PORTAGE LEARNING CHEM 210 MODULE 3 PROBLEM
SET QUESTIONS WITH ANSWERS AND EXPLANATIONS
Question 1.
Which pairing in this set correctly associates a biochemical term with its definition? Focus
on the set built around Aspartate.
A. Tertiary protein structure - Heme is a porphyrin cofactor containing iron that reversibly
binds oxygen in globins.
B. Aspartate - Aspartate has a carboxylate side chain that is negatively charged near
physiologic pH.
C. Heme - A peptide bond is the amide linkage formed between the carboxyl group of one
amino acid and the amino group of another.
D. Peptide bond - Tertiary structure is the overall three-dimensional fold of a single
polypeptide chain.
Correct Answer: B. Aspartate - Aspartate has a carboxylate side chain that is
negatively charged near physiologic pH.
Explanation: The correct pairing is Aspartate with its defining description. Each distractor
deliberately pairs a valid biochemical term with the definition of a different concept.
Matching vocabulary to mechanism is essential before applying the ideas to calculations or
molecular examples.
Question 2.
A laboratory observation shows that two cysteine residues can create a covalent cystine
linkage. Which concept best explains this finding?
A. Primary protein structure
B. Apoenzyme
C. Cysteine
D. N-terminus
Correct Answer: C. Cysteine
Explanation: Cysteine best explains the observation because cysteine contains a thiol
side chain that can oxidize to form disulfide bonds. The clue in the stem points directly to
this mechanism or structural feature. The other options involve different biochemical
properties and therefore do not account for the observation as well.
Question 3.
Which residue is most likely to disrupt an alpha helix because its side chain constrains the
backbone nitrogen?
A. Proline
B. Leucine
C. Alanine
D. Methionine
Correct Answer: A. Proline
,Explanation: Proline is the best choice based on the defining chemistry of its side chain.
The other listed residues belong to different side-chain classes or lack the relevant
functional group. Correct classification of amino-acid side chains helps predict folding,
reactivity, and protein interactions.
Question 4.
A laboratory observation shows that it is frequently buried in hydrophobic protein cores.
Which concept best explains this finding?
A. Hemoglobin
B. Tertiary protein structure
C. Competitive inhibition
D. Leucine
Correct Answer: D. Leucine
Explanation: Leucine best explains the observation because leucine is a branched-chain,
nonpolar amino acid with an isobutyl side chain. The clue in the stem points directly to this
mechanism or structural feature. The other options involve different biochemical
properties and therefore do not account for the observation as well.
Question 5.
Which pair contains hydroxyl-bearing side chains that can be phosphorylated?
A. Asparagine and glutamine
B. Aspartate and glutamate
C. Serine and threonine
D. Valine and leucine
Correct Answer: C. Serine and threonine
Explanation: Serine and threonine is the best choice based on the defining chemistry of
its side chain. The other listed residues belong to different side-chain classes or lack the
relevant functional group. Correct classification of amino-acid side chains helps predict
folding, reactivity, and protein interactions.
Question 6.
A laboratory observation shows that it can stabilize extracellular proteins and some
secreted peptides. Which concept best explains this finding?
A. Disulfide bond
B. Methionine
C. Asparagine
D. Peptide bond
Correct Answer: A. Disulfide bond
Explanation: Disulfide bond best explains the observation because a disulfide bond is a
covalent S-S linkage produced by oxidation of two cysteine thiols. The clue in the stem
points directly to this mechanism or structural feature. The other options involve different
,biochemical properties and therefore do not account for the observation as well.
Question 7.
Which pairing in this set correctly associates a biochemical term with its definition? Focus
on the set built around Glycine.
A. Aspartate - A zwitterion contains both positive and negative formal charges while
having no net charge overall.
B. Active site - Aspartate has a carboxylate side chain that is negatively charged near
physiologic pH.
C. Zwitterion - The active site is the region of an enzyme where substrate binding and
catalysis occur.
D. Glycine - Glycine has hydrogen as its side chain and is the only standard amino acid
that is achiral.
Correct Answer: D. Glycine - Glycine has hydrogen as its side chain and is the
only standard amino acid that is achiral.
Explanation: The correct pairing is Glycine with its defining description. Each distractor
deliberately pairs a valid biochemical term with the definition of a different concept.
Matching vocabulary to mechanism is essential before applying the ideas to calculations or
molecular examples.
Question 8.
A laboratory observation shows that its amide can donate and accept hydrogen bonds.
Which concept best explains this finding?
A. Active site
B. Asparagine
C. Phenylalanine
D. Bohr effect
Correct Answer: B. Asparagine
Explanation: Asparagine best explains the observation because asparagine has a polar
uncharged carboxamide side chain. The clue in the stem points directly to this mechanism
or structural feature. The other options involve different biochemical properties and
therefore do not account for the observation as well.
, Question 9.
Which pairing in this set correctly associates a biochemical term with its definition? Focus
on the set built around Disulfide bond.
A. Disulfide bond - A disulfide bond is a covalent S-S linkage produced by oxidation of two
cysteine thiols.
B. Methionine - A peptide bond is the amide linkage formed between the carboxyl group of
one amino acid and the amino group of another.
C. Peptide bond - Asparagine has a polar uncharged carboxamide side chain.
D. Asparagine - Methionine contains a nonpolar thioether side chain.
Correct Answer: A. Disulfide bond - A disulfide bond is a covalent S-S linkage
produced by oxidation of two cysteine thiols.
Explanation: The correct pairing is Disulfide bond with its defining description. Each
distractor deliberately pairs a valid biochemical term with the definition of a different
concept. Matching vocabulary to mechanism is essential before applying the ideas to
calculations or molecular examples.
Question 10.
A laboratory observation shows that its hydrophobic side chain favors nonpolar
environments. Which concept best explains this finding?
A. Noncompetitive inhibition
B. Lysine
C. Active site
D. Valine
Correct Answer: D. Valine
Explanation: Valine best explains the observation because valine is a branched-chain,
nonpolar amino acid with an isopropyl side chain. The clue in the stem points directly to
this mechanism or structural feature. The other options involve different biochemical
properties and therefore do not account for the observation as well.
Question 11.
Which statement about Asparagine is most accurate?
A. The Bohr effect is the decrease in hemoglobin oxygen affinity caused by lower pH and
increased CO2.
B. The active site is the region of an enzyme where substrate binding and catalysis occur.
C. Asparagine has a polar uncharged carboxamide side chain.
D. Phenylalanine has a nonpolar aromatic benzyl side chain.
Correct Answer: C. Asparagine has a polar uncharged carboxamide side chain.
Explanation: Asparagine has a polar uncharged carboxamide side chain. This is the
defining chemistry of Asparagine. The alternative statements describe other concepts and
would misclassify the structure, force, or process under discussion.
SET QUESTIONS WITH ANSWERS AND EXPLANATIONS
Question 1.
Which pairing in this set correctly associates a biochemical term with its definition? Focus
on the set built around Aspartate.
A. Tertiary protein structure - Heme is a porphyrin cofactor containing iron that reversibly
binds oxygen in globins.
B. Aspartate - Aspartate has a carboxylate side chain that is negatively charged near
physiologic pH.
C. Heme - A peptide bond is the amide linkage formed between the carboxyl group of one
amino acid and the amino group of another.
D. Peptide bond - Tertiary structure is the overall three-dimensional fold of a single
polypeptide chain.
Correct Answer: B. Aspartate - Aspartate has a carboxylate side chain that is
negatively charged near physiologic pH.
Explanation: The correct pairing is Aspartate with its defining description. Each distractor
deliberately pairs a valid biochemical term with the definition of a different concept.
Matching vocabulary to mechanism is essential before applying the ideas to calculations or
molecular examples.
Question 2.
A laboratory observation shows that two cysteine residues can create a covalent cystine
linkage. Which concept best explains this finding?
A. Primary protein structure
B. Apoenzyme
C. Cysteine
D. N-terminus
Correct Answer: C. Cysteine
Explanation: Cysteine best explains the observation because cysteine contains a thiol
side chain that can oxidize to form disulfide bonds. The clue in the stem points directly to
this mechanism or structural feature. The other options involve different biochemical
properties and therefore do not account for the observation as well.
Question 3.
Which residue is most likely to disrupt an alpha helix because its side chain constrains the
backbone nitrogen?
A. Proline
B. Leucine
C. Alanine
D. Methionine
Correct Answer: A. Proline
,Explanation: Proline is the best choice based on the defining chemistry of its side chain.
The other listed residues belong to different side-chain classes or lack the relevant
functional group. Correct classification of amino-acid side chains helps predict folding,
reactivity, and protein interactions.
Question 4.
A laboratory observation shows that it is frequently buried in hydrophobic protein cores.
Which concept best explains this finding?
A. Hemoglobin
B. Tertiary protein structure
C. Competitive inhibition
D. Leucine
Correct Answer: D. Leucine
Explanation: Leucine best explains the observation because leucine is a branched-chain,
nonpolar amino acid with an isobutyl side chain. The clue in the stem points directly to this
mechanism or structural feature. The other options involve different biochemical
properties and therefore do not account for the observation as well.
Question 5.
Which pair contains hydroxyl-bearing side chains that can be phosphorylated?
A. Asparagine and glutamine
B. Aspartate and glutamate
C. Serine and threonine
D. Valine and leucine
Correct Answer: C. Serine and threonine
Explanation: Serine and threonine is the best choice based on the defining chemistry of
its side chain. The other listed residues belong to different side-chain classes or lack the
relevant functional group. Correct classification of amino-acid side chains helps predict
folding, reactivity, and protein interactions.
Question 6.
A laboratory observation shows that it can stabilize extracellular proteins and some
secreted peptides. Which concept best explains this finding?
A. Disulfide bond
B. Methionine
C. Asparagine
D. Peptide bond
Correct Answer: A. Disulfide bond
Explanation: Disulfide bond best explains the observation because a disulfide bond is a
covalent S-S linkage produced by oxidation of two cysteine thiols. The clue in the stem
points directly to this mechanism or structural feature. The other options involve different
,biochemical properties and therefore do not account for the observation as well.
Question 7.
Which pairing in this set correctly associates a biochemical term with its definition? Focus
on the set built around Glycine.
A. Aspartate - A zwitterion contains both positive and negative formal charges while
having no net charge overall.
B. Active site - Aspartate has a carboxylate side chain that is negatively charged near
physiologic pH.
C. Zwitterion - The active site is the region of an enzyme where substrate binding and
catalysis occur.
D. Glycine - Glycine has hydrogen as its side chain and is the only standard amino acid
that is achiral.
Correct Answer: D. Glycine - Glycine has hydrogen as its side chain and is the
only standard amino acid that is achiral.
Explanation: The correct pairing is Glycine with its defining description. Each distractor
deliberately pairs a valid biochemical term with the definition of a different concept.
Matching vocabulary to mechanism is essential before applying the ideas to calculations or
molecular examples.
Question 8.
A laboratory observation shows that its amide can donate and accept hydrogen bonds.
Which concept best explains this finding?
A. Active site
B. Asparagine
C. Phenylalanine
D. Bohr effect
Correct Answer: B. Asparagine
Explanation: Asparagine best explains the observation because asparagine has a polar
uncharged carboxamide side chain. The clue in the stem points directly to this mechanism
or structural feature. The other options involve different biochemical properties and
therefore do not account for the observation as well.
, Question 9.
Which pairing in this set correctly associates a biochemical term with its definition? Focus
on the set built around Disulfide bond.
A. Disulfide bond - A disulfide bond is a covalent S-S linkage produced by oxidation of two
cysteine thiols.
B. Methionine - A peptide bond is the amide linkage formed between the carboxyl group of
one amino acid and the amino group of another.
C. Peptide bond - Asparagine has a polar uncharged carboxamide side chain.
D. Asparagine - Methionine contains a nonpolar thioether side chain.
Correct Answer: A. Disulfide bond - A disulfide bond is a covalent S-S linkage
produced by oxidation of two cysteine thiols.
Explanation: The correct pairing is Disulfide bond with its defining description. Each
distractor deliberately pairs a valid biochemical term with the definition of a different
concept. Matching vocabulary to mechanism is essential before applying the ideas to
calculations or molecular examples.
Question 10.
A laboratory observation shows that its hydrophobic side chain favors nonpolar
environments. Which concept best explains this finding?
A. Noncompetitive inhibition
B. Lysine
C. Active site
D. Valine
Correct Answer: D. Valine
Explanation: Valine best explains the observation because valine is a branched-chain,
nonpolar amino acid with an isopropyl side chain. The clue in the stem points directly to
this mechanism or structural feature. The other options involve different biochemical
properties and therefore do not account for the observation as well.
Question 11.
Which statement about Asparagine is most accurate?
A. The Bohr effect is the decrease in hemoglobin oxygen affinity caused by lower pH and
increased CO2.
B. The active site is the region of an enzyme where substrate binding and catalysis occur.
C. Asparagine has a polar uncharged carboxamide side chain.
D. Phenylalanine has a nonpolar aromatic benzyl side chain.
Correct Answer: C. Asparagine has a polar uncharged carboxamide side chain.
Explanation: Asparagine has a polar uncharged carboxamide side chain. This is the
defining chemistry of Asparagine. The alternative statements describe other concepts and
would misclassify the structure, force, or process under discussion.
