WGU C785 Biochemistry Final Exam –
Practice Questions with Answers &
Rationales
SECTION 1: PROTEIN STRUCTURE & AMINO ACIDS (Questions 1–25)
Q1: Which level of protein structure is disrupted through the
hydrolysis of peptide bonds?
A) Quaternary
B) Tertiary
C) Primary
D) Secondary
Answer: C) Primary
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 are maintained by non-covalent interactions
(hydrogen bonds, ionic bonds, hydrophobic interactions, disulfide bonds),
not peptide bonds themselves.
,Q2: Which level of protein structure is determined by the sequence of
amino acids?
A) Secondary structure
B) Quaternary structure
C) Tertiary structure
D) Primary structure
Answer: D) Primary structure
Rationale: The primary structure of a protein is simply the sequence of
amino acids held together by peptide bonds. This sequence determines
how the protein will fold into higher-order structures.
Q3: 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
Answer: C) Hydrogen bonding
Rationale: The secondary structure of a protein (α-helices and β-pleated
sheets) is built by hydrogen bonds between the carboxyl groups and amino
groups on the backbones of the amino acids.
Q4: Which amino acid would most likely participate in hydrogen
bonds?
,A) Amino acid with a hydrocarbon side chain
B) Amino acid with a sulfur-containing side chain
C) Amino acid with an OH group on the side chain
D) Amino acid with a charged side chain only
Answer: C) Amino acid with an OH group on the side chain
Rationale: Polar, uncharged amino acids containing oxygen or NH groups
(such as those with OH groups) can form hydrogen bonds. The OH group
provides a hydrogen bond donor and acceptor.
Q5: Secondary, tertiary, and quaternary levels of protein structure can
all be impacted by exposing a protein to which treatment?
A) Change of a hydrophobic amino acid to a different hydrophobic amino
acid
B) Addition of a reducing agent
C) Placement of the protein in a solution with a low pH
D) Increase in the concentration of the protein in solution
Answer: C) Placement of the protein in a solution with a low pH
Rationale: Changes in pH affect hydrogen bonds and ionic bonds.
Hydrogen bonds in the backbone occur in secondary structure, and both
hydrogen bonds and ionic bonds occur in side chains of tertiary and
quaternary structures. Low pH denatures proteins by disrupting these non-
covalent interactions.
, Q6: A mutation in the beta-hemoglobin gene results in the
replacement of glutamate (position 6) with valine, leading to sickle cell
anemia. If the gene were edited to replace valine with a different
amino acid, which replacement would have the best clinical outcome?
A) Any non-polar amino acid
B) Any positively charged amino acid
C) Any negatively charged amino acid
D) Any hydrophobic amino acid
Answer: C) Any negatively charged amino acid
Rationale: The original amino acid in a healthy patient is glutamate, which
is negatively charged. The mutated amino acid is valine, which is non-polar.
The best replacement would be one most like glutamate—any negatively
charged amino acid.
Q7: Which portion of the amino acid is the variable group that differs
between amino acids?
A) The amino group
B) The carboxyl group
C) The alpha carbon
D) The side chain (R group)
Answer: D) The side chain (R group)
Rationale: The side chain (R group) is the variable group of the amino acid.
Every amino acid has the same amino group, carboxylic acid group, and
alpha carbon, but the side chain differs, giving each amino acid its unique
properties.
Practice Questions with Answers &
Rationales
SECTION 1: PROTEIN STRUCTURE & AMINO ACIDS (Questions 1–25)
Q1: Which level of protein structure is disrupted through the
hydrolysis of peptide bonds?
A) Quaternary
B) Tertiary
C) Primary
D) Secondary
Answer: C) Primary
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 are maintained by non-covalent interactions
(hydrogen bonds, ionic bonds, hydrophobic interactions, disulfide bonds),
not peptide bonds themselves.
,Q2: Which level of protein structure is determined by the sequence of
amino acids?
A) Secondary structure
B) Quaternary structure
C) Tertiary structure
D) Primary structure
Answer: D) Primary structure
Rationale: The primary structure of a protein is simply the sequence of
amino acids held together by peptide bonds. This sequence determines
how the protein will fold into higher-order structures.
Q3: 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
Answer: C) Hydrogen bonding
Rationale: The secondary structure of a protein (α-helices and β-pleated
sheets) is built by hydrogen bonds between the carboxyl groups and amino
groups on the backbones of the amino acids.
Q4: Which amino acid would most likely participate in hydrogen
bonds?
,A) Amino acid with a hydrocarbon side chain
B) Amino acid with a sulfur-containing side chain
C) Amino acid with an OH group on the side chain
D) Amino acid with a charged side chain only
Answer: C) Amino acid with an OH group on the side chain
Rationale: Polar, uncharged amino acids containing oxygen or NH groups
(such as those with OH groups) can form hydrogen bonds. The OH group
provides a hydrogen bond donor and acceptor.
Q5: Secondary, tertiary, and quaternary levels of protein structure can
all be impacted by exposing a protein to which treatment?
A) Change of a hydrophobic amino acid to a different hydrophobic amino
acid
B) Addition of a reducing agent
C) Placement of the protein in a solution with a low pH
D) Increase in the concentration of the protein in solution
Answer: C) Placement of the protein in a solution with a low pH
Rationale: Changes in pH affect hydrogen bonds and ionic bonds.
Hydrogen bonds in the backbone occur in secondary structure, and both
hydrogen bonds and ionic bonds occur in side chains of tertiary and
quaternary structures. Low pH denatures proteins by disrupting these non-
covalent interactions.
, Q6: A mutation in the beta-hemoglobin gene results in the
replacement of glutamate (position 6) with valine, leading to sickle cell
anemia. If the gene were edited to replace valine with a different
amino acid, which replacement would have the best clinical outcome?
A) Any non-polar amino acid
B) Any positively charged amino acid
C) Any negatively charged amino acid
D) Any hydrophobic amino acid
Answer: C) Any negatively charged amino acid
Rationale: The original amino acid in a healthy patient is glutamate, which
is negatively charged. The mutated amino acid is valine, which is non-polar.
The best replacement would be one most like glutamate—any negatively
charged amino acid.
Q7: Which portion of the amino acid is the variable group that differs
between amino acids?
A) The amino group
B) The carboxyl group
C) The alpha carbon
D) The side chain (R group)
Answer: D) The side chain (R group)
Rationale: The side chain (R group) is the variable group of the amino acid.
Every amino acid has the same amino group, carboxylic acid group, and
alpha carbon, but the side chain differs, giving each amino acid its unique
properties.
