CHEM 210 Biochemistry Module 2: Amino Acids, Protein Structure,
and Function 2026/2027 UPDATE
1. Which amino acid is considered achiral because its R-group is a hydrogen
atom?
A. Alanine
B. Glycine
C. Proline
D. Valine
Answer: B
Rationale: Glycine is the only amino acid where the alpha-carbon is not chiral because it is
bonded to two hydrogen atoms.
2. The formation of a peptide bond between two amino acids is classified as
which type of reaction?
A. Hydrolysis
B. Reduction
C. Oxidation
D. Condensation
Answer: D
Rationale: A peptide bond forms via a condensation (or dehydration) reaction where a
water molecule is released.
,3. Which of the following amino acids is most likely to be found in the interior of
a globular protein?
A. Serine
B. Aspartate
C. Lysine
D. Phenylalanine
Answer: D
Rationale: Phenylalanine is nonpolar and hydrophobic, causing it to be buried in the
protein core to avoid water.
4. Which amino acid is capable of forming disulfide bridges to stabilize tertiary
structure?
A. Methionine
B. Serine
C. Cysteine
D. Arginine
Answer: C
Rationale: Cysteine contains a thiol (-SH) group that can oxidize to form a covalent
disulfide (S-S) bond.
5. What level of protein structure is defined by the specific linear sequence of
amino acids?
A. Primary
B. Secondary
C. Tertiary
D. Quaternary
Answer: A
Rationale: The primary structure is the unique linear sequence of amino acids linked by
peptide bonds.
, 6. In an alpha-helix, the hydrogen bonds occur between the carbonyl oxygen of
residue ‘i’ and the amide hydrogen of residue:
A. i + 3
B. i + 4
C. i + 2
D. i + 5
Answer: B
Rationale: The alpha-helix is stabilized by hydrogen bonds between the C=O of residue n
and the N-H of residue n+4.
7. Which amino acid acts as a ‘helix breaker’ due to its rigid cyclic structure?
A. Histidine
B. Proline
C. Tyrosine
D. Tryptophan
Answer: B
Rationale: Proline’s cyclic side chain limits rotation and lacks an amide hydrogen for H-
bonding, disrupting helices.
8. The pH at which an amino acid has a net charge of zero is called the:
A. Isoelectric point (pI)
B. Equivalence point
C. Buffering zone
D. pKa
Answer: A
Rationale: The isoelectric point (pI) is the specific pH value where the molecule carries no
net electrical charge.
and Function 2026/2027 UPDATE
1. Which amino acid is considered achiral because its R-group is a hydrogen
atom?
A. Alanine
B. Glycine
C. Proline
D. Valine
Answer: B
Rationale: Glycine is the only amino acid where the alpha-carbon is not chiral because it is
bonded to two hydrogen atoms.
2. The formation of a peptide bond between two amino acids is classified as
which type of reaction?
A. Hydrolysis
B. Reduction
C. Oxidation
D. Condensation
Answer: D
Rationale: A peptide bond forms via a condensation (or dehydration) reaction where a
water molecule is released.
,3. Which of the following amino acids is most likely to be found in the interior of
a globular protein?
A. Serine
B. Aspartate
C. Lysine
D. Phenylalanine
Answer: D
Rationale: Phenylalanine is nonpolar and hydrophobic, causing it to be buried in the
protein core to avoid water.
4. Which amino acid is capable of forming disulfide bridges to stabilize tertiary
structure?
A. Methionine
B. Serine
C. Cysteine
D. Arginine
Answer: C
Rationale: Cysteine contains a thiol (-SH) group that can oxidize to form a covalent
disulfide (S-S) bond.
5. What level of protein structure is defined by the specific linear sequence of
amino acids?
A. Primary
B. Secondary
C. Tertiary
D. Quaternary
Answer: A
Rationale: The primary structure is the unique linear sequence of amino acids linked by
peptide bonds.
, 6. In an alpha-helix, the hydrogen bonds occur between the carbonyl oxygen of
residue ‘i’ and the amide hydrogen of residue:
A. i + 3
B. i + 4
C. i + 2
D. i + 5
Answer: B
Rationale: The alpha-helix is stabilized by hydrogen bonds between the C=O of residue n
and the N-H of residue n+4.
7. Which amino acid acts as a ‘helix breaker’ due to its rigid cyclic structure?
A. Histidine
B. Proline
C. Tyrosine
D. Tryptophan
Answer: B
Rationale: Proline’s cyclic side chain limits rotation and lacks an amide hydrogen for H-
bonding, disrupting helices.
8. The pH at which an amino acid has a net charge of zero is called the:
A. Isoelectric point (pI)
B. Equivalence point
C. Buffering zone
D. pKa
Answer: A
Rationale: The isoelectric point (pI) is the specific pH value where the molecule carries no
net electrical charge.
