Question 1

Name four amino acids that can be converted directly (in one step)into pyruvate or a citric acid cycle intermediate,and name the intermediate formed from each.

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Question 2

Suppose you are responsible for formulating the diet for a 4-year-old boy with phenylketonuria.How do you decide what kind and amount of protein to include in the diet?

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Question 3

Explain why one might provide high concentrations of the amino acid Arg to patients who have a deficiency in one of the first three enzymes of the urea cycle.

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Question 4

Diagram the degradative pathway from proline to an intermediate of either glycolysis or the citric acid cycle.Show structures of intermediates and indicate where cofactors are involved.

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Question 5

Degradation of amino acids yields compounds that are common intermediates in the major metabolic pathways.Explain the distinction between glucogenic and ketogenic amino acids in terms of their metabolic fates.

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Question 6

Describe (a)the fundamental nutritional problem faced by individuals with genetic defects in enzymes involved in urea formation and (b)two approaches to treatment of these diseases.

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Question 7

Name one amino acid whose oxidation proceeds via the intermediate shown: (a)pyruvate; (b)oxaloacetate; (c)$\alpha$-ketoglutarate; (d)succinyl-CoA; (e)fumarate.

Accepted Answer

The question asks to name one amino acid whose oxidation results in the formation of each of the listed intermediates in the metabolic pathway. Here are the amino acids that correspond to each intermediate:
(a) Pyruvate: Alanine is an amino acid that can be directly converted into pyruvate through a transamination reaction. The enzyme alanine aminotransferase (ALT) catalyzes this reaction, where the amino group from alanine is transferred to $\alpha$-ketoglutarate to form pyruvate and glutamate.
(b) Oxaloacetate: Aspartate is an amino acid that can be converted into oxaloacetate. The enzyme aspartate aminotransferase (AST) catalyzes the transamination of aspartate and $\alpha$-ketoglutarate to oxaloacetate and glutamate.
(c) $\alpha$-Ketoglutarate: Glutamate is an amino acid that can be directly converted into $\alpha$-ketoglutarate by the enzyme glutamate dehydrogenase through oxidative deamination.
(d) Succinyl-CoA: Isoleucine, methionine, threonine, and valine are amino acids that can be catabolized to succinyl-CoA. For example, the catabolism of methionine involves several steps, including the conversion of homocysteine to cystathionine, then to $\alpha$-ketobutyrate, and eventually to succinyl-CoA.
(e) Fumarate: Phenylalanine and tyrosine are aromatic amino acids that can be catabolized into fumarate. The catabolic pathway involves several steps, including the conversion of phenylalanine to tyrosine (via phenylalanine hydroxylase), and then through a series of reactions, tyrosine is broken down into fumarate and acetoacetate.
Please note that the intermediate listed as "$\alpha$-ketoglutarate" seems to be a typographical error or a misprint. The correct intermediate is likely meant to be $\alpha$-ketoglutarate, as mentioned above.

Question 8

If you received a laboratory report showing the presence of a high concentration of phenylalanine and its metabolites in the urine of a patient,what disease would you suspect? What defect(s)in metabolism account(s)for the accumulation of phenylalanine in such patients?

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Quiz 18: Amino Acid Oxidation and the Production of Urea

Name four amino acids that can be converted directly (in one step)into pyruvate or a citric acid cycle intermediate,and name the intermediate formed from each.

Suppose you are responsible for formulating the diet for a 4-year-old boy with phenylketonuria.How do you decide what kind and amount of protein to include in the diet?

Explain why one might provide high concentrations of the amino acid Arg to patients who have a deficiency in one of the first three enzymes of the urea cycle.

Diagram the degradative pathway from proline to an intermediate of either glycolysis or the citric acid cycle.Show structures of intermediates and indicate where cofactors are involved.

Degradation of amino acids yields compounds that are common intermediates in the major metabolic pathways.Explain the distinction between glucogenic and ketogenic amino acids in terms of their metabolic fates.

Describe (a)the fundamental nutritional problem faced by individuals with genetic defects in enzymes involved in urea formation and (b)two approaches to treatment of these diseases.

Name one amino acid whose oxidation proceeds via the intermediate shown: (a)pyruvate; (b)oxaloacetate; (c) $\alpha$ -ketoglutarate; (d)succinyl-CoA; (e)fumarate.

If you received a laboratory report showing the presence of a high concentration of phenylalanine and its metabolites in the urine of a patient,what disease would you suspect? What defect(s)in metabolism account(s)for the accumulation of phenylalanine in such patients?

Quiz 18: Amino Acid Oxidation and the Production of Urea

Name four amino acids that can be converted directly (in one step)into pyruvate or a citric acid cycle intermediate,and name the intermediate formed from each.

Suppose you are responsible for formulating the diet for a 4-year-old boy with phenylketonuria.How do you decide what kind and amount of protein to include in the diet?

Explain why one might provide high concentrations of the amino acid Arg to patients who have a deficiency in one of the first three enzymes of the urea cycle.

Diagram the degradative pathway from proline to an intermediate of either glycolysis or the citric acid cycle.Show structures of intermediates and indicate where cofactors are involved.

Degradation of amino acids yields compounds that are common intermediates in the major metabolic pathways.Explain the distinction between glucogenic and ketogenic amino acids in terms of their metabolic fates.

Describe (a)the fundamental nutritional problem faced by individuals with genetic defects in enzymes involved in urea formation and (b)two approaches to treatment of these diseases.

Name one amino acid whose oxidation proceeds via the intermediate shown: (a)pyruvate; (b)oxaloacetate; (c) α\alphaα -ketoglutarate; (d)succinyl-CoA; (e)fumarate.

If you received a laboratory report showing the presence of a high concentration of phenylalanine and its metabolites in the urine of a patient,what disease would you suspect? What defect(s)in metabolism account(s)for the accumulation of phenylalanine in such patients?

Name one amino acid whose oxidation proceeds via the intermediate shown: (a)pyruvate; (b)oxaloacetate; (c) $\alpha$ -ketoglutarate; (d)succinyl-CoA; (e)fumarate.