WGU C785 Final Exam 2024 With All
The Correct Answers
Section I: Amino Acids & Protein Structure
1. Which level of protein structure is defined by the specific linear sequence of amino acids
linked by peptide bonds?
A. Secondary structure
B. Primary structure
C. Tertiary structure
D. Quaternary structure
Correct Answer: B
Rationale: Primary structure refers specifically to the linear sequence of amino acids in a
polypeptide chain, held together by covalent peptide bonds . This sequence ultimately
determines all higher levels of protein structure.
2. A patient with sickle cell anemia has a mutation replacing glutamate with valine at position
6 of the beta-globin chain. Which level of protein structure is directly altered by this
mutation?
A. Primary structure only
B. Secondary structure only
C. Tertiary structure only
D. Quaternary structure only
Correct Answer: A
Rationale: The mutation changes the amino acid sequence, which is the primary structure.
Glutamate is negatively charged and hydrophilic, while valine is nonpolar and hydrophobic . This
single amino acid substitution leads to abnormal hemoglobin polymerization and sickling.
3. Which amino acid would most likely be found in the interior of a globular protein in an
aqueous environment?
,A. Phenylalanine
B. Lysine
C. Aspartate
D. Serine
Correct Answer: A
Rationale: Hydrophobic amino acids like phenylalanine are driven into the protein interior
to avoid contact with water, minimizing the surface area of hydrophobic contact . Lysine and
aspartate are charged, and serine is polar—all would prefer the aqueous exterior.
4. Which force is most influential in determining the secondary structure of a protein?
A. Hydrophobic effect
B. Disulfide bonding
C. Hydrogen bonding
D. Electrostatic interactions
Correct Answer: C
Rationale: The secondary structure of a protein (alpha helices and beta sheets) is built by
hydrogen bonds between the carboxyl groups and amino groups on the backbones of the amino
acids . These regular hydrogen bonding patterns define secondary structure.
5. Which of the following amino acids is considered non-polar and hydrophobic?
A. Leucine
B. Glutamate
C. Lysine
D. Serine
Correct Answer: A
Rationale: Leucine has an aliphatic side chain, making it non-polar and hydrophobic .
Glutamate and lysine are charged, and serine is polar uncharged.
6. What is the major driving force for protein folding?
,A. Hydrogen bonds that stabilize alpha helices and beta sheets
B. Van der Waals forces
C. Ionic forces (salt bridges)
D. The increase in entropy of the solvent when the protein folds
Correct Answer: D
Rationale: The hydrophobic effect drives protein folding. When nonpolar side chains cluster
in the protein interior, water molecules are released from ordered solvation layers, increasing
the entropy (disorder) of the solvent . This entropic increase is thermodynamically favorable.
7. Which statement describes a solvation layer for a hydrophobic protein solute?
A. It is a highly ordered, low-entropy layer of water surrounding a solute
B. It is the exterior surface of a hydrophobic solute that often contains many salt bridges
C. It is a layer of water around the solute that is highly randomized due to few interactions with
the solute
D. It is the outer layer of the protein that contains the most polar amino acid residues
Correct Answer: A
Rationale: Water molecules form highly ordered, low-entropy cages around hydrophobic
solutes . This ordered water is entropically unfavorable, which is why hydrophobic molecules
aggregate to minimize this solvation layer.
8. Which level of protein structure is disrupted through the hydrolysis of peptide bonds?
A. Quaternary
B. Tertiary
C. Primary
D. Secondary
Correct Answer: C
Rationale: The primary structure of a protein is the sequence of amino acids held together
by peptide bonds. Peptide bonds are formed by dehydration reactions and disrupted by
hydrolysis . Secondary, tertiary, and quaternary structures involve non-covalent interactions.
, 9. A mutation in the beta-hemoglobin gene replaces glutamate with valine at position 6.
Which replacement for valine would theoretically have the best clinical outcome? (Assume
valine can be replaced with any amino acid other than glutamate.)
A. A positively charged amino acid
B. A negatively charged amino acid
C. A nonpolar amino acid
D. A polar uncharged amino acid
Correct Answer: B
Rationale: The original amino acid in a healthy patient is glutamate, which is negatively
charged. The mutated amino acid (valine) is nonpolar and causes sickle cell anemia. The best
replacement would be an amino acid most like glutamate—a negatively charged amino acid .
10. Which pair of amino acids will most likely interact through hydrophobic forces between
their side chains?
A. Two polar uncharged amino acids
B. Two charged amino acids
C. Two nonpolar amino acids
D. A polar and a charged amino acid
Correct Answer: C
Rationale: Hydrophobic interactions occur between nonpolar side chains . These
interactions cluster in the protein interior away from water.
11. An increase in beta-pleated sheet structure in some brain proteins can lead to amyloid
deposit formation. What is the primary biochemical process that follows the increase in beta-
pleated sheet structure?
A. An increase in glycogen formation in brain cells
B. Aggregation of the proteins in the brain
C. Secretion of glucagon, leading to excessive ketogenesis
D. An increase in anaerobic metabolism of glucose in the brain
Correct Answer: B
The Correct Answers
Section I: Amino Acids & Protein Structure
1. Which level of protein structure is defined by the specific linear sequence of amino acids
linked by peptide bonds?
A. Secondary structure
B. Primary structure
C. Tertiary structure
D. Quaternary structure
Correct Answer: B
Rationale: Primary structure refers specifically to the linear sequence of amino acids in a
polypeptide chain, held together by covalent peptide bonds . This sequence ultimately
determines all higher levels of protein structure.
2. A patient with sickle cell anemia has a mutation replacing glutamate with valine at position
6 of the beta-globin chain. Which level of protein structure is directly altered by this
mutation?
A. Primary structure only
B. Secondary structure only
C. Tertiary structure only
D. Quaternary structure only
Correct Answer: A
Rationale: The mutation changes the amino acid sequence, which is the primary structure.
Glutamate is negatively charged and hydrophilic, while valine is nonpolar and hydrophobic . This
single amino acid substitution leads to abnormal hemoglobin polymerization and sickling.
3. Which amino acid would most likely be found in the interior of a globular protein in an
aqueous environment?
,A. Phenylalanine
B. Lysine
C. Aspartate
D. Serine
Correct Answer: A
Rationale: Hydrophobic amino acids like phenylalanine are driven into the protein interior
to avoid contact with water, minimizing the surface area of hydrophobic contact . Lysine and
aspartate are charged, and serine is polar—all would prefer the aqueous exterior.
4. Which force is most influential in determining the secondary structure of a protein?
A. Hydrophobic effect
B. Disulfide bonding
C. Hydrogen bonding
D. Electrostatic interactions
Correct Answer: C
Rationale: The secondary structure of a protein (alpha helices and beta sheets) is built by
hydrogen bonds between the carboxyl groups and amino groups on the backbones of the amino
acids . These regular hydrogen bonding patterns define secondary structure.
5. Which of the following amino acids is considered non-polar and hydrophobic?
A. Leucine
B. Glutamate
C. Lysine
D. Serine
Correct Answer: A
Rationale: Leucine has an aliphatic side chain, making it non-polar and hydrophobic .
Glutamate and lysine are charged, and serine is polar uncharged.
6. What is the major driving force for protein folding?
,A. Hydrogen bonds that stabilize alpha helices and beta sheets
B. Van der Waals forces
C. Ionic forces (salt bridges)
D. The increase in entropy of the solvent when the protein folds
Correct Answer: D
Rationale: The hydrophobic effect drives protein folding. When nonpolar side chains cluster
in the protein interior, water molecules are released from ordered solvation layers, increasing
the entropy (disorder) of the solvent . This entropic increase is thermodynamically favorable.
7. Which statement describes a solvation layer for a hydrophobic protein solute?
A. It is a highly ordered, low-entropy layer of water surrounding a solute
B. It is the exterior surface of a hydrophobic solute that often contains many salt bridges
C. It is a layer of water around the solute that is highly randomized due to few interactions with
the solute
D. It is the outer layer of the protein that contains the most polar amino acid residues
Correct Answer: A
Rationale: Water molecules form highly ordered, low-entropy cages around hydrophobic
solutes . This ordered water is entropically unfavorable, which is why hydrophobic molecules
aggregate to minimize this solvation layer.
8. Which level of protein structure is disrupted through the hydrolysis of peptide bonds?
A. Quaternary
B. Tertiary
C. Primary
D. Secondary
Correct Answer: C
Rationale: The primary structure of a protein is the sequence of amino acids held together
by peptide bonds. Peptide bonds are formed by dehydration reactions and disrupted by
hydrolysis . Secondary, tertiary, and quaternary structures involve non-covalent interactions.
, 9. A mutation in the beta-hemoglobin gene replaces glutamate with valine at position 6.
Which replacement for valine would theoretically have the best clinical outcome? (Assume
valine can be replaced with any amino acid other than glutamate.)
A. A positively charged amino acid
B. A negatively charged amino acid
C. A nonpolar amino acid
D. A polar uncharged amino acid
Correct Answer: B
Rationale: The original amino acid in a healthy patient is glutamate, which is negatively
charged. The mutated amino acid (valine) is nonpolar and causes sickle cell anemia. The best
replacement would be an amino acid most like glutamate—a negatively charged amino acid .
10. Which pair of amino acids will most likely interact through hydrophobic forces between
their side chains?
A. Two polar uncharged amino acids
B. Two charged amino acids
C. Two nonpolar amino acids
D. A polar and a charged amino acid
Correct Answer: C
Rationale: Hydrophobic interactions occur between nonpolar side chains . These
interactions cluster in the protein interior away from water.
11. An increase in beta-pleated sheet structure in some brain proteins can lead to amyloid
deposit formation. What is the primary biochemical process that follows the increase in beta-
pleated sheet structure?
A. An increase in glycogen formation in brain cells
B. Aggregation of the proteins in the brain
C. Secretion of glucagon, leading to excessive ketogenesis
D. An increase in anaerobic metabolism of glucose in the brain
Correct Answer: B
