Question

How was ATP utilized in urea cycle?

• A. 3 ATP $\to$ 2 ADP + 1 AMP
• B. 2 ATP+ 1 AMP $\to$ 1 ATP + 2 ADP
• C. 2 ATP $\to$ 1 ADP + 1 AMP
• D. 1 ATP $\to$ 1 ADP

Answer 1

Answer: (A)

3 ATP $\to$ 2 ADP + 1 AMP

• Urea synthesis is a five-step cyclic process, with five distinctive enzymes. The first step of the urea cycle utilizes 2 ATP which is converted to 2ADP +2 PPi for the formation of carbamoyl phosphate and the third step utilizes 1 ATP which is converted into AMP+PPi for the formation of arginosuccinate. Therefore the urea cycle utilizes 3 ATP → 2 ADP + 1 AMP.

So, the correct answer is option A'.