BIOCHEMISTRY ACS FINAL PAPER 2026
COMPREHENSIVE QUESTIONS AND
ANSWERS GRADED A+
◉Two amino acids of the standard 20 contain hydroxyl-groups. They
are: ANSWER: - threonine and serine
◉There are several amino acid side chains which are always charged at
physiological pH. These are: ANSWER: - Glu, Asp, Lys, and Arg
◉Which one of the following sequences of five amino acids would most
likely be located in the interior of a globular soluble protein? ANSWER:
- Met-Phe-Pro-Ile-Leu
◉What is the net charge at pH 7.0 on a peptide with the sequence?
Ala-Thr-Leu-Asp-Ala-Lys-Pro-Glu ANSWER: - -1
◉What would be the net charge for the peptide below at pH 7.0?
Asn-Asp-Cys-Tyr-Ser-Val-Lys ANSWER: - 0
◉How many hydrophobic amino acid residues are present in the peptide
shown? ANSWER: - 2
,◉The peptide shown has the amino acid sequence: ANSWER: - Val-
Ser-Ile-Glu-Lys
◉Which statement is FALSE about the classification of amino acids?
ANSWER: - Glutamic acid and asparagine are negatively charged amino
acids.
◉One of the amino acids that is classified as having a polar side chain is
typically found buried in the hydrophobic core of soluble globular
proteins. Which of the following amino acids is it? ANSWER: - Cys
◉Which statement(s) is/are TRUE about the following peptide? Ala-
Cys-Gly-Met-Lys ANSWER: - It has four peptide bonds
◉Using the table shown, identify which proteins would bind to an anion
exchange column equilibrated at pH 7.0. ANSWER: - 2 & 4
◉Which of the following sequences of amino acids is most likely to be
on the surface of a water-soluble globular protein? ANSWER: - Glu-
Asp-Lys
◉Which amino acid can be modified to make the following synthetic
compound? ANSWER: - lysine
,◉The following compound is a non-protein water soluble amino acid
that is found in green tea. Which amino acid is the precursor for this
compound? ANSWER: - glutamic acid
◉How many charges the following peptide has at pH=7.0? ANSWER: -
-1
◉A column containing carboxymethyl groups can be used to separate
serum albumin and ribonuclease A. Serum albumin has a pI of 4.9 and
Ribonuclease A has a pI of 9.4. Which one of these 2 proteins will bind
to the column if both proteins are dissolved in a buffer solution with
pH=7.0? ANSWER: - ribonuclease A
◉Protein X has an absorptivity of 0.4 mL·mg-1·cm-1 at 280 nm. What
is the absorbance at 280 nm of a 2.0 mg ·mL-1 solution of protein X?
(Assume the light path is 1cm). ANSWER: - 0.8
◉Consider a protein with the subunit composition indicated by the
following information:Molecular mass by gel filtration: 200
kDMolecular mass by SDS-PAGE: 100 kDMolecular mass by SDS-
PAGE with 2-mercaptoethanol: 40 kD and 60 kD
What can be concluded from all of this data about the subunit
composition of this protein? ANSWER: - Two 40 kDa and two 60 kDa
subunits
◉Which of the following forces stabilize protein primary structure at
physiological pH? ANSWER: - covalent bonds
, ◉Which of the following statements is true regarding sodium
dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE)?
ANSWER: - SDS-PAGE separates proteins on the basis of their intrinsic
charge and isoelectric point.
None of the statements is true.
SDS-PAGE separates nucleic acids on the basis of their charge.
Smaller proteins move through the gel faster under the influence of the
electric field in SDS-PAGE.
ANSWER: Smaller proteins move through the gel faster under the
influence of the electric field in SDS-PAGE.
◉Using the table shown, identify which proteins would elute together in
a gel filtration experiment. ANSWER: - 1 & 2 and 4 & 5
◉Using the table shown, identify which proteins would migrate together
during SDS-PAGE in the absence of 2-mercaptoethanol. ANSWER: - 2
& 3 and 4 & 5
◉Using the table shown, identify which proteins would give more than
one product after a single cycle of Edman degradation. ANSWER: - 4 &
5
◉Which of the following is an example of a conservative amino acid
substitution in a protein structure? ANSWER: - Ser to Thr
COMPREHENSIVE QUESTIONS AND
ANSWERS GRADED A+
◉Two amino acids of the standard 20 contain hydroxyl-groups. They
are: ANSWER: - threonine and serine
◉There are several amino acid side chains which are always charged at
physiological pH. These are: ANSWER: - Glu, Asp, Lys, and Arg
◉Which one of the following sequences of five amino acids would most
likely be located in the interior of a globular soluble protein? ANSWER:
- Met-Phe-Pro-Ile-Leu
◉What is the net charge at pH 7.0 on a peptide with the sequence?
Ala-Thr-Leu-Asp-Ala-Lys-Pro-Glu ANSWER: - -1
◉What would be the net charge for the peptide below at pH 7.0?
Asn-Asp-Cys-Tyr-Ser-Val-Lys ANSWER: - 0
◉How many hydrophobic amino acid residues are present in the peptide
shown? ANSWER: - 2
,◉The peptide shown has the amino acid sequence: ANSWER: - Val-
Ser-Ile-Glu-Lys
◉Which statement is FALSE about the classification of amino acids?
ANSWER: - Glutamic acid and asparagine are negatively charged amino
acids.
◉One of the amino acids that is classified as having a polar side chain is
typically found buried in the hydrophobic core of soluble globular
proteins. Which of the following amino acids is it? ANSWER: - Cys
◉Which statement(s) is/are TRUE about the following peptide? Ala-
Cys-Gly-Met-Lys ANSWER: - It has four peptide bonds
◉Using the table shown, identify which proteins would bind to an anion
exchange column equilibrated at pH 7.0. ANSWER: - 2 & 4
◉Which of the following sequences of amino acids is most likely to be
on the surface of a water-soluble globular protein? ANSWER: - Glu-
Asp-Lys
◉Which amino acid can be modified to make the following synthetic
compound? ANSWER: - lysine
,◉The following compound is a non-protein water soluble amino acid
that is found in green tea. Which amino acid is the precursor for this
compound? ANSWER: - glutamic acid
◉How many charges the following peptide has at pH=7.0? ANSWER: -
-1
◉A column containing carboxymethyl groups can be used to separate
serum albumin and ribonuclease A. Serum albumin has a pI of 4.9 and
Ribonuclease A has a pI of 9.4. Which one of these 2 proteins will bind
to the column if both proteins are dissolved in a buffer solution with
pH=7.0? ANSWER: - ribonuclease A
◉Protein X has an absorptivity of 0.4 mL·mg-1·cm-1 at 280 nm. What
is the absorbance at 280 nm of a 2.0 mg ·mL-1 solution of protein X?
(Assume the light path is 1cm). ANSWER: - 0.8
◉Consider a protein with the subunit composition indicated by the
following information:Molecular mass by gel filtration: 200
kDMolecular mass by SDS-PAGE: 100 kDMolecular mass by SDS-
PAGE with 2-mercaptoethanol: 40 kD and 60 kD
What can be concluded from all of this data about the subunit
composition of this protein? ANSWER: - Two 40 kDa and two 60 kDa
subunits
◉Which of the following forces stabilize protein primary structure at
physiological pH? ANSWER: - covalent bonds
, ◉Which of the following statements is true regarding sodium
dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE)?
ANSWER: - SDS-PAGE separates proteins on the basis of their intrinsic
charge and isoelectric point.
None of the statements is true.
SDS-PAGE separates nucleic acids on the basis of their charge.
Smaller proteins move through the gel faster under the influence of the
electric field in SDS-PAGE.
ANSWER: Smaller proteins move through the gel faster under the
influence of the electric field in SDS-PAGE.
◉Using the table shown, identify which proteins would elute together in
a gel filtration experiment. ANSWER: - 1 & 2 and 4 & 5
◉Using the table shown, identify which proteins would migrate together
during SDS-PAGE in the absence of 2-mercaptoethanol. ANSWER: - 2
& 3 and 4 & 5
◉Using the table shown, identify which proteins would give more than
one product after a single cycle of Edman degradation. ANSWER: - 4 &
5
◉Which of the following is an example of a conservative amino acid
substitution in a protein structure? ANSWER: - Ser to Thr
