Diffusion is the movement of particles from one place to another. Diffusion
usually occurs in both gases and liquids, as those particles are free to move
around. A common type of diffusion occurs in gases, as one set of gas
particles will move from one area to another. The gas particles move from an
area of high concentration to an area of low concentration.This explained in
the diagram below.
In the left compartment there are more blue dots than red dots, therefore the
blue dots have a higher concentration In the right compartment there are less
blue dots than the left compartment so the blue dots move from left to right to
even out the numbers. The bigger the difference in concentration, the faster
the diffusion rate.
Cell membranes help with the diffusion process. Cell membranes not only
help keep the structure of the cells, but also control what moves in and out.
The cell membranes have tiny holes, which allow small particles such as
oxygen to pass through, but they do not large particles such as protein to
pass through. That is why proteins have to be broken down into smaller
articles such as amino acids.