That sodium wants to be in the water , Jamie thought. It’s more crowded outside the glass. It would be easy to just... dissolve. Float out. Downhill.

Ms. Albright was going to get the best damn explanation of active transport she had ever seen.

Usually, substances like to spread out evenly (moving from high to low concentration), a process called passive transport. But sometimes, cells need to "buck the trend" and pile up certain molecules where they are needed most. Because this goes against the natural flow, the cell must expend energy (ATP) to make it happen.

🧠 The Sodium-Potassium Pump keeps your heart beating and your brain thinking!

That was it. That was the whole secret.

Sometimes, a molecule is just too big to fit through a protein pump. In these cases, the cell uses its entire membrane to wrap around the cargo.