Facilitated diffusion via channels and carrier proteins The majority of solutes that diffuse across the plasma membrane cannot move directly through the lipid bilayer. The passive movement of such solutes (down their concentration gradients without the input of cellular energy) requires the presence of specific transport proteins, either channels or carrier proteins. Diffusion through a transport protein in the plasma membrane is called facilitated diffusion. outside cell Facilitated diffusion across the plasma membrane channel protein carrier protein inside cell Adapted from Biology by Campbell and Reece © 2008 Pearson Education, Inc. Sort the phrases into the appropriate bins depending on whether they are true only for channels, true only for carrier proteins, or true for both channels and carriers. transport solutes down a concentration or electrochemical gradient undergo a change in shape to transport solutes across the membrane provide a hydrophilic path across the membrane provide a continuous path across the membrane allow water molecules and small ions to flow quickly across the membrane transport primarily small polar organic molecules are integral membrane proteins only channels only carriers both channels and carriers
