To determine whether DNA replication is semiconservative, conservative, or dispersive, Meselson and Stahl labeled E.coli DNA with a regimen of heavy nitrogen for one round of replication and then transferred these cells to a light nitrogen regimen for two more rounds of replication.Which statement would not have been true within the context of this experiment?
A) If DNA replication was conservative, no DNA molecules of intermediate density would have been seen.
B) If DNA replication was dispersive, only DNA molecules that were of intermediate density would have been seen.
C) If DNA replication was semiconservative, the DNA molecules that were made would all be heavy.
D) If DNA replication was semiconservative, the DNA molecules would consist of one parental strand base paired to one newly replicated strand.
E) If DNA replication was semiconservative, a higher proportion of DNA molecules from future divisions would have been light.

Question

Quizplus · Accepted Answer

If DNA replication was semiconservative, the DNA molecules that were made would all be heavy. This statement is not true within the context of the experiment because the cells were transferred to a light nitrogen regimen for two more rounds of replication, so the DNA molecules would have incorporated some light nitrogen and would not all be heavy. Therefore, this statement would not have been true within the context of the experiment.

To Determine Whether DNA Replication Is Semiconservative, Conservative, or Dispersive