Question 1

For the following transamination reaction,show the products of the first half of the reaction.

Accepted Answer

The answer of For the following transamination reaction,show the products...

Question 2

The reaction catalyzed by nitrite reductase requires _______ electrons and is summarized as _____________.

Accepted Answer

A) 2;NO3- $\to$ NO2- 
B) 2;NO2- $\to$  NO- 
C) 4;NO2- $\to$  NO- $\to$  NH2OH 
D) 4;NO2- $\to$  NO- $\to$  NH3 
E) 6;NO2- $\to$  NO- $\to$  NH2OH $\to$  NH3 
A) 2;NO3- $\to$ NO2- 
B) 2;NO2- $\to$  NO- 
C) 4;NO2- $\to$  NO- $\to$  NH2OH 
D) 4;NO2- $\to$  NO- $\to$  NH3 
E) 6;NO2- $\to$  NO- $\to$  NH2OH $\to$  NH3 E

Question 3

Ubiquitin is added to _________ residues of the target protein by reaction with the terminal __________ group of ubiquitin.

Accepted Answer

A) lysine;carboxyl 
B) serine;carboxyl 
C) cysteine;carboxyl 
D) glutamate;amine 
E) glutamine;amine 
A) lysine;carboxyl 
B) serine;carboxyl 
C) cysteine;carboxyl 
D) glutamate;amine 
E) glutamine;amine A

Question 4

Which of the following is seen in the transaminase mechanism?

Accepted Answer

A) aldimine formed between pyridoxal and lysine residue 
B) Schiff base 
C) pyridoxamine phosphate that reacts only with an $\alpha$-ketoacid 
D) a carbanion that is resonance stabilized as a quinonoid intermediate 
E) all of the above 
A) aldimine formed between pyridoxal and lysine residue 
B) Schiff base 
C) pyridoxamine phosphate that reacts only with an $\alpha$-ketoacid 
D) a carbanion that is resonance stabilized as a quinonoid intermediate 
E) all of the above

Question 5

What are the products of the following transamination?

Accepted Answer

A) glutamine and pyruvate 
B) $\alpha$-ketoglutarate and alanine 
C) glutamate and alanine 
D) oxaloacetate and alanine 
E) aspartate and pyruvate 
A) glutamine and pyruvate 
B) $\alpha$-ketoglutarate and alanine 
C) glutamate and alanine 
D) oxaloacetate and alanine 
E) aspartate and pyruvate

Question 6

In the nitrogen fixation process,which step of the electron transfer process requires ATP hydrolysis?

Accepted Answer

A) transfer of electron from ferredoxin to the 4Fe-4S complex 
B) transfer of electron from 4Fe-4S complex to the P cluster 
C) transfer of electron from P cluster to iron-molybdenum cofactor (FeMo-co) 
D) transfer of electron from FeMo-co to nitrogen 
E) none of the above 
A) transfer of electron from ferredoxin to the 4Fe-4S complex 
B) transfer of electron from 4Fe-4S complex to the P cluster 
C) transfer of electron from P cluster to iron-molybdenum cofactor (FeMo-co) 
D) transfer of electron from FeMo-co to nitrogen 
E) none of the above

Question 7

Which of the following forms of tetrahydrofolate is correctly paired with the reaction for which it serves as a coenzyme?

Accepted Answer

A) 5,10-methenyl-THF: biosynthesis of purines 
B) 5-methyl-THF: dUMP $\to$ dTMP 
C) 5,10-methylene-THF: glycine $\to$ serine 
D) 5-methyl-THF: methionine $\to$ homocysteine 
E) all of the above 
A) 5,10-methenyl-THF: biosynthesis of purines 
B) 5-methyl-THF: dUMP $\to$ dTMP 
C) 5,10-methylene-THF: glycine $\to$ serine 
D) 5-methyl-THF: methionine $\to$ homocysteine 
E) all of the above

Question 8

What is a PEST sequence in a protein?

Accepted Answer

A) a sequence where phosphorylation occurs at every serine and tyrosine 
B) a sequence that confers resistance to cathepsin-mediated proteolysis 
C) a sequence of phenylalanine-glutamate-serine-threonine that is found in many proteins with half lives less than 2 hours 
D) a sequence that causes ubiquitination of the protein followed by degradation 
E) none of the above 
A) a sequence where phosphorylation occurs at every serine and tyrosine 
B) a sequence that confers resistance to cathepsin-mediated proteolysis 
C) a sequence of phenylalanine-glutamate-serine-threonine that is found in many proteins with half lives less than 2 hours 
D) a sequence that causes ubiquitination of the protein followed by degradation 
E) none of the above

Question 9

Which of the following reactions is highly active in the liver when large amounts of amino acids are moving from extrahepatic tissue to the liver?

Accepted Answer

A) conversion of glutamate to glutamine 
B) oxidation of glutamate by glutamate dehydrogenase 
C) reduction of $\alpha$-ketoglutarate by glutamate dehydrogenase 
D) transamination of glutamate and pyruvate to $\alpha$-ketoglutarate and alanine 
E) none of the above 
A) conversion of glutamate to glutamine 
B) oxidation of glutamate by glutamate dehydrogenase 
C) reduction of $\alpha$-ketoglutarate by glutamate dehydrogenase 
D) transamination of glutamate and pyruvate to $\alpha$-ketoglutarate and alanine 
E) none of the above

Question 10

In the regulation of glutamine synthetase activity,an important regulatory protein,PII exists in two states,one with UMP covalently bound (PII-UMP),the other without (PII).Which of the following statements regarding $\alpha$-ketoglutarate and PII is correct?

Accepted Answer

A) $\alpha$-ketoglutarate binds to PII causing inhibition of adenylyltransferase 
B) $\alpha$-ketoglutarate binds to PII causing activation of adenylyltransferase 
C) $\alpha$-ketoglutarate binds to PII-UMP causing inhibition of adenylyltransferase 
D) $\alpha$-ketoglutarate binds to PII-UMP causing activation of adenylyltransferase 
E) $\alpha$-ketoglutarate does not bind to either form of PII 
A) $\alpha$-ketoglutarate binds to PII causing inhibition of adenylyltransferase 
B) $\alpha$-ketoglutarate binds to PII causing activation of adenylyltransferase 
C) $\alpha$-ketoglutarate binds to PII-UMP causing inhibition of adenylyltransferase 
D) $\alpha$-ketoglutarate binds to PII-UMP causing activation of adenylyltransferase 
E) $\alpha$-ketoglutarate does not bind to either form of PII

Question 11

Which of the following amino acids relies upon the synthesis of carbamoyl phosphate?

Accepted Answer

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

Question 12

Which of the following represents a correct flow of electrons for nitrogen fixation?

Accepted Answer

A) ferredoxin $\to$ Fe protein $\to$ MoFe protein $\to$ N2 
B) Fe protein $\to$ MoFe protein $\to$ ferredoxin $\to$ N2 
C) MoFe protein $\to$ Fe protein $\to$ ferredoxin $\to$ N2 
D) ferredoxin $\to$ MoFe protein $\to$ Fe protein $\to$ N2 
E) none of the above 
A) ferredoxin $\to$ Fe protein $\to$ MoFe protein $\to$ N2 
B) Fe protein $\to$ MoFe protein $\to$ ferredoxin $\to$ N2 
C) MoFe protein $\to$ Fe protein $\to$ ferredoxin $\to$ N2 
D) ferredoxin $\to$ MoFe protein $\to$ Fe protein $\to$ N2 
E) none of the above

Question 13

What would be the energy requirements of the urea cycle if both nitrogens of urea came from glutamine (assuming that any NADH made was re-oxidized via electron transport/oxidative phosphorylation)? Explain how this is possible.

Accepted Answer

Glutamine can be converted to glutamate

Question 14

Which of the following metabolites is elevated as a result of low folate levels and poses a risk for cardiovascular disease?

Accepted Answer

A) homocysteine 
B) methionine 
C) 5-formyl-THF 
D) formate 
E) none of the above 
A) homocysteine 
B) methionine 
C) 5-formyl-THF 
D) formate 
E) none of the above

Question 15

Assuming that ammonia serves as the source of both nitrogen atoms of urea and that all cycles involved in the production of urea make one full turn,how many ATP equivalents and how many NADH are required to produce one molecule of urea?

Accepted Answer

A) 3 ATP equivalents,1 NADH 
B) 3 ATP equivalents,0 NADH 
C) 4 ATP equivalents,1 NADH 
D) 4 ATP equivalents,0 NADH 
E) none of the above 
A) 3 ATP equivalents,1 NADH 
B) 3 ATP equivalents,0 NADH 
C) 4 ATP equivalents,1 NADH 
D) 4 ATP equivalents,0 NADH 
E) none of the above

Question 16

What is the only reaction of mammalian amino acid metabolism that is dependent upon vitamin B12?

Accepted Answer

A) conversion of phenylalanine to tyrosine 
B) conversion of homocysteine to methionine 
C) isomerization of methylmalonyl-CoA to succinyl-CoA 
D) methane synthesis 
E) none of the above 
A) conversion of phenylalanine to tyrosine 
B) conversion of homocysteine to methionine 
C) isomerization of methylmalonyl-CoA to succinyl-CoA 
D) methane synthesis 
E) none of the above

Question 17

Which of the following correctly accounts for the regulation of carbamoyl phosphate synthetase I?

Accepted Answer

A) inhibited by N-acetylglutamate,activated by acetylation of a lysine residue 
B) inhibited by N-acetylglutamate,activated by phosphorylation of a tyrosine residue 
C) activated by N-acetylglutamate,inhibited by acetylation of a lysine residue 
D) activated by N-acetylglutamate,activated by phosphorylation of a tyrosine residue 
E) none of the above 
A) inhibited by N-acetylglutamate,activated by acetylation of a lysine residue 
B) inhibited by N-acetylglutamate,activated by phosphorylation of a tyrosine residue 
C) activated by N-acetylglutamate,inhibited by acetylation of a lysine residue 
D) activated by N-acetylglutamate,activated by phosphorylation of a tyrosine residue 
E) none of the above

Question 18

The reaction of ammonia with $\alpha$-ketoglutarate is catalyzed by _________ and requires _________ as a reactant.

Accepted Answer

A) glutamate synthetase;ATP 
B) glutamate synthetase;NADH or NADPH 
C) glutamate dehydrogenase;ATP 
D) glutamate dehydrogenase;NADH or NADPH 
E) none of the above 
A) glutamate synthetase;ATP 
B) glutamate synthetase;NADH or NADPH 
C) glutamate dehydrogenase;ATP 
D) glutamate dehydrogenase;NADH or NADPH 
E) none of the above

Question 19

Which of the following enzymes of ammonia incorporation is the most highly regulated?

Accepted Answer

A) glutamate dehydrogenase 
B) glutamate synthetase 
C) glutamine synthetase 
D) glutamine synthase 
E) none of the above 
A) glutamate dehydrogenase 
B) glutamate synthetase 
C) glutamine synthetase 
D) glutamine synthase 
E) none of the above

Question 20

Which of the following amino acids is exclusively ketogenic?

Accepted Answer

A) phenylalanine 
B) tyrosine 
C) isoleucine 
D) arginine 
E) leucine 
A) phenylalanine 
B) tyrosine 
C) isoleucine 
D) arginine 
E) leucine

Exam 20: Metabolism of Nitrogenous Compounds I: Principles of Biosynthesis, utilization, and Turnover

For the following transamination reaction,show the products of the first half of the reaction.

The reaction catalyzed by nitrite reductase requires _______ electrons and is summarized as _____________.

Ubiquitin is added to _________ residues of the target protein by reaction with the terminal __________ group of ubiquitin.

Which of the following is seen in the transaminase mechanism?

What are the products of the following transamination?

In the nitrogen fixation process,which step of the electron transfer process requires ATP hydrolysis?

Which of the following forms of tetrahydrofolate is correctly paired with the reaction for which it serves as a coenzyme?

What is a PEST sequence in a protein?

Which of the following reactions is highly active in the liver when large amounts of amino acids are moving from extrahepatic tissue to the liver?

In the regulation of glutamine synthetase activity,an important regulatory protein,PII exists in two states,one with UMP covalently bound (PII-UMP),the other without (PII).Which of the following statements regarding α\alphaα -ketoglutarate and PII is correct?

Which of the following amino acids relies upon the synthesis of carbamoyl phosphate?

Which of the following represents a correct flow of electrons for nitrogen fixation?

What would be the energy requirements of the urea cycle if both nitrogens of urea came from glutamine (assuming that any NADH made was re-oxidized via electron transport/oxidative phosphorylation)? Explain how this is possible.

Which of the following metabolites is elevated as a result of low folate levels and poses a risk for cardiovascular disease?

Assuming that ammonia serves as the source of both nitrogen atoms of urea and that all cycles involved in the production of urea make one full turn,how many ATP equivalents and how many NADH are required to produce one molecule of urea?

What is the only reaction of mammalian amino acid metabolism that is dependent upon vitamin B12?

Which of the following correctly accounts for the regulation of carbamoyl phosphate synthetase I?

The reaction of ammonia with α\alphaα -ketoglutarate is catalyzed by _________ and requires _________ as a reactant.

Which of the following enzymes of ammonia incorporation is the most highly regulated?

Which of the following amino acids is exclusively ketogenic?

The Scope of Biochemistry

The Matrix of Life: Weak Interactions in an Aqueous Environment

The Energetics of Life

Nucleic Acids

Introduction to Proteins: the Primary Level of Protein Structure

The Three-Dimensional Structure of Proteins

Protein Function and Evolution

Contractile Proteins and Molecular Motors

Carbohydrates: Sugars,saccharides,glycans

Lipids,membranes and Cellular Transport

Enzymes: Biological Catalysts

Chemical Logic of Metabolism

Carbohydrate Metabolism: Glycolysis, gluconeogenesis, glycogen Metabolism, and the Pentose Phosphate Pathway

Citric Acid Cycle and Glyoxylate Cycle

Electron Transport, oxidative Phosphorylation, and Oxygen Metabolism

Photosynthesis

Lipid Metabolism I: Fatty Acids,triacylglycerols,and Lipoproteins

Interorgan and Intracellular Coordination of Energy Metabolism in Vertebrates

Lipid Metabolism Ii: Membrane Lipids, steroids, isoprenoids, and Eicosanoids

Metabolism of Nitogenous Compounds Ii: Amino Acids, porphyrins, and Neurotransmitters

Nucleotide Metabolism

Mechanisms of Signal Transduction

Genes,genomes and Chromosomes

Dna Replication

Dna Restructuring: Repair,recombination,rearrangement,amplification

Information Readout: Transcription and Post-Transcriptional Processing

Information Decoding: Translation and Post-Translational Protein Processing

Regulation of Gene Expression

Filters

The reaction catalyzed by nitrite reductase requires _ electrons and is summarized as _______.

Ubiquitin is added to _ residues of the target protein by reaction with the terminal __ group of ubiquitin.

In the regulation of glutamine synthetase activity,an important regulatory protein,P_II exists in two states,one with UMP covalently bound (P_II-UMP),the other without (P_II).Which of the following statements regarding $\alpha$ -ketoglutarate and P_II is correct?

What is the only reaction of mammalian amino acid metabolism that is dependent upon vitamin B₁₂?

The reaction of ammonia with $\alpha$ -ketoglutarate is catalyzed by _ and requires _ as a reactant.