Bio 3 - Exchange of Materials - Active Transport

Active Transport differs from Diffusion and Osmosis because it absorbs substance AGAINST a concentration gradient.

That is to say, substances move from an area of low concentration, to an area of high concentration

To do this, it takes a lot of energy (Different to Diffusion, which requires none).

The energy for this comes from Cellular Respiration.

Cells involved in Active Transport usually have a lot of Mitochondria to provide the energy needed

How does Active Transport actually work?

- It starts off with the solute molecule that is needed to be absorbed. There is the cell membrane that it needs to get through, and inside it, a Transport Protein ready to help it.

- The Transport Protein then grabs the solute molecule

- This protein the rotates within the cell membrane, to face the other side of it, and releases the molecule. (This is what uses the energy)

- The protein then rotates to its orginal position (Again using energy) 

Why is Active Transport important?

Mineral ions in the soil around plants are usually found in very dilute solutions, more dilute than the solution within the plant cells. This means that diffusion will not work to absorb the ions, but the plant cells still need them to survive. So they use Active Transport so they can absorb these mineral ions Against the concentration gradient

Also, glucose is always moved out of your gut and kidney into the blood, even when it is against a large concentraion gradient