Ch. 5 - Ion Channels Flashcards by Francis Mendoza

three types of ion channels

voltage gated, ligand gated, mechanically gates

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integral membrane proteins that span the cell membrane and form conduits for the ions to pass through the lipid bilayer

ion channels

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ion channels can conduct blank ions per second

100

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ion channels that are gated to changes in membrane potential

voltage

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ion channels gated to chemical transmitters

ligand gated

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ion channels gated to pressure or stretch

mechanically gated

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resting channels are blank at rest

open

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gated channels are blank at rest

closed

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allow for continuous pathway for ions to move from inside to outside cell

ion channel

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these have two gates that allow one ion in and out at a time and is active transport and is much slower than ion channels

ion pump

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ion transported down electrochemical gradient causes energy to be blank

released

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the energy released powers the blank to go against electrochemical gradient

pump

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ion channel composed of 5 different subunits

hetero-oligomers

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ion channel composed of 6 similar subunits

homo-oligomers

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ion channel formed by repeating motifs and one chain

single polypeptide

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ion channel can also contain auxiliary subunits in this type such as blank and blnak

gamma, beta

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lipid bilayer consists of

phospholipids, proteins

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ions surrounded by water is called blank and is blank than an ion alone

hydrated, larger

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phospholipid tails have blank bonds which are blank

ester, hydrophobic

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a hydrated blank ion has a larger diameter than a hydrated blank ion because it has a higher charge even though its smaller

sodium, potassium

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blank ions are too large to get through blank channels

sodium, potassium

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a sodium channel has a blank filter that has amino acids that strip blank from the hydrated sodium ion,

selectivity, water

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three models for opening/closing of ion channel

localized conformational, generalized structural, blocking particle

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gaba stands for

gamma, amino, butynic acid

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drug that binds to gaba channels and keeps the channels open

valium

three states of voltage gated ion channels

closed resting, open, inactive

closed resting channels are blank

activatable

inactive voltage gated ion channels are blank

nonactivateable

regulatory in calcium channels

calmodulin

technique to record current through ion channels

patch clamp

patch clamp technique was created in what year

1976

this scientist formed vesicles under special conditions so the vesicles fused with the blank to form a blank

bilayer, artificial bilayer

artificial bilayer advantages

1. can access ions inside the cell in the inner membrane such as the SR 2. can study the membrane composition and ion channels

rate of flow of ion currents through ion channel

flux

direction of equilibrium constant of flux is determined by these two factors

1. electrical potential difference on outside/inside cell membrane 2. concentration gradient inside/outside

electrical potential difference and concentration gradient difference makes up blank difference

electrochemical potential

na+, k+, Ca2+ can pass through blank ion channels

cation selective

Na+ selective ion channel allows blank ions to pass through

Na+

cation selective ion channel that allow Na+, K+, and Ca2+ ions to pass through

Achr

flux of ions through ion channels is blank

passive

ion channel is either all the way blank or blank

open, closed

current is blank related to blank in the iv curve

linearly, voltage

ohms law

V = IR | volts, current (amps), resistance (ohms)

conductance formula

= 1/R

slope of the IV curve gives blank in these units

conductance, siemens

rate of current depends on the concentration of blank in the solution

ions

at a high ion concentration, a blank current can be reached making it constant

max

laws of binding of ions to special aa along the pore of an ion channel

electrodiffusion

ligand concentration at which current reaches half of the max current

dissociation constant

low dissociation constant means blank

strong bonding

transition of ion channels between closed and open

gating

linear iv curves conduct ions at a constant manner at all voltages in blank resistors/blank channels

simple, ohmic

iv curve that is non linear conducts ions more readily in one direction than the other

rectifier

comparing aa sequences in various species for blank regions

highly conserved (similar)

these channels are formed with parts derived from genes of different species

chimeric channles

site directed mutagenesis - uses a blank type ion channel and watch its function, then a mutation type of ion channel is made and its function is watched. if the functions are different, then the aa being studied plays a blank role in ion channel gating

important

each peak in the hydrophobicity plot represents the blank hydrophobicity of blank amino acids

average, 19

each peak in the hydrophobicity plot represents one piece of the blank in a cell membrane

ion channel

three superfamilies of ion channels

ligand gated (ach), gap junction, voltage gated

gap junction channel has blank subunits and blank domains

6, 4

ligand gated channels have blank subunits and blank domains

5, 4

voltage gated channels have blank motifs but is a blank polypeptide and has blank domains

4, single, 6

these channels bridge the cytoplasm of two cells at the electrical synapse

gap junction channel

there are blank related ion channels with blank regions

four, p

p region consists of a blank and blank

helix, loop

ligand gated ion channel is a blank oligomer

hetero

gap junction connexin channel is a blnak oligomer

homo

patch clamp records blank ion channels

one

scientist that made the artificial membrane bilayer

christopher miller

the p region of a bacterial potassium channel is aka the blank

selectivity filter

4 rings are formed by successive rings of blank atoms from blank amino acid residues per subunit

O, 5

fifth ring of O is formed by the OH side oxygen from blank

thrionine

in potassium ion channel, the ions have to either be in binding site blank and blank, or blank and blank because of blank

1,3 2,4 electrostatic attraction

2,4 bindings sites is the blank configuration

inner

1,3 binding sites is the blank configuration

outer

high energetic cost for a potassium to enter lipid bilayer is minimized by two parts:

1. inner chamber | 2. four helices provide dipole whose neg charge points to inner chamber

two identical subunits each forming a selective Cl pore

dimers

abnormal prolonged muscle contraction

myotonia

to pump Cl to outside cell against conc gradient, blank are moved down concentration into the cell to power that pump

H+

potassium channel is a blank channel

parallel

chlorine channel is a blank channel

antiparallel