If cells are grown in a medium containing radioactive ¹⁵N, which of these molecules will be labelled?
A)fatty acids only
B)nucleic acids only
C)proteins only
D)amylase only
E)both proteins and nucleic acids

Question

Quizplus · Accepted Answer

¹⁵N is a heavy and stable isotope of nitrogen. It will be incorporated into any molecule that contains nitrogen during biosynthesis, including proteins and nucleic acids. Fatty acids and amylase, on the other hand, do not contain nitrogen, so they would not be labeled in the presence of ¹⁵N. Therefore, the best choice is E, both proteins and nucleic acids, as they are the only macromolecules that contain nitrogen and will be labeled when grown in a medium containing ¹⁵N.

If Cells Are Grown in a Medium Containing Radioactive ¹⁵N