C785 Biochemistry Week 3: Protein Structure and Function 2026
|WGU
1. Which level of protein structure is determined solely by the sequence of
amino acids linked by peptide bonds?
A. Secondary structure
B. Quaternary structure
C. Tertiary structure
D. Primary structure
Answer: D
Rationale: The primary structure is the linear sequence of amino acids held together by
covalent peptide bonds.
2. What type of bond or interaction is primarily responsible for stabilizing alpha-
helices and beta-sheets?
A. Hydrogen bonds
B. Disulfide bridges
C. Ionic bonds
D. Hydrophobic interactions
Answer: A
Rationale: Secondary structures like alpha-helices and beta-sheets are stabilized by
hydrogen bonds between the backbone amino and carboxyl groups.
,3. The folding of a single polypeptide chain into a complex three-dimensional
shape is known as:
A. Secondary structure
B. Quaternary structure
C. Primary structure
D. Tertiary structure
Answer: D
Rationale: Tertiary structure refers to the overall 3D folding of a single polypeptide chain.
4. Which amino acid is most likely to be found in the interior of a globular
protein?
A. Valine
B. Glutamate
C. Lysine
D. Serine
Answer: A
Rationale: Valine is a non-polar, hydrophobic amino acid that tends to bury itself in the
protein interior away from water.
5. Quaternary structure is defined by:
A. The sequence of amino acids
B. Local folding patterns
C. The interaction between multiple polypeptide subunits
D. The binding of a prosthetic group
Answer: C
Rationale: Quaternary structure describes the spatial arrangement and interactions of two
or more polypeptide chains.
, 6. What is the primary driving force for the folding of proteins in an aqueous
environment?
A. Formation of disulfide bonds
B. The hydrophobic effect
C. Metal ion coordination
D. Peptide bond formation
Answer: B
Rationale: The hydrophobic effect drives non-polar side chains to the center of the protein,
increasing the entropy of the surrounding water.
7. A peptide bond is formed by a reaction between which two functional
groups?
A. An amino group and a carboxyl group
B. Two carboxyl groups
C. An amino group and a hydroxyl group
D. A phosphate group and a hydroxyl group
Answer: A
Rationale: A peptide bond forms through a dehydration reaction between the alpha-amino
group of one amino acid and the alpha-carboxyl group of another.
8. Which of the following is an example of a protein with quaternary structure?
A. Myoglobin
B. Hemoglobin
C. Ribonuclease
D. Lysozyme
Answer: B
Rationale: Hemoglobin consists of four subunits (two alpha and two beta), giving it a
quaternary structure.
|WGU
1. Which level of protein structure is determined solely by the sequence of
amino acids linked by peptide bonds?
A. Secondary structure
B. Quaternary structure
C. Tertiary structure
D. Primary structure
Answer: D
Rationale: The primary structure is the linear sequence of amino acids held together by
covalent peptide bonds.
2. What type of bond or interaction is primarily responsible for stabilizing alpha-
helices and beta-sheets?
A. Hydrogen bonds
B. Disulfide bridges
C. Ionic bonds
D. Hydrophobic interactions
Answer: A
Rationale: Secondary structures like alpha-helices and beta-sheets are stabilized by
hydrogen bonds between the backbone amino and carboxyl groups.
,3. The folding of a single polypeptide chain into a complex three-dimensional
shape is known as:
A. Secondary structure
B. Quaternary structure
C. Primary structure
D. Tertiary structure
Answer: D
Rationale: Tertiary structure refers to the overall 3D folding of a single polypeptide chain.
4. Which amino acid is most likely to be found in the interior of a globular
protein?
A. Valine
B. Glutamate
C. Lysine
D. Serine
Answer: A
Rationale: Valine is a non-polar, hydrophobic amino acid that tends to bury itself in the
protein interior away from water.
5. Quaternary structure is defined by:
A. The sequence of amino acids
B. Local folding patterns
C. The interaction between multiple polypeptide subunits
D. The binding of a prosthetic group
Answer: C
Rationale: Quaternary structure describes the spatial arrangement and interactions of two
or more polypeptide chains.
, 6. What is the primary driving force for the folding of proteins in an aqueous
environment?
A. Formation of disulfide bonds
B. The hydrophobic effect
C. Metal ion coordination
D. Peptide bond formation
Answer: B
Rationale: The hydrophobic effect drives non-polar side chains to the center of the protein,
increasing the entropy of the surrounding water.
7. A peptide bond is formed by a reaction between which two functional
groups?
A. An amino group and a carboxyl group
B. Two carboxyl groups
C. An amino group and a hydroxyl group
D. A phosphate group and a hydroxyl group
Answer: A
Rationale: A peptide bond forms through a dehydration reaction between the alpha-amino
group of one amino acid and the alpha-carboxyl group of another.
8. Which of the following is an example of a protein with quaternary structure?
A. Myoglobin
B. Hemoglobin
C. Ribonuclease
D. Lysozyme
Answer: B
Rationale: Hemoglobin consists of four subunits (two alpha and two beta), giving it a
quaternary structure.
