... a low concentrated region. In some cases, molecules are not soluble in lipids and because of this they cannot diffuse through a membrane. When this happens, facilitated diffusion takes place. This is an 'easier' way for the particles to get through the phospholipid bilyer. Between the phospholipids are carrier proteins that 'carry' the insoluble molecule over to the other side instead of it diffusing through the lipids. They are the exact shape of molecules to allow them to fit inside and travel through. The rate of diffusion depends on the number of carrier proteins there are present and that are open to 'carry' the molecules. The way by which water molecules are diffused is called Osmosis (through a semi-permeable membrane). A semi-permeable membrane allows the molecules of water to pass through, but does not allow other molecules to be diffused through it. Osmosis enables water molecules to diffuse from a region of ...

See this essay or coursework document in full right now