Question 1

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 A

Question 2

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

Accepted Answer

A) True 
 B)False  False

Question 3

The form in which nitrogen waste is removed from the body is dependent mostly on the organism's availability of water.

Accepted Answer

A) True 
 B)False  True

Question 4

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 5

A coenzyme frequently encountered in transamination reactions is

Accepted Answer

A)  tetrahydrofolate. 
B)  pyridoxal phosphate. 
C)  thiamine pyrophosphate. 
D)  biotin. 
A)  tetrahydrofolate. 
B)  pyridoxal phosphate. 
C)  thiamine pyrophosphate. 
D)  biotin.

Question 6

Pyridoxal phosphate forms a Schiff base with amino groups in transaminase reactions.

Accepted Answer

A) True 
 B)False

Question 7

Some amino acids can only be made in small quantities in humans and must be supplemented in the diet in children or during repair of injured tissue.

Accepted Answer

A) True 
 B)False

Question 8

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 9

Enzymes which carry out one-carbon transfers can use any of these compounds,except:

Accepted Answer

A)  Biotin 
B)  Pyridoxal 
C)  Folic Acid 
D)  S-adenosylmethionine 
E)  All of these can carry out one-carbon transfers. 
A)  Biotin 
B)  Pyridoxal 
C)  Folic Acid 
D)  S-adenosylmethionine 
E)  All of these can carry out one-carbon transfers.

Question 10

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 11

What intermediate of the TCA cycle is produced from aspartic acid during the urea cycle,synthesis of IMP,and conversion from IMP to adenosine?

Accepted Answer

A)  fumarate 
B)  malate 
C)  a-ketoglutarate 
D)  succinate 
A)  fumarate 
B)  malate 
C)  a-ketoglutarate 
D)  succinate

Question 12

Kwashiorkor is a malnutrition disease in which high quality proteins are lacking,even if enough calories are available for survival.

Accepted Answer

A) True 
 B)False

Question 13

Which of the following is not associated with purine synthesis?

Accepted Answer

A)  Synthesis of the base while ribose is attached. 
B)  Stimulation of ATP synthesis by GTP and of GTP synthesis by ATP 
C)  An Inosine intermediate. 
D)  Inhibition by pyrimidines. 
E)  All of these are features of purine synthesis. 
A)  Synthesis of the base while ribose is attached. 
B)  Stimulation of ATP synthesis by GTP and of GTP synthesis by ATP 
C)  An Inosine intermediate. 
D)  Inhibition by pyrimidines. 
E)  All of these are features of purine synthesis.

Question 14

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.

Question 15

Which of the following is not true regarding ammonia and fertilizers?

Accepted Answer

A)  Ammonia gas is seldom an effective plant fertilizer, since it is usually consumed by the bacteria in the soil. 
B)  Many fertilizers are made from ammonia synthesized by the Haber process 
C)  Researchers are looking for ways to incorporate the genes for nitrogenase into crop plants so that not as much fertilizer is needed 
D)  Both ammonium and nitrate ions are frequently used in fertilizers 
A)  Ammonia gas is seldom an effective plant fertilizer, since it is usually consumed by the bacteria in the soil. 
B)  Many fertilizers are made from ammonia synthesized by the Haber process 
C)  Researchers are looking for ways to incorporate the genes for nitrogenase into crop plants so that not as much fertilizer is needed 
D)  Both ammonium and nitrate ions are frequently used in fertilizers

Question 16

Nitrogenase uses which of the following cofactors?

Accepted Answer

A)  molybdenum-iron-sulfur complex 
B)  biotin 
C)  pyridoxal phosphate 
D)  thiamine pyrophosphate 
A)  molybdenum-iron-sulfur complex 
B)  biotin 
C)  pyridoxal phosphate 
D)  thiamine pyrophosphate

Question 17

Carbamoyl phosphate is made in both the mitochondria and the cytosol,because it is used in the synthesis of several different molecules which are made in either of the compartments.

Accepted Answer

A) True 
 B)False

Question 18

In the urea cycle,the molecule that is synthesized in the cytosol and transported to the mitochondrial matrix for subsequent reaction is

Accepted Answer

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

Question 19

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 20

Which of the following is not associated with pyrimidine synthesis?

Accepted Answer

A)  Synthesis of the base while ribose is attached. 
B)  Stimulation of synthesis by purines. 
C)  An orotic acid intermediate. 
D)  Inhibition by pyrimidines. 
E)  All of these are features of pyrimidine synthesis. 
A)  Synthesis of the base while ribose is attached. 
B)  Stimulation of synthesis by purines. 
C)  An orotic acid intermediate. 
D)  Inhibition by pyrimidines. 
E)  All of these are features of pyrimidine synthesis.

Exam 23: The Metabolism of Nitrogen

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

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

The form in which nitrogen waste is removed from the body is dependent mostly on the organism's availability of water.

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.

A coenzyme frequently encountered in transamination reactions is

Pyridoxal phosphate forms a Schiff base with amino groups in transaminase reactions.

Some amino acids can only be made in small quantities in humans and must be supplemented in the diet in children or during repair of injured tissue.

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

Enzymes which carry out one-carbon transfers can use any of these compounds,except:

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

What intermediate of the TCA cycle is produced from aspartic acid during the urea cycle,synthesis of IMP,and conversion from IMP to adenosine?

Kwashiorkor is a malnutrition disease in which high quality proteins are lacking,even if enough calories are available for survival.

Which of the following is not associated with purine synthesis?

The two nitrogens in urea arise directly from:

Which of the following is not true regarding ammonia and fertilizers?

Nitrogenase uses which of the following cofactors?

Carbamoyl phosphate is made in both the mitochondria and the cytosol,because it is used in the synthesis of several different molecules which are made in either of the compartments.

In the urea cycle,the molecule that is synthesized in the cytosol and transported to the mitochondrial matrix for subsequent reaction is

Humans produce these as the major nitrogen waste products.

Which of the following is not associated with pyrimidine synthesis?

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