CH. 9: Lecture Questions COMPLETE Flashcards
In a lipid bilayer, which
would polar and/or
charged head groups
face?
A) Aqueous environment
B) Hydrophobic core
A) Aqueous environment
Which is least likely (spontaneously) for a phospholipid?
Rotation
Flip-flip- catalyzed by flippases, scramblases, phospholipid translocases
Lateral Diffusion
Flexion
Flip-flip- catalyzed by flippases, scramblases, phospholipid translocases
In the single-pass
transmembrane
protein show as #4,
the side chains of the
membrane spanning
helix are mostly:
A) Hydrophobic
B) Charged
C) polar
A) Hydrophobic
An amphiphilic (a.k.a.
amphipathic) helix has
A) Mostly
hydrophobic side
chains
B) Hydrophobic side
chains on one side
and hydrophilic
side chains on the
other
B) Hydrophobic side
chains on one side
and hydrophilic
side chains on the
other
The N- and C- termini of the protein
are on ____________ of the
membrane.
A.the same side
B.opposite sides
B.opposite sides
How many oxygen atoms in
the aquaporin channel are
available (i.e. not already
involved in hydrogen bonds)
to attract a proton?
A. All of them
B. None
C. Only the oxygen atom
that’s hydrogen bonded
with the asparagine side
chains
B. None
Spacing of carbonyls on protein side chains underlies ion selectivity It’s more energetically favorable for Na+ to associate with:
A. Water
B. The carbonyls
lining the K+
channel pore
A. Water
Which state
prevents
propagation of an
action potential?
A. Closed
B. Open
C. Inactivated
(refractory)
C. Inactivated
(refractory)
Consider the following for typical ion distribution
across the plasma membrane of a mammalian cell
and a resting membrane potential around 70-80 mV
Which one moves into the cell if a plasma membrane
channel for it is open?
A. Na+
B. K+
C. Cl-
A. Na+
Nuclear proteins, cytosolic proteins, and nuclearly-
encoded mitochondrial proteins are all synthesized in:
A. The cytosol
B. The nucleus
C. The ER
A. The cytosol
The lumen of the ER is topologically equivalent to:
A. The cytosol B. the extracellular space
A. The cytosol
Which causes loading of Sar1 with GTP?
A. GEF
B. GAP
C. GDI
GEF
In this experiment, the N-
terminal fragment of the
protein is only cleaved off when
rough ER microsomes are:
A. Present
B. absent
A. Present
How does a specific protein that catalyzes protein import get to the peroxisome?
A. Insertion into ER membrane; short signal sequence directs vesicular trafficking to
peroxisome
B. C-terminus SKL sequence is an import signal for receptor-mediated uptake of fully-
folded proteins through a translocator into the peroxisome lumen from the cytosol
C. N-term hydrophobic signal sequence also mediates uptake of cytosolic proteins into
the peroxisome membrane or lumen
A. Insertion into ER membrane; short signal sequence directs vesicular trafficking to
peroxisome
How does a Peroxisomal precursor protein get to the peroxisome?
A. Insertion into ER membrane; short signal sequence directs vesicular trafficking to
peroxisome
B. C-terminus SKL sequence is an import signal for receptor-mediated uptake of fully-
folded proteins through a translocator into the peroxisome lumen from the cytosol
C. N-term hydrophobic signal sequence also mediates uptake of cytosolic proteins into
the peroxisome membrane or lumen
B. C-terminus SKL sequence is an import signal for receptor-mediated uptake of fully-
folded proteins through a translocator into the peroxisome lumen from the cytosol
What causes an
importin to release
its cargo?
A. Ran-GDP
B. Ran-GTP
B. Ran-GTP