Concept explainers
Interpretation: To determine the two molecules involved in the connecting link from the citric acid cycle to the urea cycle.
Concept introduction: A urea cycle is a cyclic biochemical pathway that involves the production of urea using ammonium ions and aspartate molecules as nitrogen sources. The desired product of the urea cycle is urea. It constitutes 4 steps. In step 1 carbamoyl phosphate transfers its carbamoyl group to ornithine to produce citrulline. Citrulline then condenses with aspartate in the second step to form argininosuccinate which then cleaves in the third step to form arginine and fumarate. In the final step, arginine reacts with water to produce urea.
The citric acid cycle is a series of eight
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- If aspartate is labeled with deuterium D (= H-2 = 12H), answer questions a-c to determine where the label will end up in oxaloacetate after the involvement of aspartate in the urea cycle. Where does the label end up in arginosuccinate? Where is the label in fumarate? Where is the label in oxaloacetate?arrow_forwardIncluding the carbamoyl phosphate synthetase step (CPS I) and the four steps of the urea cycle, how many ATP equivalents (phosphoanhydride bonds) are utilized to drive the formation of one urea molecule?arrow_forwardDescribe the Krebs bicycle. What compound links the citric acid and urea cycles?arrow_forward
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