Question

For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to radioactively label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogen atoms. Thus, labeling the nitrogen atoms would provide a stronger signal than labeling the phosphates. Why won't this experiment work?

A. Radioactive nitrogen has a half-life of 100,000 years, and the material would be too dangerous for too long.
B. There is no radioactive isotope of nitrogen.
C. Although there are more nitrogens in a nucleotide, labeled phosphates actually have 16 extra neutrons; therefore, they are more radioactive.
D. Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.

Answer 1

B. There is no radioactive isotope of nitrogen.

Step-by-step explanation:

It is not all isotopes of elements that are radioactive. Nitrogen-14 and Nitrogen-15 are stable. They are not radioactive. Therefore, they cannot be detected the way Phosphorus-32 will be detected.