Bacterial cells have only one DNA molecule, which is double stranded and is replicated in essentially the same f in eukaryotes. Imagine that, following the techniques of other scientists studying DNA, you created a bacterial ce contains only radioactive nitrogen in its DNA. You then place the cell in a culture medium containing only "regu (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

After four rounds of replication, 2 cells will contain some DNA with radioactive nitrogen. Initially, the single bacterial DNA molecule is fully radioactive. After the first replication, each daughter cell has one radioactive and one non-radioactive strand. In subsequent replications, the radioactive strand is passed on, but the new strand is non-radioactive. Thus, after four rounds, only 2 cells will have DNA with any radioactive nitrogen.

Bacterial Cells Have Only One DNA Molecule, Which Is Double