ESSENTIAL CELL BIOLOGY CHAPTER
#11 MEMBRANE STRUCTURE EXAM
QUESTIONS WITH COMPLETE
SOLUTIONS
properties that affect membrane fluidity - ANSWER-1. length of hydrophobic tails
2. level of unsaturation; the number of double bonds in fatty acids
3. presence of sterols/steroids
amphipathic - ANSWER-Have both hydrophilic and hydrophobic properties
phospholipids - ANSWER-Provide basic structure and serve as a permeability barrier.
What a cell makes in higher temps to reduce fluidity because it has more carbons and
more saturation.
properties that affect permeability - ANSWER-1. Length of hydrophobic tails
2. Level of unsaturation or the number of double bonds in fatty acids.
Shorter fatty acids - ANSWER-Reduce the tendency of the tails to interact with one
another -> increase fluidity, increase permeability
(usually have 18-20 carbons, range is 14-24)
Double bonds - ANSWER-Results in bilayers are more fluid than those with more
saturation, increased permeability.
yeast cells - ANSWER-Are a fungus that are eucaryotic
bacterial and yeast cells - ANSWER-Will have to adapt to varying temperatures and
constantly adjusting the length of the fatty acids and their saturation to maintain
membrane at constant fluidity (i.e. add carbons to make it longer, removing carbons to
make shorter, or introducing or removing double bonds.)
presence of sterols - ANSWER-In animal cells: fluidity can be regulated with the
inclusion of cholesterol.
cholesterol - ANSWER-Fills space between fatty acid tails which are saturated and
those which are unsaturated, making it more rigid and less permeable
asymmetry - ANSWER-Describes the structure of a phospholipid bilayer that proteins
are unevenly distributed on two sides of bilayer. Is established when the membrane is
synthesized.
, (cytosolic side of) endoplasmic reticulum - ANSWER-Where enzymes for membrane
synthesis are located.
membrane synthesis - ANSWER-Occurs especially when a cell has just divided or is
dividing.
vesicles - ANSWER-In eukaryotic cells allow membranes to move from one part of the
cell to another.
Because they pinch off and fuse with other parts of cell, the membrane has a distinct
"inside" and "outside" face.
cytosolic face - ANSWER-Is always adjacent to the cytosol.
noncytosolic face - ANSWER-Is exposed to either the cell exterior or the interior space
of an organelle.
golgi - ANSWER-Where enzymes which add the carbohydrates to the lipid are located.
integral membrane proteins - ANSWER-Directly attach to membranes, need to disrupt
the phospholipid bilayer to extract these proteins.
peripheral membrane proteins - ANSWER-Not directly attached to membranes and the
phospholipid bilayer does not need to disrupted to extract. May be bound to an integral
membrane protein by an ionic, hydrophobic, or hydrogen bond.
cell cortex - ANSWER-Framework of proteins attached to the membrane with
transmembrane proteins to provide support by reinforcing the extremely thin and fragile
plasma membrane. This protein framework is important for the cell to have proper
shape.
functional classes of membrane proteins - ANSWER-1. TRANSPORTERS - transport
particular nutrients, metabolites, and ions across the lipid bilayer
2. ANCHORS - some anchor the membrane to macromolecules such as microtubules,
microfilaments, or members of the cytoskeleton on either side
3. RECEPTORS - detect chemical signals in the cell's environment and relay them to
the cell interior
4. ENZYMES - catalyze specific reactions
types of associations between membrane proteins and the lipid bilayer - ANSWER-1.
TRANSMEMBRANE - extend across the bilayer as a single α helices, or as a rolled-up
β sheet (called a β barrel).
2. MONOLAYER-ASSOCIATED - Anchored to cytosolic surface by an amphipathic
alpha helix.
3. LIPID-LINKED - peripheral proteins that have a strong, covalent attachment to a
phospholipid.
#11 MEMBRANE STRUCTURE EXAM
QUESTIONS WITH COMPLETE
SOLUTIONS
properties that affect membrane fluidity - ANSWER-1. length of hydrophobic tails
2. level of unsaturation; the number of double bonds in fatty acids
3. presence of sterols/steroids
amphipathic - ANSWER-Have both hydrophilic and hydrophobic properties
phospholipids - ANSWER-Provide basic structure and serve as a permeability barrier.
What a cell makes in higher temps to reduce fluidity because it has more carbons and
more saturation.
properties that affect permeability - ANSWER-1. Length of hydrophobic tails
2. Level of unsaturation or the number of double bonds in fatty acids.
Shorter fatty acids - ANSWER-Reduce the tendency of the tails to interact with one
another -> increase fluidity, increase permeability
(usually have 18-20 carbons, range is 14-24)
Double bonds - ANSWER-Results in bilayers are more fluid than those with more
saturation, increased permeability.
yeast cells - ANSWER-Are a fungus that are eucaryotic
bacterial and yeast cells - ANSWER-Will have to adapt to varying temperatures and
constantly adjusting the length of the fatty acids and their saturation to maintain
membrane at constant fluidity (i.e. add carbons to make it longer, removing carbons to
make shorter, or introducing or removing double bonds.)
presence of sterols - ANSWER-In animal cells: fluidity can be regulated with the
inclusion of cholesterol.
cholesterol - ANSWER-Fills space between fatty acid tails which are saturated and
those which are unsaturated, making it more rigid and less permeable
asymmetry - ANSWER-Describes the structure of a phospholipid bilayer that proteins
are unevenly distributed on two sides of bilayer. Is established when the membrane is
synthesized.
, (cytosolic side of) endoplasmic reticulum - ANSWER-Where enzymes for membrane
synthesis are located.
membrane synthesis - ANSWER-Occurs especially when a cell has just divided or is
dividing.
vesicles - ANSWER-In eukaryotic cells allow membranes to move from one part of the
cell to another.
Because they pinch off and fuse with other parts of cell, the membrane has a distinct
"inside" and "outside" face.
cytosolic face - ANSWER-Is always adjacent to the cytosol.
noncytosolic face - ANSWER-Is exposed to either the cell exterior or the interior space
of an organelle.
golgi - ANSWER-Where enzymes which add the carbohydrates to the lipid are located.
integral membrane proteins - ANSWER-Directly attach to membranes, need to disrupt
the phospholipid bilayer to extract these proteins.
peripheral membrane proteins - ANSWER-Not directly attached to membranes and the
phospholipid bilayer does not need to disrupted to extract. May be bound to an integral
membrane protein by an ionic, hydrophobic, or hydrogen bond.
cell cortex - ANSWER-Framework of proteins attached to the membrane with
transmembrane proteins to provide support by reinforcing the extremely thin and fragile
plasma membrane. This protein framework is important for the cell to have proper
shape.
functional classes of membrane proteins - ANSWER-1. TRANSPORTERS - transport
particular nutrients, metabolites, and ions across the lipid bilayer
2. ANCHORS - some anchor the membrane to macromolecules such as microtubules,
microfilaments, or members of the cytoskeleton on either side
3. RECEPTORS - detect chemical signals in the cell's environment and relay them to
the cell interior
4. ENZYMES - catalyze specific reactions
types of associations between membrane proteins and the lipid bilayer - ANSWER-1.
TRANSMEMBRANE - extend across the bilayer as a single α helices, or as a rolled-up
β sheet (called a β barrel).
2. MONOLAYER-ASSOCIATED - Anchored to cytosolic surface by an amphipathic
alpha helix.
3. LIPID-LINKED - peripheral proteins that have a strong, covalent attachment to a
phospholipid.
