TEST BANK for Biochemistry: A Short Course, 4th Edition, John Tymoczko, Jeremy Berg, Gregory Gatto, Lubert Stryer. ISBN: 9781319342883, ISBN: 9781319234379. TABLE OF CONTENTS_ Part I The Molecular D esign of Life SECTION 1 Biochemistry Helps Us to Understand Our World Chapter 1 Biochemistry and the...
, TEST BANK for Biochemistry: A Short Course, 4th Edition, John
Tymoczko, Jeremy M. Berg, Gregory J. Gatto Jr., Lubert Stryer.
Chapter 1 to 7
Indicate the answer choice that best completes the statement or answers the question.
1. What is the critical feature of the Michaelis–Menten model of enzyme catalysis?
a. increasing the probability of product formation
b. shifting the reaction equilibrium
c. formation of an ES complex
d. reaching the reaction equilibrium
e. accumulation of the product
2. The formula V0 = Vmax ([S]/[S] + KM) indicates the relationship between the:
a. enzyme activity and the equilibrium constant.
b. rate of a catalyzed reaction and the equilibrium constant.
c. enzyme activity and substrate concentration.
d. probable substrate concentration and the normal concentration in vivo.
e. turnover number and the rate of catalysis.
3. Which description of the concerted model for allosteric enzymes is TRUE?
a. At a low substrate concentration, L0 is small. Upon increasing the substrate concentration, in
accordance with the symmetry rule, L0 will be increasing. The disrupted equilibrium of the enzyme
states results in a sharp increase of the reaction velocity. As the concentration reaches the threshold,
the enzyme becomes more active.
b. Upon increasing the substrate concentration, due to cooperativity, the number of enzyme molecules
in the T state will be decreasing. The equilibrium between enzyme states is disturbed due to a lower
stability of the R state. As the concentration reaches the threshold, the enzyme becomes more active.
c. At a low substrate concentration, L0 is large. Increasing the substrate concentration will result in
accumulation of the enzyme in the R state, which will increase L0. The disrupted equilibrium of the
enzyme states results in a sharp increase of the reaction velocity. When the substrate concentration is
way above KM, the enzyme activity is very sensitive to the changes in the concentration, which
results in a sharp increase of the reaction velocity.
d. Upon increasing the substrate concentration due to the symmetry rule, the number of enzyme
molecules in the T state will be increasing. The equilibrium between enzyme states is disturbed due
to a lower stability of the T state. When the substrate concentration is way above KM, the enzyme
activity is very sensitive to the changes in the concentration, which results in a sharp increase of the
reaction velocity.
e. At a low substrate concentration, L0 is large. Upon increasing the substrate concentration, L0 will be
markedly decreasing. The disrupted equilibrium of the enzyme states results in a sharp increase of
the reaction velocity. As the concentration reaches the threshold, the enzyme becomes more active.
4. Which statement about mass spectrometry is FALSE?
a. In electrospray ionization, the protein or peptide under study is co-precipitated with an organic
compound that absorbs laser light of an appropriate wavelength.
, b. In the time of flight analysis, tiny amounts of biomolecules as small as a few picomoles (pmol) or
femtomoles (fmol) can be analyzed.
c. In tandem mass spectrometry, peptides can be fragmented by bombardment with argon to generate a
family of product ions in which one or more amino acids are removed from one end of the initial
peptide analyte.
d. MALDI-TOF is one of the most accurate means of determining protein mass.
e. In MALDI-TOF, peptide masses are matched in a database against proteins that have been
"electronically cleaved" by a computer simulating the same fragmentation technique used for the
experimental sample.
5. When [S] << KM, the enzymatic velocity depends on:
a. the values of kcat/KM, [S], and [E]T.
b. Vmax of the reaction.
c. the affinity of the substrate for the catalytic site.
d. the values of kcat, [S], and [E]T.
e. the formation of the ES complex.
6. What is the common strategy by which catalysis occurs?
a. increasing the probability of product formation
b. shifting the reaction equilibrium
c. stabilizing the transition state
d. increasing the free-energy difference between the transition state and the product
e. changing the shape of substrate binding
7. When enzymes are purified, the assay is often based on:
a. light absorbance.
b. catalytic activity.
c. pH.
d. temperature changes.
e. mRNA levels.
8. What is the reaction order if the reaction rate was doubled by doubling the reactant concentration?
a. zero order
b. first order
c. second order
d. pseudo-first order
e. pseudo-second order
9. Gastroesophageal reflux disease is a common example of a pathological change in:
a. pKa of acetic acid.
, b. hydrogen bonds in a key digestive enzyme.
c. protein structure.
d. water content in cells.
e. pH level.
10. What is the driving force for formation of the unique spatial structure of water-soluble proteins?
a. the tendency of hydrophilic groups to cluster together
b. the tendency of hydrophobic groups to repel each other
c. the tendency of polar groups to interact with water molecules
d. the tendency of hydrophobic groups to cluster together
e. the tendency of hydrophilic groups to repel each other
11. Polyclonal antibodies rather than monoclonal antibodies:
a. can be obtained by fusing of antibody-producing cells and myeloma cells.
b. are generated from a large number of cells of a single kind.
c. are used in purification of receptors or other proteins by immunoprecipitation.
d. such as Trastuzumab are used to treat some forms of breast cancer.
e. have an advantage for the detection of a protein with low abundance.
12. At equilibrium, the Gibbs free energy is/has:
a. a positive value.
b. neutral.
c. a negative value.
d. zero.
e. equal to one.
13. The active site of an enzyme:
a. is a series of amino acids that bind the enzyme.
b. is a linear sequence of amino acids that react with each other.
c. binds covalently to the substrate.
d. allows water to enter into the solvate and the substrate.
e. is responsible for the specificity of some enzymes.
14. Which amino acid is more conformationally restricted and why?
a. glycine because it is achiral
b. proline because its side chain is bonded to both the nitrogen and the α-carbon atoms
c. glycine because two hydrogen atoms are bonded to the α-atom
d. proline because its side chain is aliphatic
e. proline because its side chain is bonded to both the carboxyl carbon and the α-carbon atom
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