Unit 2 Quiz
1. Which level of protein structure is disrupted through the hydrolysis of peptide bonds?
a. Primary
b. Tertiary
c. Secondary
d. Quaternary
Answer: A. 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.
2. A mutation in the beta-hemoglobin gene, which results in the replacement of the amino acid glutamate in
position 6 with the amino acid valine, leads to the development of sickle cell anemia. The structures of glutamate
and valine are shown below.
Amino acid structures of glutamate and valine
If the beta hemoglobin gene in a patient with sickle-cell anemia were to be edited so that the valine in position 6 was
replaced with a different amino acid, which replacement for valine would be expected to have the best clinical
outcome, in theory, for the patient? (Assume the valine can potentially be replaced with any amino acid other than
glutamate.)
a. b. c. d.
Answer: B. The original amino acid in a healthy patient is glutamate, which is negatively charged. The mutated amino
acid is valine, which is non-polar. Valine is causing sickle cell anemia. The best amino acid to replace valine so that the
patient is healthy again would be the one most like glutamate, so any negatively charged amino acid. Amino acid
structure C is non-polar, not charged.
,3. Secondary, tertiary, and quaternary levels of protein structure can all be impacted by exposing a protein to
which treatment?
a. Increase in the concentration of the protein in solution
b. Placement of the protein in a solution with a low pH
c. Addition of a reducing agent
d. Change of a hydrophobic amino acid to a different hydrophobic amino acid
Answer: B. The correct answer is “Placement of the protein in a solution with a low pH”. The addition of a reducing agent
would only affect disulfide bonds in the side chains of polar amino acids containing SH. These types of bonds are only
found in the tertiary and quaternary structure, not secondary structure.
4. An increase in beta-pleated sheet structure in some brain proteins can lead to an increase in amyloid deposit
formation, characteristic of some neurodegenerative diseases. What is the primary biochemical process that
follows the increase in beta-pleated sheet structure that leads to the development of the amyloid deposits?
a. An increase in anaerobic metabolism of glucose in the brain
b. Aggregation of the proteins in the brain
c. An increase in glycogen formation in the brain cells
d. Secretion of glucagon, leading to excessive ketogenesis
Answer: B. The correct answer is “Aggregation of the proteins in the brain”. This question is describing changes in protein
structure. Glycogen is a carbohydrate, not a protein, and is stored in the liver and muscles, not the brain. See Unit 6 for
more information on glycogen.
5. Which level of protein structure is determined by the sequence of amino acids?
a. Secondary structure
b. Tertiary structure
c. Primary structure
d. Quaternary structure
Answer: C. The correct answer is “Primary structure”. The primary structure of a protein is simply the sequence of
amino acids held together by peptide bonds. The quaternary structure of a protein is when two or more polypeptide
chains (“subunits”) work together to perform the function of the protein. The two or more polypeptide chains are held
together by side chain interactions, including the hydrophobic effect, ionic bonds, disulfide bonds, and hydrogen bonds.
6. Which force is most influential in determining the secondary structure of a protein?
a. Disulfide bonding
b. Hydrophobic effect
c. Hydrogen bonding
d. Electrostatic interactions
Answer: C. The secondary structure of a protein is built by hydrogen bonds between the carboxyl groups and amino
groups on the backbones of the amino acids.
,7. Which amino acid would most likely participate in hydrogen bonds?
a. b. c. d.
Answer: C. This is a polar, uncharged amino acid due to the OH group on the side chain. Polar, uncharged amino acids
containing oxygen or NH groups make hydrogen bonds.
8. Which portion of the amino acid is inside the box?
a. Amino group
b. Alpha carbon
c. Side chain
d. Carboxyl group
Answer: C. The side chain is the variable group of the amino acid, also called the R group. Every amino acid has the same
amino group, carboxylic acid group, and an alpha carbon, but the side chain is different.
, 9. Which pair of amino acids will most likely interact through hydrophobic forces between their side chains?
a. b.
c. d.
Answer: D. “Pair of amino acids (3)”. In “Pair of amino acids (4)” the left is non-polar and therefore can make
hydrophobic interactions, but it must do this with another non-polar amino acid. The amino acid on the right is polar,
uncharged due to the SH group. Please note that the “S” in the amino acid on the left is non-polar, while the “SH” group
is polar. The S must have an H to be polar and is otherwise non-polar. SH groups make disulfide bonds with other SH
groups.
10. Which portion of the amino acid is inside the box?
a. Alpha carbon
b. Amino group
c. Carboxyl group
d. Side chain
Answer: A. The alpha carbon is the central carbon on an amino acid that holds together the other groups of the amino
acid. It is always attached to the amino group, the carboxyl group, the side chain, and a single hydrogen. It is part of the
backbone of the amino acid and is found in every amino acid.
1. Which level of protein structure is disrupted through the hydrolysis of peptide bonds?
a. Primary
b. Tertiary
c. Secondary
d. Quaternary
Answer: A. 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.
2. A mutation in the beta-hemoglobin gene, which results in the replacement of the amino acid glutamate in
position 6 with the amino acid valine, leads to the development of sickle cell anemia. The structures of glutamate
and valine are shown below.
Amino acid structures of glutamate and valine
If the beta hemoglobin gene in a patient with sickle-cell anemia were to be edited so that the valine in position 6 was
replaced with a different amino acid, which replacement for valine would be expected to have the best clinical
outcome, in theory, for the patient? (Assume the valine can potentially be replaced with any amino acid other than
glutamate.)
a. b. c. d.
Answer: B. The original amino acid in a healthy patient is glutamate, which is negatively charged. The mutated amino
acid is valine, which is non-polar. Valine is causing sickle cell anemia. The best amino acid to replace valine so that the
patient is healthy again would be the one most like glutamate, so any negatively charged amino acid. Amino acid
structure C is non-polar, not charged.
,3. Secondary, tertiary, and quaternary levels of protein structure can all be impacted by exposing a protein to
which treatment?
a. Increase in the concentration of the protein in solution
b. Placement of the protein in a solution with a low pH
c. Addition of a reducing agent
d. Change of a hydrophobic amino acid to a different hydrophobic amino acid
Answer: B. The correct answer is “Placement of the protein in a solution with a low pH”. The addition of a reducing agent
would only affect disulfide bonds in the side chains of polar amino acids containing SH. These types of bonds are only
found in the tertiary and quaternary structure, not secondary structure.
4. An increase in beta-pleated sheet structure in some brain proteins can lead to an increase in amyloid deposit
formation, characteristic of some neurodegenerative diseases. What is the primary biochemical process that
follows the increase in beta-pleated sheet structure that leads to the development of the amyloid deposits?
a. An increase in anaerobic metabolism of glucose in the brain
b. Aggregation of the proteins in the brain
c. An increase in glycogen formation in the brain cells
d. Secretion of glucagon, leading to excessive ketogenesis
Answer: B. The correct answer is “Aggregation of the proteins in the brain”. This question is describing changes in protein
structure. Glycogen is a carbohydrate, not a protein, and is stored in the liver and muscles, not the brain. See Unit 6 for
more information on glycogen.
5. Which level of protein structure is determined by the sequence of amino acids?
a. Secondary structure
b. Tertiary structure
c. Primary structure
d. Quaternary structure
Answer: C. The correct answer is “Primary structure”. The primary structure of a protein is simply the sequence of
amino acids held together by peptide bonds. The quaternary structure of a protein is when two or more polypeptide
chains (“subunits”) work together to perform the function of the protein. The two or more polypeptide chains are held
together by side chain interactions, including the hydrophobic effect, ionic bonds, disulfide bonds, and hydrogen bonds.
6. Which force is most influential in determining the secondary structure of a protein?
a. Disulfide bonding
b. Hydrophobic effect
c. Hydrogen bonding
d. Electrostatic interactions
Answer: C. The secondary structure of a protein is built by hydrogen bonds between the carboxyl groups and amino
groups on the backbones of the amino acids.
,7. Which amino acid would most likely participate in hydrogen bonds?
a. b. c. d.
Answer: C. This is a polar, uncharged amino acid due to the OH group on the side chain. Polar, uncharged amino acids
containing oxygen or NH groups make hydrogen bonds.
8. Which portion of the amino acid is inside the box?
a. Amino group
b. Alpha carbon
c. Side chain
d. Carboxyl group
Answer: C. The side chain is the variable group of the amino acid, also called the R group. Every amino acid has the same
amino group, carboxylic acid group, and an alpha carbon, but the side chain is different.
, 9. Which pair of amino acids will most likely interact through hydrophobic forces between their side chains?
a. b.
c. d.
Answer: D. “Pair of amino acids (3)”. In “Pair of amino acids (4)” the left is non-polar and therefore can make
hydrophobic interactions, but it must do this with another non-polar amino acid. The amino acid on the right is polar,
uncharged due to the SH group. Please note that the “S” in the amino acid on the left is non-polar, while the “SH” group
is polar. The S must have an H to be polar and is otherwise non-polar. SH groups make disulfide bonds with other SH
groups.
10. Which portion of the amino acid is inside the box?
a. Alpha carbon
b. Amino group
c. Carboxyl group
d. Side chain
Answer: A. The alpha carbon is the central carbon on an amino acid that holds together the other groups of the amino
acid. It is always attached to the amino group, the carboxyl group, the side chain, and a single hydrogen. It is part of the
backbone of the amino acid and is found in every amino acid.
