BCH210 Test 2| 100 Questions | With
Complete Solutions
Name three factors responsible for membrane formation correct
answer: Decrease in ionic interactions with water
Decrease in membrane entropy
Non-covalent interactions between lipids and proteins
What membrane structures allow the cell membrane to modulate
cell-cell recognition? correct answer: Glycoproteins and
glycoplipids
What non-covalent forces drive spontaneous membrane
assembly? correct answer: Hydrophobic effect, hydrogen bonds
and van der Waals
What is the most important recent modification to the fluid
mosaic model of membranes? correct answer: The movement of
lipids and membrane proteins differs significantly in samples of
pure lipids vs. biological membranes
Describe and justify the rate of movement for lipids from one
leaflet to the other correct answer: Very slow due to the
membrane's hydrophobic core. Flip-flow diffusion of
polar/charged head groups across the hydrophobic interior is
energetically unfavourable
,What types of enzymes attach sugars to membrane proteins
(glycoproteins) and lipids (glycolipids)? correct answer:
Transferases
List and briefly describe the roles of the 3 translocases that
mediate membrane asymmetry correct answer: Flippase:
promotes asymmetry, uses ATP (ATPase) to move
phosphatidylethanolamine (PE) and and phosphatidylserine (PS)
from outer to cytosolic leaflet
Floppase: Another ATPase that promotes asymmetry. Moves
phospholipids from cytosolic to outer leaflet
Scramblase: ATP-independent, promotes symmetry by moving
lipids in either direction, toward equilibrium
What is FRAP? What effect would SDS have on it? A
crosslinker? correct answer: Fluorescence Recovery After
Photobleaching. SDS will break the membrane, breaking non-
covalent interactions. A crosslinker between lipids would slow
FRAP
How can single molecule tracking of a phospholipid illuminate
membrane structure? correct answer: It reveals limitations to
lipid movement, such as the presence of proteins or micro
domains (barriers to diffusion). Results in what resembles "hop"
diffusion from one area to another
True/false: diffusion of lipids within a leaflet is completely
random correct answer: False. Interactions with other
components can restrict movement
, Classify the following biological lipids according to their
purpose: Triacylglycerides, phospholipids, sphingolipids,
glycolipids, sterols, and eicosanoids correct answer: Storage:
Triacylglycerides
Structural: Phospholipids, sphingolipids, glycolipids and sterols
Signalling: Eicosanoids and sterols
Which carbon should you count from when indicating the
location of a double bond using omega notation? correct answer:
The omega 1 carbon, on the opposite end of the molecule from
the carboxyl group
Omega-3 (22:6) and omega-6 (18:2) fatty acids are
polyunsaturated. Are they considered "essential" correct answer:
Essential fatty acids are those that must be obtained from the
diet as they can't be synthesized by humans. These fatty acids
are essential, as humans can't synthesize omega fatty acids
Which membrane will be more fluid, one consisting of saturated
lipids, or one consisting of unsaturated lipids? correct answer:
Unsaturated fatty acids provide greater fluidity (higher fluidity
also corresponds with a lower melting temperature, Tm)
How do transition temperatures differ between pure lipid
samples and native membranes? correct answer: Pure lipid
samples will have sharp and well-defined transition
temperatures, while native membranes will have broad peaks
Describe the structure and purpose of triacylglycerols (TGs,
TAGs) correct answer: 3 fatty acids (saturated/unsaturated)
bound to a glycerol backbone through ester linkages. They are
Complete Solutions
Name three factors responsible for membrane formation correct
answer: Decrease in ionic interactions with water
Decrease in membrane entropy
Non-covalent interactions between lipids and proteins
What membrane structures allow the cell membrane to modulate
cell-cell recognition? correct answer: Glycoproteins and
glycoplipids
What non-covalent forces drive spontaneous membrane
assembly? correct answer: Hydrophobic effect, hydrogen bonds
and van der Waals
What is the most important recent modification to the fluid
mosaic model of membranes? correct answer: The movement of
lipids and membrane proteins differs significantly in samples of
pure lipids vs. biological membranes
Describe and justify the rate of movement for lipids from one
leaflet to the other correct answer: Very slow due to the
membrane's hydrophobic core. Flip-flow diffusion of
polar/charged head groups across the hydrophobic interior is
energetically unfavourable
,What types of enzymes attach sugars to membrane proteins
(glycoproteins) and lipids (glycolipids)? correct answer:
Transferases
List and briefly describe the roles of the 3 translocases that
mediate membrane asymmetry correct answer: Flippase:
promotes asymmetry, uses ATP (ATPase) to move
phosphatidylethanolamine (PE) and and phosphatidylserine (PS)
from outer to cytosolic leaflet
Floppase: Another ATPase that promotes asymmetry. Moves
phospholipids from cytosolic to outer leaflet
Scramblase: ATP-independent, promotes symmetry by moving
lipids in either direction, toward equilibrium
What is FRAP? What effect would SDS have on it? A
crosslinker? correct answer: Fluorescence Recovery After
Photobleaching. SDS will break the membrane, breaking non-
covalent interactions. A crosslinker between lipids would slow
FRAP
How can single molecule tracking of a phospholipid illuminate
membrane structure? correct answer: It reveals limitations to
lipid movement, such as the presence of proteins or micro
domains (barriers to diffusion). Results in what resembles "hop"
diffusion from one area to another
True/false: diffusion of lipids within a leaflet is completely
random correct answer: False. Interactions with other
components can restrict movement
, Classify the following biological lipids according to their
purpose: Triacylglycerides, phospholipids, sphingolipids,
glycolipids, sterols, and eicosanoids correct answer: Storage:
Triacylglycerides
Structural: Phospholipids, sphingolipids, glycolipids and sterols
Signalling: Eicosanoids and sterols
Which carbon should you count from when indicating the
location of a double bond using omega notation? correct answer:
The omega 1 carbon, on the opposite end of the molecule from
the carboxyl group
Omega-3 (22:6) and omega-6 (18:2) fatty acids are
polyunsaturated. Are they considered "essential" correct answer:
Essential fatty acids are those that must be obtained from the
diet as they can't be synthesized by humans. These fatty acids
are essential, as humans can't synthesize omega fatty acids
Which membrane will be more fluid, one consisting of saturated
lipids, or one consisting of unsaturated lipids? correct answer:
Unsaturated fatty acids provide greater fluidity (higher fluidity
also corresponds with a lower melting temperature, Tm)
How do transition temperatures differ between pure lipid
samples and native membranes? correct answer: Pure lipid
samples will have sharp and well-defined transition
temperatures, while native membranes will have broad peaks
Describe the structure and purpose of triacylglycerols (TGs,
TAGs) correct answer: 3 fatty acids (saturated/unsaturated)
bound to a glycerol backbone through ester linkages. They are
