ion channels overview 2

Question 1

Describe ion channels.

Answer 1

Ion channels a superfamily of transmembrane proteins that the diffusion of ions across the cell membrane, following their electrochemical gradient.

Question 2

What is the function of leak channels?

Answer 2

Leak channels are open during the resting state and allow ions to pass through the cell membrane.

Question 3

How do ion channels respond to signals?

Answer 3

Ion channels only function after milliseconds of receiving a signal, with some remaining closed until they receive a signal.

Question 4

Define the gating of ion channels.

Answer 4

Gating refers to the opening and closing of ion channels in response to specific signals or conditions.

Question 5

What is the role of ion channels in cell physiology?

Answer 5

Ion channels play a crucial role in regulating the movement of ions across cell membranes, which is essential for various cellular functions.

Question 6

What role do ion channels play in nerve and muscle cells?

Answer 6

Ion channels in nerve and muscle cells facilitate high-speed communication through action potentials.

Question 7

How do ion channels regulate the electrical potential across membranes?

Answer 7

Ion channels can regulate the electrical potential across membranes.

Question 8

What happens when ion channels admit Ca2+ into the cytoplasm?

Answer 8

Admitting Ca2+ triggers processes such as secretion and muscle contraction.

Question 9

What are some examples of organs where ion channels are involved in regulating fluid balance?

Answer 9

Salivary glands, kidney, inner ear, and plant guard cells are examples of organs where ion channels regulate fluid balance.

Question 10

Describe the structure of ion channels.

Answer 10

Ion channels have a selectivity filter at the constricted part of the channel pore (~4 Å) which allows the selective passage of certain ions.

Question 11

What is the function of the selectivity filter in ion channels?

Answer 11

The selectivity filter in ion channels acts as a quality control check, ‘scanning’ ions based on their ionic radius and charge.

Question 12

How do ion channels allow for the selective passage of certain ions?

Answer 12

Ion channels allow for the selective passage of certain ions through their selectivity filter, which determines which ions can pass based on their properties.

Question 13

Define gating mechanism in the context of ion channels.

Answer 13

The gating mechanism in ion channels refers to the process by which the channel opens and closes to allow or block the passage of ions.

Question 14

What is the role of the gating mechanism in ion channels?

Answer 14

The gating mechanism in ion channels controls the opening and closing of the channel, regulating the passage of ions.

Question 15

Describe the common structure of ion channels.

Answer 15

Ion channels have a selectivity filter at the constricted part of the channel pore, which sits on top of the gating mechanism.

Question 16

How does the selectivity filter in ion channels contribute to ion passage?

Answer 16

The selectivity filter in ion channels contributes to ion passage by selectively allowing certain ions to pass through based on their properties.

Question 17

Explain the concept of ‘scanning’ ions in ion channels.

Answer 17

Ion channels ‘scan’ ions by assessing their ionic radius and charge to determine which ions are permitted to pass through the selectivity filter.

Question 18

Describe the structure, function, and gating of ion channels.

Answer 18

Ion channels are proteins that allow the passage of ions across cell membranes. They have specific structures that determine their function and can be opened or closed (gated) to regulate ion flow.

Question 19

What are the types of selectivity ion channels?

Answer 19

The types of selectivity in ion channels include uniport (allowing one type of ion to pass), symport (allowing multiple ions to pass in the same direction), and antiport (allowing multiple ions to pass in opposite directions).

Question 20

Explain the gating mechanism of ion channels.

Answer 20

The gating mechanism of ion channels refers to the process by which the channel opens or closes to allow or block ion passage. This mechanism is crucial for regulating ion flow.

Question 21

What is the outcome of the gating mechanism of ion channels?

Answer 21

Regardless of the specific gating mechanism, the outcome is always the same: the opening or closing of the channel to control ion flow.

Question 22

How do gating mechanisms affect ion channels?

Answer 22

Gating mechanisms cause a conformational change in the channel, altering its structure to either allow or block ion passage. This change is essential for the regulation of ion flow.

Question 23

Describe the gating mechanism of voltage-gated ion channels.

Answer 23

Activated by changes in the electrical membrane potential, commonly involved in exocytosis in neuronal and secretory cells.

Question 24

Explain how ligand-gated ion channels are activated.

Answer 24

They are activated upon binding of a chemical messenger, with extracellular ligands seen in neurotransmitter-gated channels and intracellular ligands in processes like insulin secretion from pancreatic beta cells.

Question 25

Describe the role of GABA in the nervous system.

Answer 25

GABA is the major inhibitory neurotransmitter highly in inhibitory neurons and interneurons, promoting inhibitory drive.

Question 26

What type of ion channels are GABA receptors?

Answer 26

GABA receptors are ligand-gated ion channels.

Question 27

Describe the Piezo1 channels.

Answer 27

Piezo1 channels are mechanically-gated ion channels highly expressed by neurons in specific regions of the brain.

Question 28

What is Yoda-1?

Answer 28

Yoda-1 is a potent activator of Piezo1 channels.

Question 29

Define mechanotransduction.

Answer 29

Mechanotransduction is the process by which cells convert mechanical forces into biochemical signals.

Question 30

How do mechanically-gated ion channels like Piezo1?

Answer 30

They open to allow ion influx when mechanical forces are exerted on the cell membrane.

Question 31

Do mechanically activated channels play a role in various cell types?

Answer 31

Yes, they are key for most cell types and regulate processes like cell migration, proliferation, and differentiation.

Question 32

Describe the significance of studying mechanotransduction.

Answer 32

Studying mechanotransduction is crucial for understanding pathologies, elucidating disease mechanisms, and developing new therapies.

Question 33

Describe the structure of PIEZO family mechanically-gated ion channels.

Answer 33

PIEZO family channels are the largest known pore-forming multimeric ion channels, with each subunit consisting of approximately 2,500 amino acids.

Question 34

What is the function of mechanically-gated ion channels in the PIE family?

Answer 34

These channels are non-selective cation channels with low permeability for chloride. They allow influx of sodium and calcium upon mechanical activation, leading to the propagation of electrical signals and initiation of intracellular pathways.

Question 35

How do mechanically-gated ion channels in the PIEZO family respond to mechanical activation?

Answer 35

Upon mechanical activation, these channels open to allow influx of sodium and calcium, leading to the initiation of electrical signals and intracellular pathways. The macroscopic Piezo currents activate in microseconds and close in the presence of the stimulus.

Question 36

Define the gating mechanism of PIEZO family mechanically-gated ion channels.

Answer 36

The gating of PIEZO family channels is mechanically induced, meaning they open in response to mechanical stimuli. The channels allow influx of sodium and calcium, leading to the propagation of electrical signals and initiation of intracellular pathways.

Question 37

What was the significance of the PIEZO family of mechanically-gated ion channels in the Nobel Prize of 2021?

Answer 37

The discovery and understanding of the PIEZO family of mechanically-gated ion channels contributed to the Nobel Prize in 2021 for their role in cellular mechanotransduction and signaling processes.

Question 38

Describe the Patch clamp technique.

Answer 38

A method used to study ion channels by attaching a glass micropipette to a cell membrane to record electrical currents.

Question 39

What is the significance of the Nobel prize in 1991 related to the Patch clamp technique?

Answer 39

The Nobel prize was awarded for development of the Patch clamp technique.

Question 40

Define single channel recordings in the context of ion channels.

Answer 40

Recording the flow of ions through a single ion channel.

Question 41

How are macroscopic currents different from single channel recordings?

Answer 41

Macroscopic currents represent the combined activity of multiple ion channels, while single channel recordings focus on individual channels.

Question 42

What are action potentials in the context of ion channels?

Answer 42

Rapid changes in membrane potential caused by the opening and closing of ion channels.

Question 43

Do outward currents appear on the current trace at positive or negative membrane potentials?

Answer 43

Outward currents appear at positive membrane potentials.

Question 44

Describe how inward currents are represented on the current trace.

Answer 44

Inward currents are shown as downward deflections on the current trace at negative membrane potentials.