Suppose that some cells are grown in culture in the presence of radioactive nucleotides for many generations so that both strands of every DNA molecule include radioactive nucleotides. The cells are then harvested and placed in new Moderate with nucleotides that are not radioactive so that newly synthesized DNA will not be radioactive. What proportion of DNA molecules will contain radioactivity after two rounds of replication?
A) 0
B) 1/8
C) 1/4
D) 1/3
E) 1/2

Question

Quizplus · Accepted Answer

After two rounds of replication, each original radioactive DNA strand will have been used as a template twice, resulting in four DNA molecules, two of which will still contain one radioactive strand. Thus, 1/2 of the DNA molecules will contain radioactivity.

Suppose That Some Cells Are Grown in Culture in the Presence