Question 1

Which of the following is NOT a commonly used transamination pair?

Accepted Answer

A)  Phe / phenylpyruvate 
B)  Asp / oxaloacetate 
C)  Glu / α-ketoglutarate 
D)  Ala / pyruvate 
E)  all are correct 
A)  Phe / phenylpyruvate 
B)  Asp / oxaloacetate 
C)  Glu / α-ketoglutarate 
D)  Ala / pyruvate 
E)  all are correct

Question 2

Chorismate biosynthesis occurs via the shikimate pathway and is an important precursor in the synthesis of all of the following EXCEPT:

Accepted Answer

A)  vitamin K. 
B)  folic acid. 
C)  threonine. 
D)  tyrosine. 
E)  tryptophan. 
A)  vitamin K. 
B)  folic acid. 
C)  threonine. 
D)  tyrosine. 
E)  tryptophan.

Question 3

The reaction, glutamate + NAD(P)+ + H2O → NH4+ + α-ketoglutarate + NAD(P)H + H+, is catalyzed by:

Accepted Answer

A)  Nitrogenase. 
B)  carbamoyl-phosphate synthetase (CPS-I). 
C)  glutamate dehydrogenase (GDH). 
D)  glutamine synthetase (GS). 
E)  none are true. 
A)  Nitrogenase. 
B)  carbamoyl-phosphate synthetase (CPS-I). 
C)  glutamate dehydrogenase (GDH). 
D)  glutamine synthetase (GS). 
E)  none are true.

Question 4

Nitrate assimilation occurs in two steps: reduction of nitrate to ____ and further reduction to ____.

Accepted Answer

A)  ammonia; nitrogen 
B)  nitrogen; ammonia 
C)  nitrite; nitrogen 
D)  nitrite; ammonia 
E)  none are correct 
A)  ammonia; nitrogen 
B)  nitrogen; ammonia 
C)  nitrite; nitrogen 
D)  nitrite; ammonia 
E)  none are correct

Question 5

All of the following are characteristics of phenylketonuria EXCEPT:

Accepted Answer

A)  excretion of phenylpyruvate. 
B)  air oxidation causes urine to turn dark on standing. 
C)  treated by putting patient on a diet low in phenylalanine. 
D)  untreated patients suffer severe mental retardation. 
E)  deficiency or defect in phenylalanine hydroxylase. 
A)  excretion of phenylpyruvate. 
B)  air oxidation causes urine to turn dark on standing. 
C)  treated by putting patient on a diet low in phenylalanine. 
D)  untreated patients suffer severe mental retardation. 
E)  deficiency or defect in phenylalanine hydroxylase.

Question 6

Glutamine synthetase is an important enzyme in the regulation of ammonia concentrations. Which of the following would be an activator of Gln synthetase?

Accepted Answer

A)  α-ketoglutarate 
B)  glutamine 
C)  histidine 
D)  alanine 
E)  none of the above 
A)  α-ketoglutarate 
B)  glutamine 
C)  histidine 
D)  alanine 
E)  none of the above

Question 7

The involvement of ATP in the nitrogenase complex is because ATP is needed to:

Accepted Answer

A)  provide electrons. 
B)  phosphorylate the enzyme. 
C)  break the N2 triple bond. 
D)  transfer electrons from ferredoxin. 
E)  all are true. 
A)  provide electrons. 
B)  phosphorylate the enzyme. 
C)  break the N2 triple bond. 
D)  transfer electrons from ferredoxin. 
E)  all are true.

Question 8

In plants and microorganisms, amino acid biosynthesis is a matter of synthesizing the appropriate ____ followed by transamination with ____.

Accepted Answer

A)  acetyl-CoA derivatives; glutamine 
B)  α-ketoacid; glutamate 
C)  phospho-carbon skeleton; alanine 
D)  nitrogenous base; glutamate 
E)  none are true 
A)  acetyl-CoA derivatives; glutamine 
B)  α-ketoacid; glutamate 
C)  phospho-carbon skeleton; alanine 
D)  nitrogenous base; glutamate 
E)  none are true

Question 9

Glutamate synthase catalyzes the reaction ____ + ____ + ____ → 2 glutamate + NADP+

Accepted Answer

A)  α-ketoglutarate; NADPH; glutamine 
B)  glutamate; α-ketoglutarate; NADH 
C)  glutamyl-phosphate; glutamine; NADPH 
D)  N-acetylglutamate; α-ketoglutarate; NADH 
E)  none are true 
A)  α-ketoglutarate; NADPH; glutamine 
B)  glutamate; α-ketoglutarate; NADH 
C)  glutamyl-phosphate; glutamine; NADPH 
D)  N-acetylglutamate; α-ketoglutarate; NADH 
E)  none are true

Question 10

Homoserine and homocysteine are related to serine and cysteine by having:

Accepted Answer

A)  an extra amino group. 
B)  an additional methylene group. 
C)  an additional carboxyl group. 
D)  an aldehyde group. 
E)  a phosphoryl group. 
A)  an extra amino group. 
B)  an additional methylene group. 
C)  an additional carboxyl group. 
D)  an aldehyde group. 
E)  a phosphoryl group.

Question 11

All are characteristics of Maple Syrup Urine Disease EXCEPT:

Accepted Answer

A)  hereditary enzyme defect. 
B)  elevated levels of val, leu, and ile and their corresponding α-keto acids in blood and urine. 
C)  restrictive intake of proteins with val, leu and ile is required. 
D)  fatal without detection and treatment. 
E)  elevated blood levels of acetoacetate and β-hydroxybutyrate. 
A)  hereditary enzyme defect. 
B)  elevated levels of val, leu, and ile and their corresponding α-keto acids in blood and urine. 
C)  restrictive intake of proteins with val, leu and ile is required. 
D)  fatal without detection and treatment. 
E)  elevated blood levels of acetoacetate and β-hydroxybutyrate.

Question 12

All of the following are true statements regarding the 3-Phosphoglycerate (3-PG) family EXCEPT:

Accepted Answer

A)  3-PG is diverted from glycolysis by phosphoglycerate mutase. 
B)  Glycine can be derived from serine. 
C)  Serine, glycine and cysteine are all nonessential amino acids. 
D)  Production of glycine also produces N5, N10-methylene-THF which is important in the biosynthesis of purines. 
E)  Serine production is regulated by a direct feedback mechanism. 
A)  3-PG is diverted from glycolysis by phosphoglycerate mutase. 
B)  Glycine can be derived from serine. 
C)  Serine, glycine and cysteine are all nonessential amino acids. 
D)  Production of glycine also produces N5, N10-methylene-THF which is important in the biosynthesis of purines. 
E)  Serine production is regulated by a direct feedback mechanism.

Question 13

All of the following are true of the urea cycle EXCEPT:

Accepted Answer

A)  It helps in the excretion of excess nitrogen. 
B)  It is mainly confined to the liver. 
C)  It is linked to the citric acid cycle through fumarate. 
D)  Stimulation of carbamoyl-phosphate synthetase I (CPS-I) decreases the activity of the urea cycle. 
E)  It is completed by the regeneration of ornithine from arginine. 
A)  It helps in the excretion of excess nitrogen. 
B)  It is mainly confined to the liver. 
C)  It is linked to the citric acid cycle through fumarate. 
D)  Stimulation of carbamoyl-phosphate synthetase I (CPS-I) decreases the activity of the urea cycle. 
E)  It is completed by the regeneration of ornithine from arginine.

Question 14

Nitrifying bacteria obtain their chemical energy from:

Accepted Answer

A)  the reduction of NO3− to NH4+. 
B)  the formation of NH4+ from N2 gas. 
C)  the oxidation of NH4+ to N2. 
D)  the oxidation of NH4+ to NO3−. 
E)  the formation of NO2− from NO3−. 
A)  the reduction of NO3− to NH4+. 
B)  the formation of NH4+ from N2 gas. 
C)  the oxidation of NH4+ to N2. 
D)  the oxidation of NH4+ to NO3−. 
E)  the formation of NO2− from NO3−.

Question 15

N-acetylglutamate functions in ammonium incorporation into metabolic intermediates as:

Accepted Answer

A)  a coenzyme for glutamine synthetase (GS). 
B)  a competitive inhibitor for glutamine synthetase (GS). 
C)  an allosteric activator for carbamoyl-phosphate synthetase I (CPS-I). 
D)  the energy source needed for the reductive amination of α-ketoglutarate (α-KG) to yield glutamate. 
E)  the substrate for the amination of the γ-glutamylphosphate. 
A)  a coenzyme for glutamine synthetase (GS). 
B)  a competitive inhibitor for glutamine synthetase (GS). 
C)  an allosteric activator for carbamoyl-phosphate synthetase I (CPS-I). 
D)  the energy source needed for the reductive amination of α-ketoglutarate (α-KG) to yield glutamate. 
E)  the substrate for the amination of the γ-glutamylphosphate.

Question 16

The term ketogenic amino acids refers to amino acids:

Accepted Answer

A)  that are precursors for glucose synthesis. 
B)  degraded to yield acetyl CoA or acetoacetate. 
C)  that can not be converted to fatty acids or ketone bodies. 
D)  degraded to yield succinyl-CoA, pyruvate, α-ketoglutarate, fumarate and oxaloacetate. 
E)  none of the above. 
A)  that are precursors for glucose synthesis. 
B)  degraded to yield acetyl CoA or acetoacetate. 
C)  that can not be converted to fatty acids or ketone bodies. 
D)  degraded to yield succinyl-CoA, pyruvate, α-ketoglutarate, fumarate and oxaloacetate. 
E)  none of the above.

Question 17

Explain the biosynthesis of glycine.​

Accepted Answer

Glycine is made from serine via two rela

Question 18

What would be a result of a high [Gln]/[α-KG] ratio?

Accepted Answer

A)  Increase in deadenylation of glutamine synthetase. 
B)  An increase in activity of glutamine synthetase. 
C)  An increase in the degree of adenylation of glutamine synthetase. 
D)  Inhibition of AT:PIIA and stimulation of AT:PIID. 
E)  A need for ammonium fixation by glutamine synthetase. 
A)  Increase in deadenylation of glutamine synthetase. 
B)  An increase in activity of glutamine synthetase. 
C)  An increase in the degree of adenylation of glutamine synthetase. 
D)  Inhibition of AT:PIIA and stimulation of AT:PIID. 
E)  A need for ammonium fixation by glutamine synthetase.

Question 19

Which of the following amino acids plays the most central role in nitrogen and amino acid metabolism?

Accepted Answer

A)  Asn 
B)  Glu 
C)  Gly 
D)  Cys 
E)  none of the above 
A)  Asn 
B)  Glu 
C)  Gly 
D)  Cys 
E)  none of the above

Question 20

Elevated levels of homocysteine in the blood is related to all EXCEPT:

Accepted Answer

A)  homocysteinuria at very high levels. 
B)  folic acid deficiency. 
C)  folic acid-dependent conversion of homocysteine to methionine. 
D)  higher risk of heart attack and stroke. 
E)  all of the above are correct. 
A)  homocysteinuria at very high levels. 
B)  folic acid deficiency. 
C)  folic acid-dependent conversion of homocysteine to methionine. 
D)  higher risk of heart attack and stroke. 
E)  all of the above are correct.

Exam 25: Nitrogen Acquisition and Amino Acid Metabolism

Which of the following is NOT a commonly used transamination pair?

Chorismate biosynthesis occurs via the shikimate pathway and is an important precursor in the synthesis of all of the following EXCEPT:

The reaction, glutamate + NAD(P)+ + H2O → NH4+ + α-ketoglutarate + NAD(P)H + H+, is catalyzed by:

Nitrate assimilation occurs in two steps: reduction of nitrate to ____ and further reduction to ____.

All of the following are characteristics of phenylketonuria EXCEPT:

Glutamine synthetase is an important enzyme in the regulation of ammonia concentrations. Which of the following would be an activator of Gln synthetase?

The involvement of ATP in the nitrogenase complex is because ATP is needed to:

In plants and microorganisms, amino acid biosynthesis is a matter of synthesizing the appropriate ____ followed by transamination with ____.

Glutamate synthase catalyzes the reaction ____ + ____ + ____ → 2 glutamate + NADP+

Homoserine and homocysteine are related to serine and cysteine by having:

All are characteristics of Maple Syrup Urine Disease EXCEPT:

All of the following are true statements regarding the 3-Phosphoglycerate (3-PG) family EXCEPT:

All of the following are true of the urea cycle EXCEPT:

Nitrifying bacteria obtain their chemical energy from:

N-acetylglutamate functions in ammonium incorporation into metabolic intermediates as:

The term ketogenic amino acids refers to amino acids:

Explain the biosynthesis of glycine.​

What would be a result of a high [Gln]/[α-KG] ratio?

Which of the following amino acids plays the most central role in nitrogen and amino acid metabolism?

Elevated levels of homocysteine in the blood is related to all EXCEPT:

The Facts of Life: Chemistry Is the Logic of Biological Phenomena

Water: the Medium of Life

Thermodynamics of Biological Systems

Amino Acids and the Peptide Bond

Proteins: Their Primary Structure and Biological Functions

Proteins: Secondary, Tertiary, and Quaternary Structure

Carbohydrates and the Glycoconjugates of Cell Surfaces

Lipids

Membranes and Membrane Transport

Nucleotides and Nucleic Acids

Structure of Nucleic Acids

Recombinant Dna, Cloning, Chimeric Genes, and Synthetic Biology

Enzymeskinetics and Specificity

Mechanisms of Enzyme Action

Enzyme Regulation

Molecular Motors

Metabolism: an Overview

Glycolysis

The Tricarboxylic Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Gluconeogenesis, Glycogen Metabolism, and the Pentose Phosphate Pathway

Fatty Acid Catabolism

Lipid Biosynthesis

Synthesis and Degradation of Nucleotides

Metabolic Integration and Organ Specialization

Dna Metabolism: Replication, Recombination, and Repair

Transcription and the Regulation of Gene Expression

Protein Synthesis

Completing the Protein Life Cycle: Folding, Processing, and Degradation

The Reception and Transmission of Extracellular Information

Filters

The reaction, glutamate + NAD(P)⁺ + H₂O → NH₄⁺ + α-ketoglutarate + NAD(P)H + H⁺, is catalyzed by:

Nitrate assimilation occurs in two steps: reduction of nitrate to and further reduction to .

In plants and microorganisms, amino acid biosynthesis is a matter of synthesizing the appropriate followed by transamination with .

Glutamate synthase catalyzes the reaction + + → 2 glutamate + NADP⁺

Explain the biosynthesis of glycine.