Bacterial cells have only one DNA molecule, which is double stranded and is replicated in essentially the same fashion as in eukaryotes. Imagine that, following the techniques of other scientists studying DNA, you created a bacterial cell that contains only radioactive nitrogen in its DNA. You then place the cell in a culture medium containing only "regular" (nonradioactive)nitrogen, Based on this scenario and your knowledge of DNA structure and replication, how many cells will contain some DNA with radioactive nitrogen after four rounds of cell replication?

Question

Quizplus · Accepted Answer

During the first round of replication, all of the DNA in the bacterial cell would contain radioactive nitrogen. However, as the cell divides, each daughter cell will receive only half of the radioactive DNA. In the second round of replication, only half of the DNA in each daughter cell will contain radioactive nitrogen. The same pattern will continue in subsequent rounds of replication. Therefore, after four rounds of replication, there will be two cells with some radioactive nitrogen in their DNA, while the other two cells will have nonradioactive DNA.

Bacterial Cells Have Only One DNA Molecule, Which Is Double