AAMC Practice Test 2
Chem and Physics section correct
answers
What atom is the site of covalent attachment of AMC to the model
tetrapeptide
the used in answersBecause AMC is attached to the peptide on
studies? correct
the carboxyl
side. This suggests that an amide linkage involving the N atom in AMC
is used to attach the fluorophore to the
covalently
peptide
*a peptide bond between amino acids= covalent bond between carboxyl
group of
amino acid1 to amino group of other,
releasing water
What expression gives the amount of light energy (in J per photon) that is
converted
other formstobetween the fluorescence excitation (absorption) and
emission
correct events?
answersBecause E = hf=
hc/lamda
Excitation occurs are LAMDAe = 360nm, but fluoroscence is observed at
LAMDAf This
440nm. = implies that an
energy
E of
=hc/[(360 x 10^-9)-(440 x
10^-9)]
E = h x c x [(1/360 x 10^-9 ) - (1/440 x 10^-9)] J per photon converted to
other forms
between the excitation and fluorescene
events
The concentration of enzyme for each experiment was 5.0 uM. What is the
kcat for the
reaction at ph 4.5 when no chloride added when compound 3 is
substrate? correct
answers2.5E-2
s^-1
Rate for compound 3 is 125 nM/s, and rate of product formation did not
vary
for over
first time
5 minutes implies enzyme was saturated with
substate.
Kcat=Vmax/[E]= 125 nM/s/(5.0 uM)=
2.5E-2 s^-1
Absorption of ultraviolet light by organic molecules always results in
what process?
correct answersexcitation of bound electrons (since going from low to high
energy
so they'restate
excited)
-bond breaking can subsequently result, as can ionization or bond
vibration, but
guaranteed tonot
result from absorption of
ultraviolet light
-sometimes, bound electrons are ejected when light with high
frequency
metal shines
plate--> on
photoelectric effect. The alteration in intensity of light
inducesenergy
kinetic changes of in
electrons emitted
from metal
-ejected bound electron has KE=energy of photon - work of
electron in metal
,Small rf vs large rf value correct answersin column chromatography, small
rf for more
polar molecules and more elution time since polar molecule has
great affinity to
stationary
phase
-large rf= nonpolar molecules; mobile phase so less elution time since won't
have much
affinity to stationary
phase
The half-life of a radioactive material is: correct answersthe time it takes
for half
the of all
radioactive nuclei to decay into their
daughter
-their nuclei nuclei may or may not also be
daughter
radioactive
A person is sitting on the chair as
shown.
Why must the person either lean forward or slide their feet under the
chair in
stand uporder to answersTo keep the body in equilibrium
correct
while rising
-As the person is attempting to stand, the only support comes from the
feet on the
ground. The person is in equilibrium only when the center of mass is directly
aboveOtherwise,
feet. their if the person would fall backward due to the large torque
created by the
combination of the weight of the body (applied at the person's center of
mass) and
distance the the horizontal between the center of mass and the
along
support point
Which amino acid will contribute to the CD signal in the far UV region, but
NOTregion,
UV the near
when part of a fully folded protein? correct
answersAla
All chiral nonaromatic amino acids will contribute solely to the CD signal in
the far since
region UV all aromatic ones contribute to near UV
region.
-alanine only has methyl group as its R
group
Based on the relative energy of the absorbed electromagnetic
radiation, a
absorber, which
peptide bond (wavelength= 190-250 nm) or an aromatic
side chain
(wavelength=250-290 nm) exhibits an electronic excited state that is closer
in energy
the groundtostate? correct answersAn aromatic side chain; the absorbed
photon energy
is
lower
--Because aromatic side chains absorb in the near UV region of the
electromagnetic
spectrum, which has longer wavelengths, and hence lower energy
(E=hc/wavelength)
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
more hasspaced energy
closely
levels
In designing the experiment, the researchers used which type of 32P
labeled answersY32P-
correct ATP?
ATP
, -Because the phosphoryl transfer from kinases comes from the Y-
phosphate the
Therefore, of ATP.
experiment should require
Y32P-ATP
-gamma phosphates is the primary phosphate group on ATP
molecules that
hydrolyzed when is the energy is needed to drive anabolic reactions; farthest
from ribose
sugar and has higher energy of hydrolysis than either alpha or beta
phosphate
When used in place of spHM (amino acid sequence of FLGFTY), which
peptide
be most would
likely to achieve the same experimental results? correct
answersFLGFEY
--Because the phosphorylated threonine (T)would most likely be mimicked
by glutamic
acid (E)in terms of size and charge since the phosphate group would attach
fromadd
and -OH- charge, and glutamic acid is -
charged
Which statement about cooperatively of Ria/C activation and RIa
protein folding
supported is in figures 2 and 3? correct answersBoth activation and
by date
folding are
cooperativ
e
-both curves have sigmoidal shape which is indicative of cooperative
processes
-cooperativity: substrate binding changes substrate
affinity; positive
cooperativity=sigmoidal shape in allosteric sites;
noncooperative=hyperbolic shape
A patient puts on a mask with lateral openings and inhales from a tank
as shown.
What phenomenon causes static air to be drawn into the mask when
oxygen answersVenturi
correct flows?
effect
--Because oxygen pressure is the sum of the oxygen static pressure P and
the oxygen flow pressure rV^2/2. In the area of the mask openings,
Pair=P+rV^2/2, 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
Dispersion correct answersThe separation of light into its component
wavelengths
refraction or by
diffraction
What causes duplex DNA with a certain (A+T):(G+C) ratio to melt at a
higher temp length
comparable than duplex DNA with a greater (A+T):(G+C)
ratio? correct
answersIncreased number of hydrogen
bonds
-GC base pairs involve 3 hydrogen bonds and AT involve 2 so the one with
lower ratio
would melt at higher temp since would have more hydrogen bonds due
to more GC
base
pairs
What property of a substance is best used to estimate its relative vapor
pressure?
correct answersBoiling
point
Chem and Physics section correct
answers
What atom is the site of covalent attachment of AMC to the model
tetrapeptide
the used in answersBecause AMC is attached to the peptide on
studies? correct
the carboxyl
side. This suggests that an amide linkage involving the N atom in AMC
is used to attach the fluorophore to the
covalently
peptide
*a peptide bond between amino acids= covalent bond between carboxyl
group of
amino acid1 to amino group of other,
releasing water
What expression gives the amount of light energy (in J per photon) that is
converted
other formstobetween the fluorescence excitation (absorption) and
emission
correct events?
answersBecause E = hf=
hc/lamda
Excitation occurs are LAMDAe = 360nm, but fluoroscence is observed at
LAMDAf This
440nm. = implies that an
energy
E of
=hc/[(360 x 10^-9)-(440 x
10^-9)]
E = h x c x [(1/360 x 10^-9 ) - (1/440 x 10^-9)] J per photon converted to
other forms
between the excitation and fluorescene
events
The concentration of enzyme for each experiment was 5.0 uM. What is the
kcat for the
reaction at ph 4.5 when no chloride added when compound 3 is
substrate? correct
answers2.5E-2
s^-1
Rate for compound 3 is 125 nM/s, and rate of product formation did not
vary
for over
first time
5 minutes implies enzyme was saturated with
substate.
Kcat=Vmax/[E]= 125 nM/s/(5.0 uM)=
2.5E-2 s^-1
Absorption of ultraviolet light by organic molecules always results in
what process?
correct answersexcitation of bound electrons (since going from low to high
energy
so they'restate
excited)
-bond breaking can subsequently result, as can ionization or bond
vibration, but
guaranteed tonot
result from absorption of
ultraviolet light
-sometimes, bound electrons are ejected when light with high
frequency
metal shines
plate--> on
photoelectric effect. The alteration in intensity of light
inducesenergy
kinetic changes of in
electrons emitted
from metal
-ejected bound electron has KE=energy of photon - work of
electron in metal
,Small rf vs large rf value correct answersin column chromatography, small
rf for more
polar molecules and more elution time since polar molecule has
great affinity to
stationary
phase
-large rf= nonpolar molecules; mobile phase so less elution time since won't
have much
affinity to stationary
phase
The half-life of a radioactive material is: correct answersthe time it takes
for half
the of all
radioactive nuclei to decay into their
daughter
-their nuclei nuclei may or may not also be
daughter
radioactive
A person is sitting on the chair as
shown.
Why must the person either lean forward or slide their feet under the
chair in
stand uporder to answersTo keep the body in equilibrium
correct
while rising
-As the person is attempting to stand, the only support comes from the
feet on the
ground. The person is in equilibrium only when the center of mass is directly
aboveOtherwise,
feet. their if the person would fall backward due to the large torque
created by the
combination of the weight of the body (applied at the person's center of
mass) and
distance the the horizontal between the center of mass and the
along
support point
Which amino acid will contribute to the CD signal in the far UV region, but
NOTregion,
UV the near
when part of a fully folded protein? correct
answersAla
All chiral nonaromatic amino acids will contribute solely to the CD signal in
the far since
region UV all aromatic ones contribute to near UV
region.
-alanine only has methyl group as its R
group
Based on the relative energy of the absorbed electromagnetic
radiation, a
absorber, which
peptide bond (wavelength= 190-250 nm) or an aromatic
side chain
(wavelength=250-290 nm) exhibits an electronic excited state that is closer
in energy
the groundtostate? correct answersAn aromatic side chain; the absorbed
photon energy
is
lower
--Because aromatic side chains absorb in the near UV region of the
electromagnetic
spectrum, which has longer wavelengths, and hence lower energy
(E=hc/wavelength)
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
more hasspaced energy
closely
levels
In designing the experiment, the researchers used which type of 32P
labeled answersY32P-
correct ATP?
ATP
, -Because the phosphoryl transfer from kinases comes from the Y-
phosphate the
Therefore, of ATP.
experiment should require
Y32P-ATP
-gamma phosphates is the primary phosphate group on ATP
molecules that
hydrolyzed when is the energy is needed to drive anabolic reactions; farthest
from ribose
sugar and has higher energy of hydrolysis than either alpha or beta
phosphate
When used in place of spHM (amino acid sequence of FLGFTY), which
peptide
be most would
likely to achieve the same experimental results? correct
answersFLGFEY
--Because the phosphorylated threonine (T)would most likely be mimicked
by glutamic
acid (E)in terms of size and charge since the phosphate group would attach
fromadd
and -OH- charge, and glutamic acid is -
charged
Which statement about cooperatively of Ria/C activation and RIa
protein folding
supported is in figures 2 and 3? correct answersBoth activation and
by date
folding are
cooperativ
e
-both curves have sigmoidal shape which is indicative of cooperative
processes
-cooperativity: substrate binding changes substrate
affinity; positive
cooperativity=sigmoidal shape in allosteric sites;
noncooperative=hyperbolic shape
A patient puts on a mask with lateral openings and inhales from a tank
as shown.
What phenomenon causes static air to be drawn into the mask when
oxygen answersVenturi
correct flows?
effect
--Because oxygen pressure is the sum of the oxygen static pressure P and
the oxygen flow pressure rV^2/2. In the area of the mask openings,
Pair=P+rV^2/2, 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
Dispersion correct answersThe separation of light into its component
wavelengths
refraction or by
diffraction
What causes duplex DNA with a certain (A+T):(G+C) ratio to melt at a
higher temp length
comparable than duplex DNA with a greater (A+T):(G+C)
ratio? correct
answersIncreased number of hydrogen
bonds
-GC base pairs involve 3 hydrogen bonds and AT involve 2 so the one with
lower ratio
would melt at higher temp since would have more hydrogen bonds due
to more GC
base
pairs
What property of a substance is best used to estimate its relative vapor
pressure?
correct answersBoiling
point
