Question 1

Which reaction converts orotate monophosphate into uracil monophosphate?

Accepted Answer

A)  a transamination 
B)  a methylation 
C)  a decarboxylation 
D)  a carboxylation 
A)  a transamination 
B)  a methylation 
C)  a decarboxylation 
D)  a carboxylation

Question 2

The synthesis of amino acids occurs in about 5 or 6 related families of amino acids.

Accepted Answer

A) True 
 B)False

Question 3

The energy costs for synthesizing the bases for RNA and DNA is so high that salvage pathways have been developed to recycle existing bases and nucleotides.

Accepted Answer

A) True 
 B)False

Question 4

Ribonucleotide reductase uses which of the following cofactors?

Accepted Answer

A)  biotin 
B)  thiamine pyrophosphate 
C)  tetrahydrofolate 
D)  thioredoxin 
A)  biotin 
B)  thiamine pyrophosphate 
C)  tetrahydrofolate 
D)  thioredoxin

Question 5

Nitrification is the conversion of

Accepted Answer

A)  nitrogen gas to nitrate. 
B)  nitrogen gas to ammonia. 
C)  nitrate to ammonia. 
D)  nitrate to nitrogen gas. 
E)  ammonia to nitrogen gas. 
A)  nitrogen gas to nitrate. 
B)  nitrogen gas to ammonia. 
C)  nitrate to ammonia. 
D)  nitrate to nitrogen gas. 
E)  ammonia to nitrogen gas.

Question 6

Which of the following amino acids does not use glutamic acid as a precursor?

Accepted Answer

A)  arginine 
B)  glutamine 
C)  lysine 
D)  proline 
A)  arginine 
B)  glutamine 
C)  lysine 
D)  proline

Question 7

How many ATP are required for the production of two ammonia molecules (NH3) from one nitrogen molecule (N2)?

Accepted Answer

A)  2 ATP. 
B)  4 ATP. 
C)  8 ATP. 
D)  16 ATP. 
E)  32 ATP. 
A)  2 ATP. 
B)  4 ATP. 
C)  8 ATP. 
D)  16 ATP. 
E)  32 ATP.

Question 8

Lesch-Nyhan syndrome involves a genetic error in the pyrimidine salvage pathways.

Accepted Answer

A) True 
 B)False

Question 9

Humans produce these as the major nitrogen waste products.

Accepted Answer

A)  Ammonia. 
B)  Urea. 
C)  Uric Acid. 
D)  Both Urea and Uric Acid. 
E)  All three of these are used to dispose of nitrogen wastes by humans. 
A)  Ammonia. 
B)  Urea. 
C)  Uric Acid. 
D)  Both Urea and Uric Acid. 
E)  All three of these are used to dispose of nitrogen wastes by humans.

Question 10

Folic acid is an important factor necessary for the production of three of the four deoxyribonucleotides needed for DNA synthesis. For which dNTP is this factor not necessary?

Accepted Answer

A)  dATP 
B)  dCTP 
C)  dGTP 
D)  dTTP 
A)  dATP 
B)  dCTP 
C)  dGTP 
D)  dTTP

Question 11

Isoleucine, leucine and valine are all formed from the same amino acid root, aspartic acid.

Accepted Answer

A) True 
 B)False

Question 12

Which best describes the synthesis of purine nucleotides?

Accepted Answer

A)  The basic ring structure, inosine, is synthesized first and then linked to ribose. This is then modified to produce either GMP or AMP. 
B)  The basic ring structure, orotate, is synthesized stepwise on ribose. This is then modified to produce either GMP or AMP. 
C)  The basic ring structure, inosine, is synthesized stepwise on ribose. This is then modified to produce either GMP or AMP. 
D)  The basic ring structure, orotate, is synthesized first and then linked to ribose. This is then modified to produce either UMP or CMP. 
A)  The basic ring structure, inosine, is synthesized first and then linked to ribose. This is then modified to produce either GMP or AMP. 
B)  The basic ring structure, orotate, is synthesized stepwise on ribose. This is then modified to produce either GMP or AMP. 
C)  The basic ring structure, inosine, is synthesized stepwise on ribose. This is then modified to produce either GMP or AMP. 
D)  The basic ring structure, orotate, is synthesized first and then linked to ribose. This is then modified to produce either UMP or CMP.

Question 13

In animals, the synthesis of cysteine involves all of the following, except:

Accepted Answer

A)  Addition of a carbon group to glycine. 
B)  Transfer of the sulfur group from methionine. 
C)  An intermediate of homocysteine. 
D)  Participation of ATP. 
E)  All of these reactions are involved in synthesizing cysteine in animals. 
A)  Addition of a carbon group to glycine. 
B)  Transfer of the sulfur group from methionine. 
C)  An intermediate of homocysteine. 
D)  Participation of ATP. 
E)  All of these reactions are involved in synthesizing cysteine in animals.

Question 14

Which of the following is not a characteristic of pyridoxal in its active form?

Accepted Answer

A)  It is covalently bonded to its enzyme. 
B)  It requires being attached to a phosphate group. 
C)  It bonds to an amine group through by means of the phosphate group. 
D)  It has a particularly reactive carbonyl group. 
A)  It is covalently bonded to its enzyme. 
B)  It requires being attached to a phosphate group. 
C)  It bonds to an amine group through by means of the phosphate group. 
D)  It has a particularly reactive carbonyl group.

Question 15

Glutamine synthetase is subject to feedback inhibition by which of the following chemicals?

Accepted Answer

A)  histidine 
B)  carbamoyl phosphate 
C)  cytidine triphosphate (CTP) 
D)  All of these 
A)  histidine 
B)  carbamoyl phosphate 
C)  cytidine triphosphate (CTP) 
D)  All of these

Question 16

There is a curious diversity of nature for the two sulfur containing amino acids. Methionine is made from cysteine in bacteria, but cysteine is made from methionine in mammals.

Accepted Answer

A) True 
 B)False

Question 17

Which of the following statements concerning arginine is true?

Accepted Answer

A)  Arginine is only marginally an essential amino acid, since it is made in the urea cycle. 
B)  Aspartic acid is the main amino acid precursor for the carbon chain in arginine. 
C)  Lysine could substitute for arginine as a dietary source for arginine. 
D)  Arginine is only essential in adults. 
A)  Arginine is only marginally an essential amino acid, since it is made in the urea cycle. 
B)  Aspartic acid is the main amino acid precursor for the carbon chain in arginine. 
C)  Lysine could substitute for arginine as a dietary source for arginine. 
D)  Arginine is only essential in adults.

Question 18

A molecule synthesized in the mitochondrial matrix and transported to the cytosol for subsequent reaction is

Accepted Answer

A)  arginine 
B)  argininosuccinate 
C)  citrulline 
D)  ornithine 
A)  arginine 
B)  argininosuccinate 
C)  citrulline 
D)  ornithine

Question 19

The sulfur group in cysteine arises from the same source in plants, animals and bacteria.

Accepted Answer

A) True 
 B)False

Question 20

In the synthesis of purine nucleotides,

Accepted Answer

A)  the ring system is bonded to ribose phosphate only after the complete purine ring is assembled 
B)  the six-membered ring of the purine is assembled first, then the five-membered ring 
C)  there is no requirement for ATP 
D)  the ring system is synthesized onto the ribose phosphate moiety 
A)  the ring system is bonded to ribose phosphate only after the complete purine ring is assembled 
B)  the six-membered ring of the purine is assembled first, then the five-membered ring 
C)  there is no requirement for ATP 
D)  the ring system is synthesized onto the ribose phosphate moiety

Exam 23: The Metabolism of Nitrogen

Which reaction converts orotate monophosphate into uracil monophosphate?

The synthesis of amino acids occurs in about 5 or 6 related families of amino acids.

The energy costs for synthesizing the bases for RNA and DNA is so high that salvage pathways have been developed to recycle existing bases and nucleotides.

Ribonucleotide reductase uses which of the following cofactors?

Nitrification is the conversion of

Which of the following amino acids does not use glutamic acid as a precursor?

How many ATP are required for the production of two ammonia molecules (NH3) from one nitrogen molecule (N2)?

Lesch-Nyhan syndrome involves a genetic error in the pyrimidine salvage pathways.

Humans produce these as the major nitrogen waste products.

Folic acid is an important factor necessary for the production of three of the four deoxyribonucleotides needed for DNA synthesis. For which dNTP is this factor not necessary?

Isoleucine, leucine and valine are all formed from the same amino acid root, aspartic acid.

Which best describes the synthesis of purine nucleotides?

In animals, the synthesis of cysteine involves all of the following, except:

Which of the following is not a characteristic of pyridoxal in its active form?

Glutamine synthetase is subject to feedback inhibition by which of the following chemicals?

There is a curious diversity of nature for the two sulfur containing amino acids. Methionine is made from cysteine in bacteria, but cysteine is made from methionine in mammals.

Which of the following statements concerning arginine is true?

A molecule synthesized in the mitochondrial matrix and transported to the cytosol for subsequent reaction is

The sulfur group in cysteine arises from the same source in plants, animals and bacteria.

In the synthesis of purine nucleotides,

Biochemistry and the Organization of Cells

Water: the Solvent for Biochemical Reactions

Amino Acids and Peptides

The Three-Dimensional Structure of Proteins

Protein Purification and Characterization Techniques

The Behavior of Proteins: Enzymes

The Behavior of Proteins: Enzymes, Mechanisms, and Control

Lipids and Proteins Are Associated in Biological Membranes

Nucleic Acids: How Structure Conveys Information

Biosynthesis of Nucleic Acids: Replication

Transcription of the Genetic Code: Biosynthesis of RNA

Protein Synthesis: Translation of the Genetic Message

Nucleic Acid Biotechnology Techniques

Viruses, Cancer, and Immunology

The Importance of Energy Changes and Electron Transfer in Metabolism

Carbohydrates

Glycolysis

Storage Mechanisms and Control in Carbohydrate Metabolism

The Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Lipid Metabolism

Photosynthesis

Integration of Metabolism: Cellular Signaling

Filters

How many ATP are required for the production of two ammonia molecules (NH₃) from one nitrogen molecule (N₂)?