Question 1

What is the structure of compound X in the following metabolic reaction? Name the type of reaction.

Accepted Answer

This is a transamination reaction.

Question 2

Which amino acids can be directly deaminated to produce NH4+?

Accepted Answer

A)  serine and threonine 
B)  serine, asparagine, and threonine 
C)  proline and threonine 
D)  proline and valine 
E)  None of the answers is correct. 
A)  serine and threonine 
B)  serine, asparagine, and threonine 
C)  proline and threonine 
D)  proline and valine 
E)  None of the answers is correct. A

Question 3

Uricotelic organisms release nitrogen as

Accepted Answer

A)  NH4+. 
B)  arginine. 
C)  uric acid. 
D)  urea. 
E)  None of the answers is correct. 
A)  NH4+. 
B)  arginine. 
C)  uric acid. 
D)  urea. 
E)  None of the answers is correct. C

Question 4

In the urea cycle, free NH3 is coupled with carboxyphosphate to form

Accepted Answer

A)  ureatic phosphate. 
B)  pyruvate. 
C)  carbamic acid. 
D)  urea. 
E)  None of the answers is correct. 
A)  ureatic phosphate. 
B)  pyruvate. 
C)  carbamic acid. 
D)  urea. 
E)  None of the answers is correct.

Question 5

Which amino acid is a metabolite in the urea cycle but is not used as a building block of proteins?

Accepted Answer

A)  ornithine 
B)  aspartate 
C)  glutamate 
D)  lysine 
E)  arginine 
A)  ornithine 
B)  aspartate 
C)  glutamate 
D)  lysine 
E)  arginine

Question 6

What protein is used as a tag to identify proteins that are targeted for destruction?

Accepted Answer

A)  proteasome 
B)  ubiquitin 
C)  destructin 
D)  degradin 
E)  None of the answers is correct. 
A)  proteasome 
B)  ubiquitin 
C)  destructin 
D)  degradin 
E)  None of the answers is correct.

Question 7

The hydrolysis of arginine by arginase produces ornithine and ______________.

Accepted Answer

The answer of The hydrolysis of arginine by arginase produces...

Question 8

What molecule is formed from excess ammonium ions by ureotelic organisms?

Accepted Answer

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

Question 9

Which of the following is the primary proteolytic enzyme of the stomach?

Accepted Answer

A)  trypsin 
B)  chymotrypsin 
C)  elastase 
D)  carboxypeptidase A 
E)  pepsin 
A)  trypsin 
B)  chymotrypsin 
C)  elastase 
D)  carboxypeptidase A 
E)  pepsin

Question 10

The urea cycle is linked to gluconeogenesis through the TCA cycle intermediates fumarate and ________________.

Accepted Answer

The answer of The urea cycle is linked to gluconeogenesis...

Question 11

What enzyme transfers an $\alpha$-amino group from an amino acid to $\alpha$-ketoglutarate?

Accepted Answer

A)  reductive aminase 
B)  oxidative deaminase 
C)  ketotransferase 
D)  aminotransferase 
E)  None of the answers is correct. 
A)  reductive aminase 
B)  oxidative deaminase 
C)  ketotransferase 
D)  aminotransferase 
E)  None of the answers is correct.

Question 12

The eukaryotic system for ubiquitination appears to have evolved from what prokaryotic precursor?

Accepted Answer

A)  A system for protein degradation and turnover 
B)  A system for protein phosphorylation 
C)  A system for thiamine biosynthesis 
D)  A system for nucleotide degradation 
E)  None of the answers is correct. 
A)  A system for protein degradation and turnover 
B)  A system for protein phosphorylation 
C)  A system for thiamine biosynthesis 
D)  A system for nucleotide degradation 
E)  None of the answers is correct.

Question 13

Ammoniotelic organisms excrete excess nitrogen as

Accepted Answer

A)  xanthine. 
B)  NH4+. 
C)  urea. 
D)  uric acid. 
E)  None of the answers is correct. 
A)  xanthine. 
B)  NH4+. 
C)  urea. 
D)  uric acid. 
E)  None of the answers is correct.

Question 14

The C-terminal glycine of ubiquitin is covalently linked to ________________ residues of the protein destined to be degraded.

Accepted Answer

The answer of The C-terminal glycine of ubiquitin is covalently...

Question 15

What term describes a specific sequence of amino acids that indicates the particular protein should be degraded?

Accepted Answer

A)  consensus sequence 
B)  proteasome recognition sequence 
C)  degron 
D)  ubiquitin binding domain 
E)  None of the answers is correct. 
A)  consensus sequence 
B)  proteasome recognition sequence 
C)  degron 
D)  ubiquitin binding domain 
E)  None of the answers is correct.

Question 16

Surplus amino acids are

Accepted Answer

A)  stored in proteosomes. 
B)  stored in protein scaffolds. 
C)  used as metabolic fuel. 
D)  stored as albumin. 
E)  None of the answers is correct. 
A)  stored in proteosomes. 
B)  stored in protein scaffolds. 
C)  used as metabolic fuel. 
D)  stored as albumin. 
E)  None of the answers is correct.

Question 17

What is the significance of the PEST sequence?

Accepted Answer

Some cell-cycle proteins contain unique

Question 18

Write the net equation of the urea cycle and indicate whether energy is produced or consumed by the cycle.

Accepted Answer

CO₂ + NH₄⁺ + 3 ATP + Asp + 2 H₂O →

Question 19

Ketogenic amino acids are degraded to which of the following metabolites?

Accepted Answer

A)  pyruvate 
B)  acetoacetate 
C)  oxaloacetate 
D)  $\alpha$-ketoglutarate 
E)  All of the answers are correct. 
A)  pyruvate 
B)  acetoacetate 
C)  oxaloacetate 
D)  $\alpha$-ketoglutarate 
E)  All of the answers are correct.

Question 20

Which amino acid is solely ketogenic?

Accepted Answer

A)  leucine 
B)  tryptophan 
C)  valine 
D)  arginine 
E)  isoleucine 
A)  leucine 
B)  tryptophan 
C)  valine 
D)  arginine 
E)  isoleucine

Exam 23: Protein Turnover and Amino Acid Catabolism

What is the structure of compound X in the following metabolic reaction? Name the type of reaction.

Which amino acids can be directly deaminated to produce NH4+?

Uricotelic organisms release nitrogen as

In the urea cycle, free NH3 is coupled with carboxyphosphate to form

Which amino acid is a metabolite in the urea cycle but is not used as a building block of proteins?

What protein is used as a tag to identify proteins that are targeted for destruction?

The hydrolysis of arginine by arginase produces ornithine and ______________.

What molecule is formed from excess ammonium ions by ureotelic organisms?

Which of the following is the primary proteolytic enzyme of the stomach?

The urea cycle is linked to gluconeogenesis through the TCA cycle intermediates fumarate and ________________.

What enzyme transfers an α\alphaα -amino group from an amino acid to α\alphaα -ketoglutarate?

The eukaryotic system for ubiquitination appears to have evolved from what prokaryotic precursor?

Ammoniotelic organisms excrete excess nitrogen as

The C-terminal glycine of ubiquitin is covalently linked to ________________ residues of the protein destined to be degraded.

What term describes a specific sequence of amino acids that indicates the particular protein should be degraded?

Surplus amino acids are

What is the significance of the PEST sequence?

Write the net equation of the urea cycle and indicate whether energy is produced or consumed by the cycle.

Ketogenic amino acids are degraded to which of the following metabolites?

Which amino acid is solely ketogenic?

Biochemistry: an Evolving Science

Protein Composition and Structure

Exploring Proteins and Proteomes

DNA, RNA, and the Flow of Genetic Information

Exploring Genes and Genomes

Exploring Evolution and Bioinformatics

Hemoglobin: a Portrait of a Protein in Action

Enzymes: Basic Concepts and Kinetics

Oxidative Phosphorylation

Catalytic Strategies

Regulatory Strategies

Carbohydrates

Lipids and Cell Membranes

Membrane Channels and Pumps

Signal-Transduction Pathways

Metabolism: Basic Concepts and Design

Glycolysis and Gluconeogenesis

The Citric Acid Cycle

The Light Reactions of Photosynthesis

The Calvin Cycle and the Pentose Phosphate Pathway

Glycogen Metabolism

Fatty Acid Metabolism

The Biosynthesis of Amino Acids

Nucleotide Biosynthesis

Biosynthesis of Membrane Lipids and Steroids

The Integration of Metabolism

DNA Replication, Repair, and Recombination

Rna Synthesis and Processing

Protein Synthesis

The Control of Gene Expression in Prokaryotes

The Control of Gene Expression in Eukaryotes

Sensory Systems

The Immune System

Molecular Motors

Drug Development

Filters

Which amino acids can be directly deaminated to produce NH₄⁺?

In the urea cycle, free NH₃ is coupled with carboxyphosphate to form

What enzyme transfers an $\alpha$ -amino group from an amino acid to $\alpha$ -ketoglutarate?