The classic experiments conducted by Meselson and Stahl used isotopes of which element to distinguish newly synthesized DNA from parental DNA?

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Quizplus · Accepted Answer

Meselson and Stahl used isotopes of nitrogen to distinguish newly synthesized DNA from parental DNA. Specifically, they used the heavy isotope nitrogen-15, which is less abundant than the more common isotope nitrogen-14. By growing bacteria in a medium containing only nitrogen-15, they were able to ensure that all of the bacteria's DNA would contain nitrogen-15. They then transferred the bacteria to a medium containing only nitrogen-14, and allowed them to replicate their DNA. By analyzing the density of the resulting DNA using centrifugation, they were able to distinguish the newly synthesized DNA (which contained a mix of nitrogen-14 and nitrogen-15) from the parental DNA (which contained only nitrogen-15).

The Classic Experiments Conducted by Meselson and Stahl Used Isotopes