Question 1

All N2-fixing systems are nearly identical and have all of the requirements EXCEPT:

Accepted Answer

A)  ATP. 
B)  O2-free conditions. 
C)  the enzyme nitrogenase. 
D)  strong reductant such as ferredoxin. 
E)  all are true. 
A)  ATP. 
B)  O2-free conditions. 
C)  the enzyme nitrogenase. 
D)  strong reductant such as ferredoxin. 
E)  all are true. E

Question 2

All of the following are characteristic features of ATP:GS:adenylyl transferase (AT) EXCEPT:

Accepted Answer

A)  It catalyzes the adenylation of glutamine synthetase. 
B)  It exists in two forms, PIIA and PIID. PIIA causes the deadenylation of glutamine synthetase and its activity increases with an increase in glutamine. 
C)  AT:PIIA is inhibited by α-ketoglutarate. 
D)  AT:PIIA needs ATP to complete the reaction. 
E)  It is an enzyme that causes the adenylation/deadenylation of a specific tyrosine residue. 
A)  It catalyzes the adenylation of glutamine synthetase. 
B)  It exists in two forms, PIIA and PIID. PIIA causes the deadenylation of glutamine synthetase and its activity increases with an increase in glutamine. 
C)  AT:PIIA is inhibited by α-ketoglutarate. 
D)  AT:PIIA needs ATP to complete the reaction. 
E)  It is an enzyme that causes the adenylation/deadenylation of a specific tyrosine residue. B

Question 3

Amino acids biosynthesized from aspartate include all EXCEPT:

Accepted Answer

A)  asparagine. 
B)  threonine. 
C)  methionine. 
D)  lysine. 
E)  glutamate. 
A)  asparagine. 
B)  threonine. 
C)  methionine. 
D)  lysine. 
E)  glutamate. E

Question 4

Aspartate is formed from transamination of:

Accepted Answer

A)  asparagine. 
B)  aspartame. 
C)  oxaloacetate. 
D)  citrate. 
E)  α-ketoglutarate. 
A)  asparagine. 
B)  aspartame. 
C)  oxaloacetate. 
D)  citrate. 
E)  α-ketoglutarate.

Question 5

Degradation of valine, isoleucine and methionine leads to succinyl-CoA via the sequence of:
A.carboxylation using biotin and ATP
B.mutase
C.methylmalonyl-CoA
D.epimerase
E.Propionyl-CoA

Accepted Answer

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

Question 6

The reaction, 2 NH4+ + α-ketoglutarate + NADPH + ATP → glutamine + NADP+ + ADP + Pi + H2O, is the combined result of what two enzymes?

Accepted Answer

A)  first, glutamate synthase, then glutamate dehydrogenase 
B)  first, glutamate dehydrogenase ,then glutamine synthetase 
C)  first, glutamine synthetase, then glutamate synthase 
D)  first, glutamine synthetase, then glutamate dehydrogenase 
E)  none of the above 
A)  first, glutamate synthase, then glutamate dehydrogenase 
B)  first, glutamate dehydrogenase ,then glutamine synthetase 
C)  first, glutamine synthetase, then glutamate synthase 
D)  first, glutamine synthetase, then glutamate dehydrogenase 
E)  none of the above

Question 7

Herbicides (e.g., "Roundup") that inhibit biosynthesis of "essential" amino acids are supposedly safe for animal exposure because animals do not have enzymes for:

Accepted Answer

A)  synthesis of the members of the 3-phosphoglycerate family 
B)  the glyoxylate cycle. 
C)  the glutamine synthesis pathway. 
D)  Phe, Val, Leu, and Ile biosynthetic pathways. 
E)  none are correct. 
A)  synthesis of the members of the 3-phosphoglycerate family 
B)  the glyoxylate cycle. 
C)  the glutamine synthesis pathway. 
D)  Phe, Val, Leu, and Ile biosynthetic pathways. 
E)  none are correct.

Question 8

All of the following act in feedback inhibition of glutamine synthetase in prokaryotes EXCEPT:

Accepted Answer

A)  AMP. 
B)  glucosamine-6-phosphate. 
C)  histidine. 
D)  proline. 
E)  CTP. 
A)  AMP. 
B)  glucosamine-6-phosphate. 
C)  histidine. 
D)  proline. 
E)  CTP.

Question 9

Transamination of pyruvate with glutamate as amino donor gives:

Accepted Answer

A)  alanine. 
B)  serine. 
C)  cysteine. 
D)  aspartate. 
E)  valine. 
A)  alanine. 
B)  serine. 
C)  cysteine. 
D)  aspartate. 
E)  valine.

Question 10

All of the following are characteristics of alkaptonuria EXCEPT:

Accepted Answer

A)  excretion of homogentisate 
B)  air oxidation causes urine to turn dark on standing 
C)  results in mental retardation due to accumulation of Phe metabolites 
D)  homogentisate accumulation in joints may cause arthritis 
E)  all are true 
A)  excretion of homogentisate 
B)  air oxidation causes urine to turn dark on standing 
C)  results in mental retardation due to accumulation of Phe metabolites 
D)  homogentisate accumulation in joints may cause arthritis 
E)  all are true

Question 11

Nitrogen fixation involves the enzyme ____ catalyzing the reaction:
N2 + 10 ____ + ____ e− → 2 NH4+ + H2

Accepted Answer

A)  nitrate reductase; H2O; 6 
B)  nitrogenase; H+; 8 
C)  nitrogenase; H+; 2 
D)  nitrogen reductase; H2O; 6 
E)  none are true 
A)  nitrate reductase; H2O; 6 
B)  nitrogenase; H+; 8 
C)  nitrogenase; H+; 2 
D)  nitrogen reductase; H2O; 6 
E)  none are true

Question 12

All are convergent metabolic intermediates of α-amino acid carbon skeletons EXCEPT:

Accepted Answer

A)  Citrate. 
B)  α-ketoglutarate. 
C)  Oxaloacetate. 
D)  succinyl-CoA. 
E)  Fumarate. 
A)  Citrate. 
B)  α-ketoglutarate. 
C)  Oxaloacetate. 
D)  succinyl-CoA. 
E)  Fumarate.

Question 13

Which of the following directly serves as one of the nitrogen atoms of a urea molecule?

Accepted Answer

A)  the amide N of Asn 
B)  the N of Asp 
C)  the R-group N of Lys 
D)  the N of glucosamine 
E)  none of the above 
A)  the amide N of Asn 
B)  the N of Asp 
C)  the R-group N of Lys 
D)  the N of glucosamine 
E)  none of the above

Question 14

The carbon skeletons of all of the amino acids below converge to pyruvate EXCEPT:

Accepted Answer

A)  alanine. 
B)  serine. 
C)  cysteine. 
D)  glycine. 
E)  glutamate. 
A)  alanine. 
B)  serine. 
C)  cysteine. 
D)  glycine. 
E)  glutamate.

Question 15

Explain the regulation of glutamine synthetase through gene regulation in E. coli.​

Accepted Answer

The gene that encodes the GS subunit in

Question 16

Glutamine synthetase plays an important role in the incorporation of ammonia (or ammonium ions) into glutamine. Which of the following mechanisms of covalent modification controls the activity of glutamine synthetase?

Accepted Answer

A)  Phosphorylation/dephosphorylation 
B)  Adenylation/deadenylation 
C)  Acetylation/deacetylation 
D)  Methylation/demethylation 
E)  None of the above 
A)  Phosphorylation/dephosphorylation 
B)  Adenylation/deadenylation 
C)  Acetylation/deacetylation 
D)  Methylation/demethylation 
E)  None of the above

Question 17

All of the following are true of transamination EXCEPT:

Accepted Answer

A)  It is characterized by the transfer of an α-amino group from an amino acid to the α-keto position of an α-keto acid. 
B)  The amino donor becomes an α-keto acid. 
C)  The coenzyme needed is thiamin pyrophosphate (TPP). 
D)  Humans are capable of synthesizing the α-keto acid analog of nonessential amino acids and using transamination to form the amino acids, but are not able to construct carbon skeletons of the essential amino acids. 
E)  The α-keto acid acceptor becomes an α-amino acid. 
A)  It is characterized by the transfer of an α-amino group from an amino acid to the α-keto position of an α-keto acid. 
B)  The amino donor becomes an α-keto acid. 
C)  The coenzyme needed is thiamin pyrophosphate (TPP). 
D)  Humans are capable of synthesizing the α-keto acid analog of nonessential amino acids and using transamination to form the amino acids, but are not able to construct carbon skeletons of the essential amino acids. 
E)  The α-keto acid acceptor becomes an α-amino acid.

Question 18

Glutamine synthetase is activated by which of the following molecules?

Accepted Answer

A)  glycine 
B)  AMP 
C)  CTP 
D)  carbamoyl phosphate 
E)  none of the above 
A)  glycine 
B)  AMP 
C)  CTP 
D)  carbamoyl phosphate 
E)  none of the above

Question 19

Discuss the products of tryptophan degradation.​

Accepted Answer

Tryptophan (Trp) is a crucial precursor

Question 20

Animals are totally dependent on plants and microorganisms for nitrogen fixation and nitrate assimilation because animals:

Accepted Answer

A)  do not have the reducing power (NADPH) to fix nitrogen. 
B)  lack the enzyme aminotransferase. 
C)  lack the enzymes to reduce N2 and NO3− to NH4+. 
D)  lack carbamoyl-phosphate synthetase I. 
E)  lack glutamate dehydrogenase. 
A)  do not have the reducing power (NADPH) to fix nitrogen. 
B)  lack the enzyme aminotransferase. 
C)  lack the enzymes to reduce N2 and NO3− to NH4+. 
D)  lack carbamoyl-phosphate synthetase I. 
E)  lack glutamate dehydrogenase.

Exam 25: Nitrogen Acquisition and Amino Acid Metabolism

All N2-fixing systems are nearly identical and have all of the requirements EXCEPT:

All of the following are characteristic features of ATP:GS:adenylyl transferase (AT) EXCEPT:

Amino acids biosynthesized from aspartate include all EXCEPT:

Aspartate is formed from transamination of:

Degradation of valine, isoleucine and methionine leads to succinyl-CoA via the sequence of: A.carboxylation using biotin and ATP B.mutase C.methylmalonyl-CoA D.epimerase E.Propionyl-CoA

The reaction, 2 NH4+ + α-ketoglutarate + NADPH + ATP → glutamine + NADP+ + ADP + Pi + H2O, is the combined result of what two enzymes?

Herbicides (e.g., "Roundup") that inhibit biosynthesis of "essential" amino acids are supposedly safe for animal exposure because animals do not have enzymes for:

All of the following act in feedback inhibition of glutamine synthetase in prokaryotes EXCEPT:

Transamination of pyruvate with glutamate as amino donor gives:

All of the following are characteristics of alkaptonuria EXCEPT:

Nitrogen fixation involves the enzyme ____ catalyzing the reaction: N2 + 10 ____ + ____ e− → 2 NH4+ + H2

All are convergent metabolic intermediates of α-amino acid carbon skeletons EXCEPT:

Which of the following directly serves as one of the nitrogen atoms of a urea molecule?

The carbon skeletons of all of the amino acids below converge to pyruvate EXCEPT:

Explain the regulation of glutamine synthetase through gene regulation in E. coli.​

Glutamine synthetase plays an important role in the incorporation of ammonia (or ammonium ions) into glutamine. Which of the following mechanisms of covalent modification controls the activity of glutamine synthetase?

All of the following are true of transamination EXCEPT:

Glutamine synthetase is activated by which of the following molecules?

Discuss the products of tryptophan degradation.​

Animals are totally dependent on plants and microorganisms for nitrogen fixation and nitrate assimilation because animals:

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

All N₂-fixing systems are nearly identical and have all of the requirements EXCEPT:

The reaction, 2 NH₄⁺ + α-ketoglutarate + NADPH + ATP → glutamine + NADP⁺ + ADP + P_i + H₂O, is the combined result of what two enzymes?

Nitrogen fixation involves the enzyme catalyzing the reaction: N₂ + 10 + e− → 2 NH₄⁺ + H₂

Explain the regulation of glutamine synthetase through gene regulation in E. coli.

Discuss the products of tryptophan degradation.