The key difference between simple diffusion and facilitated diffusion is the difference of transport proteins.
In simple diffusion, molecules passively move down their concentration gradient directly through the plasma membrane without any help. While in facilitated diffusion, the transport of molecules occurs by the use of integral membrane proteins that form selective channels or carriers.
Although both processes are passive along an existing concentration gradient, facilitated diffusion involves proteins that lower activation energy and rapidly transport molecules that otherwise could not effectively cross the membrane.
Simple Diffusion vs Facilitated Diffusion
Here are the main differenc between Simple Diffusion and Facilitated Diffusion
| Simple Diffusion | Facilitated Diffusion |
|---|---|
| Simple diffusion is a type of passive transport where solutes move unassisted across a permeable barrier due to differences in electrochemical potentials. | Facilitated diffusion is a biological transport process where specific components of biological membranes interact with particular solutes, increasing their crossing rates. |
| The concentration gradient across the membrane drives simple diffusion. | The difference in solute concentration across the membrane drives facilitated diffusion. |
| Simple diffusion is passive and does not require energy. | Facilitated diffusion is also passive and does not require energy, although some processes may be active. |
| Simple diffusion tends to occur at a relatively low speed. | Facilitated diffusion typically occurs at a relatively higher speed. |
| Simple diffusion is not specific to particular solutes. | Facilitated diffusion is specific to solutes based on interactions with carrier molecules. |
| Along with the concentration gradient, kinetic energy of molecules drives simple diffusion. | Facilitated diffusion is driven by kinetic energy in addition to the concentration gradient. |
| Simple diffusion is not inhibited by specific molecules. | Facilitated diffusion can be inhibited by specific inhibitor molecules. |
| Particles move along the concentration gradient in simple diffusion. | Molecules can move in both directions, towards and away from the concentration gradient, in facilitated diffusion. |
| Simple diffusion primarily involves small non-polar molecules. | Facilitated diffusion commonly involves large and polar molecules. |
| Molecules move through the membrane’s surface in simple diffusion. | Facilitated diffusion involves specific channel proteins that form pores for molecule movement. |
| Examples of simple diffusion include gas exchange in lungs, gas mixing in the atmosphere, and nutrient absorption by bacteria. | Examples of facilitated diffusion include ion transfer (e.g., calcium, potassium), oxygen movement with hemoglobin in blood, and transport of amino acids and glucose into cells. |