Question

Threonine is converted to succinyl CoA through a process that produces 1 molecule of ammonia and 1 NADH while requiring 1 ATP. Consider that the resulting succinyl CoA can use a portion of the citric acid cycle to be converted to oxaloacetate. 1. (2 points) How many molecules of threonine would be required to produce one molecule of glucose? 2. (6 points) What is the net consumption or production of NADH, FADH2, and ATP for the synthesis of one molecule of glucose? 3. (4 points) Considering that the nitrogen generated by conversion of threonine to succinyl CoA needs to be eliminated as urea, how would the two sources of nitrogen, carbamoyl phosphate and Asp, be produced? 4. (4 points) What would be the net consumption or production of NADH, FADH2, and ATP for the production of urea considering that the carbon from Asp needs to be recycled? 5. (6 points) Based upon your overall calculations, what is the net consumption or production of NADH, FADH2, and ATP? If any excess NADH or FADH2 can be converted to ATP via oxidative phosphorylation, what is the net consumption or production of ATP, considering the typical limitations of the mitochondria?

Answer 1

1) Succinyl CoA through CAC creates OXALOACETATE.

Through the gluconeogenesis cycle OAA (4C) can be decarboxylated to give PEP (3C) (phosphoenolpyruvate) by PEPCK. This PEP can follow the reverse steps to make glucose (6C). Hence two molecules of OAA can give one molecule of Glucose.

So we will need one molecule of two molecules of threonine for one molecule of glucose.