Ligand-Gated Ion Channels in the Nervous System

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Questions and Answers

What is the primary function of ligand-gated ion channels?

To initiate an immune response

To synthesize proteins

To facilitate the binding of a chemical messenger to the receptor (correct)

To regulate gene expression

What type of membrane receptors are ligand-gated ion channels?

Enzyme-linked receptors

G protein-coupled receptors

One type of major membrane receptors (correct)

Transmembrane receptors

Where are ligand-gated ion channels commonly found?

Only in muscle cells

In all cells of the body

In skin cells

In electrically excitable cells like neurons (correct)

What is the term for the specific binding of a ligand to a receptor?

All of the above (D) Signup and view all the answers

What is the shape of the ligand complementary to?

The shape of the ion channel (C) Signup and view all the answers

What is the function of the kink in the ion channel?

To facilitate the binding of a ligand (A) Signup and view all the answers

What is the term for transmembrane ion channels?

Integral proteins (D) Signup and view all the answers

What is the environment inside the cell?

Intracellular environment (D) Signup and view all the answers

What happens to the closed channel when a ligand binds to the allosteric site?

The channel opens up (C) Signup and view all the answers

What is the main purpose of membrane receptors?

To respond to extracellular signals (A) Signup and view all the answers

What type of ion channels rely on the difference in membrane potential?

Voltage-gated ion channels (A) Signup and view all the answers

What is the result of ions moving through the open channel?

A change in the electrical properties of the cell (A) Signup and view all the answers

What is the term for the binding site of the ligand that is not on the channel itself?

Allosteric site (D) Signup and view all the answers

What is the effect of multiple allosteric binding sites on a protein?

The protein can bind to multiple ligands (B) Signup and view all the answers

What is the characteristic of stretch-activated ion channels?

They respond to the deformation of the cell membrane (A) Signup and view all the answers

What is the significance of the ligand binding to the allosteric site?

It allows the channel to open or close in response to the binding of a ligand (D) Signup and view all the answers

What is the result of the conversion of an extracellular ligand signal to an intracellular electrical signal?

The cell becomes more responsive to its environment (A) Signup and view all the answers

What is the characteristic of ligand-gated ion channels?

They respond to the binding of a ligand (D) Signup and view all the answers

Study Notes

Ligand-Gated Ion Channels

Ligand-gated ion channels are a type of major membrane receptors that open or close in response to the binding of a chemical messenger (ligand).
There are three categories of major membrane receptors: ligand-gated ion channels, G protein-coupled receptors, and enzyme-linked receptors.
Ligand-gated ion channels are commonly found in electrically excitable cells, such as neurons, due to their quick reaction to ligand binding.

Structure and Function

Ligand-gated ion channels are transmembrane ion channels with a channel or hole through which ions can move in and out.
The channel has a specific binding site for a ligand, which is complementary to the shape of the ligand.
Only specific ligands can bind to specific channels, following the "lock and key" or "induced fit" principle.
When a ligand binds, it causes the channel to open, allowing ions to move through the membrane.

Allosteric Binding

The binding site of the ligand is not near the actual channel, but rather at an allosteric site.
The binding of the ligand to the allosteric site causes a change in the protein conformation, which opens the channel.
The allosteric binding site can be intracellular, but it is generally located on the extracellular side.

Ion Permeability and Electrical Signal

When the channel opens, ions such as potassium, sodium, chlorine, or calcium can move through the membrane.
This change in ion permeability causes a change in the electrical properties of the cell.
The movement of ions in and out of the cell generates an intracellular electrical signal.

Key Distinctions

Ligand-gated ion channels are not the same as voltage-gated ion channels, which rely on the difference in membrane potential.
Ligand-gated ion channels are also distinct from stretch-activated ion channels, which depend on the deformation of the cell membrane.

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Description

Learn how ligand-gated ion channels enable quick reactions in the nervous system, including neurons and the brain. Understand the three categories of major membrane receptors.