Question

Meselson and Stahl cultured E. coli for several generations in a medium with a heavy isotope of nitrogen, 15N. They transferred the bacteria to a medium with a light isotope of nitrogen, 14 N. After two rounds of DNA replication, half the DNA molecules were light (both strands had 14N) and half were hybrids (15N-14N). What did the researchers conclude from these results?A. The nitrogenous bases in DNA molecules incorporate both 15N and 14N.B. DNA replication is semiconservative.C. Opposite DNA strands are complementary to each other.

Answer 1

The correct answer is B. DNA replication is semiconservative.

Step-by-step explanation:

With this experiment, Messelson and Stahl determined that there was a pattern in replication that left one original strand and added a new one in each case. Therefore, after two rounds, there will be two copies with "original" information exclusively and two copies with mixed strands or hybrids.