Lecture 6

Question 1

The rising phase of AP is dominated by what?

Answer 1

inward Na+ currents (NEGATIVE)

Question 2

The patch clamp technique was invented by who?

Answer 2

Bert Sakmann and Irwin Neher

Question 3

The patch clamp provides insight into _____ from a (single/many) channel(s) under fixed conditions

Answer 3

current ; single

Question 4

The patch clamp tells us the channel _____ _____ at (one/many) molecular level(s)

Answer 4

open time ; single

Question 5

When Na+ flows in, it makes the inside more _____ which is a (positive/negative) current?

Answer 5

positive ; negative

Question 6

Name the three steps which occur in the voltage gated-sodium channel after receiving an action potential:

Answer 6

1. voltage sensor and gate opens channels
2. selectivity filter allows Na+ in
3. gate closes, “I’ve changed my mind”, closes channel

Question 7

A voltage sensor and gate is an _____ pore subunit:

Answer 7

Alpha

Question 8

A typical membrane protein has stretches of _____ ______ inserted in the membrane.

Answer 8

amino acids

Question 9

The selectivity pore is created by alpha helices ____ and ____

Answer 9

5 and 6

Question 10

After an Na+ channel closes , the membrane potential _____ and goes to (-/+) ____-

Answer 10

deactivates ; -65mV

Question 11

Name the three steps in the absolute refractory period:

Answer 11

1. sensor activates
2. inactivation gate swings into place
3. channel deinactivates

Question 12

Define activation:

Answer 12

pore opens due to hitting Vm threshold (-55mv), moves gate sensor

Question 13

Define inactivation:

Answer 13

event where gate swings back into place, closing the channel

(buckID got you into residence hall but dorm door died, can’t get into room)

Question 14

Define deinactivation:

Answer 14

Vm goes to resting, causing inactivation gate to open, gate is closed but ready for another AP).

Question 15

TTX ____ the Na+ channel from the outside, binding to the ____ between helices 5 and 6

Answer 15

BLOCKS ; “P-loop”

(police says “nope, can’t enter the building”

Question 16

TTX is a voltage gated (Na+/K+) channel blocker

Answer 16

K+

Question 17

There are many disorders in voltage gated Na+ channels due to ______

Answer 17

mutations

Question 18

NaV# represents the voltage gated (Na+/K+) channel protein

Answer 18

Na+

Question 19

Encoding genes of sodium channelopathies are named as ____

Answer 19

SCN

Question 20

____ and ____ found the “delayed rectifier channel”?

Answer 20

Hodgkin and Huxley

Question 21

Delayed rectifier channels open during the ____

Answer 21

AP (LATE)

Question 22

T/F:

Na+ voltage gated channels and K channels are open from the AP to the refractory period:

Answer 22

FALSE

K channels can open many times and stay open for longer.

Question 23

There are ___ subfamilies of voltage-gated K+ channels

Answer 23

9

Question 24

The delayed rectifier channel genes is called _____

Answer 24

KCN

Question 25

Structure of the voltage-gated channels are important for the _____ phase of AP

Answer 25

falling

Question 26

Delayed rectifier channels were first identified in:

Answer 26

in flies

Question 27

Another name for the falling phase is _________

Answer 27

repolarization

Question 28

Inactivation of (gNa+/gK+) and increased (gNa+/gK+) caused the neuron to hit +40mV, allowing for delayed rectified channels to open, causing _____, aka the ____ channel.

Answer 28

gNa+ ; gK+ ; repolarization/falling

Question 29

Na+ and K+ channels are similar except there is/are _____ pore-forming subunit(s) in the (Na+/K+) channel where there is/are ____ pore(s) in the (Na+/K+) channel

Answer 29

FOUR ; K+ ; one ; Na+

Question 30

TEA is a (Na+/K+) channel blocker

Answer 30

K+

Question 31

T/F: The K+ channel sensor is positively charged.

Answer 31

TRUE. It responds to depolarization (increased (+) charge inside the cell).

Question 32

The K+ channel channel filters are called ___ and ____

Answer 32

S5 and S6

Question 33

The K+ structure is (primary / secondary / tertiary / quarternary)

Answer 33

Quarternary

Question 34

The selectivity filter of K+ channel is called the ____ ____.

Answer 34

pore loop

Question 35

The quarternary structure of the K+ channel is called a ____ tetramer meaning all four subunits are (same/different)

Answer 35

homo ; same

Question 36

In giant squid axons, Na+ and K+ channel blockers were used to dissect _____ _____.

Answer 36

action potentials

Question 37

Name the two things considered nature's toolbox for Neuro:

Answer 37

1. Animal venom 2 .Toxins

Question 38

In K+ channels, the (3 and 4 / 5 and 6) loop is lacking. Therefore, there is/are (none/one/two) inactivation gates.

Answer 38

3 and 4 ; none (random event but second "bouncer" after activation gate)