01 | Introduction

Question 1

What can be used as a measure of neuron activity?

Answer 1

Rate of ATP synthesis by mitochondria in neuron

Question 2

What are STORAGE GRANULES?

Answer 2

Holds vesicles at the presynaptic membrane

Question 3

RMP for normal human neurons is around…(value)

Answer 3

-70 mV

Question 4

How thick is the cell membrane? (value)

Answer 4

6 nm

Question 5

When ions pass through passively, they use __. When actively, they use __.

Answer 5

1. Ion channels

2. Transport molecules (pumps, transporters)

Question 6

3 components of an ion channel

Answer 6

1. Pore
2. Selectivity filter
3. Channel gate

Question 7

__ channel has increased probability of being open. ___ channel has decreased probability of being open.

Answer 7

1. Activated

2. Deactivated

Question 8

Define: inactivation

Answer 8

(@ electrical synapses) conformational change prevents channel from opening, even if there is a stimulus

Question 9

Define: desensitization

Answer 9

(@ chemical synapses) conformational change prevents channel from opening, even if there is a stimulus

Question 10

Define: open channel block

Answer 10

something is physically occluding the pore

Question 11

Explain voltage clamp

Answer 11

The voltage clamp is an experimental method to measure the ion currents while holding the membrane voltage at a set level.

Question 12

Whole cell patch clamp

Answer 12

• Mimic real cell

- Change intracellular concentrations

Question 13

Outside out patch clamp

Answer 13

• isolate channels

- change extracellular conc.

Question 14

Inside-out patch clamp

Answer 14

• Isolate channels
• Change intracellular concentrations
• Example receptors activated by intracellular ligands

Question 15

How many subunits does nAChR have? List them. What are the requirements?

Answer 15

5 subunits (α, β, γ, δ) that come together – any combination, but has to have at least 2 α (this becomes the ligand binding site)

Question 16

How many times does each subunit in nAChR cross the membrane? Which segment forms the pore?

Answer 16

4 times (M1-4)
M2 forms pore

Question 17

How does pore open on nAChR?

Answer 17

M helices rotate toward channel wall

Question 18

What are the 3 voltage-gated channels with similar morphologies? What is that morphology?

Answer 18

• Na, Ca, K
• 4 α subunits with 5 TM regions in each subunit (S1-6)
• 3rd residue of S4 is positive

Question 19

What does the positive residue in voltage-gated channels do?

Answer 19

• Voltage sensor

- Couples voltage changes in the membrane to channel opening mechanisms

Question 20

What are the additional subunits on Na channels? What are they used for?

Answer 20

2 TM β

- Activation and gating

Question 21

Subunits of v-gated Ca channel

Answer 21

4 α1 subunits

Question 22

What are the additional subunits on v-gated Ca channels? What are they used for?

Answer 22

Intracellular β, TM δ, extracellular α2

- Activation and gating

Question 23

How does the AA sequence of v-gated K channels compare to other v-gated ion channels?

Answer 23

v-gated K channels have shorter AA sequence

Question 24

What are the additional subunits on v-gated K channels? What are they used for?

Answer 24

Intracellular β + first few residues from N-terminal form the ball-and-chain inactivation gate

Question 25

Which TM segments on v-gated K channels form the pore (P-loop)?

Answer 25

S5-6