Define the Factors That Influence the Facilitated Diffusion

Facilitated diffusion is influenced by the following factors:

• Minor differences in the molecular structure may lead to a substantial difference in the rate of transport. Optimal transport relies on the precise fit among the molecule to be transported and the receptor site of the carrier.
• Substances along with a same molecular structure compete with one another for transport.
• Transport can be blocked by particular agents. If the blocking agent has a high affinity for the carrier, the blocking agent can as well get transported and this block is termed as competitive block (and can be overcome by high concentrations of substance whose transport has been blocked, hence is reversible). If the blocking agent binds to the carrier but does not get transported, it blocks the carrier irreversibly. Such a block is known as non-competitive block.

The relationship between the concentration of the substance and the rate at which it is transported is linear only up to a certain limit. After that, a further increase in the concentration does not increase the rate of transport. An instance of facilitated diffusion is in small intestine where fructose is absorbed by facilitated transport.