Question 1

Which drug is NOT chemotherapeutic?

Accepted Answer

A)  Azaserine 
B)  Allopurinol 
C)  Fluorouracil 
D)  Methotrexate 
E)  Acivicin 
A)  Azaserine 
B)  Allopurinol 
C)  Fluorouracil 
D)  Methotrexate 
E)  Acivicin

Question 2

The enzymatic machinery to fix atmospheric N2 into NH4+ is:

Accepted Answer

A)  a means of producing ATP when excess N2 is available. 
B)  composed of two key proteins, each containing iron. 
C)  relatively stable when exposed to O2. 
D)  specific to plant cells. 
E)  unaffected by the supply of electrons. 
A)  a means of producing ATP when excess N2 is available. 
B)  composed of two key proteins, each containing iron. 
C)  relatively stable when exposed to O2. 
D)  specific to plant cells. 
E)  unaffected by the supply of electrons.

Question 3

Diagram the biosynthetic pathway from UMP to dTTP. Use abbreviations (e.g., UMP), not complete structures, and indicate where any co-substrates participate.

Accepted Answer

The biosynthetic pathway from UMP to dTT

Question 4

Glutamine, arginine, and proline:

Accepted Answer

A)  do not have a common precursor. 
B)  may all be derived from a citric acid cycle intermediate. 
C)  may all be derived from a Cori cycle intermediate. 
D)  may all be derived from a glycolytic intermediate. 
E)  may all be derived from a urea cycle intermediate. 
A)  do not have a common precursor. 
B)  may all be derived from a citric acid cycle intermediate. 
C)  may all be derived from a Cori cycle intermediate. 
D)  may all be derived from a glycolytic intermediate. 
E)  may all be derived from a urea cycle intermediate.

Question 5

Which amino acid is NOT considered to originate from $\alpha$-ketoglutarate?

Accepted Answer

A)  arginine 
B)  glutamate 
C)  glutamine 
D)  histidine 
E)  proline 
A)  arginine 
B)  glutamate 
C)  glutamine 
D)  histidine 
E)  proline

Question 6

Cytidylate synthetase (CTP synthetase) is allosterically regulated by both ATP and UTP. How do you predict they will affect the activity of this enzyme?

Accepted Answer

Cytidylate synthetase, also known as CTP

Question 7

Carbamoyl phosphate synthetase II is activated by ATP and PRPP but inhibited by UMP. How does this make metabolic sense? How does it compare to the regulation of ATCase?

Accepted Answer

Carbamoyl phosphate synthetase II (CPS I

Question 8

Which cofactor or functional group within the context of the nitrate reductase electron-transport chain has the HIGHEST reduction potential?

Accepted Answer

A)  cysteine 
B)  NAD+ 
C)  FAD 
D)  molybdenum cofactor 
E)  cyt b557 
A)  cysteine 
B)  NAD+ 
C)  FAD 
D)  molybdenum cofactor 
E)  cyt b557

Question 9

Erythrose 4-phosphate is a precursor of:

Accepted Answer

A)  aspartate. 
B)  cysteine. 
C)  phenylalanine. 
D)  serine. 
E)  threonine. 
A)  aspartate. 
B)  cysteine. 
C)  phenylalanine. 
D)  serine. 
E)  threonine.

Question 10

Orotic aciduria is an inherited metabolic disease in which orotic acid (orotate) accumulates in the tissues, blood, and urine. The metabolic pathway in which the enzyme defect occurs is:

Accepted Answer

A)  epinephrine synthesis. 
B)  purine breakdown. 
C)  purine synthesis. 
D)  pyrimidine breakdown. 
E)  pyrimidine synthesis. 
A)  epinephrine synthesis. 
B)  purine breakdown. 
C)  purine synthesis. 
D)  pyrimidine breakdown. 
E)  pyrimidine synthesis.

Question 11

Bile pigments are:

Accepted Answer

A)  formed in the degradation of heme. 
B)  generated by oxidation of sterols. 
C)  responsible for light reception in the vertebrate eye. 
D)  secreted from the pancreas 
E)  the products of purine degradation. 
A)  formed in the degradation of heme. 
B)  generated by oxidation of sterols. 
C)  responsible for light reception in the vertebrate eye. 
D)  secreted from the pancreas 
E)  the products of purine degradation.

Question 12

If glucose labeled with 14C at C-1 were the starting material for amino acid biosynthesis, the product that would be readily formed is:

Accepted Answer

A)  serine labeled at the carboxyl carbon. 
B)  serine labeled at alpha carbon. 
C)  serine labeled at the R-group carbon. 
D)  All of the answers are correct. 
E)  None of the answers is correct. 
A)  serine labeled at the carboxyl carbon. 
B)  serine labeled at alpha carbon. 
C)  serine labeled at the R-group carbon. 
D)  All of the answers are correct. 
E)  None of the answers is correct.

Question 13

Which statement is TRUE regarding Class I ribonucleotide reductase?

Accepted Answer

A)  The $\beta$ subunit contains the regulatory sites for the enzyme. 
B)  The $\alpha$ subunit contains the active site cysteines. 
C)  The $\alpha$ subunit contains the binuclear iron center. 
D)  This enzyme catalyzes a hydrolysis reaction. 
E)  ATP is an inhibitor for most isoforms of this enzyme. 
A)  The $\beta$ subunit contains the regulatory sites for the enzyme. 
B)  The $\alpha$ subunit contains the active site cysteines. 
C)  The $\alpha$ subunit contains the binuclear iron center. 
D)  This enzyme catalyzes a hydrolysis reaction. 
E)  ATP is an inhibitor for most isoforms of this enzyme.

Question 14

The nitrogen atom in the indole ring of tryptophan is derived from which amino acid?

Accepted Answer

A)  aspartic acid 
B)  glutamic acid 
C)  glutamine 
D)  asparagine 
E)  arginine 
A)  aspartic acid 
B)  glutamic acid 
C)  glutamine 
D)  asparagine 
E)  arginine

Question 15

Which statement is TRUE regarding the regulation of nitrogen fixation?

Accepted Answer

A)  High concentrations of ADP will activate nitrogen fixation enzymes. 
B)  Elevated concentrations of ammonia will reduce expression of genes associated with nitrogen fixation. 
C)  ATP acts as a negative allosteric effector for nitrogenase. 
D)  Nitrogenase is regulated via adenylylation. 
E)  Oxygen acts as an allosteric effector for the nitrogenase complex. 
A)  High concentrations of ADP will activate nitrogen fixation enzymes. 
B)  Elevated concentrations of ammonia will reduce expression of genes associated with nitrogen fixation. 
C)  ATP acts as a negative allosteric effector for nitrogenase. 
D)  Nitrogenase is regulated via adenylylation. 
E)  Oxygen acts as an allosteric effector for the nitrogenase complex.

Question 16

An animal cell is capable of converting alanine into serine. What is the shortest pathway using known enzymes by which this conversion could be accomplished? Show intermediates and cofactors; no enzyme names are required. (Hint: The first step is removal of the nitrogen by transamination.)

Accepted Answer

The conversion of alanine to serine in a

Question 17

The amino acid that gives rise to the biological messenger NO is:

Accepted Answer

A)  glutamine. 
B)  arginine. 
C)  proline. 
D)  lysine. 
E)  histidine. 
A)  glutamine. 
B)  arginine. 
C)  proline. 
D)  lysine. 
E)  histidine.

Question 18

The plant hormone indole-3-acetate (auxin) is formed from:

Accepted Answer

A)  arginine. 
B)  histidine. 
C)  phenylalanine. 
D)  threonine. 
E)  tryptophan. 
A)  arginine. 
B)  histidine. 
C)  phenylalanine. 
D)  threonine. 
E)  tryptophan.

Question 19

Glutathione is a(n):

Accepted Answer

A)  enzyme essential in the synthesis of glutamate. 
B)  isomer of oxidized glutamic acid. 
C)  methyl-group donor in many biosynthetic pathways. 
D)  product of glutamate and methionine. 
E)  tripeptide of glycine, glutamate, and cysteine. 
A)  enzyme essential in the synthesis of glutamate. 
B)  isomer of oxidized glutamic acid. 
C)  methyl-group donor in many biosynthetic pathways. 
D)  product of glutamate and methionine. 
E)  tripeptide of glycine, glutamate, and cysteine.

Question 20

Describe two types of regulation of the enzyme glutamine synthetase and explain why the regulation of this enzyme is so complex.

Accepted Answer

Glutamine synthetase is an important enz

Exam 22: Biosynthesis of Amino Acids, Nucleotides, and Related Molecules

Which drug is NOT chemotherapeutic?

The enzymatic machinery to fix atmospheric N2 into NH4+ is:

Diagram the biosynthetic pathway from UMP to dTTP. Use abbreviations (e.g., UMP), not complete structures, and indicate where any co-substrates participate.

Glutamine, arginine, and proline:

Which amino acid is NOT considered to originate from α\alphaα -ketoglutarate?

Cytidylate synthetase (CTP synthetase) is allosterically regulated by both ATP and UTP. How do you predict they will affect the activity of this enzyme?

Carbamoyl phosphate synthetase II is activated by ATP and PRPP but inhibited by UMP. How does this make metabolic sense? How does it compare to the regulation of ATCase?

Which cofactor or functional group within the context of the nitrate reductase electron-transport chain has the HIGHEST reduction potential?

Erythrose 4-phosphate is a precursor of:

Orotic aciduria is an inherited metabolic disease in which orotic acid (orotate) accumulates in the tissues, blood, and urine. The metabolic pathway in which the enzyme defect occurs is:

Bile pigments are:

If glucose labeled with 14C at C-1 were the starting material for amino acid biosynthesis, the product that would be readily formed is:

Which statement is TRUE regarding Class I ribonucleotide reductase?

The nitrogen atom in the indole ring of tryptophan is derived from which amino acid?

Which statement is TRUE regarding the regulation of nitrogen fixation?

An animal cell is capable of converting alanine into serine. What is the shortest pathway using known enzymes by which this conversion could be accomplished? Show intermediates and cofactors; no enzyme names are required. (Hint: The first step is removal of the nitrogen by transamination.)

The amino acid that gives rise to the biological messenger NO is:

The plant hormone indole-3-acetate (auxin) is formed from:

Glutathione is a(n):

Describe two types of regulation of the enzyme glutamine synthetase and explain why the regulation of this enzyme is so complex.

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

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Hormonal Regulation and Integration of Mammalian Metabolism

Genes and Chromosomes

DNA Metabolism

RNA Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

The enzymatic machinery to fix atmospheric N₂ into NH₄⁺ is:

Which amino acid is NOT considered to originate from $\alpha$ -ketoglutarate?

If glucose labeled with ¹⁴C at C-1 were the starting material for amino acid biosynthesis, the product that would be readily formed is: