Question

The experiments of Meselson and Stahl began with bacteria with 15N DNA that were then grown for one generation in 14N. The DNA produced after one round of replication was analyzed by gradient centrifugation, and produced a single band. This band

(A) Was half 15N, half 14N
(B) Eliminated the conservative model of DNA replication
(C) Did not distinguish between semiconservative and dispersive replication
(D) All of the above

Answer 1

Meselson and Stahl's experiment involved growing bacteria with 15N-labeled DNA in 14N medium for one generation and analyzing the DNA produced through gradient centrifugation. The observed single band eliminated the conservative model of DNA replication and did not distinguish between the semiconservative and dispersive models.

Step-by-step explanation:

Meselson and Stahl's experiment involved growing bacteria with 15N-labeled DNA in 14N medium for one generation. After analyzing the DNA produced through gradient centrifugation, they observed a single band that was intermediate in density between the 15N and 14N levels. This result eliminated the conservative model of DNA replication and did not distinguish between the semiconservative and dispersive models. Therefore, the answer is (C) Did not distinguish between semiconservative and dispersive replication.