Question 1

You are investigating the transition temperature of a membrane,the origin of which you do not know.The temperature of transition for this membrane is very sharp,occurring over an extremely narrow range of temperatures.What can you say about the composition of the membrane?

Accepted Answer

It is probably composed of a single phospholipid or,at most,two or three phospholipids.

Question 2

The sodium-potassium pump makes the cell interior more ______ by pumping ____ sodium ions out of the cell for every ____ potassium ions pumped in.

Accepted Answer

A)  negative,3,2
B)  negative,2,3
C)  positive,3,2
D)  positive,2,3
E)  negative,4,3 A

Question 3

What enzyme was instrumental in the discovery of GPI-anchored proteins? It was found that this enzyme would release certain membrane proteins from a membrane.

Accepted Answer

A)  phospholipase
B)  lipase
C)  hydroxyurease
D)  protease
E)  trypsin A

Question 4

When membrane lipids are extracted from cells and used to prepare artificial lipid bilayers,cholesterol and sphingolipids tend to self-assemble into ________ that are more gelated and highly ordered than surrounding regions consisting primarily of _________.

Accepted Answer

A)  macrodomains,phosphoglycerides
B)  microdomains,integral proteins
C)  microdomains,phosphoglycerides
D)  liquid crystals,phosphoglycerides
E)  liquid crystals,microdomains

Question 5

Which proteins move the farthest during SDS-polyacrylamide gel electrophoresis?

Accepted Answer

A)  the largest
B)  the smallest
C)  the most negative
D)  the most positive
E)  both the largest and the most negative

Question 6

Synaptic malfunction or dysfunction may cause which of the following diseases?

Accepted Answer

A)  myasthenia gravis
B)  Parkinson's disease
C)  schizophrenia
D)  depression
E)  All of these are correct.

Question 7

_________ can be used to trap integral proteins and drag them through the membrane with a known force,using forces generated by a focused laser beam.This yields information about the presence of membrane barriers.

Accepted Answer

A)  FRAP
B)  SPT
C)  Fluorescence recovery after photobleaching
D)  Optical tweezers
E)  SDS-PAGE

Question 8

A membrane's transition temperature is determined and found to stretch over a wide range of temperatures.The membrane also exhibits high stability and a reduced permeability similar to that in most mammals.What membrane component is responsible for these traits and how does it do it?

Accepted Answer

The answer of A membrane's transition temperature is determined and...

Question 9

A new,promising drug in the treatment of cystic fibrosis (CF)and the improvement in the quality of life in CF patients is Bronchitol.What is Bronchitol's overall effect on the patient that allows it to improve their situation? What sugar is a major constituent of Bronchitol? How does Bronchitol cause water to move into the extracellular fluid of the airways after being inhaled? What other kinds of compounds might be used in CF treatment in the future?

Accepted Answer

The answer of A new,promising drug in the treatment of...

Question 10

Once the structure of one member of a membrane protein family has been determined,researchers can usually apply a strategy called __________ to learn about the structure and activity of other members of the family.For example,solution of the structure of the bacterial potassium channel KcsA provided a lot of data that could be applied to the structure and mechanism of action of the much more complex eukaryotic potassium channels.

Accepted Answer

A)  heterology modeling
B)  homology mapping
C)  homology modeling
D)  protein mapping
E)  homologous characterization

Question 11

In the figure below,the bilayer shown is below the transition temperature and the movement of the molecules is greatly restricted.What words can be used to describe this bilayer?

Accepted Answer

The answer of In the figure below,the bilayer shown is...

Question 12

A molecule normally enters a cell by simple diffusion through the lipid bilayer.What happens if you artificially reverse the molecule's concentration gradient?

Accepted Answer

The answer of A molecule normally enters a cell by...

Question 13

Look at the hydropathy plot in the figure below.How many transmembrane domains are indicated for glycophorin A in the plot? What is the approximate position of the stretch of amino acids that spans the membrane?

Accepted Answer

The answer of Look at the hydropathy plot in the...

Question 14

Where is the neuron cell nucleus located?

Accepted Answer

A)  axon hillock
B)  cell body
C)  dendrites
D)  axon
E)  terminal knob

Question 15

A procedure in which the gene for an integral membrane protein is altered in such a way that the spatial relationships between some of the amino acids in the protein can be revealed is called ________.

Accepted Answer

A)  site-directed mutagenesis
B)  site-directed amenuensis
C)  hydropathy plots
D)  electron paramagnetic resonance (EPR) spectroscopy
E)  infrared spectroscopy

Question 16

How might a lack of Cl- transport cause the respiratory tract symptoms of cystic fibrosis (CF),specifically the thickened mucus?

Accepted Answer

The answer of How might a lack of Cl- transport...

Question 17

What disease is caused by the disruption of the structure depicted in the figure below?

Accepted Answer

The answer of What disease is caused by the disruption...

Question 18

Usually,optical tweezers drag integral proteins a limited distance before they encounter a barrier that causes their release;upon release,they typically spring backward.What does this suggest?

Accepted Answer

A)  the presence of solid barriers
B)  the presence of elastic barriers
C)  the attachment of the proteins to the cytoskeleton
D)  the attachment of the proteins to the endoplasmic reticulum
E)  the presence of rubber in the membrane

Question 19

What are some possible explanations for the tendency of CF patients to develop chronic lung infections?

Accepted Answer

The answer of What are some possible explanations for the...

Question 20

If you were able to study nerve conduction in vitro and you added ouabain,an inhibitor of the Na+-K+ ATPase,to the system,would you expect to see the conduction of nerve impulses cease immediately?

Accepted Answer

The answer of If you were able to study nerve...

Exam 4: The Structure and Function of the Plasma Membrane