iGenetics 3rd Edition by Peter Russell

Exercise 5

Hershey and Chase showed that when phages were labeled witH₃2 P and 35 S, the 35 S remained outside the cell and could be removed without affecting the course of infection, whereas the 32 P entered the cell and could be recovered in progeny phages.
a. What distribution of isotopes would you expect to see if parental phages were labeled with isotopes of
i. C?
ii. N?
iii. H?
b. Based on your answer, explain why Hershey and Chase used isotopes of phosphorus and sulfur in their experiments.