🔋 The Sodium-Potassium Pump – Active Transport & Resting Potential
The sodium-potassium pump (Na⁺/K⁺-ATPase) is a classic DAT topic because it integrates:
Membrane biology
Active transport
Ion gradients and neuron function
You’ll need to know:
How it works
What it transports
Why ATP is required
Its role in resting membrane potential
🔄 What Is the Na⁺/K⁺ Pump?
Found in all animal cells, especially neurons
Primary active transport → uses ATP directly
Moves 3 Na⁺ out and 2 K⁺ in
Maintains high extracellular Na⁺ and high intracellular K⁺
🧠 Creates a net negative charge inside the cell—important for action potentials.
⚙️ Step-by-Step: How the Pump Works
| Step | Action | Molecules Involved |
|---|---|---|
| 1 | 3 Na⁺ bind inside the cell | Na⁺, pump, ATP |
| 2 | ATP hydrolyzed to ADP + Pi | Energy released |
| 3 | Pump changes shape, releases Na⁺ outside | Na⁺ exits |
| 4 | 2 K⁺ bind from outside | K⁺ enters binding site |
| 5 | Phosphate released, pump resets, K⁺ enters cell | K⁺ enters |
✅ ATP provides energy to move ions against their gradient.
🧬 Functions of the Na⁺/K⁺ Pump on the DAT
| Function | DAT Relevance |
|---|---|
| Resting membrane potential | Maintains neuron voltage (-70mV) |
| Cell volume control | Prevents osmotic swelling |
| Secondary active transport | Drives glucose & amino acid uptake |
| Thermogenesis | Uses ATP, generates heat |
🧠 Enables cotransporters like Na⁺/glucose symporters in the intestine.
📈 DAT-Style Practice Question
Q: The Na⁺/K⁺ pump moves ions in what ratio and direction?
A) 3 Na⁺ in, 2 K⁺ out
B) 2 Na⁺ out, 3 K⁺ in
✅ C) 3 Na⁺ out, 2 K⁺ in
D) 2 Na⁺ in, 3 K⁺ out
🎯 DAT Strategy Tips
✅ Memorize: 3 Na⁺ out, 2 K⁺ in, 1 ATP used
✅ Know it’s primary active transport
✅ Understand how it contributes to resting potential
✅ Recognize it supports secondary transport
More active transport visuals at kingofthecurve.org/studyscience
🚀 Call-to-Action
Want to actively transport your DAT score?
Download the KOTC App for:
Flashcards on transport types
Na⁺/K⁺ pump animations
Challenge quizzes + Curve Coins
Core physiology visual guides
🔋 Keep your score charged—study with KOTC.
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