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ACS Biochemistry Final Review – Questions With Correct Solutions
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ACS Biochemistry Final Review – Questions With Correct Solutions
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ACS Biochemistry Final Review – Questions WithCorrect Solutions
C4, 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
Amidophosphoribosyl transferase is activated by this molecule Right Ans -
Glycine
Aspartate
Formate
Glutamine
IMP
PRPP
Two amino acids of the standard 20 contain hydroxyl-groups. They are:
Right Ans - threonine and serine
There are several amino acid side chains which are always charged at
physiological pH. These are: Right Ans - 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? Right Ans - 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 Right Ans - -1
,What would be the net charge for the peptide below at pH 7.0?
Asn-Asp-Cys-Tyr-Ser-Val-Lys Right Ans - 0
How many hydrophobic amino acid residues are present in the peptide
shown? Right Ans - 2
The peptide shown has the amino acid sequence: Right Ans - Val-Ser-Ile-
Glu-Lys
Which statement is FALSE about the classification of amino acids? Right
Ans - 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? Right Ans - Cys
Which statement(s) is/are TRUE about the following peptide? Ala-Cys-Gly-
Met-Lys Right Ans - It has four peptide bonds
Using the table shown, identify which proteins would bind to an anion
exchange column equilibrated at pH 7.0. Right Ans - 2 & 4
Which of the following sequences of amino acids is most likely to be on the
surface of a water-soluble globular protein? Right Ans - Glu-Asp-Lys
Which amino acid can be modified to make the following synthetic
compound? Right Ans - 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?
Right Ans - glutamic acid
How many charges the following peptide has at pH=7.0? Right Ans - -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? Right Ans -
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). Right Ans - 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? Right Ans - Two 40 kDa and two 60 kDa subunits
Which of the following forces stabilize protein primary structure at
physiological pH? Right Ans - covalent bonds
Which of the following statements is true regarding sodium dodecylsulphate
polyacrylamide gel electrophoresis (SDS-PAGE)? Right Ans - 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. Right Ans - 1 & 2 and 4 & 5
Using the table shown, identify which proteins would migrate together during
SDS-PAGE in the absence of 2-mercaptoethanol. Right Ans - 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. Right Ans - 4 & 5
Which of the following is an example of a conservative amino acid substitution
in a protein structure? Right Ans - Ser to Thr
, Which of the following is NOT a conservative amino acid substitution in a
protein structure? Right Ans - Arg to Phe
Which of the following amino acids is MOST likely to be a conservative
substitution for glycine? Right Ans - ANSWER: Ala
Lue
Pro
Thr
Which reagent reduces disulfide bonds to sulfhydryl groups? Right Ans - 2-
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. Right
Ans - Glu --> Lys
Which of the following statements is not true about the Bradford assay?
Right Ans - It 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: Right Ans -
Proteins 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:
Right Ans - In 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.
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