Question 1

The CF mutation is present at very high levels within the Caucasian population and is thought to have arisen more than 50,000 years ago to reach its present level.Since an individual homozygous for the recessive mutant allele has such poor health,what could explain this allele rising to such a high level in the population?

Accepted Answer

The high frequency of the defective alle...

Question 2

Which of the following cell processes depend on the movement of membrane components and would probably not be possible if membranes were rigid,nonfluid structures?

Accepted Answer

A)  cell movement
B)  cell division
C)  formation of intercellular junctions
D)  endocytosis
E)  All of these are correct.F) C) and E)
G) A) and C)

Question 3

How might a liposome be prepared that could potentially be used in the treatment of a tumor whose cells have a protein called tumor cell antigen (TCA)in their membranes? This protein is missing from all normal cells.

Accepted Answer

Make an antibody to the TCA protein and ...

Question 4

What complications in the story of the CFTR and its relationship to CF have been introduced by subsequent studies?

Accepted Answer

CFTR also conducts bicarbonate...

Question 5

In the 1950s,J.D.Robertson reported that any membrane that he observed in the electron microscope looked the same.This led to his proposal of the Unit Membrane model of membrane structure suggesting that all membranes were exactly alike.Why was this model eventually rejected?

Accepted Answer

It was eventually discovered that differ...

Question 6

What did Davson and Danielli add to their model of enzyme structure to explain the passage of polar solutes and ions through the membrane and to account for their selective permeability?

Accepted Answer

A)  They proposed protein-lined pores.
B)  They proposed lipid-lined pores.
C)  They proposed carbohydrate-lined pores.
D)  They proposed a protein coating on the cytoplasmic surface of the membrane.
E)  They proposed a carbohydrate coating on the external surface of the membrane.F) B) and D)
G) D) and E)

Question 7

Cocaine acts by _________.

Accepted Answer

A)  enhancing the degradation of acetylcholine.
B)  depressing the degradation of acetylcholine
C)  interfering with dopamine reuptake from the synaptic cleft
D)  enhancing dopamine reuptake from the synaptic cleft
E)  destroying dopamine in the synapseF) B) and E)
G) None of the above

Question 8

What technique below is often used to identify transmembrane segments of integral proteins?

Accepted Answer

A)  Lineweaver-Burk plot
B)  Michaelis-Menten plot
C)  hydrophilicity plot
D)  hydropathy plot
E)  titration plotF) B) and C)
G) A) and D)

Question 9

Which of the following is a function of membranes?

Accepted Answer

A)  compartmentalization
B)  selectively permeable barrier
C)  mediates intercellular interactions
D)  helps cells respond to external stimuli
E)  All of these are correct.F) C) and E)
G) A) and C)

Question 10

A process in liver cells stops when they are exposed to the inhibitor ouabain,which is an inhibitor of the Na+-K+ pump.What do you conclude about the liver cell process?

Accepted Answer

The Na+-K+ pump is involved in the proce...

Question 11

Why are integral membrane proteins difficult to study?

Accepted Answer

A)  They are difficult to isolate in soluble form due to their hydrophobic transmembrane domains.
B)  They are difficult to isolate in soluble form due to their hydrophilic transmembrane domains.
C)  They are so small.
D)  They are so large.
E)  None of these are correct.F) A) and D)
G) B) and D)

Question 12

What word describes a molecule that contains both hydrophilic and hydrophobic portions?

Accepted Answer

A)  amphoteric
B)  ambidextrous
C)  amphipathic
D)  rings
E)  straightF) A) and B)
G) C) and E)

Question 13

Enzymes that move certain phospholipids between leaflets have also which of the following properties?

Accepted Answer

A)  Play a role in establishing and maintaining membrane lipid asymmetry
B)  Interacts with neighboring epithelial cells,or the basal membrane
C)  Blocks post-synaptic membrane
D)  Transport proteins
E)  All of the aboveF) A) and D)
G) None of the above

Question 14

Integral membrane proteins have been engineered to lack the portion that normally projects into the extracellular space.When the gene is inserted in cells,what happens to the mobility of this protein in the membrane?

Accepted Answer

A)  They move at a much greater rate than the wild type protein.
B)  They move at a much smaller rate than the intact protein.
C)  They do not move at all.
D)  They are not inserted into the membrane so nothing can be learned about their mobility.
E)  They flip to the opposite leaflet.F) C) and D)
G) A) and E)

Question 15

How is a nerve impulse usually transmitted across a synapse from a presynaptic to a postsynaptic cell?

Accepted Answer

A)  via a direct connection
B)  via a spark
C)  via a neurotransmitter
D)  via Na+ ions
E)  via plasmodesmataF) C) and E)
G) B) and D)

Question 16

______ trigger fusion of synaptic vesicles with the synaptic membranes of the presynaptic cell.This same stimulus also triggers ________.

Accepted Answer

A)  Ca2+ ions,exocytosis
B)  Ca2+ ions,endocytosis
C)  acetylcholine,exocytosis
D)  acetylcholine,endocytosis
E)  Na+ ions,exocytosisF) A) and C)
G) A) and E)

Question 17

Which part of a neuron conducts impulses away from the cell body toward the target cell(s) ?

Accepted Answer

A)  axon hillock
B)  cell body
C)  dendrites
D)  axon
E)  terminal knobF) A) and E)
G) A) and B)

Question 18

What directly or indirectly determines the transition temperature?

Accepted Answer

A)  the ability of lipid molecules to be packed together
B)  whether the fatty acid chains of the lipids are saturated or unsaturated
C)  the extent to which the fatty acid chains of the lipids contain double bonds
D)  the length of the fatty acid chains
E)  All of these are correct.F) B) and D)
G) A) and D)

Question 19

How do the cholesterol molecules depicted in the figure below enhance membrane fluidity?

Accepted Answer

They interfere with ...

Question 20

Hemolytic anemias are characterized by fragile,abnormally shaped erythrocytes;the disease has been traced to mutations in ________.

Accepted Answer

A)  actin
B)  ankyrin
C)  hemoglobin
D)  spectrin
E)  both ankyrin and spectrinF) A) and D)
G) A) and C)

Exam 4: The Structure and Function of the Plasma Membrane

What technique below is often used to identify transmembrane segments of integral proteins?

Correct Answer
verified

Integral membrane proteins have been engineered to lack the portion that normally projects into the extracellular space.When the gene is inserted in cells,what happens to the mobility of this protein in the membrane?

Correct Answer
verified

Which of the following cell processes depend on the movement of membrane components and would probably not be possible if membranes were rigid,nonfluid structures?

Correct Answer
verified

What complications in the story of the CFTR and its relationship to CF have been introduced by subsequent studies?

Correct Answer
verified
CFTR also conducts bicarbonate...
View Answer

How do the cholesterol molecules depicted in the figure below enhance membrane fluidity?

Correct Answer
verified
They interfere with ...
View Answer

Enzymes that move certain phospholipids between leaflets have also which of the following properties?

Correct Answer
verified

Which of the following is a function of membranes?

Correct Answer
verified

Which part of a neuron conducts impulses away from the cell body toward the target cell(s) ?

Correct Answer
verified

A process in liver cells stops when they are exposed to the inhibitor ouabain,which is an inhibitor of the Na+-K+ pump.What do you conclude about the liver cell process?

Correct Answer
verified
The Na+-K+ pump is involved in the proce...
View Answer

In the 1950s,J.D.Robertson reported that any membrane that he observed in the electron microscope looked the same.This led to his proposal of the Unit Membrane model of membrane structure suggesting that all membranes were exactly alike.Why was this model eventually rejected?

Correct Answer
verified
It was eventually discovered that differ...
View Answer

Hemolytic anemias are characterized by fragile,abnormally shaped erythrocytes;the disease has been traced to mutations in ________.

Correct Answer
verified

What did Davson and Danielli add to their model of enzyme structure to explain the passage of polar solutes and ions through the membrane and to account for their selective permeability?

Correct Answer
verified

What directly or indirectly determines the transition temperature?

Correct Answer
verified

How might a liposome be prepared that could potentially be used in the treatment of a tumor whose cells have a protein called tumor cell antigen (TCA)in their membranes? This protein is missing from all normal cells.

Correct Answer
verified
Make an antibody to the TCA protein and ...
View Answer

Why are integral membrane proteins difficult to study?

Correct Answer
verified

How is a nerve impulse usually transmitted across a synapse from a presynaptic to a postsynaptic cell?

Correct Answer
verified

Correct Answer
verified
The high frequency of the defective alle...
View Answer

What word describes a molecule that contains both hydrophilic and hydrophobic portions?

Correct Answer
verified

Cocaine acts by _________.

Correct Answer
verified

trigger fusion of synaptic vesicles with the synaptic membranes of the presynaptic cell.This same stimulus also triggers __.

Correct Answer
verified

Exam 4: The Structure and Function of the Plasma Membrane

What technique below is often used to identify transmembrane segments of integral proteins?

Correct AnswerverifiedShow Answer

Integral membrane proteins have been engineered to lack the portion that normally projects into the extracellular space.When the gene is inserted in cells,what happens to the mobility of this protein in the membrane?

Correct AnswerverifiedShow Answer

Which of the following cell processes depend on the movement of membrane components and would probably not be possible if membranes were rigid,nonfluid structures?

Correct AnswerverifiedShow Answer

What complications in the story of the CFTR and its relationship to CF have been introduced by subsequent studies?

Correct AnswerverifiedCFTR also conducts bicarbonate...View AnswerShow Answer

How do the cholesterol molecules depicted in the figure below enhance membrane fluidity?

Correct AnswerverifiedThey interfere with ...View AnswerShow Answer

Enzymes that move certain phospholipids between leaflets have also which of the following properties?

Correct AnswerverifiedShow Answer

Which of the following is a function of membranes?

Correct AnswerverifiedShow Answer

Which part of a neuron conducts impulses away from the cell body toward the target cell(s) ?

Correct AnswerverifiedShow Answer

A process in liver cells stops when they are exposed to the inhibitor ouabain,which is an inhibitor of the Na+-K+ pump.What do you conclude about the liver cell process?

Correct AnswerverifiedThe Na+-K+ pump is involved in the proce...View AnswerShow Answer

In the 1950s,J.D.Robertson reported that any membrane that he observed in the electron microscope looked the same.This led to his proposal of the Unit Membrane model of membrane structure suggesting that all membranes were exactly alike.Why was this model eventually rejected?

Correct AnswerverifiedIt was eventually discovered that differ...View AnswerShow Answer

Hemolytic anemias are characterized by fragile,abnormally shaped erythrocytes;the disease has been traced to mutations in ________.

Correct AnswerverifiedShow Answer

What did Davson and Danielli add to their model of enzyme structure to explain the passage of polar solutes and ions through the membrane and to account for their selective permeability?

Correct AnswerverifiedShow Answer

What directly or indirectly determines the transition temperature?

Correct AnswerverifiedShow Answer

How might a liposome be prepared that could potentially be used in the treatment of a tumor whose cells have a protein called tumor cell antigen (TCA)in their membranes? This protein is missing from all normal cells.

Correct AnswerverifiedMake an antibody to the TCA protein and ...View AnswerShow Answer

Why are integral membrane proteins difficult to study?

Correct AnswerverifiedShow Answer

How is a nerve impulse usually transmitted across a synapse from a presynaptic to a postsynaptic cell?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedThe high frequency of the defective alle...View AnswerShow Answer

What word describes a molecule that contains both hydrophilic and hydrophobic portions?

Correct AnswerverifiedShow Answer

Cocaine acts by _________.

Correct AnswerverifiedShow Answer

______ trigger fusion of synaptic vesicles with the synaptic membranes of the presynaptic cell.This same stimulus also triggers ________.

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
CFTR also conducts bicarbonate...
View Answer

Correct Answer
verified
They interfere with ...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
The Na+-K+ pump is involved in the proce...
View Answer

Correct Answer
verified
It was eventually discovered that differ...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
Make an antibody to the TCA protein and ...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
The high frequency of the defective alle...
View Answer

Correct Answer
verified

Correct Answer
verified

trigger fusion of synaptic vesicles with the synaptic membranes of the presynaptic cell.This same stimulus also triggers __.

Correct Answer
verified