©Themoon EXAM SOLUTIONS
25/11/2024 09:27AM
Bioc 201 Preclass Questions and Answers
Which one of the following statements about enzymes and enzyme-catalyzed chemical
reactions is CORRECT?
a. Spontaneous chemical reactions are relatively fast.
b.Enzymes are always made of protein.
c. Enzymes are typically promiscuous, e.g, an enzyme that catalyzes a reaction involving a
specific sugar can typically catalyzes reactions with many other types of sugars.
d. Enzymes often change shape when they bind their substrate(s). - Answers✓✓d. Enzymes
often change shape when they bind their substrate(s).
Which one of the following statements concerning enzyme regulation is FALSE?
a. The allosteric site is never the same as the active site.
b. ATP can be a substrate at the active site of an enzyme or it can bind to the allosteric site as
an inhibitor.
c. Most enzymes regulated by allosteric mechanisms contain one or more polypeptides
(subunits).
, ©Themoon EXAM SOLUTIONS
25/11/2024 09:27AM
d. Many metabolic pathways are regulated by the binding of their end product to an enzyme
that acts in an early step of the pathway, a type of feedback inhibition. - Answers✓✓a. The
allosteric site is never the same as the active site.
Which one of the following statements concerning polypeptide(s) or protein(s) is
INCORRECT?
a. A protein is made up of one or more polypeptides.
b. The primary structure of a polypeptide determines where (along the length of the
polypeptide) secondary structures such as alpha-helices or beta-sheets can form.
c. Polypeptide synthesis involves addition of amino acid monomers only at the C- (COOH-)
terminus of the polypeptide.
d. The initial, most rapid, folding reactions of a linear polypeptide is driven by hydrophobic
collapse where the nonpolar side chains are more likely to end up in the interior region of the
folded polypeptide. - Answers✓✓d. The initial, most rapid, folding reactions of a linear
polypeptide is driven by hydrophobic collapse where the nonpolar side chains are more likely
to end up in the interior region of the folded polypeptide.
Which one of the following statements concerning protein folding in cells is INCORRECT?
a. The chaperone HSP70 can bind to a nascent polypeptide.
b. Ubiquitin ligase-mediated attachment of ubiquitin to a newly synthesized polypeptide leads
to hydrolysis (breakdown, degradation) of that polypeptide by the proteasome.
, ©Themoon EXAM SOLUTIONS
25/11/2024 09:27AM
c. The chaperone HSP70 has an ATP-dependent mechanism for delaying the folding of a newly
synthesized polypeptide.
d. Protein folding in cells is highly efficient with more than 95% of all newly synthesized
polypeptides folding into their native, fully functional shapes. - Answers✓✓d. Protein folding
in cells is highly efficient with more than 95% of all newly synthesized polypeptides folding
into their native, fully functional shapes.
Which one of the following statements concerning the regulation of enzyme activity is FALSE?
a. The enzyme activity of some proteins is regulated by the noncovalent binding of other
proteins, i.e., by protein-protein interaction.
b. A phosphorylated protein (polypeptide) has a phosphate molecule covalently attached to the
side chain of an amino acid (for example, serine) in the polypeptide.
c. Covalent modification of an enzyme protein by protein kinase-mediated phosphorylation can
cause increases or decreases in catalytic activity, depending on the protein kinase substrate.
d. A positively-acting allosteric ligand typically remains on the allosteric site of an enzyme for
an extended period of time, thereby providing a kind of memory and sustaining an active
enzyme state. - Answers✓✓d. A positively-acting allosteric ligand typically remains on the
allosteric site of an enzyme for an extended period of time, thereby providing a kind of memory
and sustaining an active enzyme state.
Which one of the following statements concerning a plasma membrane (cell membrane) is
CORRECT?
, ©Themoon EXAM SOLUTIONS
25/11/2024 09:27AM
a. Phospholipids move very rapidly by themselves from one layer (leaflet) of the bilayer to the
other.
b. Plasma membrane carbohydrates (polysaccharides) are mostly covalently attached to lipids,
with the combined molecule called a glycolipid.
c. The plasma membrane of bearberry (an arctic tundra plant) has more unsaturated fatty acids
(fatty acids with double bonds) in its phospholipids than does that of guava (a tropical plant).
d. Most transmembrane proteins move from one surface of the plasma membrane to the other. -
Answers✓✓c. The plasma membrane of bearberry (an arctic tundra plant) has more unsaturated
fatty acids (fatty acids with double bonds) in its phospholipids than does that of guava (a
tropical plant).
Which one of the following statements regarding transport of solute molecules across the
plasma membrane is INCORRECT?
a. Movement of oxygen molecules across the plasma membrane does not require assistance by
membrane proteins.
b. Rapid diffusion of water across a plasma membrane requires assistance by membrane
proteins.
c. The sodium-potassium pump actively transports sodium ions (Na+) and potassium ions (K+)
in equal numbers across the plasma membrane of animal cells.
d. Animal cells use transport proteins to maintain a potassium ion gradient across their plasma
membrane, with higher concentration of K+ inside the cell than outside. - Answers✓✓c. The
25/11/2024 09:27AM
Bioc 201 Preclass Questions and Answers
Which one of the following statements about enzymes and enzyme-catalyzed chemical
reactions is CORRECT?
a. Spontaneous chemical reactions are relatively fast.
b.Enzymes are always made of protein.
c. Enzymes are typically promiscuous, e.g, an enzyme that catalyzes a reaction involving a
specific sugar can typically catalyzes reactions with many other types of sugars.
d. Enzymes often change shape when they bind their substrate(s). - Answers✓✓d. Enzymes
often change shape when they bind their substrate(s).
Which one of the following statements concerning enzyme regulation is FALSE?
a. The allosteric site is never the same as the active site.
b. ATP can be a substrate at the active site of an enzyme or it can bind to the allosteric site as
an inhibitor.
c. Most enzymes regulated by allosteric mechanisms contain one or more polypeptides
(subunits).
, ©Themoon EXAM SOLUTIONS
25/11/2024 09:27AM
d. Many metabolic pathways are regulated by the binding of their end product to an enzyme
that acts in an early step of the pathway, a type of feedback inhibition. - Answers✓✓a. The
allosteric site is never the same as the active site.
Which one of the following statements concerning polypeptide(s) or protein(s) is
INCORRECT?
a. A protein is made up of one or more polypeptides.
b. The primary structure of a polypeptide determines where (along the length of the
polypeptide) secondary structures such as alpha-helices or beta-sheets can form.
c. Polypeptide synthesis involves addition of amino acid monomers only at the C- (COOH-)
terminus of the polypeptide.
d. The initial, most rapid, folding reactions of a linear polypeptide is driven by hydrophobic
collapse where the nonpolar side chains are more likely to end up in the interior region of the
folded polypeptide. - Answers✓✓d. The initial, most rapid, folding reactions of a linear
polypeptide is driven by hydrophobic collapse where the nonpolar side chains are more likely
to end up in the interior region of the folded polypeptide.
Which one of the following statements concerning protein folding in cells is INCORRECT?
a. The chaperone HSP70 can bind to a nascent polypeptide.
b. Ubiquitin ligase-mediated attachment of ubiquitin to a newly synthesized polypeptide leads
to hydrolysis (breakdown, degradation) of that polypeptide by the proteasome.
, ©Themoon EXAM SOLUTIONS
25/11/2024 09:27AM
c. The chaperone HSP70 has an ATP-dependent mechanism for delaying the folding of a newly
synthesized polypeptide.
d. Protein folding in cells is highly efficient with more than 95% of all newly synthesized
polypeptides folding into their native, fully functional shapes. - Answers✓✓d. Protein folding
in cells is highly efficient with more than 95% of all newly synthesized polypeptides folding
into their native, fully functional shapes.
Which one of the following statements concerning the regulation of enzyme activity is FALSE?
a. The enzyme activity of some proteins is regulated by the noncovalent binding of other
proteins, i.e., by protein-protein interaction.
b. A phosphorylated protein (polypeptide) has a phosphate molecule covalently attached to the
side chain of an amino acid (for example, serine) in the polypeptide.
c. Covalent modification of an enzyme protein by protein kinase-mediated phosphorylation can
cause increases or decreases in catalytic activity, depending on the protein kinase substrate.
d. A positively-acting allosteric ligand typically remains on the allosteric site of an enzyme for
an extended period of time, thereby providing a kind of memory and sustaining an active
enzyme state. - Answers✓✓d. A positively-acting allosteric ligand typically remains on the
allosteric site of an enzyme for an extended period of time, thereby providing a kind of memory
and sustaining an active enzyme state.
Which one of the following statements concerning a plasma membrane (cell membrane) is
CORRECT?
, ©Themoon EXAM SOLUTIONS
25/11/2024 09:27AM
a. Phospholipids move very rapidly by themselves from one layer (leaflet) of the bilayer to the
other.
b. Plasma membrane carbohydrates (polysaccharides) are mostly covalently attached to lipids,
with the combined molecule called a glycolipid.
c. The plasma membrane of bearberry (an arctic tundra plant) has more unsaturated fatty acids
(fatty acids with double bonds) in its phospholipids than does that of guava (a tropical plant).
d. Most transmembrane proteins move from one surface of the plasma membrane to the other. -
Answers✓✓c. The plasma membrane of bearberry (an arctic tundra plant) has more unsaturated
fatty acids (fatty acids with double bonds) in its phospholipids than does that of guava (a
tropical plant).
Which one of the following statements regarding transport of solute molecules across the
plasma membrane is INCORRECT?
a. Movement of oxygen molecules across the plasma membrane does not require assistance by
membrane proteins.
b. Rapid diffusion of water across a plasma membrane requires assistance by membrane
proteins.
c. The sodium-potassium pump actively transports sodium ions (Na+) and potassium ions (K+)
in equal numbers across the plasma membrane of animal cells.
d. Animal cells use transport proteins to maintain a potassium ion gradient across their plasma
membrane, with higher concentration of K+ inside the cell than outside. - Answers✓✓c. The
