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Question 1

The cell membrane is made of a __________ that is impermeable to __________.

Answer 1

Phospholipid bilayer,

ions.

Question 2

Ion channels are ________, which means

Answer 2

transmembrane proteins,

They’re made of a string of amino acids in a simple sequence.

Question 3

A typical ion channel doesn’t just have _____ alpha helix

Answer 3

one

Question 4

Ion channels are made of what?

Answer 4

Proteins

Question 5

What structural feature of an ion channel spans the lipid membrane?

Answer 5

Alpha helix

Question 6

The ion channel pore is largely composed of what?

Answer 6

Water

Question 7

Which statement about transporters is NOT true?

• Transporters move ions at slower rates than ion channels.
• Transporters passively transport ions along the electro-chemical gradient.
• Transporters do not have an aqueous pore.

Answer 7

Transporters passively transport ions along the electro-chemical gradient.

Question 8

Ion channels are characterized by gating and ______.

Answer 8

selectivity

Question 9

Ion channels can flip from open (conducting) to closed (non-conducting) states on the _______ timescale.

Answer 9

microsecond

Question 10

Changing the open probability of ion channels is an important way to regulate transmembrane _____.

Answer 10

current flow

Question 11

Selectivity is a preference of ion channels to conduct a _____.

Answer 11

specific ion

Question 12

The degree of selectivity can vary between different _______.

Answer 12

ion channels

Question 13

There are _____ types of non-selective channels

Answer 13

many

Question 14

Transporters move ions at a _____ rate than ion channels

Answer 14

slower

Question 15

Transporters can work against the ______.

Answer 15

electro-chemical gradient

Question 16

Transporters do not have an _____ pore.

Answer 16

aqueous

Question 17

The ______ causes an attraction or a repulsion for ions of a given charge.

Answer 17

membrane potential

Question 18

If there is a negative potential on the inside, then _____ ions will be attracted inside, down the electric-field gradient.

Answer 18

potassium

Question 19

One major determinant of ionic movement across ion channels is the _______. The other major push that moves ions from one side of a membrane to another is _______.

Answer 19

electric field,

concentration.

Question 20

______ and ______ gradients are the two main forces that drive electrochemical diffusion across the plasma membrane.

Answer 20

electrical,

concentration.

Question 21

If we make the inside of a cell more negative, then that will then try to attract _____ ions inside the cell.

Answer 21

positive

Question 22

The potassium ions are high ________, and low ______.

Answer 22

intracellularly (at about 150 mM)

extracellularly (aroung 4 mM)

Question 23

Sodium ions are low _______, and high _______.

Answer 23

inside cells (around 12 mM)

outside the cell (140 mM)

Question 24

Chloride concentration is low ______ the cell, and high ______ the cell.

Answer 24

inside (4 or 5 mM)

outside (120 mM)

Question 25

Calcium ions are _____ inside cells, and much _____ outside cells.

Answer 25

low (at about 100 nM) **nM not mM

higher (1-2 mM)

Question 26

Reversal potential (AKA Nernst potential)

Answer 26

The reversal potential of an ion is the membrane potential at which there is no net (overall) flow of that particular ion from one side of the membrane to the other.

Question 27

Ohm’s law

Answer 27

Voltage = current flow * resistance

V = I R

Question 28

If the cell has a high resistance, a low conductance, then the time course is ____, it takes a long time to change.

Answer 28

long

Question 29

In general, making the membrane potential more positive is called a _______.

Answer 29

depolarization

Question 30

If we make the membrane potential more negative, then it’s called a _______.

Answer 30

hyperpolarization

Question 31

To hyperpolarize a neuron, we need to open a _____ or a _____ conductance.

Answer 31

chloride,

potassium

Question 32

If you want to depolarize a neuron, you’d want to open a _____ conductance.

Answer 32

sodium

Question 33

Electrochemical diffusion describes ion flow through ion channels and defines ______ equilibrium potentials.

Answer 33

Nernst

Question 34

Independently regulated ion channel conductances with selective permeability control _______.

Answer 34

membrane potential