Question

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3. Formation of carbamoyl phosphate and the subsequent urea cycle cost a lot of ATP. How does the cell use amino acid metabolism to pay back this cost? (4 pts) 4. Adding one-carbon groups to organic molecules can be done in several ways, including by carboxylase-catalyzed reactions. What are three one-carbon donors, including coenzymes, that can be used to do this? (6 pts)

Answer 1

3. Ans- Cell used amino acid metabolism to pay back this cost that generates glutamate and alanine followed by oxidative deamination to form NADPH which is converted to ATP. Amino acid metabolism gives preferably glutamine and asparagine which intestine oxidizes glutamine and the amine group is separated and incorporated into urea and as well as carbon skeleton that is oxidized to CO2 and H2O that later on used for gluconeogenesis and ketogenesis. Glutaminase and glutamate used for synthesis for carbomyl phosphate followed by formation of glutamine. In muscles amino groups are transferred to pyruvate to form alanine so they act as a carriers of amines from other cells and as a results it shows that glutamine is the second important energy source that produces abundant ATP to pay back this cost.

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