Exam 1: Practice Questions COMPLETE Flashcards
The force for insertion of a protein co-translationally through the ER membrane protein translocator is from:
chaperones
a cytoskeletal motor protein
action of the ribosome that’s translating the protein
a V-type ATPase
action of the ribosome that’s translating the protein
The aqueous pore of an ion channel is lined with carbonyl groups (O=C-R), with the oxygen atoms facing the channel. This channel would most likely allow passage of:
an anion (negatively charged)
a cation (positively charged)
both
a cation (positively charged)
Detergents are able to solubilize lipid bilayers because of their __________ nature.
hydrophilic
amphipathic
hydrophobic
amphipathic
A protein can be transported from the extracellular fluid on one side of a polarized cell to the extracellular fluid on the other face of the cell by:
cotranslational insertion into the ER lumen and subsequent trafficking
transcytosis
chaperone-mediated uptake
simple diffusion
a signal recognition particle
transcytosis
The resolution value of transmission electron microcopy is about 200 times smaller than the resolution value of conventional light micrcocopy predominantly due to the ____ component of the resolution equation.:
λ
θ
n
λ
A protein that lacks a signal/targeting sequence will be localized to:
the extracellular space
the rough ER
the perinuclear space
the cytosol
the nuclear compartment
the cytosol
What is least likely to be a component of a leaflet of a lipid bilayer?
Triacylglycerol
Ran-GTP stimulates _______
binding of importins to cargo and also binding of exportins to Ran-GTP and cargo
release of cargo from importins and also dissociation of exportins, cargo, and Ran-GTP
release of cargo from importins and binding of exportins to Ran-GTP and cargo
binding of importins to cargo and dissociation of exportins, cargo, and Ran-GTP
release of cargo from importins and binding of exportins to Ran-GTP and cargo
At the resting membrane potential of a typical mamalian cell, the Na+ movement goes:
against an electrical gradient
against a concentration (chemical) gradient
both of the above
both of the above
This process involves assembly of a new membrane in the cytosol that is not directly derived from the plasma membrane.:
macropinocytosis
phagocytosis
autophagy
pinocytosis
endocytosis
autophagy
Where are nuclearly-encoded mitochondrial proteins synthesized?
cytosol
nucleus
rough ER
mitochondria
cytosol
Given the location where N-linked protein glycosylation occurs, one would not expect to find N-glycosylated proteins in:
the lumen of a lysosome
the Golgi lumen
the extracellular space
the ER lumen
the nuclear compartment
the nuclear compartment
The side chains in the transmembrane alpha-helix of a single-pass transmembrane protein are most likely to be generally:
hydrophilic
amphipathic (hydrophobic facing one side and hydrophilic facing the other)
hydrophobic
hydrophobic
Movement of protons across a membrane by a V-type ATPase proton pump is an example of:
facilitated diffusion
secondary active transport
active transport
simple diffusion
active transport
Which would be the best tool (of the choices below) for determining whether two macromolecules directly interact with each other?:
fluorescence microscopy after photobleaching (FRAP)
fluorescence resonance energy transfer (FRET)
phase contrast microscopy
bright-field microscopy
fluorescence resonance energy transfer (FRET)
Which would be LEAST likely to be found in a lipid raft?:
cholesterol
amphipathic lipids with unsaturated, relatively short fatty acid tails
polar lipids with saturated, relatively long fatty acid tails
glycophosphatidylinositol (GPI) linked proteins
amphipathic lipids with unsaturated, relatively short fatty acid tails
The transport path for localization of a nuclearly-encoded mitochondrial protein to the intermembrane space is through:
TOM and TIM23
TOM, TIM23, and OXA
OXA
TOM
MIM1
TOM
Which approach uses swelling of specimens to improve resolution of cellular structures?:
expansion microscopy
image deconvolution
single molecule localization
stimulated emission depletion
structured illumination microscopy
expansion microscopy
Which of these movements of membrane phospholipids requires activity of a protein?:
flip-flop
rotation
lateral diffusion
flexion
flip-flop
Which type of channel opens in response to an action potential and mediates rapid repolarization of membrane potential?:
sarcoplasmic/endoplasmic reticulum Ca2+ ATPase
voltage-gated K+ channels
voltage-gated Ca2+ channels
voltage-gated Na+ channels
voltage-gated K+ channels
A protein will localize to the nuclear compartment is synthesized in:
the rough ER
the cytosol
the nucleus
the cytosol
The cellular uptake of nutrients (proline, lysine, lactose, succinate)is an example of what transport:
active transport
secondary active transport
simple diffusion
facilitated diffusion
secondary active transport
If the K+ channels were to open while the Na+ channels were still open, this would _________
increase the amplitude of the action potential
decrease the amplitude of the action potential
have no effect on the action potential
decrease the amplitude of the action potential
A secreted protein started as a pro-protein with:
an ER signal sequence
a nuclear exit signal
a nuclear localization signal
a peroxisomal import signal
no signal/targeting sequence
an ER signal sequence
Where would you expect most types of membrane phospholipids to be randomly distributed to one or the other of the two leaflets of the membrane?
plasma membrane
Golgi
ER
endosomes
ER
Acidification of the lysosomal lumen is mediated by:
Cl-, HCO3- exchange
a v-type H+ ATPase
Na+, H+ exchange
a Ca2+ pump
a v-type H+ ATPase
Which of these channelrhodopsins would cause depolarization when activated?
K+ out/Na2+,Ca2+ in
H+ out
Cl- in
K+ out/Na2+,Ca2+ in
Which are sometimes referred to as “membraneless organelles?”:
cytoskeleton
multivesicular bodies
vesicular tubular structures
extracellular vesicles
biological condensates
biological condensates
Clathrin, retromer, COP1, and COPII coat proteins all bend membranes so that vesicles bud toward:
the lumen of a compartment
the cytosol
the extracellular space
the cytosol
Which involves partial complexing of a v-SNARE and a t-SNARE-like bundle and later rapid membrane fusion and secretion initiated by a local increase in [Ca2+]?
fusion of an extracellular viral particle with the plasma membrane
formation of intralumenal vesicles
synaptic signaling
retreival of vesicles from the ER to the Golgi
formation of vesicular tubular clusters
synaptic signaling
Proteins are N-glycosylated in the ___________, so if an N-glycosylated membrane protein is trafficked to the plasma membrane, the oligosaccharide will face the __________.
ER lumen; extracellular space
cytosol; cytosol
ER lumen; cytosol
cytosol; extracellular space
ER lumen; extracellular space
What’s the general nature of the side chains the alpha-helix of the membrane protein in only one side of the leaflet?
hydrophilic
hydrophobic
amphipathic (hydrophobic facing one side and hydrophilic facing the other)
amphipathic (hydrophobic facing one side and hydrophilic facing the other)
In which type of electron microscopy are electrons detected after being reflected off the surface of a specimen?
single particle reconstruction
electron microscopy tomography
scanning electron microscopy
transmission electron microscopy
scanning electron microscopy
A protein in the ER lumen has __________ amino acids in its sequence than are predicted from the translated region of the related mRNA.
fewer
the same number of
more
fewer
What prevents nuclearly-encoded mitochondrial proteins from folding before insertion into or through the mitochondrial outer membrane?
cytosolic ATP-dependent chaperones
chaperones in the matrix or intermembrane space
an N-terminal mitochondrial targeting sequence
a proton gradient
cytosolic ATP-dependent chaperones
A mannose 6-phosphate receptor would be most likely (of the choices below) to bind an acid hydrolase as cargo in
lysosomes
the Golgi
endosomes
the cytosol
the nucleus
the Golgi
Which allows Sar1 to associate with the cytosolic face of the ER lumen and recuit vesicle coat proteins?
a Sar1 guanine nucleotide exchange factor (GEF)
a Sar1 GDP dissociation inhibitor (GDI)
a Sar1 GTPase activating protein (GAP)
a Sar1 guanine nucleotide exchange factor (GEF)
