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BCMB 311 ADVANCED CELL
BIOLOGY 2026 ACTUAL EXAM
QUESTIONS AND ANSWERS TIPS
WITH HOMEWORK ALSO INCLUDED
1. All channel and transporter proteins are multi-pass transmembrane proteins.
T- p 599 “all membrane transport proteins that have been studied in detail are
multipass transmembrane proteins…”
2. Active transport across membranes is carried out by channel proteins or
pore complexes. FALSE- active transport is carried out by transporter
proteins/pumps.
3. For each molecule of ATP hydrolyzed, the eukaryotic Na+-K+ pump moves 2
Na+ ions out and 3 K+ ions in.``
FALSE- the pump moves 3 Na+ out and 2 K+ in.
4. Conformational changes in the glucose transporter facilitate the binding of
glucose and sodium on the cytosolic face of the plasma membrane and reduce
the affinity of binding on the extracellular side.
FALSE- glucose and Na+ move INTO the cell. Na+ is much more abundant in the
extracellular space so glucose is more likely to bind in the outward-open
conformation.
5. A lipid raft is a region of a membrane that contains specific lipids and/or
proteins at high concentrations.
TRUE
6. The cell membrane contains a homogenous mixture of lipids and proteins due
to rapid lateral diffusion within the membrane.
FALSE- The membrane can have specific domains that restrict movement of
proteins. Thus, certain areas can be more heavily concentrated with proteins or
lipids.
7. The Vmax of solute transport mediated by a transporter depends on the
rate it can flip between conformational states, while in diffusion the rate of
,2
transport is dependent on concentration.
TRUE- Vmax depends on how quickly a transporter can change conformations and
simple diffusion rate is proportionate to the concentration of the solute
8. If a protein has one segment of 20-30 amino acids that are nearly all
hydrophobic but no other hydrophobic segments longer than a few amino
acids, it is very likely a single-pass transmembrane protein.
TRUE- a transmembrane helix is usually 20-30 amino acids in length
, 3
9. In each β-strand of a β-barrel transmembrane protein, hydrophobic amino acids
alternate with hydrophilic amino acids.
TRUE- every other amino acid is hydrophobic in a β-strand.
10. Separate transmembrane alpha-helices almost never interact with each other;
their hydrophobic side-chains are inert and react only with the fatty acid tails of
the phopholipids. FALSE- alpha-helices do interact with one another and displace
lipid molecules surrounding the helices (p581)
11. Hydropathy plots are useful for identifying both α-helical and β-barrel-type
transmembrane domains. FALSE. Hydropathy plots allow for the visualization of
hydrophobicity over the length of a peptide sequence. A hydropathy scale which
is based on the hydrophobic and hydrophilic properties of the 20 amino acids is
used. Hydropathy plots only can only identify alpha helices
12. The majority of eukaryotic transmembrane domains fold into beta-barrel
structures.
FALSE- most are alpha helices
β-barrels are mostly found in mitochondria, chloroplast, and bacterial membranes
13. Chemical gradients, electrochemical gradients, ATP and light are all sources of
energy used to drive transport across membranes.
TRUE
14. The selectivity of the K+ channel is due to the action of the selectivity
filter that allows solvents to diffuse halfway through the lipid bilayer.
*****TRUE???- the selectivity filter allows only K+ ions to pass with high
specificity (due to the perfect interaction of the K+ ion with the carbonyl
groups). I assume this would mean that Na+ and other ions could still enter the
vestibule but would not pass the selectivity filter. Thoughts?
^^^ Sounds right… I don’t think that diffusing halfway through plays a role in
the selectivity. The vestibule allows for the ion to cross half way through the
membrane and influences the selectivity filter.
If this is an essay question on the exam, I’d talk more about the positioning
of the carbonyl groups in the channel
****Just found part on slides that makes it look like the “selectivity filter that
BCMB 311 ADVANCED CELL
BIOLOGY 2026 ACTUAL EXAM
QUESTIONS AND ANSWERS TIPS
WITH HOMEWORK ALSO INCLUDED
1. All channel and transporter proteins are multi-pass transmembrane proteins.
T- p 599 “all membrane transport proteins that have been studied in detail are
multipass transmembrane proteins…”
2. Active transport across membranes is carried out by channel proteins or
pore complexes. FALSE- active transport is carried out by transporter
proteins/pumps.
3. For each molecule of ATP hydrolyzed, the eukaryotic Na+-K+ pump moves 2
Na+ ions out and 3 K+ ions in.``
FALSE- the pump moves 3 Na+ out and 2 K+ in.
4. Conformational changes in the glucose transporter facilitate the binding of
glucose and sodium on the cytosolic face of the plasma membrane and reduce
the affinity of binding on the extracellular side.
FALSE- glucose and Na+ move INTO the cell. Na+ is much more abundant in the
extracellular space so glucose is more likely to bind in the outward-open
conformation.
5. A lipid raft is a region of a membrane that contains specific lipids and/or
proteins at high concentrations.
TRUE
6. The cell membrane contains a homogenous mixture of lipids and proteins due
to rapid lateral diffusion within the membrane.
FALSE- The membrane can have specific domains that restrict movement of
proteins. Thus, certain areas can be more heavily concentrated with proteins or
lipids.
7. The Vmax of solute transport mediated by a transporter depends on the
rate it can flip between conformational states, while in diffusion the rate of
,2
transport is dependent on concentration.
TRUE- Vmax depends on how quickly a transporter can change conformations and
simple diffusion rate is proportionate to the concentration of the solute
8. If a protein has one segment of 20-30 amino acids that are nearly all
hydrophobic but no other hydrophobic segments longer than a few amino
acids, it is very likely a single-pass transmembrane protein.
TRUE- a transmembrane helix is usually 20-30 amino acids in length
, 3
9. In each β-strand of a β-barrel transmembrane protein, hydrophobic amino acids
alternate with hydrophilic amino acids.
TRUE- every other amino acid is hydrophobic in a β-strand.
10. Separate transmembrane alpha-helices almost never interact with each other;
their hydrophobic side-chains are inert and react only with the fatty acid tails of
the phopholipids. FALSE- alpha-helices do interact with one another and displace
lipid molecules surrounding the helices (p581)
11. Hydropathy plots are useful for identifying both α-helical and β-barrel-type
transmembrane domains. FALSE. Hydropathy plots allow for the visualization of
hydrophobicity over the length of a peptide sequence. A hydropathy scale which
is based on the hydrophobic and hydrophilic properties of the 20 amino acids is
used. Hydropathy plots only can only identify alpha helices
12. The majority of eukaryotic transmembrane domains fold into beta-barrel
structures.
FALSE- most are alpha helices
β-barrels are mostly found in mitochondria, chloroplast, and bacterial membranes
13. Chemical gradients, electrochemical gradients, ATP and light are all sources of
energy used to drive transport across membranes.
TRUE
14. The selectivity of the K+ channel is due to the action of the selectivity
filter that allows solvents to diffuse halfway through the lipid bilayer.
*****TRUE???- the selectivity filter allows only K+ ions to pass with high
specificity (due to the perfect interaction of the K+ ion with the carbonyl
groups). I assume this would mean that Na+ and other ions could still enter the
vestibule but would not pass the selectivity filter. Thoughts?
^^^ Sounds right… I don’t think that diffusing halfway through plays a role in
the selectivity. The vestibule allows for the ion to cross half way through the
membrane and influences the selectivity filter.
If this is an essay question on the exam, I’d talk more about the positioning
of the carbonyl groups in the channel
****Just found part on slides that makes it look like the “selectivity filter that
