Question 1

Which of the following is NOT correct concerning the ABC proteins?

Accepted Answer

A)  They undergo conformational changes upon ATP binding. 
B)  All are also members of the P-loop NTPase superfamily. 
C)  The ATP-binding domains are referred to as ATP-binding cassettes. 
D)  They transfer a phosphate to a conserved Asp residue. 
E)  They are all true statements. 
A)  They undergo conformational changes upon ATP binding. 
B)  All are also members of the P-loop NTPase superfamily. 
C)  The ATP-binding domains are referred to as ATP-binding cassettes. 
D)  They transfer a phosphate to a conserved Asp residue. 
E)  They are all true statements.

Question 2

Multidrug resistance in tumor cells is

Accepted Answer

A)  due to the action of a membrane pump that transports small molecules out of the cells. 
B)  the development of resistance to several drugs following an initial resistance to a single drug. 
C)  caused by a mutation in the cystic fibrosis gene. 
D)  due to the action of a membrane pump that transports small molecules out of the cells and the development of resistance to several drugs following an initial resistance to a single drug. 
E)  All of the answers are correct. 
A)  due to the action of a membrane pump that transports small molecules out of the cells. 
B)  the development of resistance to several drugs following an initial resistance to a single drug. 
C)  caused by a mutation in the cystic fibrosis gene. 
D)  due to the action of a membrane pump that transports small molecules out of the cells and the development of resistance to several drugs following an initial resistance to a single drug. 
E)  All of the answers are correct.

Question 3

How does energy affect the functioning of the Na+-K+ ATPase?

Accepted Answer

ATP provides the energy for th

Question 4

What technique is used to measure conductance across a membrane?

Accepted Answer

A)  osmotic flow analysis 
B)  electron crystallography 
C)  stop-flow 
D)  patch-clamp 
E)  None of the answers is correct. 
A)  osmotic flow analysis 
B)  electron crystallography 
C)  stop-flow 
D)  patch-clamp 
E)  None of the answers is correct.

Question 5

Membrane transporters that couple the downhill flow of one species to the uphill flow of another species in the opposite direction are called

Accepted Answer

A)  antiporters. 
B)  symporters. 
C)  exchangers. 
D)  P-type transporters. 
E)  None of the answers is correct. 
A)  antiporters. 
B)  symporters. 
C)  exchangers. 
D)  P-type transporters. 
E)  None of the answers is correct.

Question 6

Channels that open in response to membrane depolarization are called __________ channels.

Accepted Answer

A)  voltage-gated 
B)  symport 
C)  ligand-gated 
D)  ion-gated 
E)  None of the answers is correct. 
A)  voltage-gated 
B)  symport 
C)  ligand-gated 
D)  ion-gated 
E)  None of the answers is correct.

Question 7

What is the function of selectivity filter amino acids in an ion channel?

Accepted Answer

A)  They close the channel pore after ion passage. 
B)  They determine the preference for a particular ion. 
C)  They limit the number of ions passing through the channel. 
D)  They make sure that only positively charged ions move through the channel 
E)  None of the answers is correct. 
A)  They close the channel pore after ion passage. 
B)  They determine the preference for a particular ion. 
C)  They limit the number of ions passing through the channel. 
D)  They make sure that only positively charged ions move through the channel 
E)  None of the answers is correct.

Question 8

Inorganic ions and most metabolites can flow between the interiors of cells joined by _______________.

Accepted Answer

The answer of Inorganic ions and most metabolites can flow...

Question 9

In a cell-to-cell junction, 12 molecules of what protein form the gap junction?

Accepted Answer

A)  actin 
B)  keratin 
C)  connexin 
D)  tubulin 
E)  None of the answers is correct. 
A)  actin 
B)  keratin 
C)  connexin 
D)  tubulin 
E)  None of the answers is correct.

Question 10

When an uncharged molecule moves from a concentration of 10 - 4 M to 10 - 2 M, is the process spontaneous, at equilibrium, or does it require an input of energy?

Accepted Answer

A)  spontaneous 
B)  at equilibrium 
C)  input of energy required 
D)  It depends on the membrane potential. 
E)  None of the answers is correct. 
A)  spontaneous 
B)  at equilibrium 
C)  input of energy required 
D)  It depends on the membrane potential. 
E)  None of the answers is correct.

Question 11

Which of the following are true about gap junctions?

Accepted Answer

A)  They are important for intercellular communication. 
B)  Polar molecules smaller than 1 kDa can pass through them. 
C)  The channels stay open seconds to minutes. 
D)  All of the answers are correct. 
E)  None of the answers is correct. 
A)  They are important for intercellular communication. 
B)  Polar molecules smaller than 1 kDa can pass through them. 
C)  The channels stay open seconds to minutes. 
D)  All of the answers are correct. 
E)  None of the answers is correct.

Question 12

If the selectivity filter binds the potassium ion tightly, how are ions released to pass through the membrane?

Accepted Answer

The selectivity filter has four binding

Question 13

___________________ are an important class of channels that increase the rate at which water flows through membranes.

Accepted Answer

The answer of ___________________ are an important class of channels...

Question 14

Many pumps are members of the P-type ATPases. If you discovered a new enzyme with similar function, what reaction intermediate would help convince you that your enzyme was a member of this family?

Accepted Answer

The members of this family tra

Question 15

A channel that opens in response to binding a particular molecule is called a ________ channel.

Accepted Answer

A)  passive diffusion 
B)  symport 
C)  ligand-gated 
D)  ABC-protein 
E)  None of the answers is correct. 
A)  passive diffusion 
B)  symport 
C)  ligand-gated 
D)  ABC-protein 
E)  None of the answers is correct.

Question 16

What type of membrane transporter moves two species in opposite directions across a membrane?

Accepted Answer

A)  symporter 
B)  antiporter 
C)  uniporter 
D)  cotransporter 
E)  None of the answers is correct. 
A)  symporter 
B)  antiporter 
C)  uniporter 
D)  cotransporter 
E)  None of the answers is correct.

Question 17

The acetylcholine receptor is an example of a ____________-gated channel.

Accepted Answer

The answer of The acetylcholine receptor is an example of...

Question 18

What is the "ball-and-chain" model?

Accepted Answer

"Ball-and-chain" is a model of inactivat

Question 19

Tetrodotoxin, isolated from puffer fish, binds tightly and specifically to ___________ channels in nerve cells.

Accepted Answer

The answer of Tetrodotoxin, isolated from puffer fish, binds tightly...

Question 20

What are the similarities between sodium, potassium, and calcium ion channels?

Accepted Answer

A)  All allow passage of multiple different ions. 
B)  They contain homologous domains in the membrane spanning regions. 
C)  They all contain voltage-sensing segments that close the channel in response to a particular membrane potential. 
D)  They are capable of moving ions in both directions across a membrane. 
E)  None of the answers is correct. 
A)  All allow passage of multiple different ions. 
B)  They contain homologous domains in the membrane spanning regions. 
C)  They all contain voltage-sensing segments that close the channel in response to a particular membrane potential. 
D)  They are capable of moving ions in both directions across a membrane. 
E)  None of the answers is correct.

Exam 13: Membrane Channels and Pumps

Which of the following is NOT correct concerning the ABC proteins?

Multidrug resistance in tumor cells is

How does energy affect the functioning of the Na+-K+ ATPase?

What technique is used to measure conductance across a membrane?

Membrane transporters that couple the downhill flow of one species to the uphill flow of another species in the opposite direction are called

Channels that open in response to membrane depolarization are called __________ channels.

What is the function of selectivity filter amino acids in an ion channel?

Inorganic ions and most metabolites can flow between the interiors of cells joined by _______________.

In a cell-to-cell junction, 12 molecules of what protein form the gap junction?

When an uncharged molecule moves from a concentration of 10 - 4 M to 10 - 2 M, is the process spontaneous, at equilibrium, or does it require an input of energy?

Which of the following are true about gap junctions?

If the selectivity filter binds the potassium ion tightly, how are ions released to pass through the membrane?

___________________ are an important class of channels that increase the rate at which water flows through membranes.

Many pumps are members of the P-type ATPases. If you discovered a new enzyme with similar function, what reaction intermediate would help convince you that your enzyme was a member of this family?

A channel that opens in response to binding a particular molecule is called a ________ channel.

What type of membrane transporter moves two species in opposite directions across a membrane?

The acetylcholine receptor is an example of a ____________-gated channel.

What is the "ball-and-chain" model?

Tetrodotoxin, isolated from puffer fish, binds tightly and specifically to ___________ channels in nerve cells.

What are the similarities between sodium, potassium, and calcium ion channels?

Biochemistry: an Evolving Science

Protein Composition and Structure

Exploring Proteins and Proteomes

DNA, RNA, and the Flow of Genetic Information

Exploring Genes and Genomes

Exploring Evolution and Bioinformatics

Hemoglobin: a Portrait of a Protein in Action

Enzymes: Basic Concepts and Kinetics

Oxidative Phosphorylation

Catalytic Strategies

Regulatory Strategies

Carbohydrates

Lipids and Cell Membranes

Signal-Transduction Pathways

Metabolism: Basic Concepts and Design

Glycolysis and Gluconeogenesis

The Citric Acid Cycle

The Light Reactions of Photosynthesis

The Calvin Cycle and the Pentose Phosphate Pathway

Glycogen Metabolism

Fatty Acid Metabolism

Protein Turnover and Amino Acid Catabolism

The Biosynthesis of Amino Acids

Nucleotide Biosynthesis

Biosynthesis of Membrane Lipids and Steroids

The Integration of Metabolism

DNA Replication, Repair, and Recombination

Rna Synthesis and Processing

Protein Synthesis

The Control of Gene Expression in Prokaryotes

The Control of Gene Expression in Eukaryotes

Sensory Systems

The Immune System

Molecular Motors

Drug Development

Filters

How does energy affect the functioning of the Na⁺-K⁺ ATPase?

When an uncharged molecule moves from a concentration of 10 ^- ⁴M to 10 ^- ² M, is the process spontaneous, at equilibrium, or does it require an input of energy?