Question 1

Denitrifying bacteria are capable of all EXCEPT:

Accepted Answer

A)  reducing NO3− to N2. 
B)  using NO3− as an electron acceptor in their energy-producing pathways. 
C)  oxidizing NH4+ to NO3−. 
D)  reducing the combined-nitrogen levels. 
E)  being utilized in water treatment plants to reduce nitrogen entering lakes and streams. 
A)  reducing NO3− to N2. 
B)  using NO3− as an electron acceptor in their energy-producing pathways. 
C)  oxidizing NH4+ to NO3−. 
D)  reducing the combined-nitrogen levels. 
E)  being utilized in water treatment plants to reduce nitrogen entering lakes and streams.

Question 2

Which of the following sequence of events best explains the mechanism of carbamoyl phosphate synthetase?

Accepted Answer

A)  CO2 and ATP form a carbonic-phosphoric anhydride (CP
A) , then NH3 performs a nucleophilic attack on the CPA to form carbamate 
B)  Activated CO2 is transferred to biotin, then reacts with NH3 to produce carbamate 
C)  NH3 reacts with ATP, which then reacts with CO2 to produce carbamate 
D)  NH3 reacts with CO2 to produce carbamate followed by reaction with ATP 
E)  None of the above 
A)  CO2 and ATP form a carbonic-phosphoric anhydride (CP
A) , then NH3 performs a nucleophilic attack on the CPA to form carbamate 
B)  Activated CO2 is transferred to biotin, then reacts with NH3 to produce carbamate 
C)  NH3 reacts with ATP, which then reacts with CO2 to produce carbamate 
D)  NH3 reacts with CO2 to produce carbamate followed by reaction with ATP 
E)  None of the above

Question 3

Bacterial glutamine synthetase monomers are inactive because they must be:

Accepted Answer

A)  phosphorylated for activity. 
B)  activated by binding glutamine. 
C)  stacked for interface active site development. 
D)  combined for allosteric regulation. 
E)  none are true. 
A)  phosphorylated for activity. 
B)  activated by binding glutamine. 
C)  stacked for interface active site development. 
D)  combined for allosteric regulation. 
E)  none are true.

Question 4

Discuss the components of the metalloproteins that form the nitrogenase complex.​

Accepted Answer

Two metalloproteins constitute the nitro

Question 5

____ is an intermediate in biosynthesis of ornithine and a regulator of carbamoyl-phosphate synthetase-I

Accepted Answer

A)  γ-Glutamyl-phosphate 
B)  α-Ketoglutarate 
C)  N-Acetylglutamate 
D)  Glutamine 
E)  Glutamine-5-phosphate 
A)  γ-Glutamyl-phosphate 
B)  α-Ketoglutarate 
C)  N-Acetylglutamate 
D)  Glutamine 
E)  Glutamine-5-phosphate

Question 6

Nitrite reductase requires ____ electrons to reduce NO2− to NH4+ and the electrons are provided in higher plants through photosynthesis as reduced ____.

Accepted Answer

A)  2; plastoquinone 
B)  3; plastoquinone 
C)  4; heme 
D)  5; heme 
E)  6; ferredoxin 
A)  2; plastoquinone 
B)  3; plastoquinone 
C)  4; heme 
D)  5; heme 
E)  6; ferredoxin

Question 7

Which of the following is both an essential amino acid (for humans) and also an exclusively ketogenic amino acid?

Accepted Answer

A)  proline 
B)  valine 
C)  glutamine 
D)  leucine 
E)  phenylalanine 
A)  proline 
B)  valine 
C)  glutamine 
D)  leucine 
E)  phenylalanine

Question 8

What is nitrogen fixation?

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 9

Control over nitrogenase activity is accomplished by which of the following?

Accepted Answer

A)  ATP serves as an allosteric activator 
B)  AMP serves as an allosteric inhibitor 
C)  NH4+ prevents expression of the genes that encode nitrogenase 
D)  phosphorylation prevents activity 
E)  none of the above 
A)  ATP serves as an allosteric activator 
B)  AMP serves as an allosteric inhibitor 
C)  NH4+ prevents expression of the genes that encode nitrogenase 
D)  phosphorylation prevents activity 
E)  none of the above

Question 10

The correct sequence for electron-transport in nitrate reductase is:
A.NADH
B.−SH
C.FAD
D.Cyt b557
E.MoCo
F.NO3−

Accepted Answer

A)  A, B, C, D, E, F 
B)  B, C, A, D, F, E 
C)  D, A, B, C, E, F 
D)  A, C, B, D, F, E 
E)  C, A, B, D, E, F 
A)  A, B, C, D, E, F 
B)  B, C, A, D, F, E 
C)  D, A, B, C, E, F 
D)  A, C, B, D, F, E 
E)  C, A, B, D, E, F

Question 11

In the process of amino acid biosynthesis, how are glutamic acid, glutamine, proline, and arginine all related?

Accepted Answer

A)  They are all derived from α-KG. 
B)  They are all derivatives of acetyl CoA. 
C)  They are all derivatives of pyruvate. 
D)  They are all derived from aspartate. 
E)  They are all derivatives of 3-phosphoglycerate. 
A)  They are all derived from α-KG. 
B)  They are all derivatives of acetyl CoA. 
C)  They are all derivatives of pyruvate. 
D)  They are all derived from aspartate. 
E)  They are all derivatives of 3-phosphoglycerate.

Question 12

What reaction does glutamate dehydrogenase (GDH) catalyze?

Accepted Answer

A)  The reductive amination of α-ketoglutarate to yield glutamate. 
B)  Phosphorylation of carbamate to yield carbamoyl-phosphate. 
C)  The amidation of the γ-carboxyl group of glutamate to form glutamine. 
D)  The deadenylation of glutamine synthetase. 
E)  The adenylation of glutamine synthetase. 
A)  The reductive amination of α-ketoglutarate to yield glutamate. 
B)  Phosphorylation of carbamate to yield carbamoyl-phosphate. 
C)  The amidation of the γ-carboxyl group of glutamate to form glutamine. 
D)  The deadenylation of glutamine synthetase. 
E)  The adenylation of glutamine synthetase.

Question 13

Ornithine serves three metabolically important roles, but is not found in proteins. What is one of the important roles of ornithine?

Accepted Answer

A)  amine donor for many transamination reactions 
B)  an intermediate in the urea cycle 
C)  involved in the synthesis of serine, which serves as a precursor for glycine and cysteine 
D)  its reaction with methenyl tetrahydrofolate produces lysine 
E)  none of the above 
A)  amine donor for many transamination reactions 
B)  an intermediate in the urea cycle 
C)  involved in the synthesis of serine, which serves as a precursor for glycine and cysteine 
D)  its reaction with methenyl tetrahydrofolate produces lysine 
E)  none of the above

Question 14

All of the carbons and nitrogens of ornithine come biosynthetically from:

Accepted Answer

A)  proline. 
B)  valine. 
C)  alanine. 
D)  glutamate. 
E)  glycine. 
A)  proline. 
B)  valine. 
C)  alanine. 
D)  glutamate. 
E)  glycine.

Question 15

Discuss the significance of glutamine synthetase.​

Accepted Answer

​Glutamine synthetase (GS) catalyzes the

Exam 25: Nitrogen Acquisition and Amino Acid Metabolism

Denitrifying bacteria are capable of all EXCEPT:

Which of the following sequence of events best explains the mechanism of carbamoyl phosphate synthetase?

Bacterial glutamine synthetase monomers are inactive because they must be:

Discuss the components of the metalloproteins that form the nitrogenase complex.​

____ is an intermediate in biosynthesis of ornithine and a regulator of carbamoyl-phosphate synthetase-I

Nitrite reductase requires ____ electrons to reduce NO2− to NH4+ and the electrons are provided in higher plants through photosynthesis as reduced ____.

Which of the following is both an essential amino acid (for humans) and also an exclusively ketogenic amino acid?

What is nitrogen fixation?

Control over nitrogenase activity is accomplished by which of the following?

The correct sequence for electron-transport in nitrate reductase is: A.NADH B.−SH C.FAD D.Cyt b557 E.MoCo F.NO3−

In the process of amino acid biosynthesis, how are glutamic acid, glutamine, proline, and arginine all related?

What reaction does glutamate dehydrogenase (GDH) catalyze?

Ornithine serves three metabolically important roles, but is not found in proteins. What is one of the important roles of ornithine?

All of the carbons and nitrogens of ornithine come biosynthetically from:

Discuss the significance of glutamine synthetase.​

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

Discuss the components of the metalloproteins that form the nitrogenase complex.

Nitrite reductase requires electrons to reduce NO₂− to NH₄⁺ and the electrons are provided in higher plants through photosynthesis as reduced .

The correct sequence for electron-transport in nitrate reductase is: A.NADH B.−SH C.FAD D.Cyt b₅₅₇ E.MoCo F.NO₃−

Discuss the significance of glutamine synthetase.