Meselson and Stahl designed an experiment that would allow them to discern whether DNA replication occurs in a dispersive, semiconservative, or conservative manner. They started with E. coli that had been growing for many generations in medium containing 15N. They then transferred the bacteria into medium containing only 14N, and allowed the bacteria to undergo two rounds of DNA replication. After each round of replication, the scientists performed density-gradient centrifugation of the DNA. The scientists reasoned that each of the three models would predict different DNA banding patterns after the two rounds of replication. Can you identify the banding patterns predicted by each model after the first round of replication

Question

Moshe Houston

Biology

6 April, 06:41

Meselson and Stahl designed an experiment that would allow them to discern whether DNA replication occurs in a dispersive, semiconservative, or conservative manner. They started with E. coli that had been growing for many generations in medium containing 15N. They then transferred the bacteria into medium containing only 14N, and allowed the bacteria to undergo two rounds of DNA replication. After each round of replication, the scientists performed density-gradient centrifugation of the DNA. The scientists reasoned that each of the three models would predict different DNA banding patterns after the two rounds of replication. Can you identify the banding patterns predicted by each model after the first round of replication

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Riley Roberts · Answer 1

Meselson and Stahl performed the experiment on the E. coli bacteria to study how the DNA molecule separates by studying the density centrifuge technique.

They predicted that the DNA replicates in one of the manner: conservative, semi-conservative and dispersive.

After the first round of replication, he observed only one band which showed the density above the heavy band. This means that the 14 N (light isotope) now has been incorporated in the DNA which shows that the DNA divides wither by dispersive way or semi-conservative way.

In generation two, two bands were formed which showed that out of these two ways, DNA divides by the semi-conservative mode.