試題詳解

28. Which of the following statements concerning the nitrogen excretion and the urea cycle in mammals is false?
(A) The reaction of the combination of ammonia with glutamate to form glutamine requires ATP. y-Glutamyl phosphate is an intermediate in the reaction.
(B) Glutamate is metabolically converted to a-ketoglutarate and by a process described as oxidative deamination.
(C) generated in liver mitochondria is immediately used, together with CO₂ (as ), to form carbamoyl phosphate. This reaction is catalyzed by carbamoyl phosphate synthetase I and requires ATP.
(D) The urea cycle causes a net conversion of oxaloacetate to malate.
(E) The pathways of the citric acid cycles and the urea cycles are interconnected, and the pathway interconnections decrease the energetic cost of urea synthesis.