Question 1

Under which circumstances are amino acids not metabolized via oxidative degradation?

Accepted Answer

A)  Starvation
B)  Plants growing in nutrient-rich soils
C)  Normal protein turnover
D)  A diet rich in proteins
E)  Uncontrolled diabetesF) All of the above
G) A) and E)

Question 2

In the urea cycle,ornithine transcarbamoylase catalyzes:

Accepted Answer

A)  cleavage of urea to ammonia.
B)  formation of citrulline from ornithine and another reactant.
C)  formation of ornithine from citrulline and another reactant.
D)  formation of urea from arginine.
E)  transamination of arginine.F) A) and D)
G) None of the above

Question 3

The coenzyme involved in a transaminase reaction is:

Accepted Answer

A)  biotin phosphate.
B)  lipoic acid.
C)  nicotinamide adenine dinucleotide phosphate (NADP+) .
D)  pyridoxal phosphate (PLP) .
E)  thiamine pyrophosphate (TPP) .F) A) and B)
G) A) and C)

Question 4

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?

Accepted Answer

A growing child needs a certain amount o...

Question 5

Which substance is not involved in the production of urea from NH4+ via the urea cycle?

Accepted Answer

A)  Aspartate
B)  ATP
C)  Carbamoyl phosphate
D)  Malate
E)  OrnithineF) B) and C)
G) A) and E)

Question 6

Transamination reactions are catalyzed by a family of enzymes,all of which require __________ as a coenzyme.In the first step of a transamination,the coenzyme in the aldehyde form condenses with the _________ group of an amino acid to form a(n)_________.

Accepted Answer

pyridoxal phosphate ...

Question 7

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.

Accepted Answer

(1)aspartate;oxaloacetate; (2)...

Question 8

In the digestion of protein that occurs in the small intestine,which enzyme is critical in the activation of zymogens?

Accepted Answer

A)  Enteropeptidase
B)  Hexokinase
C)  Papain
D)  Pepsin
E)  SecretinF) A) and B)
G) B) and D) A

Question 9

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.

Accepted Answer

(a)A defect in urea synthesis can result...

Question 10

In the treatment of diabetes,insulin is given intravenously.Why can't this hormone,a small protein,be taken orally?

Accepted Answer

First,the biological activity of insulin...

Question 11

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.

Accepted Answer

The glucogenic amino acids are those that are catabolized to intermediates that can serve as substrates for gluconeogenesis: pyruvate and any of the four- or five-carbon intermediates of the citric acid cycle.Ketogenic amino acids are catabolized to yield acetyl-CoA or acetoacetyl-CoA,the precursors for ketone body formation.

Question 12

Which of the following statements is false in reference to the mammalian synthesis of urea?

Accepted Answer

A)  Krebs was a major contributor to the elucidation of the pathway involved.
B)  The amino acid arginine is the immediate precursor to urea.
C)  The carbon atom of urea is derived from mitochondrial HCO3-.
D)  The precursor to one of the nitrogens of urea is aspartate.
E)  The process of urea production is an energy-yielding series of reactions.F) B) and E)
G) None of the above

Question 13

The conversion of glutamate to an  α\alphaα -ketoacid and NH4+:

Accepted Answer

A)  does not require any cofactors.
B)  is a reductive deamination.
C)  is accompanied by ATP hydrolysis catalyzed by the same enzyme.
D)  is catalyzed by glutamate dehydrogenase.
E)  requires ATP. F) A) and D)
G) B) and E)

Question 14

The human genetic disease phenylketonuria (PKU) can result from:

Accepted Answer

A)  deficiency of protein in the diet.
B)  inability to catabolize ketone bodies.
C)  inability to convert phenylalanine to tyrosine.
D)  inability to synthesize phenylalanine.
E)  production of enzymes containing no phenylalanine.F) A) and B)
G) None of the above

Question 15

In the human genetic disease maple syrup urine disease,the metabolic defect involves:

Accepted Answer

A)  a deficiency of the vitamin niacin.
B)  oxidative decarboxylation.
C)  synthesis of branched chain amino acids.
D)  transamination of an amino acid.
E)  uptake of branched chain amino acids into liver.F) A) and B)
G) C) and D)

Question 16

Give the name and draw the structure of the $\alpha$-keto acid resulting when the following amino acids undergo transamination with $\alpha$-ketoglutarate: (a)glutamate; (b)aspartate; (b)alanine.

Accepted Answer

(a)<img  loading="lazy" src="/assets/images/blured-textbook.svg" class="d-inline m-1" alt="blured image" width="139" height="30">-ketogl...

Question 17

Which of these is not a protease that acts in the small intestine?

Accepted Answer

A)  Chymotrypsin
B)  Elastase
C)  Enteropeptidase
D)  Secretin
E)  TrypsinF) A) and D)
G) A) and E)

Question 18

Describe the three different forms of nitrogen by which different organisms dispose of excess nitrogen obtained in the diet.Give examples of organisms that produce these different forms.

Accepted Answer

(1)Ammonotelic: release into the surroun...

Question 19

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.

Accepted Answer

The shortest pathway is from p...

Question 20

Which of these directly donates a nitrogen atom for the formation of urea during the urea cycle?

Accepted Answer

A)  Adenine
B)  Aspartate
C)  Creatine
D)  Glutamate
E)  OrnithineF) B) and D)
G) A) and C) B

Exam 18: Amino Acid Oxidation and the Production of Urea

Under which circumstances are amino acids not metabolized via oxidative degradation?

Correct Answer
verified

In the urea cycle,ornithine transcarbamoylase catalyzes:

Correct Answer
verified

The coenzyme involved in a transaminase reaction is:

Correct Answer
verified

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?

Correct Answer
verified
A growing child needs a certain amount o...
View Answer

Which substance is not involved in the production of urea from NH₄⁺ via the urea cycle?

Correct Answer
verified

Transamination reactions are catalyzed by a family of enzymes,all of which require ______ as a coenzyme.In the first step of a transamination,the coenzyme in the aldehyde form condenses with the _ group of an amino acid to form a(n)_____.

Correct Answer
verified
pyridoxal phosphate ...
View Answer

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.

Correct Answer
verified
(1)aspartate;oxaloacetate; (2)...
View Answer

In the digestion of protein that occurs in the small intestine,which enzyme is critical in the activation of zymogens?

Correct Answer
verified
A

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.

Correct Answer
verified
(a)A defect in urea synthesis can result...
View Answer

In the treatment of diabetes,insulin is given intravenously.Why can't this hormone,a small protein,be taken orally?

Correct Answer
verified
First,the biological activity of insulin...
View Answer

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.

Which of the following statements is false in reference to the mammalian synthesis of urea?

Correct Answer
verified

The conversion of glutamate to an $\alpha$ -ketoacid and NH₄⁺:

Correct Answer
verified

The human genetic disease phenylketonuria (PKU) can result from:

Correct Answer
verified

In the human genetic disease maple syrup urine disease,the metabolic defect involves:

Correct Answer
verified

Give the name and draw the structure of the $\alpha$ -keto acid resulting when the following amino acids undergo transamination with $\alpha$ -ketoglutarate: (a)glutamate; (b)aspartate; (b)alanine.

Correct Answer
verified
(a)-ketogl...
View Answer

Which of these is not a protease that acts in the small intestine?

Correct Answer
verified

Describe the three different forms of nitrogen by which different organisms dispose of excess nitrogen obtained in the diet.Give examples of organisms that produce these different forms.

Correct Answer
verified
(1)Ammonotelic: release into the surroun...
View Answer

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.

Correct Answer
verified
The shortest pathway is from p...
View Answer

Which of these directly donates a nitrogen atom for the formation of urea during the urea cycle?

Correct Answer
verified
B

Exam 18: Amino Acid Oxidation and the Production of Urea

Under which circumstances are amino acids not metabolized via oxidative degradation?

Correct AnswerverifiedShow Answer

In the urea cycle,ornithine transcarbamoylase catalyzes:

Correct AnswerverifiedShow Answer

The coenzyme involved in a transaminase reaction is:

Correct AnswerverifiedShow Answer

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?

Correct AnswerverifiedA growing child needs a certain amount o...View AnswerShow Answer

Which substance is not involved in the production of urea from NH4+ via the urea cycle?

Correct AnswerverifiedShow Answer

Transamination reactions are catalyzed by a family of enzymes,all of which require __________ as a coenzyme.In the first step of a transamination,the coenzyme in the aldehyde form condenses with the _________ group of an amino acid to form a(n)_________.

Correct Answerverifiedpyridoxal phosphate ...View AnswerShow Answer

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.

Correct Answerverified(1)aspartate;oxaloacetate; (2)...View AnswerShow Answer

In the digestion of protein that occurs in the small intestine,which enzyme is critical in the activation of zymogens?

Correct AnswerverifiedA

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.

Correct Answerverified(a)A defect in urea synthesis can result...View AnswerShow Answer

In the treatment of diabetes,insulin is given intravenously.Why can't this hormone,a small protein,be taken orally?

Correct AnswerverifiedFirst,the biological activity of insulin...View AnswerShow Answer

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.

Which of the following statements is false in reference to the mammalian synthesis of urea?

Correct AnswerverifiedShow Answer

The conversion of glutamate to an α\alphaα -ketoacid and NH4+:

Correct AnswerverifiedShow Answer

The human genetic disease phenylketonuria (PKU) can result from:

Correct AnswerverifiedShow Answer

In the human genetic disease maple syrup urine disease,the metabolic defect involves:

Correct AnswerverifiedShow Answer

Give the name and draw the structure of the α\alphaα -keto acid resulting when the following amino acids undergo transamination with α\alphaα -ketoglutarate: (a)glutamate; (b)aspartate; (b)alanine.

Correct Answerverified(a)-ketogl...View AnswerShow Answer

Which of these is not a protease that acts in the small intestine?

Correct AnswerverifiedShow Answer

Describe the three different forms of nitrogen by which different organisms dispose of excess nitrogen obtained in the diet.Give examples of organisms that produce these different forms.

Correct Answerverified(1)Ammonotelic: release into the surroun...View AnswerShow Answer

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.

Correct AnswerverifiedThe shortest pathway is from p...View AnswerShow Answer

Which of these directly donates a nitrogen atom for the formation of urea during the urea cycle?

Correct AnswerverifiedB

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
A growing child needs a certain amount o...
View Answer

Which substance is not involved in the production of urea from NH₄⁺ via the urea cycle?

Correct Answer
verified

Transamination reactions are catalyzed by a family of enzymes,all of which require ______ as a coenzyme.In the first step of a transamination,the coenzyme in the aldehyde form condenses with the _ group of an amino acid to form a(n)_____.

Correct Answer
verified
pyridoxal phosphate ...
View Answer

Correct Answer
verified
(1)aspartate;oxaloacetate; (2)...
View Answer

Correct Answer
verified
A

Correct Answer
verified
(a)A defect in urea synthesis can result...
View Answer

Correct Answer
verified
First,the biological activity of insulin...
View Answer

Correct Answer
verified

The conversion of glutamate to an $\alpha$ -ketoacid and NH₄⁺:

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Give the name and draw the structure of the $\alpha$ -keto acid resulting when the following amino acids undergo transamination with $\alpha$ -ketoglutarate: (a)glutamate; (b)aspartate; (b)alanine.

Correct Answer
verified
(a)-ketogl...
View Answer

Correct Answer
verified

Correct Answer
verified
(1)Ammonotelic: release into the surroun...
View Answer

Correct Answer
verified
The shortest pathway is from p...
View Answer

Correct Answer
verified
B