densities.
D) After two generations, half of the DNA was intermediate and half light.
E) After two generations, half of the DNA was intermediate and half heavy.

Question

Quizplus · Accepted Answer

The Meselson-Stahl experiment showed that after two generations of DNA replication in a medium with a lighter isotope of nitrogen, half of the DNA was of intermediate density (indicating one old and one new strand) and half was light (indicating two new strands). This observation supported the semi-conservative model of DNA replication and ruled out the dispersive model, which would have resulted in DNA molecules of uniform density.

In the Meselson-Stahl Experiment, the Dispersive Model of DNA Replication