The de novo biosynthesis of which of the following nucleotides would be the LEAST inhibited by methotrexate?

Question

Quizplus · Accepted Answer

Methotrexate inhibits the enzyme dihydrofolate reductase, which catalyzes the conversion of dihydrofolate to tetrahydrofolate. This reaction is necessary for the biosynthesis of thymidine monophosphate (dTMP), which is derived from deoxyuridine monophosphate (dUMP). Therefore, the de novo biosynthesis of dTMP would be most inhibited by methotrexate. On the other hand, the biosynthesis of UMP is not directly affected by methotrexate, as UMP does not require tetrahydrofolate as a precursor. Therefore, UMP would be the least inhibited by methotrexate.

The De Novo Biosynthesis of Which of the Following Nucleotides