Purines and pyrimidines are:

A. Dietary essential
B. Dietary nonessential
C. Derived from essential fatty acids
Derivatives of essential amino acid

Which statement for purine biosynthesis is incorrect?

A. Requires vitamin B12
B. Assembled on ribose phosphate
C. Requires PRPP
D. Requires glycine

Nitrogen or carbon atoms are contributed to the structure of the purine ring by amino acids, except:

A. Glycine
B. Glutamine
C. Aspartate
D. Glutamate

Lesch-Nyhan syndrome may lead to:

A. Self-destructive behavior
B. Gout
C. Elevated levels of PRPP
D. All of the above

Lesch-Nyhan syndrome is due to the lack of:

A. HGPRTase
B. APRTase
C. Adenosine deaminase
D. PRPP amidotransferase

( )是嘌呤核苷酸从头合成的限速酶。在IMP转变为AMP的反应中，消耗( )；而在IMP转变为GMP的反应中，消耗( )。这样的好处是( )。

哺乳动物嘧啶核苷酸从头合成的限速酶是( )，其反馈抑制剂是( )，别构激活剂是( )。

嘌呤核苷酸在人体内分解的终产物是( )，通风是关节和肾脏中该终产物晶体的积聚引起的。治疗痛风的特效药是别嘌呤醇，其为( )的一种自杀性底物。

Asp、Gln和CO2是嘌呤核苷酸和嘧啶核苷酸从头合成的共同前体。

A. 对
B. 错