If 14C-labeled uracil is added to the growth medium of cells, what macromolecules will be labeled?
A) phospholipids
B) DNA
C) RNA
D) both DNA and RNA
E) proteins

Question

Quizplus · Accepted Answer

Uracil is a nitrogenous base that is found in RNA, but not in DNA. Therefore, if 14C-labeled uracil is added to the growth medium of cells, it will label RNA. However, since RNA is involved in the synthesis of DNA, the labeled uracil may also be incorporated into newly synthesized DNA, depending on the stage of the cell cycle. Therefore, both RNA and DNA can potentially be labeled with 14C-labeled uracil. The other options (A, B, and E) are incorrect, as they do not contain uracil or are not synthesized using uracil.

If 14C-Labeled Uracil Is Added to the Growth Medium of Cells