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Biology Lecture 09/17/25

Active Transport

Celles occasionally need to move atoms and molecules from an active os low concentration to an area of high concentration

  • Another way to say this is "molecules up their concentration gradient"

This requires active transport. In active transport, a protein releases engery by breaking

Example: Sodium-potassium pump

  • Every single call in animals have this transport protein

The action of the sodium-potassium pump creates permanent concentration gradients of NA+ and K+ ions between the ICF and ECF. This means in an animals cell: Sodium will always diffuse into the ICF and Potassium will always diffuse into the ECF

ATP is said to be the primary energy storage molecule in the cell... and this is true but not the complete story.

The total amount ("pool") of ATP in a cell in finite. There is a maximum amount of ATP a cell can have . Above that maximum the chemical processses of the cell can

The cells uses its excess ATp to create the sodium and potassium gradients. THis energy is not lost, it is transforms into chemical potential energy. Chemical potentantial energy is released when sodium or potassium ions diffuse dow their concentration gradient

We use energy (in the form of ATP) to create the sodium and potassium gradients. THat energy is not lost or spe, it is instead transformed into that stored in the cgradients os sodium and potassium. When atoms or molecules diffuse down their gradient, they release thar stored energy. Diffusion is a passiver transport process and passive transport releases energy. THe energy released by sodiu

THe sodium and potassium gradients act like a battery that stores cellular energy. One of the main uses for this is transport work. Transport porteins can us the chemical potential engery released by tfacilitTES DIFFUSION OF na+ or K+.... to provide the energy for active transport of another molecule instead of spending ATP. This is called transport coupling

Active transport terminology

The part of the system that breaks down ATP to transport atoms molecules is called the primary active transporter. <