Substances diffuse from areas of higher concentration to areas of lower concentration. This is referred to as the concentration gradient.
The diffusion rate is affected by the concentration gradient, size of molecules involved, temperature, the distance a molecule has to travel, solubility of the molecule and the surface area of the membrane.
Diffusion can be accelerated by membrane proteins.
The diffusion of water is referred to as osmosis.
The three main types of diffusion are facilitated, channel and simple diffusion.
Diffusion is fastest in gases because the particles move quickly in gases.
Diffusion in liquids is slower compared to gases because particles move slowly in liquids.
Diffusion does not occur in solids because particles in a solid only vibrate on the spot, rather than moving from place to place.
Diffusion plays an important role in life of a cell. The transportation of amino acids, nutrients and other important substances is facilitated by diffusion.
The rate of diffusion can be calculated by dividing the product of the gradient, temperature, surface area, solubility of the molecule by the product of the distance and square root of the molecular mass.