Two students decided to repeat the Hershey and Chase experiment, with modifications. Like Hershey and Chase they used radioactive sulfur but they substituted radioactive nitrogen for radioactive 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. Which of the following is the biggest shortcoming in their experimental design?
A) There is no radioactive isotope of nitrogen.
B) Radioactive nitrogen has a half-life of 100,000 years, therefore, the material would be too dangerous for too long.
C) The signal from the nucleotide would be so strong that it would overwhelm the signal from sulfur.
D) The radioactivity would not distinguish between DNA and proteins because proteins contain nitrogen.

Question

Quizplus · Accepted Answer

The biggest shortcoming in their experimental design is that the radioactivity would not distinguish between DNA and proteins because both contain nitrogen, making it impossible to determine if the genetic material is DNA or protein based on the radioactive signal.

Two Students Decided to Repeat the Hershey and Chase Experiment