AAMC MCAT UPDATED EXAM SCRIPT QUESTIONS AND
ANSWERS GUARANTEE A+
C
✔✔C/P: The side chain of tryptophan will give rise to the largest CD signal in the near
UV region when:
A) present as a free amino acid
B) part of an a-helix
C) part of a B-sheet
D) part of a fully folded protein - ✔✔D) part of a fully folded protein
The answer to this question is D because tryptophan has an aromatic side chain that
will give rise to a significant CD signal in the near UV region if it is found in a fully folded
protein.
✔✔C/P: Which amino acid will contribute to the CD signal in the far UV region, but NOT
the near UV region, when part of a fully folded protein?
"Asymmetry resulting from tertiary structural features causes the largest increase in CD
signal intensity in the near UV region of peptides. The side chains of amino acid
residues absorb in this region.
The peptide bond absorbs in the far UV region (190-250 nm). The CD signals of these
bonds are dramatically impacted by their proximity to secondary structural elements."
A) Trp
B) Phe
C) Ala
D) Tyr - ✔✔C) Ala
✔✔C/P: Based on the relative energy of the absorbed electromagnetic radiation, which
absorber, a peptide bond or an aromatic side chain, exhibits an electronic excited state
that is closer in energy to the ground state?
"Asymmetry resulting from tertiary structural features causes the largest increase in CD
signal intensity in the near UV region of peptides. The side chains of amino acid
residues absorb in this region.
The peptide bond absorbs in the far UV region (190-250 nm). The CD signals of these
bonds are dramatically impacted by their proximity to secondary structural elements."
A) An aromatic side chain; the absorbed photon energy is higher.
B) An aromatic side chain; the absorbed photon energy is lower.
C) A peptide bond; the absorbed photon energy is higher.
,D) A peptide bond; the absorbed photon energy is lower. - ✔✔B) An aromatic side
chain; the absorbed photon energy is lower.
The answer to this question is B because aromatic side chains absorb in the near UV
region of the electromagnetic spectrum, which has longer wavelengths, and hence
lower energy, than peptide bonds. Because the energy of the photon matches the
energy gap between the ground and the excited state, this implies that the aromatic side
chain has more closely spaced energy levels.
✔✔C/P: What is the net charge of sT-loop at pH 7.2?
"A synthetic peptide with the amino acid sequence KTFCGPEYLA was generated as a
mimic of the T-loop. This synthetic T-loop (sT-loop) was incubated with 32P-labeled
ATP in the presence of PDK1 for different time periods at 37 ° C and pH 7.2, and the
amount of radioactivity incorporated into sT-loop was measured by detection of β-
decay."
A) -2
B) -1
C) 0
D) +1 - ✔✔C) 0
The answer to this question is C because at pH 7.2, the N-terminus will be positively
charged and the C-terminus will be negatively charged. In addition, the lysine side chain
will carry one positive charge and the glutamic acid side chain will carry one negative
charge.
✔✔C/P: In designing the experiment, the researchers used which type of P-32 labeled
ATP?
A) aP32-ATP
B) BP32-ATP
C) γP32-ATP
D) δP-32 ATP - ✔✔D) δP-32 ATP
The answer to this question is C because the phosphoryl transfer from kinases comes
from the γ-phosphate of ATP. Therefore, the experiment should require γ32P-ATP.
✔✔C/P: When used in place of spHM, which peptide would be most likely to achieve
the same experimental results?
"This experiment was repeated in the presence of a synthetic peptide that mimics the
HM domain (sHM) of Ser/Thr kinases with the amino acid sequence FLGFTY.
Phosphorylated sHM (spHM) was also used in place of sHM."
A) FLGFAY
B) FLGFQY
,C) FLGFGY
D) FLGFEY - ✔✔D) FLGFEY
The answer to this question is D because the phosphorylated threonine would most
likely be mimicked by glutamic acid in terms of size and charge.
✔✔C/P: Based on the information in the passage, PDK1 catalyzes the addition of
phosphate to what functional group?
"This experiment was repeated in the presence of a synthetic peptide that mimics the
HM domain (sHM) of Ser/Thr kinases with the amino acid sequence FLGFTY.
Phosphorylated sHM (spHM) was also used in place of sHM."
A) Hydroxyl
B) Amine
C) Carboxyl
D) Phenyl - ✔✔A) Hydroxyl
The answer to this question is A because reactions involving either Ser or Thr would
involve the hydroxyl group in the side chain of these amino acids.
✔✔C/P: Which statement about the cooperativity of RIα/C activation and RIα protein
folding is supported by the data in figures 2 and 3?
A) Both activation and folding are cooperative.
B) Activation is cooperative, but folding is not.
C) Folding is cooperative, but activation is not.
D) Neither activation nor folding is cooperative - ✔✔A) Both activation and folding are
cooperative.
The answer to this question is A because both curves have a sigmoidal shape, which is
indicative of cooperative processes.
✔✔C/P: A patient puts on a mask with lateral openings and inhales oxygen from a tank.
Which phenomenon causes static air to be drawn into the mask when oxygen flows?
A) Doppler effect
B) Venturi effect
C) Diffusion
D) Dispersion - ✔✔B) Venturi effect
The answer to this question is B because oxygen pressure is the sum of the oxygen
static pressure P and the oxygen flow pressure rv2/2. In the area of the mask openings,
Pair = P + rv2/2, thus Pair > P. Air enters the mask because the static pressure of the
, air is larger than the static pressure of the oxygen in flow. This is the Venturi effect, and
the mask is called the Venturi mask.
✔✔Doppler effect - ✔✔an increase (or decrease) in the frequency of sound, light, or
other waves as the source and observer move toward (or away from) each other
This effect causes the sudden change noticeable in a passing siren, as well as the
redshift seen by astronomers.
✔✔Venturi effect - ✔✔reduction in fluid pressure that results when a fluid flows through
a constricted section of a pipe
✔✔diffusion - ✔✔net movement of molecules from a region of higher concentration to a
region of lower concentration
✔✔dispersion - ✔✔the separation of light into colors by refraction or diffraction with
formation of a spectrum
✔✔C/P: What causes duplex DNA with a certain (A + T):(G + C) ratio to melt at a higher
temperature than comparable length duplex DNA with a greater (A + T):(G + C) ratio?
A) Stronger van der Waals forces of pyrimidines
B) Stronger van der Waals forces of purines
C) Increased number of hydrogen bonds
D) Reduced electrostatic repulsion of phosphates - ✔✔C) Increased number of
hydrogen bonds
The answer to this question is C. GC base pairs involve three hydrogen bonds, while AT
base pairs involve only two. This disparity has often been used to explain the increased
melting temperature of DNA rich in GC content.
✔✔C/P: Which property of a substance is best used to estimate its relative vapor
pressure?
A) Melting point
B) Boiling point
C) Molecular weight
D) Dipole moment - ✔✔B) Boiling point
The answer to this question is B because of the properties listed, the boiling point of a
substance will give the best estimate of its relative vapor pressure.
✔✔C/P: What are the structural features possessed by storage lipids?
A) Two fatty acids ester-linked to a single glycerol plus a charged head group
B) Three fatty acids ester-linked to a single glycerol
C) Two fatty acids ester-linked to a single sphingosine plus a charged head group
ANSWERS GUARANTEE A+
C
✔✔C/P: The side chain of tryptophan will give rise to the largest CD signal in the near
UV region when:
A) present as a free amino acid
B) part of an a-helix
C) part of a B-sheet
D) part of a fully folded protein - ✔✔D) part of a fully folded protein
The answer to this question is D because tryptophan has an aromatic side chain that
will give rise to a significant CD signal in the near UV region if it is found in a fully folded
protein.
✔✔C/P: Which amino acid will contribute to the CD signal in the far UV region, but NOT
the near UV region, when part of a fully folded protein?
"Asymmetry resulting from tertiary structural features causes the largest increase in CD
signal intensity in the near UV region of peptides. The side chains of amino acid
residues absorb in this region.
The peptide bond absorbs in the far UV region (190-250 nm). The CD signals of these
bonds are dramatically impacted by their proximity to secondary structural elements."
A) Trp
B) Phe
C) Ala
D) Tyr - ✔✔C) Ala
✔✔C/P: Based on the relative energy of the absorbed electromagnetic radiation, which
absorber, a peptide bond or an aromatic side chain, exhibits an electronic excited state
that is closer in energy to the ground state?
"Asymmetry resulting from tertiary structural features causes the largest increase in CD
signal intensity in the near UV region of peptides. The side chains of amino acid
residues absorb in this region.
The peptide bond absorbs in the far UV region (190-250 nm). The CD signals of these
bonds are dramatically impacted by their proximity to secondary structural elements."
A) An aromatic side chain; the absorbed photon energy is higher.
B) An aromatic side chain; the absorbed photon energy is lower.
C) A peptide bond; the absorbed photon energy is higher.
,D) A peptide bond; the absorbed photon energy is lower. - ✔✔B) An aromatic side
chain; the absorbed photon energy is lower.
The answer to this question is B because aromatic side chains absorb in the near UV
region of the electromagnetic spectrum, which has longer wavelengths, and hence
lower energy, than peptide bonds. Because the energy of the photon matches the
energy gap between the ground and the excited state, this implies that the aromatic side
chain has more closely spaced energy levels.
✔✔C/P: What is the net charge of sT-loop at pH 7.2?
"A synthetic peptide with the amino acid sequence KTFCGPEYLA was generated as a
mimic of the T-loop. This synthetic T-loop (sT-loop) was incubated with 32P-labeled
ATP in the presence of PDK1 for different time periods at 37 ° C and pH 7.2, and the
amount of radioactivity incorporated into sT-loop was measured by detection of β-
decay."
A) -2
B) -1
C) 0
D) +1 - ✔✔C) 0
The answer to this question is C because at pH 7.2, the N-terminus will be positively
charged and the C-terminus will be negatively charged. In addition, the lysine side chain
will carry one positive charge and the glutamic acid side chain will carry one negative
charge.
✔✔C/P: In designing the experiment, the researchers used which type of P-32 labeled
ATP?
A) aP32-ATP
B) BP32-ATP
C) γP32-ATP
D) δP-32 ATP - ✔✔D) δP-32 ATP
The answer to this question is C because the phosphoryl transfer from kinases comes
from the γ-phosphate of ATP. Therefore, the experiment should require γ32P-ATP.
✔✔C/P: When used in place of spHM, which peptide would be most likely to achieve
the same experimental results?
"This experiment was repeated in the presence of a synthetic peptide that mimics the
HM domain (sHM) of Ser/Thr kinases with the amino acid sequence FLGFTY.
Phosphorylated sHM (spHM) was also used in place of sHM."
A) FLGFAY
B) FLGFQY
,C) FLGFGY
D) FLGFEY - ✔✔D) FLGFEY
The answer to this question is D because the phosphorylated threonine would most
likely be mimicked by glutamic acid in terms of size and charge.
✔✔C/P: Based on the information in the passage, PDK1 catalyzes the addition of
phosphate to what functional group?
"This experiment was repeated in the presence of a synthetic peptide that mimics the
HM domain (sHM) of Ser/Thr kinases with the amino acid sequence FLGFTY.
Phosphorylated sHM (spHM) was also used in place of sHM."
A) Hydroxyl
B) Amine
C) Carboxyl
D) Phenyl - ✔✔A) Hydroxyl
The answer to this question is A because reactions involving either Ser or Thr would
involve the hydroxyl group in the side chain of these amino acids.
✔✔C/P: Which statement about the cooperativity of RIα/C activation and RIα protein
folding is supported by the data in figures 2 and 3?
A) Both activation and folding are cooperative.
B) Activation is cooperative, but folding is not.
C) Folding is cooperative, but activation is not.
D) Neither activation nor folding is cooperative - ✔✔A) Both activation and folding are
cooperative.
The answer to this question is A because both curves have a sigmoidal shape, which is
indicative of cooperative processes.
✔✔C/P: A patient puts on a mask with lateral openings and inhales oxygen from a tank.
Which phenomenon causes static air to be drawn into the mask when oxygen flows?
A) Doppler effect
B) Venturi effect
C) Diffusion
D) Dispersion - ✔✔B) Venturi effect
The answer to this question is B because oxygen pressure is the sum of the oxygen
static pressure P and the oxygen flow pressure rv2/2. In the area of the mask openings,
Pair = P + rv2/2, thus Pair > P. Air enters the mask because the static pressure of the
, air is larger than the static pressure of the oxygen in flow. This is the Venturi effect, and
the mask is called the Venturi mask.
✔✔Doppler effect - ✔✔an increase (or decrease) in the frequency of sound, light, or
other waves as the source and observer move toward (or away from) each other
This effect causes the sudden change noticeable in a passing siren, as well as the
redshift seen by astronomers.
✔✔Venturi effect - ✔✔reduction in fluid pressure that results when a fluid flows through
a constricted section of a pipe
✔✔diffusion - ✔✔net movement of molecules from a region of higher concentration to a
region of lower concentration
✔✔dispersion - ✔✔the separation of light into colors by refraction or diffraction with
formation of a spectrum
✔✔C/P: What causes duplex DNA with a certain (A + T):(G + C) ratio to melt at a higher
temperature than comparable length duplex DNA with a greater (A + T):(G + C) ratio?
A) Stronger van der Waals forces of pyrimidines
B) Stronger van der Waals forces of purines
C) Increased number of hydrogen bonds
D) Reduced electrostatic repulsion of phosphates - ✔✔C) Increased number of
hydrogen bonds
The answer to this question is C. GC base pairs involve three hydrogen bonds, while AT
base pairs involve only two. This disparity has often been used to explain the increased
melting temperature of DNA rich in GC content.
✔✔C/P: Which property of a substance is best used to estimate its relative vapor
pressure?
A) Melting point
B) Boiling point
C) Molecular weight
D) Dipole moment - ✔✔B) Boiling point
The answer to this question is B because of the properties listed, the boiling point of a
substance will give the best estimate of its relative vapor pressure.
✔✔C/P: What are the structural features possessed by storage lipids?
A) Two fatty acids ester-linked to a single glycerol plus a charged head group
B) Three fatty acids ester-linked to a single glycerol
C) Two fatty acids ester-linked to a single sphingosine plus a charged head group
