Study_guide_8_-_Question_16-31

What is x-ray crystallography used for, and how does it work?

X-ray crystallography is used to determine the atomic and molecular structure of a crystal.

What are the distinguishing features of ion channels that contribute to their diversity?

Different types of gating mechanisms, ion selectivity, and structural variability.

What is a unique feature of voltage-gated ion channels and how does it work?

They open or close in response to changes in membrane potential.

What is the difference between heteromeric and homomeric channels?

Heteromeric channels consist of different subunits, while homomeric channels consist of identical subunits.

What determines ion channel selectivity?

The size and charge of the ion and the structure of the selectivity filter.

How does the selectivity filter interact with the ion?

By restricting ions based on size and charge.

What is the difference between ohmic and rectifying channels and what makes these differences possible?

Ohmic channels have a linear current-voltage relationship, while rectifying channels do not.

What is ion channel gating? What are the three states of ion channel gating?

Ion channel gating is the process by which ion channels switch between open and closed states. The three states are open, closed, and inactivated.

What is the difference between inactivation and desensitization?

Inactivation is a fast process that stops ion flow, while desensitization refers to a slower response.

What are the types of ion channels based on gating – know what stimulus opens each and what special features these channels have?

Types include voltage-gated, ligand-gated, and mechanically-gated channels.

What are aquaporin and connexon and what type of molecules can these channels conduct?

Aquaporin conducts water, and connexon conducts small ions or molecules.

Which ion channels regulate the resting membrane potential primarily?

Potassium channels.

Be able to recognize the various K+ channels we discussed.

Focus on specific names and properties of those K+ channels.

How do the Na/K-ATPase, Na/Cl antiporter, NKCC1, and NKCC2 work?

Na/K-ATPase pumps 3 Na+ out and 2 K+ in; Na/Cl antiporter, NKCC1, and NKCC2 involve sodium and chloride transport mechanisms.

What is the difference between pumps and transporters (i.e., antiporters, symporters)?

Pumps use ATP for energy, while transporters can move ions passively or actively.

How do Cl- symporters change across the life span and in epilepsy?

By changing their expression or activity levels.

How is membrane potential related to whether a channel is open?

Changes in membrane potential can trigger channel opening or closing.

What is the difference between the gating of the K+ versus Na+ channels that drive the action potential?

K+ channels open more slowly than Na+ channels.

How do voltage sensors respond to changes in membrane potential?

They undergo conformational changes that lead to channel gating.

How many pores do Cl- channels have?

One pore.

What are the general functions of Cl- channels?

Regulating ion balance and influencing neuronal excitability.

What type of charge do voltage sensors carry on Cl- channels?

Positive charge.

What are channelopathies and with what type of diseases are they associated?

Diseases caused by dysfunctional ion channels.

Which channels are more selective – voltage or ligand gated?

Voltage-gated channels are typically more selective than ligand-gated channels.