Question: Meselson And Stahl Experiment This classic experiment demonstrated that DNA replicated in a semi-…

Meselson And Stahl Experiment
This classic experiment demonstrated that DNA replicated in a
semi-conservative mode. The key to understanding this experiment is
to compare predicted results for each mode of replication with what
is actually seen in the experiment.
A. Diagram predicted results for each of the 3 possible modes of
replication, from time 0 through generation 3. Use 2 vertical lines
to represent a DNA molecule, and have 1 color for “heavy” DNA
chains and another color for “light” DNA chains.
B. Next, show how these predicted scenarios would have actually
looked in the density gradient centrifugation tubes of the expt.
For each of the hypothetical modes of replication, draw a tube for
each generation, using horizontal lines to indicate relative
locations in the tube where the DNA would be expected to
settle.
C. Explain why Meselson & Stahl needed to run the experiment
for 3 generations of DNA replication.