Question

There are several different types of gated channel proteins. Name one and describe under what conditions the channel is open and what conditions it is closed.

Answer 1

Sodium potassium gated channel

The sodium/potassium pump(ATPase) is responsible for maintaining the membrane potential at -70mv, the protein actively pumps three sodium ions out of the cell and pumps two potassium ions into the cell. Voltage gated potassium channels open, and potassium leaves the cell down it's concentration gradient.

Depolarization, Native voltage-gated K+ channels in excitable cells are normally activated by membrane depolarization. Voltage-gated K+ channels open typically in response to Na+ or Ca2+ dependent action potentials that are generated in neurons, skeletal muscle and secretory cells. And typically sodium channels are in a resting or closed state in neurons or muscle cells that are at rest(with a membrane potential of approximately -60 to -80 mV). Closed sodium channels do not conduct sodium ions, but are ready to be activated or opened when stimulated by membrane depolarization. All the voltage gated sodium channels open when the membrane potential reaches around -55mV and their is a large influx of sodium, causing a sharp rise in voltage.