Electrochemical potentials of ion transport and Ion Channels

Question 1

What is the resting membrane of cells and how is it established?

Answer 1

-70mV

it is established by having leak K+ channels, present in low numbers, but they are always open and allow K+ to leak in

Question 2

What would occur to the resting membrane potential if you open Na+ or Ca2+ channels?

What would occur to the resting membrane potential if you open a K+ channel?

Answer 2

The cell will become more depolarized meaning it would be more positive.

(Na Ek=60mV and Ca2+ Ek=123mV)

The cell will become more hyperpolarized meaning it would be more negative.

(K+ Ek=-90mV)

Question 3

True or False:

The Nernst equation is used to calculate the concentration gradient.

Answer 3

False

The Nernst equation is used to calculate the electrochemical gradient.

Consist of the

Chemical Component

Electrical component

Question 4

What are the equilibrium potentials for these ions:

Na+

Ca2+

K+

Cl-

Answer 4

In order

60mV

123mV

• 90mV
• 64mV

Question 5

Fill in the blanks

A drug that acts as __ or ___ channel blockers and __ or ___ channel openers will result in less depolarization.

Answer 5

Na+

Ca2+

K+

Cl-

Question 6

Fill in the blanks

A drug that can act as ___ or ____ channel blockers and ____ or ____ channel openers will cause more depolarization.

Answer 6

K+

Cl-

Na+

Ca2+

Question 7

Answer as True or False for the following statements (all of these statements are Ion Channel Characteristics)

____ They are single membrane proteins.

___ They form gated pores in membranes.

___ They are composed of a single subunit.

___ For most ion channels, the pore is in the center and the subunit surrounds it.

____ There are ~230 ion channel genes in the human genome, making it the most receptor genes in a human genome. GCPR genes and Enzyme Genes are second and third.

__ Some channels only pass one kind of ion (highly selective)

Answer 7

False –> They must be transmembrane proteins

True

False –> they are composed of multiple subunits

False –> The pore is in the center and the multiple subunits surround the pore.

False –> There are ~230 genes for ion channels but they are not the most receptor-encode genes in a human genome. First is GCPR, then enzymes, and finally ion channels.

True

Question 8

What are two examples of excitatory and inhibitory ligand- and voltage-gated ion channels? Do not forget to explain why?

Answer 8

Excitatory (they pass only Na+ and/or Ca2+ ions)

Voltage-Gated

Trp and CNG

Ligand Gated

ACh

5HT

Inhibitory ( they pass only K+ or Cl- ions)

Voltage-gated

Cl

Ligand-gated

GABA

Gly