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Biochem > Exam 1 2023 Version A (minus photo Q) > Flashcards

Exam 1 2023 Version A (minus photo Q) Flashcards

1
Q
  1. One driving force for protein folding is hydrophobic interaction. Which of the following is true regarding hydrophobic interactions between nonpolar molecules or groups?

A) They are the result of strong repulsion between water and nonpolar regions.

B) They are the result of strong attractions between nonpolar regions.

C) The association of nonpolar groups is entropy-driven, resulting from the release of water molecules.

D) They result from the tendency to maximize water’s contact with nonpolar molecules.

A

C) The association of nonpolar groups is entropy-driven, resulting from the release of water molecules.

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2
Q
  1. A protein critical for maintaining the blood pH is ____; when the blood pH begins to rise, ____________.

A) Hemoglobin; more carbonic acid is excreted.

B) Carbonic anhydrase; less CO2 is exhaled.

C) Myoglobin; less CO2 is exhaled.

D) Carbonic anhydrase; more protons combine with bicarbonate.

A

B) Carbonic anhydrase; less CO2 is exhaled.

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3
Q
  1. The conjugate base for glutamic acid is:

A) Glutamine
B) Glutamate
C) Asparagine
D) Aspartate

A

B) Glutamate

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4
Q
  1. The sequence of the peptide Phe-Asp-Gln-Ile is ________; among the four residues in this peptide, which
    one has a side chain that is polar and uncharged from pH 1-13?

A) FDQI; Gln
B) FENI; Phe
C) FDNI; Gln
D) YDQI; Asp

A

A) FDQI; Gln

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5
Q
  1. What is in common among Ser, Thr, and Tyr?

A) They have a non-polar side chain.

B) They are positively charged at physiological pH.

C) They have a hydroxyl group that can potentially be phosphorylated.

D) They have two chiral centers and thus four different isomers

A

C) They have a hydroxyl group that can potentially be phosphorylated.

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6
Q
  1. Which of the following is a set of essential amino acids?

A) Leu, Ile, Pro
B) Leu, Gly, Ala
C) Val, His, Phe
D) Val, Ser, Asp

A

C) Val, His, Phe

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7
Q
  1. Arginine has three ionizable groups: α-carboxyl, α-amino, and side chain. Their pKa values are 2.17,
    9.04, and 12.48, respectively. Calculate the isoelectric point of arginine.

A) 2.17 + 9.04
B) (2.17 + 9.04) / 2
C) (9.04 + 12.48) / 2
D) (2.17+9.04+12.48) /3

A

C) (9.04 + 12.48) / 2

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8
Q
  1. Which of the following residues are not compatible with the formation of alpha-helix?

A) Ala and Glu
B) Pro and Gly
C) Ile and Phe
D) Tyr and Ala

A

B) Pro and Gly

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9
Q
  1. Which of the following is a correct match?

A) The shape of myoglobin is roughly spherical – tertiary structure

B) Hemoglobin consists of four polypeptide chains – quaternary structure

C) The lysozyme molecule contains regions of helical structure – secondary structure

D) All of above are correct.

A

D) All of above are correct.

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10
Q
  1. Which of the following sequences is compatible with the formation of an amphipathic beta-strand?

A) FADELIGH

B) FDAELHIN

C) DEHNFALI

D) FALIDEHN

A

B) FDAELHIN

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11
Q
  1. Which of the following describes X-ray crystallography?

A) Purifying the protein; acquiring the protein images in all possible
orientations; solving the structure.

B) Purifying the protein; growing protein crystal; obtaining diffraction
pattern; solving the structure.

C) Getting the whole cell lysate; subjecting the lysate to X-ray; solving
the structure.

D) Purifying the protein; subjecting the protein to a magnetic field; solving the structure.

A

B) Purifying the protein; growing protein crystal; obtaining diffraction
pattern; solving the structure.

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12
Q
  1. Which of the following sets of amino acid residues is likely to be prevalent (common) in intrinsically unstructured proteins?

A) Phe, Ala, Ile
B) Leu, Pro, Trp
C) Asn, Ser, Asp
D) Val, Phe, Met

A

C) Asn, Ser, Asp

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13
Q
  1. Which of the following is the correct pairing between the major obstacles of protein folding and the folding accessory proteins?

A) Incorrect disulfide bonds/PPI; incorrect Pro conformation/molecular chaperone; aggregation/PPI

B) Incorrect disulfide bonds/PDI; incorrect Pro conformation/PPI; aggregation/molecular chaperone

C) Incorrect disulfide bonds/molecular chaperone; incorrect Pro conformation/PDI; aggregation/PPI

D) Incorrect disulfide bonds/PPI; incorrect Pro conformation/molecular chaperone; aggregation/PDI

A

B) Incorrect disulfide bonds/PDI; incorrect Pro conformation/PPI; aggregation/molecular chaperone

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14
Q
  1. In the ubiquitin-proteasome pathway, ubiquitin molecule is often covalently linked to which of the
    following residues on a substrate protein?

A) Ala
B) Gly
C) His
D) Lys

A

D) Lys

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15
Q
  1. Ubiquitin is conjugated to a substrate protein via the action of three enzymes: E1, E2, and E3. Among
    these three enzymes, which one is responsible for specifying the substrate protein for ubiquitination?

A) E1
B) E2
C) E3
D) E1 and E2

A

C) E3

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16
Q
  1. Which of the following peptides binds most tightly to a cationexchanger at pH 7.0? Note that a cation-exchanger itself is negatively charged.

A) MDECKNPYNCQ

B) IDLSNGPTRLYS

C) MRCKSNLHYNP

D) ELSDIRNEPGDY

A

C) MRCKSNLHYNP

17
Q
  1. Which of the following electrophoresis techniques requires the usage of a gel with a stable pH gradient?

A) SDS-PAGE
B) Agarose gel
C) Isoelectric focusing
D) Native gel electrophoresis

A

C) Isoelectric focusing

18
Q
  1. A blotting technique that uses a specific antibody to detect a protein of interest in a sample is called:

A) Eastern blotting
B) Western blotting
C) Northern blotting
D) Southern blotting

A

B) Western blotting

Lecture 7

19
Q
  1. Among the three types of filaments, i.e., actin filaments, intermediate filaments, and microtubules, which
    one provides support for plasma membrane and plays an important role in determining the shape of a cell?

A) Actin filaments
B) Intermediate filaments
C) Microtubules
D) Neither of these

A

A) Actin filaments

20
Q
  1. Which of the following sequences has the feature of heptad repeats?

A) DETLARSCETYNKADLSMAKN

B) SPTNARACETLNKASVSKAFN

C) LETLARAIETLNKAVESLAKN

D) LETNAPAIEPQNFAVELSAKN

A

C) LETLARAIETLNKAVESLAKN

21
Q
  1. Ser195 is a catalytic residue in chymotrypsin. Mutating Ser195 to an alanine abolishes the enzymatic
    activity of chymotrypsin. Such a mutant would likely result in which of the following changes regarding the digestion of a chymotrypsin substrate?

I. The time required for the reaction to achieve equilibrium would increase.

II. The equilibrium constant Keq of the reaction would decrease.

III. The equilibrium constant Keq of the reaction would increase.

A) I only
B) III only
C) I and II only
D) I and III only

A

A) I only

22
Q
  1. Mg2+ is a required cofactor for DNA polymerase. Removing Mg2+ from polymerase results in which of
    the following?

A) Converting an apoenzyme to a holoenzyme.

B) Increasing the speed of DNA synthesis.

C) Converting a holoenzyme to an apoenzyme.

D) Increasing the stability of the DNA polymerase

A

C) Converting a holoenzyme to an apoenzyme.

23
Q
  1. An enzyme kinetics assay reveals that Vmax = 100 nmol/s and Km = 10 µM. For this assay, if the substrate
    concentration is 30 µM, what is the reaction rate V0?

A) 10 nmol/s
B) 30 nmol/s
C) 75 nmol/s
D) 100 nmol/s

A

C) 75 nmol/s

24
Q
  1. Scientists predict that gene copy number is proportional to protein expression for pyruvate kinase. If this
    hypothesis is correct, which kinetic parameter for pyruvate kinase would be expected to double when the
    gene copy number doubles?

A) Catalytic efficiency (kcat/Km)
B) Maximum velocity (Vmax)
C) Catalytic turnover (kcat)
D) Equilibrium constant (Keq)

A

B) Maximum velocity (Vmax)

25
Q
  1. Scientists could confirm that a regulator molecule increases the catalytic efficiency of an enzyme if it has
    what effect on kcat and Km?

A) kcat decreases, and Km increases
B) kcat decreases, and Km remains unchanged
C) kcat increases, and Km decreases
D) kcat remains unchanged, and Km increases

A

C) kcat increases, and Km decreases

26
Q
  1. Which of the following peptides can be digested by trypsin into smaller fragments?

A) MTHEQNTSGVNK

B) ASKLGHKLNSTLR

C) GNSHMPNQSGFR

D) SLGMTSLNPQNTV

A

B) ASKLGHKLNSTLR

27
Q
  1. What makes hemoglobin a better O2-transporting protein than myoglobin?

A) Hemoglobin has a higher affinity to O2 than myoglobin.

B) Hemoglobin has a quaternary structure that allows cooperative binding and release of O2.

C) Hemoglobin has heme group as a cofactor.

D) Hemoglobin is more thermostable than myoglobin

A

B) Hemoglobin has a quaternary structure that allows cooperative binding and release of O2.

28
Q
  1. In which phase of clinical trial, only healthy volunteers (not patients who may benefit from the drug being examined) are recruited?

A) Phase I
B) Phase II
C) Phase III
D) Patients (not healthy volunteers) are tested in every phase

A

A) Phase I

29
Q
  1. Functional magnetic resonance imaging (fMRI) is a powerful technique allowing scientists to monitor activity in specific regions of the brain. Which of the following is the basis of fMRI?

A) The active region of the brain expresses more myoglobin molecules.

B) The magnetic behavior of the heme iron differs in oxyhemoglobin and deoxyhemoglobin.

C) The active region of the brain has relatively high levels of deoxyhemoglobin.

D) All of the above are important basis for fMRI.

A

B) The magnetic behavior of the heme iron differs in oxyhemoglobin and deoxyhemoglobin.

30
Q
  1. Sickle-cell anemia and thalassemia are hemoglobin-related diseases. What
    are the causes of these diseases?

A) Sickle-cell anemia is caused by the incorporation of gamma-chain into hemoglobin.

B) Thalassemia is caused by the incorporation of gamma-chain into hemoglobin.

C) Sickle-cell anemia is caused by a mutation (Glu to Val) in the beta-chain.

D) Thalassemia is caused by a mutation (Glu to Val) in the beta-chain.

A

C) Sickle-cell anemia is caused by a mutation (Glu to Val) in the beta-chain.

31
Q
  1. In drug development, Lipinski’s rule is often used to estimate the oral absorption of a drug. Which of the
    following is NOT a part of Lipinski’s rule?

A) The molecular weight of the drug.

B) The numbers of hydrogen bond donors and acceptors.

C) The hydrophobicity of the drug.

D) The dissociation constant of the drug.

A

D) The dissociation constant of the drug.

Biochem (15 decks)

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