Question

Are carrier proteins active or passive?

Answer 1

Active transport:

1. In this transport system ATP is used to pump molecules AGAINST/UP the concentration gradient.
2. Transportation happens from lower concentration solution to higher concentration solution.
3. It requires cellular energy as the transfer is against the concentration.

Passive transport:

1. In this transport system, molecule transportation is done down the concentration.
2. It goes from a high to a low concentration to keep the cells in balance.
3. It does not need any energy to transfer molecules.

Carrier proteins:

1. They are essential proteins that carry chemicals across the membrane/cell in both the direction against and down the concentration gradient.
2. It requires energy while transferring substances against the concentration gradient.
3. Carrier proteins are both active and passive.
4. Example: sodium-potassium pump, glucose-sodium cotransport, etc.
5. Valinomycin acts as a passive carrier protein that increases the permeability of potassium ions down its gradient from higher concentration to lower concentration without the use of energy.
6. The sodium-potassium ATPase pump transports molecules actively using ATPs. It moves two sodium ions out of the cell for every three potassium ions moved inside.