Nucleic Acids and the Genetic Material Problem Set 1

Problem 6: Meselson-Stahl DNA replication experiment

In the Meselson-Stahl DNA replication experiment, if the cells were first grown for many generations in 15N containing media, and then switched to 14N containing media, what percent of the DNA had 1 light strand and 1 heavy strand after 2 generations of growth in 15N growth media?
A 0

B 25

C 50

After one generation in light 14N, all DNAs would be intermediate density. A second generation of semiconservative replication would leave half the DNAs as intermediate density and half as light density.

D 75

E 100

The Biology Project
University of Arizona
Thursday, October 3, 1996
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