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.

hydroxyl -oh

alcohols, always polar, can form hydrogen bonds with h2o molecules

carboxyl -cooh  

cargoxylic acids, has acidic properties which is a source of hydrogen ions, found in cells in ionized for with a charge of oh-1

carbonyl > co

ketone if within skeleton, aldehyde if group is at the end of skeleton, k & a may be structural isomers, it determines 2 sugars (ketose & aldose)

amino -nh2

amines, acts as a base, it can pick up h+ ions from surrounding solution, ionized with charge of 1+

methyl ch2

addition to rna/dna affects and gene expression

phosphate -opo3 ²⁻

organic phosphates, contributes to negative charge to, molecule that it is a part of, and potential to react with h20

sulfhydryl -sh

thiols, cross-linking stabilize the protein, and it is structure