Lecture 9 - Channels

Question 1

The 2 main determinants of channel selectivity are the diameter of the channel and the ______ energy (keep in mind the ions bind water within the channel.)

Answer 1

Dehydration

Question 2

Gating of channels occurs on the ______ side.

Answer 2

Intracellular

Question 3

The _____ segment of the potassium channel acts as the voltage sensor with its positively charged _____ (amino acid.) As + charge builds intracellularly, the segment is “repelled,” changing the conformation of the channel.

Answer 3

S4 segment

Arg

Question 4

An experiment with _____, a cleaving enzyme, showed that without the “ball and chain,” channels were not inactivated. Keep in mind that all S1-4 subunits of the voltage-gated channel have a ball and chain that can inactivate it. S5 and S6 form the _____.

Answer 4

Trypsin

Pore

Question 5

Long QT syndrome is linked with ______.

Answer 5

Arrhythmia

Question 6

The QT interval is the time between ___ contraction and repolarization.

Answer 6

Ventricle

Question 7

LQT1 is typically caused by emotional stress or ______, especially diving or swimming. LQT2 is typically caused by sudden noises or surprises. LQT3 typically occurs during _____.

Answer 7

Exercise

Sleep

Question 8

LQT1 can also be caused by a mutation in a potassium efflux channel (Ik) which is active during phase 3 of the action potential when _____ starts.

Answer 8

Repolarization

Question 9

LQT3 is caused by upregulation of a _____ channel. This causes persistent _____ current, leading to prolonged action potential.

Answer 9

Na

Na

Question 10

Epilepsy is a CNS disease that can be caused by upregulation of ____ channel (gain of function.) This should make sense given the spastic movements of epileptics.

Answer 10

Ca channel

Question 11

Diabetes can be caused by mutations in ____-sensitive ____ channel. The ____ subunit is the regulatory subunit. Keep in mind _____ also controls opening or closing of the channel.

Answer 11

ATP-sensitive Potassium

SUR

ATP