BICH 410 EXAM 3 QUESTIONS
WITH CORRECT DETAILED
ANSWERS
Which one of the following statements is consistent with the structure of biological
membranes?
a. All membrane proteins are integral and associate with the hydrophobic region of the
membrane.
b. Both proteins and lipids readily undergo transverse ("flip-flop") diffusion from the
inside to the outside of the membrane.
c. Membranes are symmetric.
d. A biological membrane consists of proteins sandwiched between two layers of lipids,
referred to as a lipid bilayer.
e. The membrane lipids self-assemble to form the lipid bilayer. - Answer- e. The
membrane lipids self-assemble to form the lipid bilayer.
Which of the following statements describe integral membrane proteins?
I. They protect the contents of the cell from chaotropic agents such as urea.
II. They are easily dissociated from the membrane by changes in pH or high salt
concentration.
III. They are held tightly in the membrane by the hydrophobic effect.
a. I
b. II
c. III
d. I, I, III
e. I, III - Answer- c. III
Carbohydrates residues attached to the membrane lipids are
a. always positioned on the extracellular side of the membrane.
b. always positioned on the intracellular side of the membrane.
c. always positioned on the inside center of the bilayer.
d. always positioned equally on both sides of the membrane.
e. always covalently attached to membrane proteins. - Answer- a. always positioned on
the extracellular side of the membrane.
How many molecules thick are membranes?
a. one
b. two
c. infinite
d. varying thickness, depending on structure
, e. none of the above - Answer- b. two
Which of the following amino acids from an integral membrane protein would likely
contact the membrane?
a. Asn
b. Ala
c. Gln
d. Glu
e. Asp - Answer- b. Ala
The energy for ____________ transport comes from the gradient itself.
a. passive
b. active
c. facilitated
d. pumped
e. ATP- mediated - Answer- a. passive
Which of the following statements about cholesterol is FALSE?
a. The headgroup of cholestrol is the hydroxyl, -OH.
b. Liquid-ordered membrane microdomains are rich in cholesterol and sphingolipids.
c. The plasma membrane of animal cells is rich in cholesterol.
d. The role of cholesterol in biological membranes is to lower the melting point (Tm).
e. Cholesterol is a planar lipid that packs in the stiff-chain region of the bilayer. -
Answer- b. Liquid-ordered membrane microdomains are rich in cholesterol and
sphingolipids.
Which of the following statements about membranes is false?
a. In the cell, regions of high membrane curvature are also highly dynamic.
b. Palamitate is a (16:0) fatty acid.
c. Oleic acid is commonly found connected to the carbon 2 position on the glycerol
backbone.
d. According to the raft hypothesis, oleic acid promotes raft assembly.
e. Cererbrosides are found in the outer leaflet of the plasma membrane. - Answer- d.
According to the raft hypothesis, oleic acid promotes raft assembly.
The degree of the membrane fluidity depends on
a. the percentage of unsaturated fatty acids
b. the percentage of lipids that contain choline
c. the percentage of glycolipds
d. the percentage of free fatty acids
e. none of the above - Answer- a. the percentage of unsaturated fatty acids
Which of these statements is generally true of integral membrane proteins?
a. They are unusually susceptible to degradation by trypsin.
b. The domains that protude on the cytoplasmic face of the plasma membrane nearly
always have covalently attached oligosaccarides.
WITH CORRECT DETAILED
ANSWERS
Which one of the following statements is consistent with the structure of biological
membranes?
a. All membrane proteins are integral and associate with the hydrophobic region of the
membrane.
b. Both proteins and lipids readily undergo transverse ("flip-flop") diffusion from the
inside to the outside of the membrane.
c. Membranes are symmetric.
d. A biological membrane consists of proteins sandwiched between two layers of lipids,
referred to as a lipid bilayer.
e. The membrane lipids self-assemble to form the lipid bilayer. - Answer- e. The
membrane lipids self-assemble to form the lipid bilayer.
Which of the following statements describe integral membrane proteins?
I. They protect the contents of the cell from chaotropic agents such as urea.
II. They are easily dissociated from the membrane by changes in pH or high salt
concentration.
III. They are held tightly in the membrane by the hydrophobic effect.
a. I
b. II
c. III
d. I, I, III
e. I, III - Answer- c. III
Carbohydrates residues attached to the membrane lipids are
a. always positioned on the extracellular side of the membrane.
b. always positioned on the intracellular side of the membrane.
c. always positioned on the inside center of the bilayer.
d. always positioned equally on both sides of the membrane.
e. always covalently attached to membrane proteins. - Answer- a. always positioned on
the extracellular side of the membrane.
How many molecules thick are membranes?
a. one
b. two
c. infinite
d. varying thickness, depending on structure
, e. none of the above - Answer- b. two
Which of the following amino acids from an integral membrane protein would likely
contact the membrane?
a. Asn
b. Ala
c. Gln
d. Glu
e. Asp - Answer- b. Ala
The energy for ____________ transport comes from the gradient itself.
a. passive
b. active
c. facilitated
d. pumped
e. ATP- mediated - Answer- a. passive
Which of the following statements about cholesterol is FALSE?
a. The headgroup of cholestrol is the hydroxyl, -OH.
b. Liquid-ordered membrane microdomains are rich in cholesterol and sphingolipids.
c. The plasma membrane of animal cells is rich in cholesterol.
d. The role of cholesterol in biological membranes is to lower the melting point (Tm).
e. Cholesterol is a planar lipid that packs in the stiff-chain region of the bilayer. -
Answer- b. Liquid-ordered membrane microdomains are rich in cholesterol and
sphingolipids.
Which of the following statements about membranes is false?
a. In the cell, regions of high membrane curvature are also highly dynamic.
b. Palamitate is a (16:0) fatty acid.
c. Oleic acid is commonly found connected to the carbon 2 position on the glycerol
backbone.
d. According to the raft hypothesis, oleic acid promotes raft assembly.
e. Cererbrosides are found in the outer leaflet of the plasma membrane. - Answer- d.
According to the raft hypothesis, oleic acid promotes raft assembly.
The degree of the membrane fluidity depends on
a. the percentage of unsaturated fatty acids
b. the percentage of lipids that contain choline
c. the percentage of glycolipds
d. the percentage of free fatty acids
e. none of the above - Answer- a. the percentage of unsaturated fatty acids
Which of these statements is generally true of integral membrane proteins?
a. They are unusually susceptible to degradation by trypsin.
b. The domains that protude on the cytoplasmic face of the plasma membrane nearly
always have covalently attached oligosaccarides.
