Molecular Biology of The Cell Chapter 011 TEST Quiz Exam
with combined Q & A 2023/2024 VERIFIED
Ion channels correct answers What are not open all of the time rather a specific signal triggers a change
in conformation which leads to its opening (i.e. gating)?
Selectivity filter correct answers The channel pore narrows significantly in its what? It is a narrow
opening that largely determines which ions can pass)
The channel correct answers What has a pore lined with hydrophilic amino acids which form the channel
opening and hydrophobic amino acids arranged along the outside of the channel to interact with the
lipid bilayer.
Aqueous 'holes' in the membrane; correct answers Ion channels do not make what?
Ions correct answers Ion channels are highly selective in the whats that can pass through them?
The right size and charge correct answers Only what kind of ions (without their bound water) can pass
through a specific channel?
An open and closed state (based on the presence or absence of a specific stimulus) correct answers Ion
channels fluctuate between what two states?
Gating correct answers What is the the property of the channel 'opening briefly' upon stimulation?
B correct answers Which ion channel is open?
1. Ion selectivity (the types of ions that can pass through a channel)
2. Gating (the conditions that influence their opening and closing)
3. Their abundance and subcellular localization correct answers There are more than 100 different types
of ion channels that differ from one another based what three characteristics?
1. Voltage gating (Probability of opening is controlled by membrane potential)
2. Ligand gating (Chemical ligand (molecule) binding controls channel opening)
3. Stress gating (Mechanical forces placed on the channel controls opening) correct answers Give three
kinds of stimuli that regulate channel gating
Active electrogenic pumps and passive ion diffusion correct answers What are two activities that
contribute to the membrane potential?
The "membrane potential". correct answers The movement of ions across a membrane, if not exactly
balanced by oppositely charged ions, can be detected as an accumulation of electric charge referred to
as what?
Membrane potential correct answers What results from a thin layer of ions sitting close to the
membrane due to their attraction to their counterparts of the other side of the membrane. All that is
required for the establishment of it is the movement of only a small fraction of the total charge?
, In the mitochondria correct answers In what organelle does the membrane potential across the inner
membrane is due to the activity of the electrogenic proton pumps?
Proton pumps correct answers In plants and fungi, what establishes the membrane potential across the
plasma membrane
Intracellular K+ correct answers High level of intracellular (-) charged organic molecules is
balanced by the levels of what?
Na+-K+ pump correct answers High intracellular K+ is generated by the what in the
plasma membrane?
K+ leak channels correct answers What channel in the plasma membrane randomly switch between an
open and a closed state (i.e. regardless of conditions)?
K+ correct answers K+ channels are the main ion channels open in a resting cell making the plasma
membrane more permeable to what ion than any other ion?
Unpaired (-) charges which generates the membrane potential (an electrical field). correct answers The
movement of K+ out of the cell (down its concentration
gradient) through the K+ leak channels transfers (+) charges
outside of the cell. This leaves behind what? It generates what?
Animal cells correct answers What kind of cells where the electrical potential across the plasma
membrane is due to the passive transport of potassium ions through K+ leak channels?
Negative correct answers K+ leak channels makes the inside of the cell slightly more what than the
outside?
The Na+/K+ pump correct answers What pump plays a small role in generating the membrane potential
by pumping 3 sodium ions out for every 2 potassium ions it pumps in?
A high K+ concentration correct answers Na+.K+ pump establishes a low intracellular Na+ concentration
which is balanced by what?
They move down their concentration gradient out of the cell correct answers Where do the intracellular
K+ ions go?
A charge difference across the membrane correct answers The loss of (+) charged ions leaves behind an
unbalanced (-) charge generating what?
Potassium leak channels correct answers K+ ions will move down their gradient through what until they
are balanced by their attraction to the (-) charged interior?
There is no net flow of ions across the membrane correct answers K+ ions will move down their gradient
through potassium leak channel s until they are balanced by their attraction to the (-) charged interior.
What happens next?
with combined Q & A 2023/2024 VERIFIED
Ion channels correct answers What are not open all of the time rather a specific signal triggers a change
in conformation which leads to its opening (i.e. gating)?
Selectivity filter correct answers The channel pore narrows significantly in its what? It is a narrow
opening that largely determines which ions can pass)
The channel correct answers What has a pore lined with hydrophilic amino acids which form the channel
opening and hydrophobic amino acids arranged along the outside of the channel to interact with the
lipid bilayer.
Aqueous 'holes' in the membrane; correct answers Ion channels do not make what?
Ions correct answers Ion channels are highly selective in the whats that can pass through them?
The right size and charge correct answers Only what kind of ions (without their bound water) can pass
through a specific channel?
An open and closed state (based on the presence or absence of a specific stimulus) correct answers Ion
channels fluctuate between what two states?
Gating correct answers What is the the property of the channel 'opening briefly' upon stimulation?
B correct answers Which ion channel is open?
1. Ion selectivity (the types of ions that can pass through a channel)
2. Gating (the conditions that influence their opening and closing)
3. Their abundance and subcellular localization correct answers There are more than 100 different types
of ion channels that differ from one another based what three characteristics?
1. Voltage gating (Probability of opening is controlled by membrane potential)
2. Ligand gating (Chemical ligand (molecule) binding controls channel opening)
3. Stress gating (Mechanical forces placed on the channel controls opening) correct answers Give three
kinds of stimuli that regulate channel gating
Active electrogenic pumps and passive ion diffusion correct answers What are two activities that
contribute to the membrane potential?
The "membrane potential". correct answers The movement of ions across a membrane, if not exactly
balanced by oppositely charged ions, can be detected as an accumulation of electric charge referred to
as what?
Membrane potential correct answers What results from a thin layer of ions sitting close to the
membrane due to their attraction to their counterparts of the other side of the membrane. All that is
required for the establishment of it is the movement of only a small fraction of the total charge?
, In the mitochondria correct answers In what organelle does the membrane potential across the inner
membrane is due to the activity of the electrogenic proton pumps?
Proton pumps correct answers In plants and fungi, what establishes the membrane potential across the
plasma membrane
Intracellular K+ correct answers High level of intracellular (-) charged organic molecules is
balanced by the levels of what?
Na+-K+ pump correct answers High intracellular K+ is generated by the what in the
plasma membrane?
K+ leak channels correct answers What channel in the plasma membrane randomly switch between an
open and a closed state (i.e. regardless of conditions)?
K+ correct answers K+ channels are the main ion channels open in a resting cell making the plasma
membrane more permeable to what ion than any other ion?
Unpaired (-) charges which generates the membrane potential (an electrical field). correct answers The
movement of K+ out of the cell (down its concentration
gradient) through the K+ leak channels transfers (+) charges
outside of the cell. This leaves behind what? It generates what?
Animal cells correct answers What kind of cells where the electrical potential across the plasma
membrane is due to the passive transport of potassium ions through K+ leak channels?
Negative correct answers K+ leak channels makes the inside of the cell slightly more what than the
outside?
The Na+/K+ pump correct answers What pump plays a small role in generating the membrane potential
by pumping 3 sodium ions out for every 2 potassium ions it pumps in?
A high K+ concentration correct answers Na+.K+ pump establishes a low intracellular Na+ concentration
which is balanced by what?
They move down their concentration gradient out of the cell correct answers Where do the intracellular
K+ ions go?
A charge difference across the membrane correct answers The loss of (+) charged ions leaves behind an
unbalanced (-) charge generating what?
Potassium leak channels correct answers K+ ions will move down their gradient through what until they
are balanced by their attraction to the (-) charged interior?
There is no net flow of ions across the membrane correct answers K+ ions will move down their gradient
through potassium leak channel s until they are balanced by their attraction to the (-) charged interior.
What happens next?
