TRANSPORT – Active Transport

TRANSPORT – Active Transport

Active Transport – The non-passive net movement of ions/molecules from a region of low concentration of solutes to a high concentration (against the conc. gradient)

Process:

• ATP (energy transfer molecule) provides energy (from resp.) to change the shape of the carrier proteins when specific substances bind to it, thus releasing the contents on the other side.

Stages of Sodium-Potassium Pump:

1. The carrier protein is open (in a triangular shape)
2. Na from the inside of the cell binds to the shape of the carrier protein
3. ATP energy comes across
4. ATP donates ones of its P atoms which binds to the carrier protein à the remaining molecule is now ADP
5. The energy from the P atom causes the carrier protein to change shape and release the contents (Na) to the outside of the cell
6. The shape has now been changed (to a V shape)
7. The K from the outside of the cell enters and binds to the carrier protein
8. The P energy is released, and so the shape cannot hold on so it changes back to original (triangular) shape
9. The K is released inside the cell
10. The process starts again