Concept explainers
(a)
Interpretation: To identify whether carbon monoxide is encountered in the (1) urea cycle, (2) heme degradation process, or (3) oxidative deamination reaction.
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.
Heme potion of hemoglobin undergoes a stepwise degradation to biliverdin, to bilirubin, and then to bile pigments that are excreted from the body.
A biochemical reaction in which an
(b)
Interpretation: To identify whether stercobilin is encountered in the (1) urea cycle, (2) heme degradation process, or (3) oxidative deamination reaction.
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.
Heme potion of hemoglobin undergoes a stepwise degradation to biliverdin, to bilirubin, and then to bile pigments that are excreted from the body.
A biochemical reaction in which an
(c)
Interpretation: To identify whether biliverdin is encountered in the (1) urea cycle, (2) heme degradation process, or (3) oxidative deamination reaction.
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.
Heme potion of hemoglobin undergoes a stepwise degradation to biliverdin, to bilirubin, and then to bile pigments that are excreted from the body.
A biochemical reaction in which an
(d)
Interpretation: To identify whether ornithine is encountered in the (1) urea cycle, (2) heme degradation process, or (3) oxidative deamination reaction.
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.
Heme potion of hemoglobin undergoes a stepwise degradation to biliverdin, to bilirubin, and then to bile pigments that are excreted from the body.
A biochemical reaction in which an
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General, Organic, and Biological Chemistry
- Why is the Urea cycle important in protein catabolism? A. Urea transports amino acids to the liver. B. Urea synthesis prevents ammonium toxicity C. Urea is unstable and rapidly metabolized by the liver. D. Urea is a source of amino acidsarrow_forwardWhich of the following statements regarding the urea cycle is true? (A) Fumarate acts as a connecting link between urea cycle and the CAC.(B) The urea cycle occurs solely in the mitochondria.(C) Citrulline and arginine reacts to form argininosuccinate.(D) Ornithine formed in the last reaction of the urea cycle is excreted from the body along with urea.(E) The purpose of the urea cycle is to produce energy (4 ATP per ammonia that enters) for the liver.arrow_forwardDefine the following terms: a. ketogenic amino acid b. glucogenic amino acid c. L-amino acid oxidase d. Krebs urea cycle e. CPSIarrow_forward
- Urea synthesis begins with the formation of _____________.arrow_forwardA. List all the materials required for beta-oxidation of fatty acids. How does this process differ from the Biosynthesis of fatty acids? B. Outline the pathway involved in the synthesis of cholesterol from six-carbon intermediate Mevalonate. C. Describe all the stages involved in the urea cycle (Transmination, Ammonia Transport, and stages of the urea cycle).arrow_forwardWhat enzyme catalyzes the committed reaction of the urea cycle? carbamoyl phosphate synthetase II carbamoyl phosphate dehydrogenase I carbamoyl phosphate synthetase I carboxyphosphate synthetase II carboxyphosphate synthetase Iarrow_forward
- Why can’t humans simply excrete waste nitrogen atoms asammonia rather than utilize the energetically expensive process of urea synthesis?arrow_forwardThe immediate donors of the nitrogen atoms of urea are: a. Aspartate and glutamate b. Glutamate and carbamoyl phosphate c. Aspartate and carbamoyl phosphate d. Glutamine and aspartatearrow_forwardWhat is the source of carbon in the formation of urea?arrow_forward
- Which amino acids in the urea cycle are the links to thecitric acid cycle? Show how these links occurarrow_forwardIf 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.arrow_forwardWhy is diethyl urea not hydrolyzed by urease?arrow_forward