For living organisms and for most viruses genome replication

For living organisms and for most viruses, genome replication is semiconservative. If you allowed replication to occur with radioactive nucleotides, it would allow you to distinguish the old strands (not radioactive) from the new strands (radioactive). Which pattern would you expect to see after a single round of replication if DNA genome replication were conservative instead of semiconservative?

a. None of the DNA molecules would contain radioactive nucleotides.

b. Some DNA molecules (the new molecules) would contain only radioactive nucleotides while the old strands would have no radioactive nucleotides.

c. All of the DNA molecules would contain radioactive nucleotides.

d. All of the DNA molecules would have one radioactive strand and one non-radioactive strand.

Solution

In conservative method of DNA replicaiton, the parental DNA strand directs synthesis of new double stranded molecule and after one round of replication, one parental molecule and one new DNA molecule exist.

So the new molecules would contain only radioactive nucleotides while the old strands would have no radioactive nucleotides.