Question 1

Name one amino acid whose oxidation proceeds via the intermediate shown:

Accepted Answer

A)  pyruvate; 
B)  oxaloacetate; 
C)  $\alpha$-ketoglutarate; 
D)  succinyl-CoA; 
E)  fumarate. 
A)  pyruvate; 
B)  oxaloacetate; 
C)  $\alpha$-ketoglutarate; 
D)  succinyl-CoA; 
E)  fumarate.

Question 2

Which compound is a zymogen that can be converted to an endopeptidase that hydrolyzes peptide bonds adjacent to Lys and Arg residues?

Accepted Answer

A)  chymotrypsinogen 
B)  pepsin 
C)  pepsinogen 
D)  trypsin 
E)  trypsinogen 
A)  chymotrypsinogen 
B)  pepsin 
C)  pepsinogen 
D)  trypsin 
E)  trypsinogen

Question 3

Which reaction associated with the urea cycle occurs in the cytosol?

Accepted Answer

A)  the synthesis of carbamoyl phosphate 
B)  the synthesis of citrulline 
C)  the synthesis of arginosuccinate 
D)  the synthesis of both carbamoyl phosphate and citrulline 
E)  the synthesis of both citrulline and arginosuccinate 
A)  the synthesis of carbamoyl phosphate 
B)  the synthesis of citrulline 
C)  the synthesis of arginosuccinate 
D)  the synthesis of both carbamoyl phosphate and citrulline 
E)  the synthesis of both citrulline and arginosuccinate

Question 4

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)  secretin 
A)  enteropeptidase 
B)  hexokinase 
C)  papain 
D)  pepsin 
E)  secretin

Question 5

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

The fundamental nutritional problem face

Question 6

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?

Accepted Answer

The presence of a high concentration of

Question 7

Which statement is TRUE regarding lysine?

Accepted Answer

A)  This is a nonessential amino acid. 
B)  Catabolism of lysine shares multiple steps with that of tryptophan. 
C)  Carbons of lysine catabolism enter the citric acid cycle at succinyl-CoA. 
D)  Lysine is both glucogenic and ketogenic enzyme. 
A)  This is a nonessential amino acid. 
B)  Catabolism of lysine shares multiple steps with that of tryptophan. 
C)  Carbons of lysine catabolism enter the citric acid cycle at succinyl-CoA. 
D)  Lysine is both glucogenic and ketogenic enzyme.

Question 8

Which hormone is triggered by the entry of acidic stomach content into the intestine?

Accepted Answer

A)  gastrin 
B)  insulin 
C)  cholecystokinin 
D)  secretin 
A)  gastrin 
B)  insulin 
C)  cholecystokinin 
D)  secretin

Question 9

Which hormone is triggered by the entry of protein into the stomach?

Accepted Answer

A)  gastrin 
B)  insulin 
C)  cholecystokinin 
D)  secretin 
A)  gastrin 
B)  insulin 
C)  cholecystokinin 
D)  secretin

Question 10

Conversion of ammonia to carbamoyl phosphate in mitochondria consumes how many ATP equivalents?

Accepted Answer

A)  none 
B)  one 
C)  two 
D)  three 
A)  none 
B)  one 
C)  two 
D)  three

Question 11

Tetrahydrofolate (THF) and its derivatives shuttle _____ between different substrates.

Accepted Answer

A)  electrons 
B)  H+ 
C)  acyl groups 
D)  one carbon units 
E)  NH2 groups 
A)  electrons 
B)  H+ 
C)  acyl groups 
D)  one carbon units 
E)  NH2 groups

Question 12

Which amino acid enters the citric acid cycle as $\alpha$-ketoglutarate during their catabolism?

Accepted Answer

A)  proline 
B)  threonine 
C)  aspartate 
D)  leucine 
E)  None of the answers is correct. 
A)  proline 
B)  threonine 
C)  aspartate 
D)  leucine 
E)  None of the answers is correct.

Question 13

Which compound is NOT an intermediate in the conversion of alanine's carbon skeleton into that of aspartate?

Accepted Answer

A)  acetyl-CoA 
B)  pyruvate 
C)  lactate 
D)  oxaloacetate 
E)  neither acetyl-CoA nor lactate 
A)  acetyl-CoA 
B)  pyruvate 
C)  lactate 
D)  oxaloacetate 
E)  neither acetyl-CoA nor lactate

Question 14

Which compound is NOT a protease that acts in the small intestine?

Accepted Answer

A)  chymotrypsin 
B)  elastase 
C)  enteropeptidase 
D)  secretin 
E)  trypsin 
A)  chymotrypsin 
B)  elastase 
C)  enteropeptidase 
D)  secretin 
E)  trypsin

Question 15

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

Question 16

In amino acid catabolism, the first reaction for many amino acids is a(n):

Accepted Answer

A)  decarboxylation requiring thiamine pyrophosphate (TPP). 
B)  hydroxylation requiring NADPH and O2. 
C)  oxidative deamination requiring NAD+. 
D)  reduction requiring pyridoxal phosphate (PLP). 
E)  transamination requiring pyridoxal phosphate (PLP). 
A)  decarboxylation requiring thiamine pyrophosphate (TPP). 
B)  hydroxylation requiring NADPH and O2. 
C)  oxidative deamination requiring NAD+. 
D)  reduction requiring pyridoxal phosphate (PLP). 
E)  transamination requiring pyridoxal phosphate (PLP).

Question 17

If 15N-labeled glutamate is introduced into liver cells, what compounds in the urea cycle will NOT be rapidly labeled with the nitrogen?

Accepted Answer

A)  ornithine 
B)  aspartate 
C)  arginine 
D)  urea 
E)  both ornithine and aspartate 
A)  ornithine 
B)  aspartate 
C)  arginine 
D)  urea 
E)  both ornithine and aspartate

Question 18

Which product is created during the conversion of threonine into glycine during amino acid catabolism?

Accepted Answer

A)  acetyl-CoA 
B)  water 
C)  NADH 
D)  both acetyl-CoA and NADH 
E)  both water and NADH 
A)  acetyl-CoA 
B)  water 
C)  NADH 
D)  both acetyl-CoA and NADH 
E)  both water and NADH

Exam 18: Amino Acid Oxidation and the Production of Urea

Name one amino acid whose oxidation proceeds via the intermediate shown:

Which compound is a zymogen that can be converted to an endopeptidase that hydrolyzes peptide bonds adjacent to Lys and Arg residues?

Which reaction associated with the urea cycle occurs in the cytosol?

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

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.

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?

Which statement is TRUE regarding lysine?

Which hormone is triggered by the entry of acidic stomach content into the intestine?

Which hormone is triggered by the entry of protein into the stomach?

Conversion of ammonia to carbamoyl phosphate in mitochondria consumes how many ATP equivalents?

Tetrahydrofolate (THF) and its derivatives shuttle _____ between different substrates.

Which amino acid enters the citric acid cycle as α\alphaα -ketoglutarate during their catabolism?

Which compound is NOT an intermediate in the conversion of alanine's carbon skeleton into that of aspartate?

Which compound is NOT a protease that acts in the small intestine?

The coenzyme involved in a transaminase reaction is:

In amino acid catabolism, the first reaction for many amino acids is a(n):

If 15N-labeled glutamate is introduced into liver cells, what compounds in the urea cycle will NOT be rapidly labeled with the nitrogen?

Which product is created during the conversion of threonine into glycine during amino acid catabolism?

The Foundations of Biochemistry

Water

Amino Acids, Peptides, and Proteins

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

DNA-Based Information Technologies

Lipids

Biological Membranes and Transport

Biosignaling

Bioenergetics and Biochemical Reaction Types

Glycolysis, Gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, Nucleotides, and Related Molecules

Hormonal Regulation and Integration of Mammalian Metabolism

Genes and Chromosomes

DNA Metabolism

RNA Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

Which amino acid enters the citric acid cycle as $\alpha$ -ketoglutarate during their catabolism?

If ¹⁵N-labeled glutamate is introduced into liver cells, what compounds in the urea cycle will NOT be rapidly labeled with the nitrogen?