A NASA probe returned samples of rocks from the surface of Mars. From these rocks, a prokaryotic organism was isolated and remained viable under conditions similar to that of Mars. The organisms are capable of dividing to replicate themselves. An experiment was performed to determine whether the DNA replication of these organisms was semi- conservative using N15/N14 , similar to that of Mendelson and Stahl. If the method of DNA replication were conservative, after one generation one would expect to see
A)all of the DNA in the light (N14)band.
B)all of the DNA in the heavy (N15)band.
C)half of the DNA in the light band, the other half in the heavy band.
D)all of the DNA at a point midway between the heavy and light bands.
E)none of the above

Question

Quizplus · Accepted Answer

In conservative replication, the original DNA molecule remains intact, and a completely new copy is made. After one generation, you would expect to see half of the DNA in the light band (new DNA) and the other half in the heavy band (original DNA).

A NASA Probe Returned Samples of Rocks from the Surface