Active transport

Active transport is the movement of particles from an area of lower concentration to an area of higher concentration. This process requires energy from respiration in the form of ATP.

Energy is needed as particles move up (or against) a concentration gradient.

As a result, active transport is described as an active process.

Carrier proteins

Like facilitated diffusion, active transport involves the use of carrier proteins to transport molecules or ions across membranes. The process works in the following way:

Factors affecting the rate of active transport

There are four key factors that affect the rate of active transport:

1. Temperature - At higher temperatures, particles have more kinetic energy and travel faster. Respiration also increases with temperature. Very high temperatures denature carrier proteins, decreasing the rate of active transport.
2. Thickness of membrane - Particles travel shorter distances through thin exchange surfaces, so travel faster.
3. Number of carrier proteins - The more of these proteins, the faster the rate of active transport.
4. Rate of respiration - The more respiration, the more ATP available for active transport.