So we are not using energy, we are not using any type of integral protein and our molecules are moving down our electrochemical gradient. Now, let's move on to a different type of cell membrane transport known as facilitated diffusion or passive transport. So certain molecules, such as sugar molecules, are too large and simply too polar to actually pass across our cell membrane via the process of passive diffusion. Yes, these molecules must enter the cell if the cell is to actually survive for a long period of time. So such molecules can be assisted by integral proteins known also as transfer proteins or carrier proteins. And such a mode of transport is known as facilitated diffusion.