Deck 12: Membrane Structure and Function

Question 1

An increase in the ratio of saturated to unsaturated fatty acid chains in a membrane _______________ the fluidity of the membrane.

Answer 1

decreases

Question 2

The temperature at which a phospholipid membrane transitions from a rigid to a fluid state is referred to as _______________.

Answer 2

Tm, or melting temperature

Question 3

Membranes are said to be ____________ because their two faces always differ from each other.

Answer 3

asymmetric

Question 4

The _______________ of small molecules is correlated with their relative solubilities in water and nonpolar solvents.

Question 5

_______________ membrane proteins are bound primarily by electrostatic and hydrogen-bond interactions with the head groups of lipids.

Question 6

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) glycolipids
b) closed biomolecular sheets
c) lateral diffusion
d) integral
e) hydrophobic effect
f) acetylsalicylic acid (aspirin)
g) water
h) lipid raft
i) hydrophobic
j) ions
k) high
l) peripheral
m) low
____________ membrane proteins are embedded in the hydrocarbon chains of membrane lipids.

Question 7

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) glycolipids
b) closed biomolecular sheets
c) lateral diffusion
d) integral
e) hydrophobic effect
f) acetylsalicylic acid (aspirin)
g) water
h) lipid raft
i) hydrophobic
j) ions
k) high
l) peripheral
m) low
Lipid biolayers spontaneously form ____________.

Question 8

_______________ are bilayer lipid vesicles with an aqueous compartment.

Question 9

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) glycolipids
b) closed biomolecular sheets
c) lateral diffusion
d) integral
e) hydrophobic effect
f) acetylsalicylic acid (aspirin)
g) water
h) lipid raft
i) hydrophobic
j) ions
k) high
l) peripheral
m) low
The driving force for the formation of membrane bilayers is/are the:

Question 10

The rate of lateral diffusion is such that a phospholipid molecule can travel from one end of a bacterium to the other in _______________ of time.

Question 11

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) glycolipids
b) closed biomolecular sheets
c) lateral diffusion
d) integral
e) hydrophobic effect
f) acetylsalicylic acid (aspirin)
g) water
h) lipid raft
i) hydrophobic
j) ions
k) high
l) peripheral
m) low
____________: This substance inhibits prostaglandin H2 synthase-1 by blocking the channel through which the substrate, arachidonate, travels.

Question 12

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) glycolipids
b) closed biomolecular sheets
c) lateral diffusion
d) integral
e) hydrophobic effect
f) acetylsalicylic acid (aspirin)
g) water
h) lipid raft
i) hydrophobic
j) ions
k) high
l) peripheral
m) low
____________: The type of amino acid found in the transmembrane helix of an integral protein.

Question 13

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) glycolipids
b) closed biomolecular sheets
c) lateral diffusion
d) integral
e) hydrophobic effect
f) acetylsalicylic acid (aspirin)
g) water
h) lipid raft
i) hydrophobic
j) ions
k) high
l) peripheral
m) low
____________: A complex between cholesterol and membrane phospholipids.

Question 14

_______________ inserts into lipid bilayers, disrupting interactions between fatty acids, thereby helping to maintain membrane fluidity.

Question 15

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) glycolipids
b) closed biomolecular sheets
c) lateral diffusion
d) integral
e) hydrophobic effect
f) acetylsalicylic acid (aspirin)
g) water
h) lipid raft
i) hydrophobic
j) ions
k) high
l) peripheral
m) low
____________ has a high permeability through lipid bilayers.

Question 16

Most cell membranes are electrically polarized, the inside being _______________ relative to the outside.

Question 17

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) glycolipids
b) closed biomolecular sheets
c) lateral diffusion
d) integral
e) hydrophobic effect
f) acetylsalicylic acid (aspirin)
g) water
h) lipid raft
i) hydrophobic
j) ions
k) high
l) peripheral
m) low
Cells maintain a ____________ concentration of intracellular potassium as compared to the extracellular concentration.

Question 18

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) glycolipids
b) closed biomolecular sheets
c) lateral diffusion
d) integral
e) hydrophobic effect
f) acetylsalicylic acid (aspirin)
g) water
h) lipid raft
i) hydrophobic
j) ions
k) high
l) peripheral
m) low
____________: These membrane components contain carbohydrates.

Question 19

________________ is the noncovalent force which favors close packing of the tails of the lipids in a membrane.

Question 20

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) glycolipids
b) closed biomolecular sheets
c) lateral diffusion
d) integral
e) hydrophobic effect
f) acetylsalicylic acid (aspirin)
g) water
h) lipid raft
i) hydrophobic
j) ions
k) high
l) peripheral
m) low
____________: The process by which lipids and proteins move in the membrane bilayer.

Question 21

Which is the proper order of permeability of molecules across a membrane, from the most permeable to the least?

A) water, glucose, urea, sodium ion
B) water, indole, glucose, sodium ion
C) water, indole, sodium ion, glucose
D) indole, glucose, urea, sodium ion
E) indole, water, glucose, sodium ion

Question 22

Which 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) The membrane lipids self-assemble to form the lipid bilayer.
E) A biological membrane consists of proteins sandwiched between two layers of lipids, which is referred to as a lipid bilayer.

Question 23

Draw a cross-section of a membrane bilayer and a liposome.

Question 24

Which of the following is true?

A) Membranes are lipid bilayers.
B) Membrane lipids have both hydrophobic and hydrophilic properties.
C) Many membranes are electrically polarized.
D) All of the above.
E) None of the above.

Question 25

The fluorescence recovery after photobleaching (FRAP) technique has been used to study:

A) membrane composition.
B) the lateral diffusion in membranes.
C) protein structural motifs in membranes.
D) All of the above.
E) None of the above.

Question 26

Instead, its function is to inhibit:

A) the Na+-K+ pump.
B) fatty acid intake.
C) calcium channels.
D) potassium and sodium pores.
E) dropsy channel.

Question 27

The most common motif found in membrane-spanning proteins is:

A) ɑ helices of nonpolar amino acids that pass through the membrane.
B) ɑ helices of charged amino acids that form channels via extensive hydrogen bonding.
C) a triple helix of ɑ helices.
D) a helix-turn-helix arrangement of the peptide strands.
E) None of the above.

Question 28

Which of the following helps regulate membrane fluidity in animals?

A) protein
B) cholesterol
C) ATP
D) magnesium ion
E) None of the above.

Question 29

How do proteins function to make membranes selectively permeable?

Question 30

Carbohydrate residues attached to the membrane lipids are:

A) always positioned on the intracellular side of the membrane.
B) always positioned on the inside center of the bilayer.
C) always positioned on the extracellular side of the membrane.
D) always positioned equally on both sides of the membrane.
E) also covalently attached to membrane proteins.

Question 31

Describe a lipid raft and its potential role in a cell.

Question 32

What force(s) stabilize(s) the lipid bilayers?

A) van der Waals interactions
B) electrostatic and hydrogen bonding between the polar heads and surrounding water
C) covalent bonds between the lipid tails
D) covalent bonds between the lipids and membrane proteins
E) A and B

Question 33

The degree of membrane fluidity depends on:

A) the percentage of lipids that contain choline.
B) the percentage of glycolipids.
C) the percentage of free fatty acids.
D) the percentage of unsaturated fatty acids.
E) None of the above.

Question 34

Why are membranes impermeable to most substances?

Question 35

The low incidence of protein or lipid flip-flop in a membrane preserves:

A) membrane fluidity.
B) membrane melting temperatures.
C) membrane asymmetry.
D) All of the above.
E) None of the above.

Question 36

This is evidence for what?

Question 37

What are the key biochemical elements for transmembrane-spanning proteins?

Question 38

How many molecules thick are membranes?

A) 2
B) 1
C) infinite
D) they are of varying thickness, depending on their structure
E) None of the above.

Question 39

Which of the following membranes would be the most fluid?

A) a bilayer made of lipids with polyunsaturated 18-carbon fatty acids
B) a bilayer made of lipids with saturated 18-carbon fatty acids
C) a bilayer made of lipids with saturated 16-carbon fatty acids
D) a bilayer made of lipids with polyunsaturated 16-carbon fatty acids
E) All of the above are equivalent in fluidity.

Question 40

An antiporter and a symporter are examples of:

A) passive diffusion.
B) primary active transporters.
C) entropy-driven pores.
D) an ABC transporter.
E) a secondary transporter.

Question 41

Draw a bilayer membrane that has both an integral and peripheral protein present.

Question 42

What is multidrug resistance?

Question 43

What are liposomes? What are some of their current commercial applications?

Question 44

What is the function of prostaglandin H2 synthase-1? How does its position in the membrane facilitate its activity?

Question 45

How do secondary transporters drive the transport of a substance up its concentration gradient?

Question 46

Describe the effect of introducing a sodium ion pore into a membrane containing the Na+-glucose symporter.

Question 47

How are lipid bilayers formed? What is the driving force?

Question 48

Why do most phospholipids preferentially form sheets instead of micelles?

Question 49

Describe the selectivity of the potassium ion channel.