Question 1

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 2

_____ catalyzes the synthesis of ____, a molecule that signals vasodilation, from the precursor _____

Accepted Answer

A)  NOS; nitric oxide (NO) ; arginine
B)  Nitrous oxidase; nitrous oxide; arginine
C)  Arginate; nitric oxide (NO) ; citrulline
D)  Citrulline dehydrogenase; nitrous oxide; citrulline
E)  none of the above

Question 3

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 →\rarr→  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  A

Question 4

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 E

Question 5

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 6

Matching 
Choose the correct answer from the list. Not all the answers will be used.
-Aminotransferases utilize a coenzyme synthesized from ______.

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 7

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 8

The synthesis of which of the following uses an aminotransferase in the first step of the synthesis?

Accepted Answer

A)  glutamine
B)  proline
C)  serine
D)  valine
E)  all of the above

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

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 11

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 12

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 13

The aminotransferase reaction, in which an enzyme-PLP Schiff base forms,
I.is ATP dependent.
II.results in formation of a hydroxylaldehyde.
III.results in formation of an  α\alphaα -ketoacid.
IV.requires an active site lysine.

Accepted Answer

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

Question 14

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 15

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 16

Which enzyme catalyses a reaction via an enzyme-bound adenylated intermediate?

Accepted Answer

A)  glutamine synthetase
B)  argininosuccinate synthetase
C)  carbamoyl phosphate synthetase I
D)  Ac-CoA decarboxylase
E)  arginase

Question 17

Which of the following is required for synthesis of tryptophan?

Accepted Answer

A)  serine
B)  phosphoenolpyruvate
C)  erythrose-4-phosphate
D)  all of the above
E)  none of the above

Question 18

Heme biosynthesis

Accepted Answer

A)  requires that synthesis of the protoporphryin ring occur in the mitochondria due to difficulties in transporting large molecule.
B)  is inhibited in lead poisoning.
C)  can be completed using enzymes from the cytosol.
D)  A and B
E)  A, B, and C

Question 19

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 20

The majority of amino acids are deaminated by a ______ reaction.

Accepted Answer

A)  reduction
B)  transaminmation
C)  condensation
D)  transacetylation
E)  oxidation A

Exam 21: Amino Acid Metabolism

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

_____ catalyzes the synthesis of ____, a molecule that signals vasodilation, from the precursor _____

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 →\rarr→ F.High levels of F directly alter the activity of enzyme A and result in control over the overall pathway.Enzyme A

Correct AnswerverifiedA

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 AnswerverifiedE

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

Matching Choose the correct answer from the list. Not all the answers will be used. -Aminotransferases utilize a coenzyme synthesized from ______.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

The synthesis of which of the following uses an aminotransferase in the first step of the synthesis?

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

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

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

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 aminotransferase reaction, in which an enzyme-PLP Schiff base forms, I.is ATP dependent. II.results in formation of a hydroxylaldehyde. III.results in formation of an α\alphaα -ketoacid. IV.requires an active site lysine.

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 enzyme catalyses a reaction via an enzyme-bound adenylated intermediate?

Correct AnswerverifiedShow Answer

Which of the following is required for synthesis of tryptophan?

Correct AnswerverifiedShow Answer

Heme biosynthesis

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

The majority of amino acids are deaminated by a ______ reaction.

Correct AnswerverifiedA

Correct Answer
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_ catalyzes the synthesis of , a molecule that signals vasodilation, from the precursor _

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 $\rarr$ 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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A

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E

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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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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
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
verified

The aminotransferase reaction, in which an enzyme-PLP Schiff base forms, I.is ATP dependent. II.results in formation of a hydroxylaldehyde. III.results in formation of an $\alpha$ -ketoacid. IV.requires an active site lysine.

Correct Answer
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A