Question 1

Give the equations for the two-step reaction sequence catalyzed by glutamine synthetase.

Accepted Answer

Glutamine synthetase catalyzes the biosy

Question 2

Which statement is FALSE regarding the synthesis of glycine from 3-phosphoglycerate (3PG)?

Accepted Answer

A)  Oxidation of 3PG creates an $\alpha$-keto acid. 
B)  Pyridoxal phosphate is a required cofactor for this process. 
C)  The uncommon amino acid phosphoserine is an intermediate in the process. 
D)  A dehydration reaction produces glycine from serine. 
E)  A phosphatase catalyzes one of the reaction steps. 
A)  Oxidation of 3PG creates an $\alpha$-keto acid. 
B)  Pyridoxal phosphate is a required cofactor for this process. 
C)  The uncommon amino acid phosphoserine is an intermediate in the process. 
D)  A dehydration reaction produces glycine from serine. 
E)  A phosphatase catalyzes one of the reaction steps.

Question 3

Precursors for the biosynthesis of the pyrimidine ring system include:

Accepted Answer

A)  carbamoyl phosphate and aspartate. 
B)  glutamate, NH3, and CO2. 
C)  glycine and succinyl-CoA. 
D)  glycine, glutamine, CO2, and aspartate. 
E)  inosine and aspartate. 
A)  carbamoyl phosphate and aspartate. 
B)  glutamate, NH3, and CO2. 
C)  glycine and succinyl-CoA. 
D)  glycine, glutamine, CO2, and aspartate. 
E)  inosine and aspartate.

Question 4

Which statement is FALSE regarding ladderanes?

Accepted Answer

A)  Ladderanes are classified as phospholipids. 
B)  Ladderanes are associated with annamoxosomes. 
C)  Ladderanes are amphipathic membrane components. 
D)  Ladderanes have less conformational flexibility than equivalent fatty acids. 
E)  None of the statements is false. 
A)  Ladderanes are classified as phospholipids. 
B)  Ladderanes are associated with annamoxosomes. 
C)  Ladderanes are amphipathic membrane components. 
D)  Ladderanes have less conformational flexibility than equivalent fatty acids. 
E)  None of the statements is false.

Question 5

Which molecule is NOT a high-energy molecule involved in the synthesis of arginine from glutamate?

Accepted Answer

A)  Acetyl-CoA 
B)  ATP 
C)  NADH/NADPH 
D)  FADH2 
E)  All of these molecules are involved in this pathway. 
A)  Acetyl-CoA 
B)  ATP 
C)  NADH/NADPH 
D)  FADH2 
E)  All of these molecules are involved in this pathway.

Question 6

Show the biosynthetic pathway for the conversion of a citric acid cycle intermediate into proline. Indicate where any cofactors participate.

Accepted Answer

The biosynthetic pathway for the convers

Question 7

Degradation of purines in primates leads to the formation of what major excreted product?

Accepted Answer

A)  allantoin 
B)  ammonia 
C)  hypoxanthine 
D)  urea 
E)  uric acid 
A)  allantoin 
B)  ammonia 
C)  hypoxanthine 
D)  urea 
E)  uric acid

Question 8

A cell that is unable to synthesize or obtain tetrahydrofolic acid (H4 folate) would probably be deficient in the biosynthesis of:

Accepted Answer

A)  CMP. 
B)  GMP. 
C)  orotate. 
D)  thymidylate (TMP). 
E)  UMP. 
A)  CMP. 
B)  GMP. 
C)  orotate. 
D)  thymidylate (TMP). 
E)  UMP.

Question 9

Which statement is FALSE regarding aspartate transcarbamoylase (ATCase) in prokaryotes?

Accepted Answer

A)  This enzyme catalyzes the rate-limiting step in cytidine biosynthesis. 
B)  This enzyme is inhibited by pyrimidine triphosphates. 
C)  Aspartate is a homotropic activator for ATCase. 
D)  CTP is a heterotropic inhibitor for ATCase. 
E)  ATCase is regulated by product inhibition. 
A)  This enzyme catalyzes the rate-limiting step in cytidine biosynthesis. 
B)  This enzyme is inhibited by pyrimidine triphosphates. 
C)  Aspartate is a homotropic activator for ATCase. 
D)  CTP is a heterotropic inhibitor for ATCase. 
E)  ATCase is regulated by product inhibition.

Question 10

The hormones epinephrine and norepinephrine are derived biosynthetically from:

Accepted Answer

A)  arginine. 
B)  histidine. 
C)  isoleucine. 
D)  tryptophan. 
E)  tyrosine. 
A)  arginine. 
B)  histidine. 
C)  isoleucine. 
D)  tryptophan. 
E)  tyrosine.

Question 11

Explain how lack of adenosine deaminase leads to a 100-fold increase in dATP, yet also causes a deficiency in dNTPs required for replication of T-cells and B-cells required for a functioning immune system.

Accepted Answer

Adenosine deaminase (ADA) is an enzyme t

Question 12

Which statement CORRECTLY describes the biosynthetic pathway for purine nucleotides?

Accepted Answer

A)  Purine deoxynucleotides are made by the same path as ribonucleotides, followed by reduction of the ribose moiety. 
B)  The first enzyme in the path is aspartate transcarbamoylase (ATCase). 
C)  The nitrogen in the purine base that is bonded to ribose in the nucleotide is derived originally from glycine. 
D)  The pathway occurs only in plants and bacteria, not in animals. 
E)  The purine rings are first synthesized, then condensed with ribose phosphate. 
A)  Purine deoxynucleotides are made by the same path as ribonucleotides, followed by reduction of the ribose moiety. 
B)  The first enzyme in the path is aspartate transcarbamoylase (ATCase). 
C)  The nitrogen in the purine base that is bonded to ribose in the nucleotide is derived originally from glycine. 
D)  The pathway occurs only in plants and bacteria, not in animals. 
E)  The purine rings are first synthesized, then condensed with ribose phosphate.

Question 13

Which statement about the fixation of atmospheric nitrogen (N2) into NH3 by living cells is FALSE?

Accepted Answer

A)  It involves the transfer of eight electrons per mol of N2. 
B)  It occurs in certain microorganisms, but not in humans. 
C)  It requires a source of electrons, normally ferredoxin. 
D)  It requires one ATP per mol of N2 fixed. 
E)  It requires two key protein components, each containing iron. 
A)  It involves the transfer of eight electrons per mol of N2. 
B)  It occurs in certain microorganisms, but not in humans. 
C)  It requires a source of electrons, normally ferredoxin. 
D)  It requires one ATP per mol of N2 fixed. 
E)  It requires two key protein components, each containing iron.

Question 14

The nitrogen atom in the side chain of lysine 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 does NOT accurately describe a difference between heme b and the siroheme found in nitrite reductase?

Accepted Answer

A)  Siroheme contains larger negative charge than heme b. 
B)  Siroheme contains no vinyl groups, while heme b does. 
C)  Siroheme contains tetrahedral carbons in the porphyrin ring, while heme b does not. 
D)  Siroheme contains four propionate groups, while heme b contains two. 
E)  Siroheme contains Fe2+, while heme b contains Fe3+. 
A)  Siroheme contains larger negative charge than heme b. 
B)  Siroheme contains no vinyl groups, while heme b does. 
C)  Siroheme contains tetrahedral carbons in the porphyrin ring, while heme b does not. 
D)  Siroheme contains four propionate groups, while heme b contains two. 
E)  Siroheme contains Fe2+, while heme b contains Fe3+.

Question 16

In purine biosynthesis, which ring nitrogens are contributed by the sidechain of glutamine?

Accepted Answer

A)  N1 only 
B)  N1 and N3 
C)  N1, N3, and N9 
D)  N1 and N9 
E)  N3 and N9 
A)  N1 only 
B)  N1 and N3 
C)  N1, N3, and N9 
D)  N1 and N9 
E)  N3 and N9

Question 17

Which amino acid derives its nitrogen from a purine ring?

Accepted Answer

A)  histidine 
B)  lysine 
C)  arginine 
D)  glutamine 
E)  tryptophan 
A)  histidine 
B)  lysine 
C)  arginine 
D)  glutamine 
E)  tryptophan

Question 18

In which group are all the amino acids closely interrelated metabolically?

Accepted Answer

A)  arginine, hydroxyproline, and histidine 
B)  arginine, tyrosine, and glutamate 
C)  glycine, valine, glutamine, and aspartate 
D)  ornithine, alanine, glycine, and valine 
E)  ornithine, proline, arginine, and glutamate 
A)  arginine, hydroxyproline, and histidine 
B)  arginine, tyrosine, and glutamate 
C)  glycine, valine, glutamine, and aspartate 
D)  ornithine, alanine, glycine, and valine 
E)  ornithine, proline, arginine, and glutamate

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

Give the equations for the two-step reaction sequence catalyzed by glutamine synthetase.

Which statement is FALSE regarding the synthesis of glycine from 3-phosphoglycerate (3PG)?

Precursors for the biosynthesis of the pyrimidine ring system include:

Which statement is FALSE regarding ladderanes?

Which molecule is NOT a high-energy molecule involved in the synthesis of arginine from glutamate?

Show the biosynthetic pathway for the conversion of a citric acid cycle intermediate into proline. Indicate where any cofactors participate.

Degradation of purines in primates leads to the formation of what major excreted product?

A cell that is unable to synthesize or obtain tetrahydrofolic acid (H4 folate) would probably be deficient in the biosynthesis of:

Which statement is FALSE regarding aspartate transcarbamoylase (ATCase) in prokaryotes?

The hormones epinephrine and norepinephrine are derived biosynthetically from:

Explain how lack of adenosine deaminase leads to a 100-fold increase in dATP, yet also causes a deficiency in dNTPs required for replication of T-cells and B-cells required for a functioning immune system.

Which statement CORRECTLY describes the biosynthetic pathway for purine nucleotides?

Which statement about the fixation of atmospheric nitrogen (N2) into NH3 by living cells is FALSE?

The nitrogen atom in the side chain of lysine is derived from which amino acid?

Which statement does NOT accurately describe a difference between heme b and the siroheme found in nitrite reductase?

In purine biosynthesis, which ring nitrogens are contributed by the sidechain of glutamine?

Which amino acid derives its nitrogen from a purine ring?

In which group are all the amino acids closely interrelated metabolically?

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

A cell that is unable to synthesize or obtain tetrahydrofolic acid (H₄ folate) would probably be deficient in the biosynthesis of:

Which statement about the fixation of atmospheric nitrogen (N₂) into NH₃ by living cells is FALSE?