Final Exam - Most Missed Questions Flashcards
When a carboxylate side-chain of one amino acid in a protein is in close proximity to a
charged amino group of another amino acid, we call the resulting interaction a(n)
a. ion - dipole bond
b. ionic bond
c. van der Waal’s bond
d. salt bridge
d. salt bridge
The pKa of acetic acid is 4.76.What is the pH of a solution containing 9 mM acetic acid and 1 mM
sodium acetate.(Hint: Refer to the Henderson-Hasselbalch equation on the last page.)
a. 3.76
b. 4.76
c. 5.76
d. 8.8
e. 10.8
a. 3.76
The ratio of a weak acid and its conjugate base at the point of maximum buffering capacity
is
a. 1/1
b. 1/10
c. 10/1
d. no definite ratio is needed
a. 1/1
Hydrogen bonds define the repetitive structure in this type of structure in proteins:
a. primary structure
b. secondary structure
c. tertiary structure
d. quaternary structure
e. All of these
b. secondary structure
Disulfide bonds are most important in this type of structure:
a. primary structure
b. secondary structure
c. tertiary structure
d. quaternary structure
e. All of these
c. tertiary structure
The protein myoglobin
a. contains a high degree of β-pleated sheet structure
b. carries oxygen in the bloodstream
c. contains no histidine
d. contains a heme group
d. contains a heme group
Which of the following is true about the enzyme chymotrypsin?
a. The enzyme can cleave peptides.
b. The enzyme can cleave esters.
c. The enzyme only binds to aromatic substrates.
d. The enzyme can cleave substrates which are not naturally occurring.
e. All of these are correct
e. All of these are correct
In the reaction catalyzed by chymotrypsin, a graph in which the rate is plotted against the
concentration of substrate
a. is sigmoidal, characteristic of an allosteric enzyme
b. shows that cooperative kinetics are observed
c. shows that the reaction is zero order
d. is hyperbolic, characteristic of a nonallosteric enzyme
d. is hyperbolic, characteristic of a nonallosteric enzyme
Refer to Exhibit 4B. Which one shows hydrogen bonding of the peptide backbone?
a. M
b. N
c. P
d. M and N
e. All of these
d. M and N
Refer to Exhibit 3B. Which point most likely represents the pK for the carboxyl group?
a. 1
b. 2
c. 3
d. 4
e. 5
b. 2
Is the Michaelis-Menten equation useful when studying allosteric enzymes?
a. Yes
b. No
c. Only if the enzyme displays positive cooperativity.
d. Only if the enzyme displays negative cooperativity
b. No
Where do allosteric inhibitors bind on an enzyme?
a. They always bind at a site different from the active site.
b. They always bind at the active site.
c. They can bind at either active site or another site.
d. They always bind directly to the substrate
e. none of these
a. They always bind at a site different from the active site.
Allosteric enzymes must exhibit which of the following?
a. feedback inhibition
b. a phosphorylation site
c. general acid-base catalysis
d. a quaternary structure
e. none of these must be exhibited
d. a quaternary structure
Which amino acid takes on a positive charge when the R-group gains a proton?
a. Glutamic Acid
b. Glutamine
c. Histidine
d. Glycine
e. Tyrosine
c. Histidine
A fatty acid with eighteen carbons and one double bond could be designated all EXCEPT:
a. linoleic acid.
b. 18:1.
c. cis-9-octadecenoic acid.
d. oleic acid.
e. elaidic acid
a. linoleic acid.
In the following structure, which carbon is the anomeric carbon?
a. A
b. B
c. C
d. D
e. E
e. E
Which of the following enzymes contains an FAD prosthetic group?
a. succinate dehydrogenase
b. isocitrate dehydrogenase
c. malate dehydrogenase
d. pyruvate dehydrogenase
e. α-ketoglutarate dehydrogenase
a. succinate dehydrogenase
The glycogen debranching enzyme is required for __________.
a. the transfer of 3-glucose units from one branch to another
b. the transfer of phosphate from one position to another
c. cleaving α (1 → 6) sugar linkages
d. A and C
e. A, B, and C
d. A and C
Which enzyme catalyzes a reaction most similar to that catalyzed by α-ketoglutarate dehydrogenase?
a. malate dehydrogenase
b. glyceraldehyde-3-phosphate dehydrogenase
c. isocitrate dehydrogenase
d. succinate dehydrogenase
e. pyruvate dehydrogenase
c. isocitrate dehydrogenase
What makes the reaction catalyzed by citrate synthase highly exergonic?
a. hydrolysis of ATP
b. decarboxylation reaction
c. hydrolysis of GTP
d. conversion from keto to enol tautomer
e. hydrolysis of thioester
e. hydrolysis of thioester
Which of the following IS NOT a property of integral membrane proteins
(intrinsic proteins)?
a. they contain both hydrophobic surfaces and hydrophilic surfaces
b. they dissociate from the membrane by treatment with salt solutions
c. they are exposed to at least one aqueous surface surrounding the membrane
d. they are inserted into the membrane and sequestered largely by hydrophobic
interactions
e. they have significant lateral mobility
b. they dissociate from the membrane by treatment with salt solutions
The cytochrome that passes electrons directly to oxygen is
a. cytochrome c1.
b. cytochrome b.
c. cytochrome c.
d. the cytochrome a/a3 complex.
d. the cytochrome a/a3 complex.
Which equation best expresses the membrane potential (voltage)?
a. ΔG = RT ln ([H+]out/[H+]in)
b. ΔG = ZFΔψ
c. ΔG = RT ln ([H+]out/[H+]in) + ZFΔψ
d. E = E0’ - 0.026V ln ([Areduced]/[Aoxidized])
b. ΔG = ZFΔψ
Which equation is best to express the protonmotive force?
a. ΔG = RT ln ([H+]out/[H+]in)
b. ΔG = ZFΔψ
c. ΔG = RT ln ([H+]out/[H+]in) + ZFΔψ
d. E = E0’ - 0.026V ln ([Areduced]/[Aoxidized])
c. ΔG = RT ln ([H+]out/[H+]in) + ZFΔψ
The oxidation of unsaturated fatty acids specifically requires
a. a cis-trans isomerase and a reductase.
b. a cis-trans isomerase and a dehydrogenase.
c. a dehydrogenase and a reductase.
d. a dehydrogenase and a hydrase
a. a cis-trans isomerase and a reductase.
Which of the following reactants is required in both fatty acid synthesis
and fatty acid breakdown?
a. CO2.
b. Malonyl-CoA
c. NADPH.
d. Phosphopantetheine
d. Phosphopantetheine
The nitrogen-fixing enzyme system, nitrogenase, is found exclusively
in
a. plants
b. bacteria
c. some viruses
d. animals
b. bacteria
The two nitrogens in urea arise directly from:
a. Ammonia and aspartic acid.
b. Carbamoyl phosphate and aspartic acid.
c. Carbamoyl phosphate and glutamic acid.
d. Ammonia and glutamic acid.
e. Carbamoyl phosphate and glutamine.
b. Carbamoyl phosphate and aspartic acid.
Which of the following is true of the glucose transporter?
a. binding of glucose causes a conformational change so that the transporter opens to one side of the membrane or the other
b. it can transport glucose into a cell against a concentration gradient
c. it will also transport any hexose
d. both A & B
e. both A & C
a. binding of glucose causes a conformational change so that the transporter opens to one side of the membrane or the other
In a variation of the Cori cycle, what amino acid is transported from the
muscle to the liver?
a. glycine
b. glutamate
c. aspartate
d. alanine
e. glutamine
d. alanine
Which of the following is NOT an essential amino acid in humans?
a. valine
b. lysine
c. leucine
d. methionine
e. serine
e. serine
