Question 1

Which of the following statements about phenylalanine is(are) TRUE?

Accepted Answer

A)  The enzymatic degradation of phenylalanine requires the biopterin cofactor.
B)  Individuals with defects in phenylalanine catabolism require tyrosine in their diet.
C)  An inability to hydroxylate phenylalanine results in increased blood levels of phenylalanine,causing mental retardation.
D)  A and C
E)  A,B,and C

Question 2

Matching
Choose the correct answer from the list.Not all the answers will be used.

-_____ are involved in the nonselective degradation of proteins in well nourished cells.

Accepted Answer

A)   ribosomes
B)   jaundice
C)   channeling
D)   26S proteasome
E)   glutamine synthetaseF)  alanineG)  glutamateH)  vitamin B6I)  anammoxJ)  glutamine transferaseK)  THFL)  autotrophM)  vitamin DN)  lysosomesO)  diazotrophs

Question 3

Ketogenic amino acids can be converted to
(I) glucose
(II) fatty acids
(III) ketone bodies
(IV) pyruvate

Accepted Answer

A)  I,III
B)  II,IV
C)  I,II
D)  I,II,III
E)  I,IV

Question 4

Oxidative deamination of glutamate
(I) generates NAD(P) H and  α\alphaα -ketoglutarate.
(II) is inhibited by glutamate.
(III) is activated by GTP.
(IV) eliminates the keto group from  α\alphaα -ketoacids.

Accepted Answer

A)  I only
B)  I,II
C)  I,III
D)  II,IV
E)  III,IV

Question 5

Which of the following glycolytic intermediates is the common precursor to serine,cysteine,and glycine?

Accepted Answer

A)  fructose-6-phosphate
B)  glyceraldehyde-3-phosphate
C)  dihydroxyacetone phosphate
D)  3-phosphoglycerate
E)  pyruvate

Question 6

Which of the following is TRUE about glutamine?
(I) It is formed from  α\alphaα -ketoglutarate.
(II) It donates an amino group to aspartate to form asparagine.
(III) It is directly required for ornithine synthesis.
(IV) It is a precursor to homoserine.

Accepted Answer

A)  I,II
B)  I,II,III
C)  II,III,IV
D)  II,IV
E)  I,III

Question 7

The amino acids Ala,Cys,Gly,Ser,and Thr are all degraded to the metabolic intermediate ___ and are considered ____.

Accepted Answer

A)  acetyl-CoA;glucogenic
B)  acetyl-CoA;ketogenic
C)  pyruvate;glucogenic
D)  pyruvate;ketogenic
E)  acetoacetate;ketogenic

Question 8

Proteins targeted for destruction via the ubiquitin pathway include
(I) proteins with a destabilizing N-end rule component.
(II) proteins with a PEST sequence.
(III) proteins that contain the RING finger E3 component named E3a.
(IV) protein with polyubiquitin proteins.

Accepted Answer

A)  I only
B)  II only
C)  I,II,III
D)  I,II,IV
E)  II,IV

Question 9

A number of compounds,including neurotransmitters,are synthesized from amino acids via decarboxylations.The enzymes catalyzing these steps usually use _______ as a cofactor.

Accepted Answer

A)  pyridoxal-5ꞌ-phosphate
B)  thiamine pyrophosphate
C)  biotin
D)  cobalt containing compounds [vitamin B12]
E)  tetrahydrofolate

Question 10

Which of the following is(are) advantages to the constant degradation and reformation of proteins?

Accepted Answer

A)  Nutrients can be stored as proteins,which can be used during periods of metabolic need.
B)  Damaged proteins are eliminated so they do not accumulate.
C)  Metabolism can be efficiently regulated by the synthesis and degradation of enzymes.
D)  All of the above are advantages.
E)  None of the above is an advantage.

Question 11

Which of the following control the urea cycle?
(I) substrate concentration of the cycle enzymes
(II) allosteric activation of carbamoyl phosphate synthetase I
(III) concentration of glutamate
(IV) availability of glucose

Accepted Answer

A)  I,III
B)  II,III
C)  II,IV
D)  I,II,III
E)  I,IV

Question 12

The presence of SGOT and SGPT in the serum indicate potential

Accepted Answer

A)  starvation and brain tissue damage.
B)  inflammation.
C)  heart attack or liver damage.
D)  lung or breast cancer.
E)  none of the above

Question 13

Which of the following is TRUE regarding catabolism of leucine?

Accepted Answer

A)  The pathway begins with aspartate.
B)  The pathway requires  α\alphaα -ketoglutarate.
C)  The pathway requires TPP.
D)  The pathway generates HMG-CoA.
E)  none of the above

Question 14

The activity of bacterial glutamine synthetase is
(I) inhibited allosterically by tryptophan.
(II) inhibited allosterically by glucosamine-6-phosphate.
(III) activated by nine allosteric feedback inhibitors.
(IV) altered by covalent modification.

Accepted Answer

A)  I,III
B)  III,IV
C)  I,II
D)  I,IV
E)  I,II,III,IV

Question 15

Enzyme A is involved in the metabolism of metabolite C to metabolite D.Enzyme A is part of a linear pathway involving ten enzymes ultimately converting B  →	o→  F.High levels of F directly alter the activity of enzyme A and result in control over the overall pathway.Enzyme A

Accepted Answer

A)  likely has high rates of degradation and synthesis.
B)  is likely a nonessential enzyme.
C)  likely has low rates of degradation and synthesis.
D)  is likely involved in a nonessential pathway.
E)  none of the above

Question 16

Which of the following require a cyclic carbohydrate precursor for synthesis?
(I) histidine
(II) alanine
(III) arginine
(IV) tyrosine

Accepted Answer

A)  I,II
B)  II only
C)  I,III
D)  I ,IV
E)  II,IV

Question 17

The metabolite chorismate

Accepted Answer

A)  allosterically enhances production of aromatic amino acids.
B)  is an important intermediate in the production of Trp,Tyr,and Phe.
C)  is a derivative of glucose.
D)  A and B
E)  B and C

Question 18

The lifetime of a protein in cells actively involved in metabolism

Accepted Answer

A)  is longer in eukaryotes than in prokaryotes.
B)  ranges from months to years.
C)  is independent of the function and activity of the protein.
D)  can change in response to changes in metabolic hormone levels.
E)  none of the above

Question 19

Which of the following amino acid breakdown reactions would be catalyzed by an aminotransferase?

Accepted Answer

A)  Threonine  →	o→  Acetyl CoA
B)  Alanine  →	o→  Pyruvate
C)  Asparagine  →	o→  Aspartate
D)  Homocysteine  →	o→  Methionone
E)  HMG-CoA  →	o→  Acetoacetate

Question 20

Matching
Choose the correct answer from the list.Not all the answers will be used.

-The enzyme ______ is critical to regulating nitrogen metabolism.

Accepted Answer

A)   ribosomes
B)   jaundice
C)   channeling
D)   26S proteasome
E)   glutamine synthetaseF)  alanineG)  glutamateH)  vitamin B6I)  anammoxJ)  glutamine transferaseK)  THFL)  autotrophM)  vitamin DN)  lysosomesO)  diazotrophs

Exam 21: Amino Acid Metabolism

Which of the following control the urea cycle? (I) substrate concentration of the cycle enzymes (II) allosteric activation of carbamoyl phosphate synthetase I (III) concentration of glutamate (IV) availability of glucose

Correct AnswerverifiedShow Answer

Oxidative deamination of glutamate (I) generates NAD(P) H and α\alphaα -ketoglutarate. (II) is inhibited by glutamate. (III) is activated by GTP. (IV) eliminates the keto group from α\alphaα -ketoacids.

Correct AnswerverifiedShow Answer

The activity of bacterial glutamine synthetase is (I) inhibited allosterically by tryptophan. (II) inhibited allosterically by glucosamine-6-phosphate. (III) activated by nine allosteric feedback inhibitors. (IV) altered by covalent modification.

Correct AnswerverifiedShow Answer

The lifetime of a protein in cells actively involved in metabolism

Correct AnswerverifiedShow Answer

The amino acids Ala,Cys,Gly,Ser,and Thr are all degraded to the metabolic intermediate ___ and are considered ____.

Correct AnswerverifiedShow Answer

Matching Choose the correct answer from the list.Not all the answers will be used. -The enzyme ______ is critical to regulating nitrogen metabolism.

Correct AnswerverifiedShow Answer

The presence of SGOT and SGPT in the serum indicate potential

Correct AnswerverifiedShow Answer

Which of the following is TRUE about glutamine? (I) It is formed from α\alphaα -ketoglutarate. (II) It donates an amino group to aspartate to form asparagine. (III) It is directly required for ornithine synthesis. (IV) It is a precursor to homoserine.

Correct AnswerverifiedShow Answer

Which of the following is(are) advantages to the constant degradation and reformation of proteins?

Correct AnswerverifiedShow Answer

Matching Choose the correct answer from the list.Not all the answers will be used. -_____ are involved in the nonselective degradation of proteins in well nourished cells.

Correct AnswerverifiedShow Answer

Proteins targeted for destruction via the ubiquitin pathway include (I) proteins with a destabilizing N-end rule component. (II) proteins with a PEST sequence. (III) proteins that contain the RING finger E3 component named E3a. (IV) protein with polyubiquitin proteins.

Correct AnswerverifiedShow Answer

Which of the following is TRUE regarding catabolism of leucine?

Correct AnswerverifiedShow Answer

Ketogenic amino acids can be converted to (I) glucose (II) fatty acids (III) ketone bodies (IV) pyruvate

Correct AnswerverifiedShow Answer

Which of the following require a cyclic carbohydrate precursor for synthesis? (I) histidine (II) alanine (III) arginine (IV) tyrosine

Correct AnswerverifiedShow Answer

Which of the following glycolytic intermediates is the common precursor to serine,cysteine,and glycine?

Correct AnswerverifiedShow Answer

Enzyme A is involved in the metabolism of metabolite C to metabolite D.Enzyme A is part of a linear pathway involving ten enzymes ultimately converting B →\to→ F.High levels of F directly alter the activity of enzyme A and result in control over the overall pathway.Enzyme A

Correct AnswerverifiedShow Answer

Which of the following amino acid breakdown reactions would be catalyzed by an aminotransferase?

Correct AnswerverifiedShow Answer

The metabolite chorismate

Correct AnswerverifiedShow Answer

A number of compounds,including neurotransmitters,are synthesized from amino acids via decarboxylations.The enzymes catalyzing these steps usually use _______ as a cofactor.

Correct AnswerverifiedShow Answer

Which of the following statements about phenylalanine is(are) TRUE?

Correct AnswerverifiedShow Answer

Correct Answer
verified

Oxidative deamination of glutamate (I) generates NAD(P) H and $\alpha$ -ketoglutarate. (II) is inhibited by glutamate. (III) is activated by GTP. (IV) eliminates the keto group from $\alpha$ -ketoacids.

Correct Answer
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Correct Answer
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Correct Answer
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The amino acids Ala,Cys,Gly,Ser,and Thr are all degraded to the metabolic intermediate _ and are considered __.

Correct Answer
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Correct Answer
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Correct Answer
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Which of the following is TRUE about glutamine? (I) It is formed from $\alpha$ -ketoglutarate. (II) It donates an amino group to aspartate to form asparagine. (III) It is directly required for ornithine synthesis. (IV) It is a precursor to homoserine.

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Enzyme A is involved in the metabolism of metabolite C to metabolite D.Enzyme A is part of a linear pathway involving ten enzymes ultimately converting B $\to$ F.High levels of F directly alter the activity of enzyme A and result in control over the overall pathway.Enzyme A

Correct Answer
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Correct Answer
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