During an experiment performed by Meselson and Stahl to study DNA replication, bacteria were grown in a medium containing N15. The N15 is a

During an experiment performed by Meselson and Stahl to study DNA replication, bacteria were grown in a medium containing N15. The N15 is a heavy isotope. Unlike a radioactive isotope that is very unstable, a heavy isotope more neutrons than in the normal isotope. Nitrogen 14 (N14) is the common form and Nitrogen 15 (N15) is the heavy isotope.