Functions of Channels and Transporters

Question 1

what is the electrochemical gradient

Answer 1

a gradient consisting of a chemical gradient and an electrical gradient. the difference can be interpreted as a type of PE available to do work in the cell

Question 2

what is membrane potential

Answer 2

the difference in electric potential between the interior and the exterior of a biological cell

Question 3

what are the functions of membrane potential

Answer 3

• gives the cell the power to operate a variety of molecular devices embedded in the membrane
• transmitting signals

Question 4

what is the nernst equation used for

Answer 4

calculating the membrane potential based on internal and external concentrations of ion

Question 5

what is the specific inhibitor for K+ in the Na+ K+ pump

Answer 5

ouabain

Question 6

describe how a NT synapse works

Answer 6

a NT is released from the presynaptic neuron and binds to a receptor on the post synaptic neuron to activate an electrical response or second messenger pathway

Question 7

describe how an electrical synapse works

Answer 7

presynaptic and postsynaptic cell membranes are connected by a gap junction that pass electric current

Question 8

how are ion channels different from aqueous pores

Answer 8

they show ion selectivity and not continuously open

Question 9

give the location and function of K+ leak channels

Answer 9

located in plasma membrane

function: maintain resting membrane potential

Question 10

give the location and function of voltage gated Na+ channels

Answer 10

location: plasma membrane of nerve cell axon
function: to generate APs

Question 11

give the location and function of voltage gated K+ channels

Answer 11

location: plasma membrane of nerve cell axon
function: to return membrane to resting potential after AP initiation

Question 12

give the located and function of voltage gates Ca2+ channels

Answer 12

location: plasma membrane of nerve terminal
function: to stimulate NT release

Question 13

give the location and function of acetylcholine receptors

Answer 13

location: plasma membrane of muscle cell
function: excitatory synaptic signaling

Question 14

give the location and function of GABA receptors

Answer 14

location: plasma membrane of many neurons 
function inhibitory synaptic signaling

Question 15

give the location and function of stress activated cation channel

Answer 15

location: auditory hair cell in inner ear
function: detection of sound vibratiosn

Question 16

what are the major classes of channels

Answer 16

voltage gated, ligand gated extracellular, ligand gated intracellular, and stress activated

Question 17

what are ABC transporters

Answer 17

integral membrane proteins responsible for ATP powered translocation of many molecules

Question 18

how many domains are on an ABC transporter and what are they

Answer 18

4 domains, 2 hydrophobic, 2 ATP binding

Question 19

explain receptor mediated endocytosis of LDL

Answer 19

LDL binds to its receptor, it is transported through the cell by a clatharin coated vesicle where it binds to an endosome that then transfers to a lysosome and LDL is degraded into free cholesterol and the receptor buds off the endosome in a vesicle that is then recycled back to the plasma membrane