Sodium-Potassium Pump Mechanism

Questions and Answers

What is the primary function of the sodium-potassium pump?

To enable the synthesis of ATP from ADP

To transport calcium ions into the cell

To facilitate the movement of glucose across the membrane

To maintain the resting potential of the cell (correct)

How does ATP influence the sodium-potassium pump?

It is hydrolyzed to drive the movement of potassium ions into the cell

It binds directly to sodium ions to facilitate their exit

It directly alters the permeability of the cell membrane

It donates a phosphate group to the pump, allowing sodium ions to be expelled (correct)

What is the correct stoichiometry of ion exchange for the sodium-potassium pump?

3 sodium ions in, 2 potassium ions out

1 sodium ion in, 3 potassium ions out

3 sodium ions out, 2 potassium ions in (correct)

4 sodium ions out, 1 potassium ion in

What happens to the pump after sodium ions have been released to the extracellular fluid?

<p>The phosphate group unbinds, returning the pump to its original shape</p> Signup and view all the answers

What is the end result of the sodium-potassium pump's activity on membrane potential?

<p>It establishes a negative resting potential inside the cell</p> Signup and view all the answers

Study Notes

Sodium (Na+) and Potassium (K+) Pump Overview

The sodium-potassium pump is essential for maintaining cell membrane potential.
Operates by exchanging sodium (Na+) and potassium (K+) ions across the cell membrane.
Conforms to the ratio: 3 sodium ions are pumped out of the cell, and 2 potassium ions are pumped in.

Mechanism of Action

ATP is the energy currency utilized for the pump's operation; one molecule of ATP is consumed per cycle.
Phosphate is transferred from ATP to the pump protein (phosphorylation), enabling shape change that facilitates ion movement.

Phosphorylation Process

The three Na+ ions bind to the pump, triggering phosphorylation.
This phosphorylation alters the pump's configuration, allowing Na+ to be released into the extracellular fluid (ECF).
The pump then opens to the outside, creating binding sites for K+ ions.

Potassium Ion Entry

The pump contains two specific binding sites for K+.
K+ ions enter the cell after the conformational change caused by the binding of phosphate.
Once K+ is bound, the phosphate group is released, restoring the pump to its original configuration, which facilitates the release of K+ into the cell.

Importance for Cellular Function

The activity of this pump is crucial for establishing the negative resting potential within the cell.
Disruption of Na+/K+ pump function can lead to imbalances affecting cell excitability and communication.

Description

This quiz focuses on the Sodium-Potassium pump, a vital protein in cellular function. It explores how the pump operates, including the process of phosphorylation and the movement of sodium and potassium ions across the cell membrane. Understanding this mechanism is essential for grasping the concept of resting membrane potential.