Question

I Q.9. (5 points) What result would Meselson and Stahl have obtained if the replication of DNA were conservative? Give the expected distribution of "heavy", "light" and "hybrid" DNA molecules after 1.0 and 2.0 generations for conservative replication.

please explain in details the answer

Answer 1

First, let's have a look at the experiment's semi-conservative nature, as the name suggests that during replication one template of DNA in newly formed strand would come from parents and another would be newly synthesized. The DNA strands formed in daughter cells are hybrid N₁₅N₁₄, as one strand has been synthesizes newly and one has come from parents.

In this case, if the replication is conservative then in the first generation (1.0), the parent strand will synthesize the new strands but newly synthesized DNA strands would be heavy only. Hence in this generation, only N₁₅N₁₅ will be observed only. Because of conservative nature, the N₁₄N₁₄ will remain in parents only, since the strands will not separate.

In generation 2.0 all the molecule will again be heavy only, N₁₅N₁₅, no hybrids will be detected in any of the generations.