試題詳解

23. Which of the following description purine and pyrimidine de novo synthesis INCORRECT?
(A) The initial reaction of purine biosynthesis is forming phosphoribosyl pyrophosphate (PRPP).
(B) Both adenosine monophosphate (AMP) and guanosine monophosphate (GMP) can be derived from inosine monophosphate (IMP).
(C) The so-called orotate pathway of pyrimidine de novo synthesis involves using PRPP serves as a scaffold for the subsequent assembly of the pyrimidine ring to form uridine 5'-monophosphate (UMP).
(D) Thymidylate synthase is the sole enzyme responsible for de novo biosynthesis of thymidine monophosphate (TMP).
(E) Cross-regulation exists between purine and pyrimidine biosynthesis, suggesting coordinated control of their biosynthesis.