In facilitated diffusion, what is the role of the transport protein? see concept 7.3 (page 135) in facilitated diffusion, what is the role of the transport protein? see concept 7.3 (page 135) transport proteins provide a protein site for atp hydrolysis, which facilitates the movement of a solute across a membrane. transport proteins provide a hydrophilic route for the solute to cross the membrane. transport proteins provide the energy for diffusion of the solute. transport proteins organize the phospholipids to allow the solute to cross the membrane.

Facilitated diffusion is the term given for passive transport of molecules or ions across a biological membrane, facilitated by transport proteins. The molecules or ions move down a concentration gradient; therefore, no chemical energy is required and no ATP hydrolysis is needed. The transport proteins may be responsible for carrying larger molecules across the membrane by changing their conformation, or water-soluble transport proteins may carry non-polar molecules with poor water solubility across. Since no energy is involved in the diffusion, options a) and c) are incorrect. Since the molecules being carried are not altered in any way, option d) is incorrect. Option b) ‘transport proteins provide a hydrophilic route for the solute to cross the membrane’ is correct as water-soluble carrier proteins are able to facilitate the diffusion of non-polar molecules with poor water solubility.