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The rate of chemical ____ of an atom/molecule depends on its mass, the solvent/medium, its concentration gradient, as well as the temperature and pressure.
Diffraction
Diffusion
Solubility
Refraction
Permeability
Diffusion
The lipid bilayer ______.
Prevents diffusion of most hydrophilic molecules across it
Is very thin, only about 4-5 nm in diameter
Is a component of the plasma membrane and intracellular membranes
All of these answers
Allows small hydrophobic molecules like oxygen and steroids to diffuse across it
All of these answers
Membranes contain _____ proteins that allow selective movement of ______ molecules across the membrane
Transport, hydrophobic
Channel, all
Cytoplasmic, soluble
All of these answers
Transmembrane, hydrophilic
transmembrane, hydrophilic
Which of the following best describes passive transport?
Channels or carriers are required to facilitate transport of polar uncharged and polar charged molecules
It is essential for establishing the overall ion gradients inside and outside of neurons
There is one type called simple diffusion
Atoms/molecules can move either up/against or down/along their concentration gradient
Only hydrophobic molecules can move by passive transport
channels or carriers are required to facilitate transport of polar uncharged and polar charged molecules
_________ move from the extracellular fluid rapidly across the plasma membrane to the cytoplasm by the process of simple diffusion.
Ions such as Na+ and Cl-
Polar molecules such as water and urea
Sugars such as glucose and sucrose
Gases such as oxygen and carbon dioxide
Peptides and proteins
Gases such as oxygen and carbon dioxide
Active transporters ________.
Are involved in the transport of different types of molecules including ions, sugars, amino acids, and vitamins
Can function in both directions to move molecules into or out of the cell
Are expressed in all cells
All of these answers
Can be expressed/localized to both the plasma membrane and intracellular membranes
All of these answers
Which of the following BEST DESCRIBES the Na+/K+ ATPase/pump?
It is the main mechanism that establishes and maintains the Na+ and K+ gradients in cells
It is a type of secondary active transporter
It pumps ATP out of the cell
It becomes phosphorylated by phospholipids as an intermediate
It is non-electrogenic because it pumps 3 K+ in for every 3 Na+ out
It is the main mechanism that establishes and maintains the Na+ and K+ gradients in cells
All of the following are types of primary active transporters EXCEPT ______.
H+ (proton) ATPase/pump
Na+/K+ ATPase/pump
Ca2+ ATPase/pump
electron transport chain
Mg2+/ATPase/pump
Mg2+/ATPase/pump
The primary active transporters that uses redox energy from NADH/FADH2 to move ions across the membrane are the ______.
Na+/K+ ATPases at the plasma membrane
Nuclear pore complexes in the nucleus
Enzymes involved in glycolysis in the cytoplasm
Electron transport chains in mitochondria
All of these answers
electron transport chains in mitochondria
Secondary active transporters _______.
All of these answers
Use the energy stored in an ion gradient to move another atom/molecule across the membrane
Are involved in the transport of many types of molecules including ions, sugars and lipids up/against their concentration gradients
Can be co-transporters/symporters or antiporters/exchangers
Involve movement of at least two types of atoms or molecules
All of these answers
It is has been proposed that one important function for the _____ gradient(s) in ALL cells is so it/they can be used to co-transport essential nutrient molecules like glucose, amino acids and vitamins into the cell.
All of these answers
Na+ and K+
Electron
ATP
Proton
Na+ and K+
The main similarity between active transport and facilitated passive transport is that _____.
Both can involve conformational changes in the protein responsible for movement of the atom/molecule
Both contribute to the selective permeability of the plasma membrane
Both involve the movement of hydrophilic molecules across the membrane
Both involve transmembrane proteins with multiple transmembrane spanning domains
All of these answers
All of these answers
The main difference between active transport and facilitated passive transport is that ____.
Active transport requires energy while facilitated passive transport does not
All of these answers
Active transport functions all the time while facilitated passive transport involves proteins that can be gated or ungated
Active transport is involved in moving many different types of ions and nutrients while facilitated passive transport is involved in the movement of primarily water and ions
Active transport can move atoms/molecules up/against their concentration gradient while facilitated passive transport allows molecules to move only down/along their concentration gradient
All of these answers
Because ions are BOTH charged particles and chemicals, ion gradients have ____.
Electrochemical potential
Energy stored in the gradient
Electrical potential
Chemical potential
All of these answers
all of these answers
The Nernst/equilibrium potential _______.
Depends on the chemical/concentration gradient of an ion and valence/charge of an ion
Calculates the electrochemical potential stored in the ionic concentration gradient and is expressed in mV
Is Ex and equals +60 mV/z x log [out]/[in], where z is the valence, [out] is the ion concentration outside and [in] is the ion concentration inside the cell
Is the membrane potential at which there would be no net movement of that ion across the membrane
All of these answers
all of these answers
Given a concentration of Na+ outside the neuron of 150 mM and inside of 15 mM, the Nernst potential for Na+ is ____.
-120 mV
-60 mV
+60 mV
0 mV
+120 mV
+60 mV
Given a concentration for K+ of 4 mM outside and 100 mM inside, the Nernst potential for K+ would be ___. (note the log 1/25 = -1.4)
+84 mV
0 mV
+61.4 mV
-84 mV
-61.4 mV
-84 mV
In diabetes, which leads to hyperglycemia, the concentration of glucose is about 10 times higher in the extracellular fluid than it is in the intracellular cytoplasm. What would the Nernst potential for glucose be?
+120 mV
-60 mV
0 mV
+60 mV
-120 mV
0 mV
Although there are individual ionic gradients, the overall (bulk) extracellular fluid and intracellular cytosol/cytoplasm in a neuron are ______.
At equilibrium
Identical in composition
Hypotonic and hypo-osmotic
Isotonic and iso-osmotic
Hypertonic and hyper-osmotic
isotonic and iso-osmotic
When healthy neurons are at rest, they are in a situation ______.
Called steady state
Where the Gibbs free energy = 0
All of these answers
Where energy output is greater than energy input
Called equilibrium
Called steady state
Electric ____ is the physical property of matter that causes it to experience a force when placed in an electromagnetic field, with two types-called positive and negative.
Energy
Field
Charge
Potential
Charge
An electric charge produces or induces a(n) ______; expressed another way, a(n) ________ surrounds an electric charge.
Coulomb force
Electric potential energy
Electrical potential
Electric field
Electric field
The ______ force is the electrostatic force that acts between two electric charges.
Electric potential
Electric charge
Electric field
Coulomb
Coulomb
The ______ is defined as the amount of work needed to move a unit of charge from a reference point to a specific point inside an electric field. The unit of this is volts (joules per coulomb).
Electric field
Electric potential
Electric charge
Coulomb force
Electric potential
Biological membranes are ideal for establishing and maintaining the membrane potential because they are _________.
Selectively permeable to ions and very thin
Composed of phospholipids which have charged head groups that bind ions tightly
Highly permeable to small polar molecules such as water and glucose at rest
Composed of lipids and constantly undergo endocytosis
Permeable to oxygen and small hydrophobic molecules
Selectively permeable to ions and very thin
Which of the following BEST DESCRIBES the membrane potential? The membrane potential _____.
Involves the separation of electrons across the plasma membrane
Is the difference in electric potential between the inside and outside of the plasma membrane
Exists in only neurons and muscles cells
Remains constant in a neuron
Is the difference in electric charge between the total/bulk intracellular cytoplasm and extracellular fluid
Is the difference in electric potential between the inside and outside of the plasma membrane
The membrane potential involves a separation and movement of _____ across the membrane.
Oxygen and protons
Cations and anions
All of these answers
Free electrons
Lipids and water
Cations and anions
The Na+/K+ATPase is called electrogenic since it pumps 3 Na+ ions out for each 2 K+ ions in. This electrogenic feature of the Na+/K+ATPase ________.
Does not contribute to the resting membrane potential
Contributes a small amount (between -7 mV to -10 mV) to the resting membrane potential
Prevents Na+ and K+ from moving across the membrane through leak channels
Is responsible for the majority of the resting membrane potential
Provides the energy for the activation of leak channels
Contributes a small amount (between -7 mV to -10 mV) to the resting membrane potential
The resting membrane potential is determined predominantly by the _____.
Electrogenic nature of the Na+/K+ ATPase/pump
Secondary active transporters and gated ion channels
Diffusion of Na+ and K+ up their chemical gradients
Difference between incoming potentials and outgoing potentials
Na+/K+ ATPase/pump and leak ion channels
Na+/K+ ATPase/pump and leak ion channels
The typical resting membrane potential in neurons is about -67 mV, and is determined by the expression of about 20-40 times more plasma membrane ____ at rest.
Gated ion channels
Leak and gated Na+, K+ and Cl- channels
Leak K+ channels
Leak Na+ and leak Cl- channels
Na+/K+ ATPase transporters
Leak K+ channels
In neurons, the reason that the resting membrane potential (RMP) is close to, but not as negative as the Nernst potential for K+ is because _____.
Secondary active transporters are activated at the RMP
All of these answers
The Na+/K+ ATPase pumps K+ back into the cell at the RMP
Leak Na+ and leak Cl- channels contribute to the RMP
Some leak K+ channels are closed at the RMP
Leak Na+ and leak Cl- channels contribute to the RMP
What can determine the number and type of specific ion channel proteins that are present at the plasma membrane?
The endosomal pathway
All of these answers
The biosynthetic/secretory pathway
Gene expression
Membrane trafficking
All of these answers
Since there is about 10 times less Cl- in the intracellular cytosol-cytoplasm compared with the extracellular fluid, what are the anions inside the cell that ensures it is electrically neutral?
Acetate and bicarbonate
All of these answers
Chloride, fluoride and iodide
Proteins with negatively charged amino acids on their surface
Phosphate and sulphate
All of these answers
The GHK equation calculates the_______.
Membrane potential
Chemical potential
Electrochemical potential
Electric force
Nernst potential
Membrane potential
The membrane is said to be "selectively permeable." What is the basis of this?
Selective permeability means that the membrane allows only certain molecules to move across from the outside to inside or inside to outside. The membrane is selectively permeable to hydrophobic molecules because of the lipid bilayer. Hydrophobic molecules like oxygen and steroids can diffuse directly across the lipid bilayer but hydrophilic (polar uncharged and polar charged) molecules can't diffuse across the lipid bilayer. However, the membrane also contains transmembrane proteins and it is selectively permeable to some hydrophilic molecules because of the presence of transporters and channels that allow specific molecules to move across the membrane by active or passive transport.
The rate of chemical diffusion of an atom or molecule depends on _____.
Its diffusion coefficient
All of these answers
The concentration gradient
The Temperature, Pressure, and solvent/medium
Its Mass
All of these answers
Which of the following is NOT TRUE about selective permeability of biological membranes?
It requires the lipid bilayer
It allows the movement of all small hydrophobic molecules
It requires channels, transporters, and/or carriers
It prevents the movement of all hydrophilic molecules
It requires transmembrane proteins
It prevents the movement of all hydrophilic molecules
Which of the following is NOT TRUE about passive membrane transport?
Small gases such as Oxygen and Carbon Dioxide can move easily across the membrane by the process of simple diffusion
It is essential for nutrients such as glucose and fatty acids to be taken up into the cell
It does not require energy directly
Atoms/molecules move down/along their concentration gradient (or down their electrochemical gradient of the atom/molecule is charged)
For facilitated diffusion, channels or carriers are required to facilitate transport of polar uncharged and polar charged molecules
It is essential for nutrients such as glucose and fatty acids to be taken up into the cell
Which of the following is NOT TRUE about the Na+/K+/ATPase/ Pump?
It is called an ATPase because it is used to produce ATP
It is called a pump since it pumps Na+ out of the cell (against its concentration gradient) and pumps K+ into the cell (against its concentration gradient)
It is electrogenic since it transports 3 Na+ out for every 2 K+ in
It is a type of primary active transporter
It establishes the overall Na+ and K+ gradients
It is called an ATPase because it is used to produce ATP
Active transporters (including primary and secondary) are _________.
The only mechanisms that establish the ion gradients and uptake of nutrients in cells
The only mechanisms that allow the movement of ions in or out of the cells
Expressed only in excitable cells
Localized to only the plasma membrane and mitochondrial membrane
Functioning in only one direction to move molecules inside cells
The only mechanisms that establish the ion gradients and uptake of nutrients in cells
The ER membrane and synaptic vesicle membrane contain __________, which allows them to uptake H+, Ca2+, or neurotransmitters inside the organelle.
Active transporters
Transport vesicles
Specialized lipid bilayers
All of these answers
Ion Channels
Active transporters
Which of the following is NOT a type of active transporter?
H+ ATPase
Ca2+ ATPase
Electron Transport Chain
Na+/K+ ATPase
Cl- ATPase
Cl- ATPase
The main difference(s) between active and passive transport is that active transport _______.
Involves transporter proteins while passive transport involves channels and carriers
Requires energy while passive transport does not
Moves at least one atom/molecule against/up its concentration gradient while passive transport allows the movement of atoms/molecules down its concentration gradient
Is always active while passive transport can involve leak channels that are always open and gated channels that require activation to be open
All of these answers
All of these answers
The reason that an ion has electric potential energy when placed in an electric field is because it ________.
Is small and contains electrons
Contains an atom
Is hydrophilic
All of these answers
Has an electric charge
Has an electric charge
The electric _______ is defined as the amount of work needed to move a unit of charge from a reference point to a specific point inside an electric field, and its unit is the volt (joules per coulomb).
Field
Energy
Charge
Potential
Force
Potential
An electric charge will produce or induce an electric __________. Described another way, an electric ____________ surrounds an electric charge.
Force
Energy
Field
Potential
Energy
Field
Because ions are both charged particles and chemicals, in a cell, an ion gradient has all of the following EXCEPT __________.
Energy stored in the gradient that has the ability to do work
Electrical potential
The ability to transfer electrons
Electrochemical potential
Chemical potential
The ability to transfer electrons
Which of the following is NOT TRUE about the Nernst/Equilibrium potential. It _________.
Is the membrane potential at which there would be no net movement of an ion across the membrane (for a specific ion gradient)
Transforms the electrical potential of an ion into a chemical gradient of the ion
Depends on the valence/charge of an ion
Depends on the chemical/concentration gradient of an ion
Converts the ionic concentration gradient into an electrical term (mV)
Transforms the electrical potential of an ion into a chemical gradient of the ion
The Nernst equation calculates the _________ potential stored in the concentration gradient of the ion.
All of these answers
Electrochemical
Electrode
Membrane
Steady-state and equilibrium
Electrochemical
Which of the following best describes the Nernst equation, where z is the valence of the ion, [out] is the concentration outside and [in] is the concentration inside.
Ex= -60 mV * ln [in]/[out]
Ex= +60 mV/z * log [out]/[in]
Ex= -60 mV * log [out]/[in]
Ex= +60 V/z * log [in]/[out]
Ex= z * +60 V/z * log [out]/[in]
Ex= +60 mV/z * log [out]/[in]
Given a concentration of K+ outside the neuron of 4 mM and inside of 100 mM, the Nernst potential for K+ would be ____________. Note the log [4/100] = log [.04] = -1.4 and the charge/valence of K+ is +1
+84 mV
0 mV
-61.4 mV
+61.4 mV
-84 mV
-84 mV
Given a concentration of Cl- outside the neuron of 100 mM and inside of 10 mM, the Nernst potential for Cl- would be ________. Note the log [100/10] = log [10] = +1 and the charge/valence of Cl- is -1.
-1 mV
+1 mV
0 mV
-60 mV
+60 mV
-60 mV
Which of the following is NOT TRUE about the membrane potential? It __________.
Is the difference in electric charge between the total/bulk intracellular cytoplasm and extracellular fluid
Can be measured by a recording electrode and is expressed in millivolts
Involves the separation of negative and positive ions across the plasma membrane
Is the electric potential difference between the inside and outside of the plasma membrane
Is present in all cells, which have a resting membrane potential
Is the difference in electric charge between the total/bulk intracellular cytoplasm and extracellular fluid
The membrane potential involves a separation and movement of ________ across the membrane.
Both hydrophilic and hydrophobic molecules
Only free electrons
Only ions and free electrons
All Hydrophilic molecules
Only ions
Only ions
Biological membranes are ideal for establishing and maintaining the membrane potential because they are ____________.
Composed of lipids and constantly undergo endocytosis
Composed of phospholipids which have charged head groups that bind ions tightly
Selectively permeable to ions and very thin
Permeable to oxygen and small hydrophobic molecules
Highly permeable to small polar molecules such as water and glucose at rest
Selectively permeable to ions and very thin
The resting membrane potential is about -67 mV and is established and maintained predominantly by the ______.
Electrogenic nature of the Na+/K+ ATPase/pump
Diffusion of Na+ and K+ up their electrochemical gradients
Difference between incoming potentials and outgoing potentials
Active transporters and leak channels
Transporters and gated ion channels
Active transporters and leak channels
The number and type of transporters and channels that are present in a neuron’s plasma membrane is determined by _________.
All of these answers
The ion concentration gradients
The relative ratio of active and passive transport
Gene expression and membrane trafficking
The Nernst potentials
Gene expression and membrane trafficking
The reason(s) that the resting membrane potential is negative on the inside (about -67 mV) is because at rest, ______.
All of these answers
Leak channels are always open at rest
The membrane is more permeable to K+ than to Na+ or Cl-
The Na+/K+ ATPase establishes the gradients with high Na+ outside and high K+ inside
There are between 20-30 times more leak K+ channels than leak Na+ or leak Cl- channels
All of these answers
The reason(s) the resting membrane potential is not as negative as the Nernst potential for K+ is because _____.
Neurons activated gated Na+ and Cl- channels at rest to adjust the resting membrane potential
The leak K+ channels are endocytosed after they allow K+ to flow through
Neurons change their Na+ and K+ gradients to adjust the resting membrane potential
All of these answers
There are also leak Na+ and Cl- channels open at rest
There are also leak Na+ and Cl- channels open at rest
The reason that all cells express the Na+/K+ ATPase and have a resting membrane potential is because _____.
All cells use electrical signaling to communicate
They use the Na+ and K+ gradients to produce ATP
All of these answers
They use the Na+ and K+ gradients to transport essential nutrients
If they didn’t they would become hypo-osmotic and shrink
They use the Na+ and K+ gradients to transport essential nutrients
The GHK equation is used to calculate the _______.
Nernst potential
Equilibrium potential
Electrode potential
Membrane potential
All of these answers
Membrane potential
In the GHK equation for a neuron under normal healthy conditions at constant temperature and pressure, the variable(s) that can change during signaling is/are the ______ of the ions.
All of these answers
Relative permeabilities
Faraday and gas constants
Valences/charges
Concentration gradients
Relative permeabilities
If ATP was rapidly deleted from the cell, the concentrations of Na+ and K+ would be the same inside and outside the cell (all gradients would be lost), and the resting membrane potential would be close to _____.
-84 mV
-60 mV
+60 mV
-10 mV
0 mV
0 mV
In an individual with acute hyponatremia, the Na+ concentration outside the cell is lowered to 37.5 mM while the inside concentration is normal at 12.5 mM. In this condition, the Nernst potential for Na+ would be ______ and the resting membrane potential would be ______ than normal. Note the log [37.5/12.5] = log [3] = 0.5 and the charge/valence of Na+ is +1
+30 mV; more negative/less positive
+60 mV; greater
0 mV; depolarized
+30 mV; more positive/less negative
+60 mV; identical
+30 mV; more negative/less positive
Assuming normal ion gradients and Nernst potentials, and a resting membrane potential of about -67 mV, what effect would the following have on the RMP?
10 times more leak K+ channels
10 times more leak Na+ channels
10 times more leak Cl- channels
10 times more Na+/K+ ATPases
RMP would be more negative/less positive
RMP would be more positive/less negative
RMP would be about the same
RMP would be about the same