Neurobiology Final Exam

Question 1

Which of the following channels share the greatest structural similarity in having one large pore forming subunit? (alpha subunit)

1. Voltage gated sodium channels and voltage gated potassium channels
2. Voltage gated sodium channels and voltage gated calcium channels
3. Voltage gated chloride channels and voltage gated sodium channels
4. Voltage gated chloride channels and voltage gated potassium channel

Answer 1

Voltage gated sodium channels and voltage gated calcium channels

VG Na+
VG Ca+2

Question 2

For cations (positively charged ions such as Na+, K+, H+, and Ca2+), a positive driving force (i.e., VDF > 0) predicts ion movement to be ________cell

out of
into

Answer 2

Out of

Question 3

In which of the following ways do voltage gated potassium channels in the squid giant axon differ from voltage gated sodium channels? (channels involved in the Action Potential)

Once the potassium channels open in response to a voltage step command, they tend to remain open (no inactivation).

The potassium channels are only opened at rest

The potassium channels are non-specific

The sodium channels are non-specific

Answer 3

Once the potassium channels open in response to a voltage step command, they tend to remain open (no inactivation).

Question 4

Which of the following explains the refractory period?

inactivation of VG K+ channels

activation of VG K+ channels

activation of VG Na+ channels

inactivation of VG Na+ channels

Answer 4

inactivation of VG Na+ channels

Question 5

Which of the following is a major advantage to researchers of the Xenopus oocyte expression system?

Answer 5

It allows physiological characterization of genetically modified ion channel genes by expression of channel mRNA or DNA

Question 6

Which of the following can gate channels? (more than one answer is possible)

neurotransmitters

ions like Ca2+

TTX

voltage

myelin

Answer 6

neurotransmitters

ions like Ca2+

voltage

Question 7

VG-Ca2+ channels

Answer 7

CACNA genes

Question 8

VG-K+ channels

Answer 8

KCN genes

Question 9

VG-Cl- channels

Answer 9

CLCN genes

Question 10

VG-Na+ channels

Answer 10

SCN genes

Question 11

Which of the following represents a reasonable AP conduction speed for a myelinated axon?

Answer 11

• 100 m/s
• 50 m/s

Question 12

Which of the following plays a big role in the selectivity filter of ion channels?
- hydrophobicity of ions like Na+
- size of the ions themselves
- the S4 voltage sensor domain
- beta subunit confirmation

Answer 12

• Size of the ions themselves

Question 13

VG-K+ channels have 4 subunits that form the pore. How many genes?

Answer 13

4 genes

Question 14

VG-Na+ channels have 1 subunit that forms the pore. How many genes?

Answer 14

1 genes

Question 15

The rising phase of the action potential occurs because

Answer 15

more sodium ions diffuse into the cell than potassium ions diffuse out of it.

Question 16

Currents recorded from one single channel using ________ ________ recordings are considered __________ .

Answer 16

patch-clamp; microscopic

Question 17

Although the membrane of a “resting” neuron is highly permeable to potassium ions, its membrane potential does not exactly match the equilibrium potential for potassium because the neuronal membrane is also ________.

Answer 17

slightly permeable to sodium ions

Question 18

equilibrium potential for sodium is at?

Answer 18

The peak of an action potential

Question 19

The driving force for Na+ is the biggest at label ________.

Answer 19

At the hyper polarizing phase dip where it starts to return to the resting membrane potential

Question 20

Action potentials move along axons ________.

Answer 20

more rapidly in myelinated than in unmyelinated axons

Question 21

If you experimentally increase the concentration of K+ outside a cell while maintaining other ion concentrations as they were, what would happen to the cell’s membrane potential at rest?

Answer 21

The membrane potential would become less negative

Question 22

What would probably happen if a long neuron had one continuous myelin sheath down the length of the axon with no nodes of Ranvier?

Answer 22

The signal would fade because it is not renewed by the opening of more sodium channels

Question 23

If you were interested in isolating K+ currents, what would you use to suppress the Na+ current?

Answer 23

Scorpion toxin

Question 24

During an action potential, depolarization is _________________________.

Answer 24

An increase in membrane potential, the result of Na+ ions rushing into the cell

Question 25

During an action potential, hyperpolarization is ________________________.

Answer 25

A decrease in membrane potential, the result of K+ ions rushing out of the cell

Question 26

Which of the following happens during the falling phase of the Action potential?

Answer 26

The voltage-gated sodium channels inactivate.

Question 27

The refractory period generally lasts about:

Answer 27

9 mseconds

Question 28

VG sodium channels in general can be expressed/found in which of the following? heart brain dorsal root ganglia all of the above

Answer 28

All of the above

Question 29

Which of the following was shown to eliminate the early inward current in squid giant axons?

Answer 29

Removal of external sodium

Question 30

Action potentials

Answer 30

321 NOKIA VG Na and VG K

Question 31

resting membrane potentials in neurons

Answer 31

Leak Channels, especially K+ leak channels

Question 32

Which of the following is the site of action potential initiation:

Answer 32

AIS

Question 33

Which of the following is correct about the inward current observed during depolarization?

Answer 33

- it is transient - it inactivates

Question 34

X-ray crystallography is a method used to study?

Answer 34

- channel structure

Question 35

Which of the following require a change in the channel protein conformation or 3D structure? inactivation activation closing all of the above

Answer 35

- All of the above

Question 36

Using I=g(Vm-Ek), what is Vm-Ek?

Answer 36

driving force of potassium

Question 37

Why is it difficulty to study one specific ion channel at a time in a neuron with the tools that we have available? (more than one answer)

Answer 37

- hard to tell individual neurons appart because there are so many different kinds - pharmacological agents are not perfect in their ability to blocke one channel at a time

Question 38

Multiple sclerosis involves which of the following:

Answer 38

axon demyelination

Question 39

Voltage gated sodium channels can be expressed in which of the following tissues: heart brain skeletal muscle DRG (dorsal root ganglion) all of the above

Answer 39

- All of the above

Question 40

Which of the following is not a function known for Voltage Gated Calcium Channels?

Answer 40

resting membrane potential

Question 41

Episodic Ataxia Type 2 is caused by mutations in which type of voltage gated channel?

Answer 41

Calcium

Question 42

HERG channels are voltage-gated potassium channels that help regulate repolarization of the (cardiac or brain) action potential. Mutations in these channels can cause a syndrome called

Answer 42

cardiac and called Long QT syndrome

Question 43

Nav1.4 mutations leading to equine periodic paralysis can be uncovered when external _______ goes up, favoring repetitive openings of the defective channels and further depolarization

Answer 43

K+

Question 44

GEFS (generalized epilepsy with febrile seizures) can be caused by a mutation in the ___________ (skeletal or brain) beta subunit of the voltage gated sodium channels which normally affects the sodium channel ___________ (activation or inactivation)

Answer 44

brain; inactivation

Question 45

Which of the following types of K+ channels can be activated by hyperpolarization rather than depolarization?

Answer 45

Inward rectifying

Question 46

P/Q Type (hint important for neurotransmitter release)

Answer 46

Voltage gated calcium channels

Question 47

Kv3.1

Answer 47

Voltage gated Potassium Channels

Question 48

KCa (hint requires calcium and voltage to open)

Answer 48

Calcium activated potassium channels

Question 49

Kir4.1

Answer 49

Inward rectifying potassium channels

Question 50

Gap junctions may exhibit all of the following features except for the ability to:

Answer 50

amplify small incoming electrical signals into large regenerative potentials.

Question 51

Listed below are the events that make up chemical synaptic transmission. 1. Diffusion of transmitter across the synaptic cleft 2. Depolarization of the presynaptic terminal 3. Vesicle fusion with plasma membrane 4. Opening of voltage-gated ion channels 5. Activation of presynaptic, calcium-sensitive proteins that allow vesicle fusion Which of the following is the correct sequence of these events?

Answer 51

2; 4; 5; 3; 1 - Depolarization of the presynaptic terminal - Opening of voltage-gated ion channels - Activation of presynaptic, calcium-sensitive proteins that allow vesicle fusion - Vesicle fusion with plasma membrane - Diffusion of transmitter across the synaptic cleft

Question 52

Miniature end-plate potentials, or MEPPs, are produced

Answer 52

by spontaneous release of neurotransmitter.

Question 53

Which of the following are not associated with neuromuscular junctions?

Answer 53

IPSP

Question 54

The dopamine transporter is resposible for the reuptake of dopamine once it has been released in a synapse. Which of the following can bind to the dopamine transporter? More than one answer is possible.

Answer 54

- dopamine - cocaine

Question 55

Which of the following contributes to the maintenance of high levels of calcium outside of the neuron?

Answer 55

Na+/Ca+ exchanger Ca2+ pump

Question 56

Which of these is true regarding the Cas9 protein? (more than one answer is possible)

Answer 56

- it is a double stranded DNA endonuclease - it recognizes its target based on the guide RNA that it is associated with

Question 57

Muscle contraction occurs as a result of Ca2+ release from the:

Answer 57

sarcoplasmic reticulum

Question 58

Ligand gated channels

Answer 58

less selective than voltage gated channels

Question 59

Thermosensitive channels

Answer 59

Displacement of membrane lipids upon opening/heat sensitive

Question 60

Voltage gated channels

Answer 60

Highly selective for specific ions

Question 61

Piezo channels

Answer 61

respond to membrane tension

Question 62

Which of the following experiments indicates a role for calcium in transmitter secretion? Inhibition of postsynaptic potentials (PSPs) in the presence of calcium channel blockers Induction of transmitter release by injection of calcium directly into the presynaptic terminal Blockade of transmitter release by injection of calcium buffer (to sop up all the calcium) into the presynaptic terminal All of the above experiments

Answer 62

All of the above experiments

Question 63

Which of the following genetic manipulations would impair calcium channel-dependent neurotransmitter release: (more than one answer is possible)

Answer 63

- knocking out the synaptotagmin gene leading to a loss of synaptotagmin protein - knocking out voltage gated calcium channels

Question 64

Which of the following processes require clathrin?

Answer 64

budding

Question 65

A patient is experiencing muscle weakness and difficulty walking. Following a blood test, antibodies against P/Q Voltage Gated Calcium Channels are identified. What is the best hypothesis regarding the synaptic deficit?

Answer 65

there is not enough calcium for efficient vesicle exocytosis

Question 66

The quantal hypothesis of neurotransmitter release, states that neurotransmitters are released in discrete packets of relatively uniform size.

Answer 66

True

Question 67

Hyperkalemic Periodic Paralysis Disease (HYPP)/Impressive Disease is due to a mutation that cause voltage gated Nav1.4 channels to stay open:

Answer 67

Longer

Question 68

The beta subunit associated with neuronal voltage gated sodium channels normally does which of the following?

Answer 68

- speeds up inactivation of the channel

Question 69

Which of the following has been associated with autism spectrum disorder?

Answer 69

Cav1.2

Question 70

Epilepsy/Seizures has been found to be associated with which of the following channel mutations? Na+ channels Ca2+ channels K+ channels all of the above

Answer 70

- All of the above

Question 71

chemical synapse

Answer 71

requires an action potential for neurotransmitter release is found at neuromuscular junctions

Question 72

electrical synapse

Answer 72

Does not need neurotransmitter uses connexons

Question 73

Mark whether each scenario is likely to lead to an action potential being fired as a neuron is getting post-synaptic information

Answer 73

Only when three EPSPs close together or two EPSP's are close together

Question 74

Which of the following binds calcium and is necessary for vesicle fusion?

Answer 74

Synaptotagmin

Question 75

Which event is the first in the series of events that take place during chemical synaptic transmission?

Answer 75

Voltage-gated Ca2+ channels open.

Question 76

If the distribution of EPP amplitudes has peaks at 0.4 mV, 0.8 mV, 1.2 mV, 1.6 mV, and 2.0 mV, what is the most likely amplitude of the MEPP?

Answer 76

0.4 mV

Question 77

You conduct a voltage clamp experiment in which you hold the presynaptic terminal of a glutamatergic neuron (a neuron that releases glutamate) at 0 mV. When you treat the terminal with TTX, an inward current is recorded. Which ion and ion channels are responsible for the current you observe?

Answer 77

Sodium; ligand-gated non-specific cation channels

Question 78

SNARE proteins participate in vesicle exocytosis by

Answer 78

forming a protein complex that pulls the vesicle membrane against the plasma membrane.

Question 79

The two main families of neurotransmitter receptors are

Answer 79

ionotropic and metabotropic.