Meselson - Stahl Experiment 1958

Alternative Modes of DNA replication:
Semiconservative, Conservative, & Dispersive

The Meselson-Stahl experiment used density gradient centrigugation to follow the behavior of newly-synthesized DNA strands. The experimental results are shown on the right, as they appear in the original 1958 paper.

Homework: The diagrams show the alternative "conservative" and "dispersive" models, and the actual results.
(1) Explain how the data support the semi-conservative model.
(2) At which timepoint is it possible to eliminate the alternative Conservative and Dispersive models of replication? Explain.