HYPOTHESIZED MODELS OF DNA REPLICATION

Meselson and Stahl cultured bacteria on heavy-nitrogen (¹⁵N), transferred the same bacteria to light-nitrogen (¹⁴N) and centrifuged half after 20 and half 40 minutes (see below chart) to isolate the DNA for inspection.

Based on these principles light DNA will rise, heavy DNA will sink, moderate DNA will be in the middle.

Time	Conservative model	Semi-conservative model	Dispersive model
After 20 minutes
After 40 minutes

Next:  "DNA Replication."