Ion Channels And Hyper

Question 1

Major intracellular and extracellular ions

Answer 1

K and Na

Question 2

Monovalent cations

Answer 2

Na and K

Question 3

Divalent cations

Answer 3

Ca and Mg

Question 4

Ionic gradient

Answer 4

More K inside and Na outside

Question 5

Ion channels

Answer 5

Membrane proteins that allow contorted movement of charged ions across the cell membrane

Question 6

Ion channel properties

Answer 6

Membrane pores
Ionotropic receptors
Gates
Ion selectivity

Question 7

Types of gated channels and what they are activated by

Answer 7

Voltage gated - voltage
Ligand gates - ligands (intra and extraellular)
Mechanically gated - force in plasma membrane `

Question 8

Ligand gates ion channel structure

Answer 8

Single subunit architecture :
- Transmembrane domains
- N and C terminal
- Lops link the TM domains together

Assembled architecture :
- multi subunit composition (Can have different numbers of subunits which help categorise into different categories/families )
- pentameric, tetrameric or trimeric

Question 9

Ligand gated ion channel families

Answer 9

Cys-loop family
- nicotine acetylcholine receptor

Other
- glutamate receptors

Question 10

Voltage gated ion channel

Answer 10

Transmebrane potential exist across plasma membrane
Inside cell is negative
Voltage gates have multiple domains
One domain is the voltage sensor - detect electrical change and rotation opens the channel pore

Question 11

Voltage gated at -70mV, -50 to +30mv and +30mv to -50mv

Answer 11

-70mV - > closed and no Na can get through

-50 to +30mv -> open and starts to depolarise

+30mv to -50mv -> inactive. Doesn’t stay open long and conduct enough Na to depolarise the cell. Ball and chain blocks ion conduction

Question 12

In alpha one how many TMD

Answer 12

24 organised into 4 repeating segments, each with 6 domains

1s1, 1s2, 1s3, 1s4. 1s5, 1s6
2s1, 2s2, 2s3, 2s4, 2s5, 2s6
3s1, 3s2, 3s3, 3s4, 3s5, 3s6
4s1, 4s2, 4s3, 4s4, 4s5, 4s6

Question 13

A1 subunit

Answer 13

Is the channel pore, there will be no hole it eh middle without it

Several different A1 exist and are known as different CaV (CaV1, CaV2)

Question 14

Auxhillary subunits

Answer 14

B, Y and a2-s

They are like friends forming a group and cannot have a channel without the all

They help the a1 subunit get to the membrane like a police escort and they regulate ion channel properties

Question 15

Voltage gated K channels again families

Answer 15

Kv and inward rectifying channels

Different structure to NaV and CaV

Each Kv subunit has 6 TMD

4x a subunits come together as a tetramer

Question 16

Permeability and selectivity of channels

Answer 16

Channels are permeable to ions

Non-selective channels allow more than one type of ion through

Cationic channels permeable to Na, K etc

A ionic channels permeable to Cl

Question 17

The ions that can permeate is defined by

Answer 17

The structural features of the TMD lining the channel pore

Act as a selectivity filter

Question 18

Measuring ion channels

Answer 18

Patch clamp electrophysiology

Question 19

Channel activation to in-activation

Answer 19

CaV channels sense the membrane potential

As it reaches -40mV it starts to open

Will close again while membrane is still depolarised