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ACS Biochemistry Final Review Questions and Answers fully solved
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ACS Biochemistry Final Review
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ACS Biochemistry Final ReviewC4, CS, and N7 of the purine structure originates from this molecule
N1 of the purine structure originates from this molecule.
C2 of the purine structure originates from this molecule
N3 and N9 of the purine structure originates from this
Precursor to both AMP and GMP
Amido phosphoribosyl transferase is activated by this molecule - answer Glycine
Aspartate
Formate
Glutamine
IMP
PRPP
Two amino acids of the standard 20 contain hydroxyl-groups. They are: -
answerthreonine and serine
There are several amino acid side chains which are always charged at physiological pH.
These are: - answerGlu, 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? - answerMet-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 - answer0
How many hydrophobic amino acid residues are present in the peptide shown? -
answer2
,The peptide shown has the amino acid sequence: - answerVal-Ser-Ile-Glu-Lys
Which statement is FALSE about the classification of amino acids? - answerGlutamic
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? - answerCys
Which statement(s) is/are TRUE about the following peptide? Ala-Cys-Gly-Met-Lys -
answerIt has four peptide bonds
Using the table shown, identify which proteins would bind to an anion exchange column
equilibrated at pH 7.0. - answer2 & 4
Which of the following sequences of amino acids is most likely to be on the surface of a
water-soluble globular protein? - answerGlu-Asp-Lys
Which amino acid can be modified to make the following synthetic compound? -
answerlysine
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? - answerglutamic 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? - answerribonuclease 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). -
answer0.8
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? - answerTwo 40 kDa and two 60 kDa subunits
Which of the following forces stabilize protein primary structure at physiological pH? -
answercovalent bonds
,Which of the following statements is true regarding sodium dodecylsulphate
polyacrylamide gel electrophoresis (SDS-PAGE)? - answerSDS-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. - answer1 & 2 and 4 & 5
Using the table shown, identify which proteins would migrate together during SDS-
PAGE in the absence of 2-mercaptoethanol. - answer2 & 3 and 4 & 5
Using the table shown, identify which proteins would give more than one product after a
single cycle of Edman degradation. - answer4 & 5
Which of the following is an example of a conservative amino acid substitution in a
protein structure? - answerSer to Thr
Which of the following is NOT a conservative amino acid substitution in a protein
structure? - answerArg to Phe
Which of the following amino acids is MOST likely to be a conservative substitution for
glycine? - answerANSWER: Ala
Lue
Pro
Thr
Which reagent reduces disulfide bonds to sulfhydryl groups? - answer2-
mercaptoethanol and DTT (dithiothreitol)
Identify the least conservative amino acid substitution, assuming that these two
residues occur at the same position in two homologous proteins. - answerGlu --> Lys
Which of the following statements is not true about the Bradford assay? - answerIt
involves the absorbance of light in the UV region by phenylalanine, tryptophan, and
tyrosine.
Which of the following statements is not true about SDS-PAGE: - answerProteins are
separated based on their size, shape and electric charge at a given pH.
Which of the following statements about affinity chromatography is not true: - answerIn
metal chelate affinity chromatography, the matrix contains metal ions ligands (like Zn2+
, or Ni2+) so that proteins bearing metal-chelating groups (e.g., multiple His side chains)
can be retained.
The stronger the interaction between the ligand and the protein, the better the result of
the affinity purification.
The bound protein can be eluted by washing the column with a solution containing a
high concentration of free ligand or a solution of different pH or ionic strength.
ANSWER: It is a very effective means of separation because one can "fish out" the
target protein from a mixture of several proteins by exploiting its unique biochemical
affinity for the ligand.
A molecule (a ligand) that specifically binds to the protein of interest (e.g., a non-
reactive analog of an enzyme's substrate) is covalently attached to an inert matrix.
Which chemical reagent promotes peptide bond cleavage on the C-side (carboxyl side)
of lysine and arginine residues if the next residue is not proline? - answertrypsin
What would be the order of elution (from first --> last) of the proteins carbonic
anhydrase (pI = 7.0), carboxypeptidase B (pI = 6.2) and chymotrypsin (pI = 8.0) run on a
CM (carboxymethyl) ion exchange column at pH 6.6 eluted with an increasing NaCl
gradient: - answercarboxypeptidase B, carbonic anhydrase, chymotrypsin.
Three of the 20 amino acids that are incorporated into proteins are aromatic. They are: -
answertyrosine, phenylalanine, and tryptophan.
Which of the following series of amino acids is most likely to be buried in the center of a
water-soluble globular protein? - answerAla, Leu, Phe
Two amino acids of the standard 20 contain sulfur-groups. They are: -
answermethionine and cysteine.
Which amino acid can be modified to make the following synthetic compound? -
answerproline
Which structure shows the protein at its isoelectric point (pI)? - answer3
Which of the following statements is/are true?
I. If pH > pI, a molecule will have a positive charge.
II If pH < pI, a molecule will have a positive charge.
III If pH = pI, a molecule will have no charge - answerII and III
Which of the following proteins will elute last in gel filtration chromatography? -
answerProteinase Inhibitor III 3.4 kD
Given a mixture of two nickel-binding proteins, Protein A with a Kd of 2mM and Protein
B with a Kd of 0.2mM, which one will elute first from a nickel affinity column? -
answerProtein A
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