Question 1

The two nitrogens in urea arise directly from:

Accepted Answer

A)  Ammonia and aspartic acid. 
B)  Carbamoyl phosphate and aspartic acid. 
C)  Carbamoyl phosphate and glutamic acid. 
D)  Ammonia and glutamic acid. 
E)  Carbamoyl phosphate and glutamine. 
A)  Ammonia and aspartic acid. 
B)  Carbamoyl phosphate and aspartic acid. 
C)  Carbamoyl phosphate and glutamic acid. 
D)  Ammonia and glutamic acid. 
E)  Carbamoyl phosphate and glutamine. B

Question 2

Deoxyribonucleotides are formed

Accepted Answer

A)  by a pathway entirely different from that of ribonucleotides 
B)  exclusively by hydrolysis of the DNA of the organism 
C)  as monophosphates by reduction of ribonucleoside monophosphates 
D)  as diphosphates by reduction of ribonucleoside disphosphates 
A)  by a pathway entirely different from that of ribonucleotides 
B)  exclusively by hydrolysis of the DNA of the organism 
C)  as monophosphates by reduction of ribonucleoside monophosphates 
D)  as diphosphates by reduction of ribonucleoside disphosphates D

Question 3

Nitrogenase uses which of the following cofactors?

Accepted Answer

A)  molybdenum-iron-sulfur complex 
B)  biotin 
C)  pyridoxal phosphate 
D)  thiamine pyrophosphate 
E)  none of these 
A)  molybdenum-iron-sulfur complex 
B)  biotin 
C)  pyridoxal phosphate 
D)  thiamine pyrophosphate 
E)  none of these A

Question 4

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 5

How many ATP equivalents are required to produce one molecule of urea from ammonia and aspartate?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  6 
A)  1 
B)  2 
C)  3 
D)  4 
E)  6

Question 6

How many electrons are required for the reduction of one nitrogen molecule (N2) to two molecules of ammonia (NH3) and molecule of hydrogen (H2)?

Accepted Answer

A)  2 electrons. 
B)  4 electrons. 
C)  6 electrons. 
D)  8 electrons. 
E)  12 electrons. 
A)  2 electrons. 
B)  4 electrons. 
C)  6 electrons. 
D)  8 electrons. 
E)  12 electrons.

Question 7

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

Accepted Answer

A) True 
 B)False

Question 8

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 9

Glycine, alanine, serine, histidine, tryptophan, CTP, AMP, and carbamoyl-phosphate all have what in common?

Accepted Answer

A)  They are all inhibitors of glutamine synthase 
B)  They are all amino acids 
C)  They are all cofactors in transamination reactions 
D)  They are activators of the urea cycle 
A)  They are all inhibitors of glutamine synthase 
B)  They are all amino acids 
C)  They are all cofactors in transamination reactions 
D)  They are activators of the urea cycle

Question 10

Which group of small molecules best fit the boxes associated with the reaction shown?

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  IV 
A)  I 
B)  II 
C)  III 
D)  IV

Question 11

Which of the following is not a component of the nitrogenase complex?

Accepted Answer

A)  a molybdenum complex 
B)  a nonheme iron-sulfur protein (Fe protein) 
C)  ferredoxin 
D)  pyridoxal phosphate 
A)  a molybdenum complex 
B)  a nonheme iron-sulfur protein (Fe protein) 
C)  ferredoxin 
D)  pyridoxal phosphate

Question 12

Fluorouracil is an effective inhibitor of

Accepted Answer

A)  ribonucleotide reductase 
B)  thymidylate synthase 
C)  xanthine oxidase 
D)  carbamoyl phosphate synthetase 
A)  ribonucleotide reductase 
B)  thymidylate synthase 
C)  xanthine oxidase 
D)  carbamoyl phosphate synthetase

Question 13

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 14

One way in which the anabolism of pyrimidine nucleotides differs from that of purine nucleotides is that

Accepted Answer

A)  the pyrimidine ring is assembled before being bonded to the ribose phosphate, whereas the purine ring is bonded to the ribose phosphate as it is formed 
B)  there is no feedback inhibition in the anabolism of pyrimidine nucleotides, while feedback inhibition is important in the synthesis of purine nucleotides 
C)  glycine appears in the pathway for formation of pyrimidine nucleotides but not in that for the formation of purine nucleotides 
D)  argininosuccinate is a key intermediate in pyrimidine biosynthesis 
A)  the pyrimidine ring is assembled before being bonded to the ribose phosphate, whereas the purine ring is bonded to the ribose phosphate as it is formed 
B)  there is no feedback inhibition in the anabolism of pyrimidine nucleotides, while feedback inhibition is important in the synthesis of purine nucleotides 
C)  glycine appears in the pathway for formation of pyrimidine nucleotides but not in that for the formation of purine nucleotides 
D)  argininosuccinate is a key intermediate in pyrimidine biosynthesis

Question 15

Cancer treatments which disrupt the function of folic acid have significant side effects, since this therapy also affects the growth of such rapidly dividing tissues as all of the following, except :

Accepted Answer

A)  Skin cells. 
B)  Red and white blood cells. 
C)  Nerve tissue. 
D)  Sperm. 
E)  All of these cell types are affected by this therapy. 
A)  Skin cells. 
B)  Red and white blood cells. 
C)  Nerve tissue. 
D)  Sperm. 
E)  All of these cell types are affected by this therapy.

Question 16

The carbon skeleton used to make serine is:

Accepted Answer

A)  3-phosphoglycerate 
B)  glutamate 
C)  á -ketoglutarate 
D)  oxaloacetate 
E)  pyruvate 
A)  3-phosphoglycerate 
B)  glutamate 
C)  á -ketoglutarate 
D)  oxaloacetate 
E)  pyruvate

Question 17

The conversion of α -ketoglutarate to glutamate is

Accepted Answer

A)  a transamination. 
B)  a reductive amination. 
C)  an amidation. 
D)  an oxidation. 
E)  an isomerization 
A)  a transamination. 
B)  a reductive amination. 
C)  an amidation. 
D)  an oxidation. 
E)  an isomerization

Question 18

Which of the following is not a carrier of one-carbon groups?

Accepted Answer

A)  S -adenosylmethionine 
B)  biotin 
C)  tetrahydrofolate 
D)  thiamine pyrophosphate 
A)  S -adenosylmethionine 
B)  biotin 
C)  tetrahydrofolate 
D)  thiamine pyrophosphate

Question 19

Which of the following are all essential amino acids in humans?

Accepted Answer

A)  leucine, lysine, valine 
B)  methionine, threonine, serine 
C)  arginine, histidine, cysteine 
D)  glutamate, glutamine, arginine 
E)  valine, isoleucine, glycine 
A)  leucine, lysine, valine 
B)  methionine, threonine, serine 
C)  arginine, histidine, cysteine 
D)  glutamate, glutamine, arginine 
E)  valine, isoleucine, glycine

Question 20

​ The amino acids central to the amino acid biosynthesis process are _____.

Accepted Answer

A)  serine and cysteine 
B)  tyrosine and threonine 
C)  glutamate and glutamine 
D)  asparagine and histamine 
A)  serine and cysteine 
B)  tyrosine and threonine 
C)  glutamate and glutamine 
D)  asparagine and histamine

Exam 23: The Metabolism of Nitrogen

The two nitrogens in urea arise directly from:

Deoxyribonucleotides are formed

Nitrogenase uses which of the following cofactors?

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

How many ATP equivalents are required to produce one molecule of urea from ammonia and aspartate?

How many electrons are required for the reduction of one nitrogen molecule (N2) to two molecules of ammonia (NH3) and molecule of hydrogen (H2)?

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

Which reaction converts orotate monophosphate into uracil monophosphate?

Glycine, alanine, serine, histidine, tryptophan, CTP, AMP, and carbamoyl-phosphate all have what in common?

Which group of small molecules best fit the boxes associated with the reaction shown?

Which of the following is not a component of the nitrogenase complex?

Fluorouracil is an effective inhibitor of

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.

One way in which the anabolism of pyrimidine nucleotides differs from that of purine nucleotides is that

Cancer treatments which disrupt the function of folic acid have significant side effects, since this therapy also affects the growth of such rapidly dividing tissues as all of the following, except :

The carbon skeleton used to make serine is:

The conversion of α -ketoglutarate to glutamate is

Which of the following is not a carrier of one-carbon groups?

Which of the following are all essential amino acids in humans?

​ The amino acids central to the amino acid biosynthesis process are _____.

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 the 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 electrons are required for the reduction of one nitrogen molecule (N₂) to two molecules of ammonia (NH₃) and molecule of hydrogen (H₂)?

The amino acids central to the amino acid biosynthesis process are _____.