Question 1

Describe the functional domains of the sarcoplasmic reticulum Ca2+ ATPase.

Accepted Answer

The protein has an integral membrane domain and a cytosolic head with three separate domains. One of the head domains is responsible for binding ATP, another accepts the phosphoryl group, and another appears to serve as the actuator. The membrane-spanning domain is the site of calcium ion binding.

Question 2

What is simple diffusion? Provide an example.

Accepted Answer

In simple diffusion, molecules pass through a membrane from areas of higher to lower concentration. Only lipophilic molecules can easily pass through the membrane. An example would be a steroid hormone molecule.

Question 3

Which of the following is a plant extract of steroids used to treat heart failure?

Accepted Answer

A)  digitalis 
B)  nitroglycerin 
C)  St. John's wort 
D)  salicylic acid 
E)  warfarin 
A)  digitalis 
B)  nitroglycerin 
C)  St. John's wort 
D)  salicylic acid 
E)  warfarin A

Question 4

How does active transport differ from passive?

Accepted Answer

In active transport, molecules

Question 5

What amino acid residue receives a phosphoryl group from P-type ATPases?

Accepted Answer

A)  serine 
B)  tyrosine 
C)  cysteine 
D)  lysine 
E)  aspartate 
A)  serine 
B)  tyrosine 
C)  cysteine 
D)  lysine 
E)  aspartate

Question 6

Since we know that certain amino acids are likely to be found in membranes, why is it so difficult to predict the structure of a channel protein?

Accepted Answer

A single membrane-binding domain is unli

Question 7

Describe the acetylcholine receptor shape.

Accepted Answer

The acetylcholine receptor is a tetramer

Question 8

Why is it dangerous to eat puffer fish that are not properly prepared?

Accepted Answer

Puffer fish contain tetrodotox

Question 9

Where are gap junctions found?

Accepted Answer

A)  between nerve cells 
B)  in plasma membranes of apposed cells 
C)  in the synaptic cleft 
D)  between the ER and Golgi apparatus 
E)  None of the answers is correct. 
A)  between nerve cells 
B)  in plasma membranes of apposed cells 
C)  in the synaptic cleft 
D)  between the ER and Golgi apparatus 
E)  None of the answers is correct.

Question 10

Membrane pumps ____________________(consume, produce, or transduce) energy.

Accepted Answer

The answer of Membrane pumps ____________________(consume, produce, or transduce) energy....

Question 11

A P-glycoprotein transporter is also referred to as MDR protein, which is an acronym for _________________________.

Accepted Answer

multidrug-

Question 12

Give the structure of the modified residue that is involved as an intermediate of P-type ATPases.

Accepted Answer

β-phosphor

Question 13

What clues provided evidence of the mechanism of channel inactivation?

Accepted Answer

A)  Trypsin digestion of the cytoplasmic side caused the channel to stay open. 
B)  Protein mutants have different inactivation kinetics. 
C)  Inactivation could be restored by the addition of part of a missing peptide. 
D)  A and B 
E)  All of the answers are correct. 
A)  Trypsin digestion of the cytoplasmic side caused the channel to stay open. 
B)  Protein mutants have different inactivation kinetics. 
C)  Inactivation could be restored by the addition of part of a missing peptide. 
D)  A and B 
E)  All of the answers are correct.

Question 14

Why are gap junctions sealed when high concentrations of calcium ions and protons are present?

Accepted Answer

These conditions are common wh

Question 15

Ion channels

Accepted Answer

A)  can be selective. 
B)  exist in open and closed states. 
C)  in the open state often spontaneously convert into an inactivated state. 
D)  can be selective and exist in open and closed states. 
E)  All of the answers are correct. 
A)  can be selective. 
B)  exist in open and closed states. 
C)  in the open state often spontaneously convert into an inactivated state. 
D)  can be selective and exist in open and closed states. 
E)  All of the answers are correct.

Question 16

What membrane proteins allow specifically charged species to flow freely across a membrane?

Accepted Answer

A)  aquaporins 
B)  sodium potassium ATPase 
C)  glucose transporter 
D)  ion channels 
E)  None of the answers is correct. 
A)  aquaporins 
B)  sodium potassium ATPase 
C)  glucose transporter 
D)  ion channels 
E)  None of the answers is correct.

Question 17

How does the potassium channel maintain selectivity for potassium versus sodium ions?

Accepted Answer

A)  The ion size is the determining factor. 
B)  The size of the ion and associated waters relative to the pore size are the determining factors in channel selectivity. 
C)  Dehydration of the potassium ion is compensated energetically by interactions with oxygen atoms in the selectivity filter, which is not possible with sodium ions. 
D)  Potassium ions associate with six molecules of water while sodium associates with four, thus allowing selectivity. 
E)  None of the answers is correct. 
A)  The ion size is the determining factor. 
B)  The size of the ion and associated waters relative to the pore size are the determining factors in channel selectivity. 
C)  Dehydration of the potassium ion is compensated energetically by interactions with oxygen atoms in the selectivity filter, which is not possible with sodium ions. 
D)  Potassium ions associate with six molecules of water while sodium associates with four, thus allowing selectivity. 
E)  None of the answers is correct.

Question 18

The lactose permease transports lactose into the cell along with a(n) ______________.

Accepted Answer

The answer of The lactose permease transports lactose into the...

Question 19

As potassium moves through the ion channel, the associated water molecules

Accepted Answer

A)  are shed. 
B)  remain bound. 
C)  are rearranged around the ion. 
D)  react with CO2. 
E)  None of the answers is correct. 
A)  are shed. 
B)  remain bound. 
C)  are rearranged around the ion. 
D)  react with CO2. 
E)  None of the answers is correct.

Question 20

In the potassium ion channel, which of the following is critical in the function of the selectivity filter?

Accepted Answer

A)  The K+ binds to a critical Glu residue. 
B)  The K+ binds to the amide groups of three residues in the selectivity filter. 
C)  The K+ binds to the carbonyl groups of the backbone of a conserved pentapeptide sequence. 
D)  An ATP molecule must be bound for the selectivity filter to operate. 
E)  None of the answers is correct. 
A)  The K+ binds to a critical Glu residue. 
B)  The K+ binds to the amide groups of three residues in the selectivity filter. 
C)  The K+ binds to the carbonyl groups of the backbone of a conserved pentapeptide sequence. 
D)  An ATP molecule must be bound for the selectivity filter to operate. 
E)  None of the answers is correct.

Exam 13: Membrane Channels and Pumps

Describe the functional domains of the sarcoplasmic reticulum Ca2+ ATPase.

What is simple diffusion? Provide an example.

Which of the following is a plant extract of steroids used to treat heart failure?

How does active transport differ from passive?

What amino acid residue receives a phosphoryl group from P-type ATPases?

Since we know that certain amino acids are likely to be found in membranes, why is it so difficult to predict the structure of a channel protein?

Describe the acetylcholine receptor shape.

Why is it dangerous to eat puffer fish that are not properly prepared?

Where are gap junctions found?

Membrane pumps ____________________(consume, produce, or transduce) energy.

A P-glycoprotein transporter is also referred to as MDR protein, which is an acronym for _________________________.

Give the structure of the modified residue that is involved as an intermediate of P-type ATPases.

What clues provided evidence of the mechanism of channel inactivation?

Why are gap junctions sealed when high concentrations of calcium ions and protons are present?

Ion channels

What membrane proteins allow specifically charged species to flow freely across a membrane?

How does the potassium channel maintain selectivity for potassium versus sodium ions?

The lactose permease transports lactose into the cell along with a(n) ______________.

As potassium moves through the ion channel, the associated water molecules

In the potassium ion channel, which of the following is critical in the function of the selectivity filter?

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

Describe the functional domains of the sarcoplasmic reticulum Ca²⁺ ATPase.