Examples of diffusion are illustrated below. Once the molecule is released the protein's shape reverts to the original or unoccupied state. Review the details about facilitated diffusion by reading the Mini Essay from Kimballs Biology Pages. Cell Junctions Cells of plants and animals are frequently connected in order to communicate and share resources. In animals these connections are called gap junctions .
Materials move between certain animal cells through pores called gap junctions.
Each pore is formed by the arrangement of 6 transmembranal proteins lined up back to back welding the membranes of adjacent cells together. For plants their cytoplasm interconnects through plasmodesmata . For a thorough but concise discussion of cell junctions you can link to Kimball's Biology Pages here.