Question

A new bacterial life form is discovered on Mars. The Meselson and Stahl experimental protocol is used to determine the mode of DNA replication in this species. The bacteria is grown first in heavy nitrogen (15N) and then switched to 14N, and then centrifuged. It is discovered that DNA replicates via the conservative mode of replication in this species. What experimental results led to this conclusion?

Answer 1

After the centrifugation, you would find two fractions of DNA, one composed of DNA composed ONLY by 15N, and other one composed only by 14N. In the case of semiconservative DNA replication (the way it does on earth), you find DNA strands composed of both species of nitrogen, 14N and 15N.

Step-by-step explanation: