concept 7.2: membrane structure results in selective permeability

why do plasma membranes need to be selectively permeable

because they need to control the input of needed and unneeded substances

what kind of molecule struggles to pass through the membrane

hydrophilic molecules molecules including ions and polar molecules

why is it hard for ions and charged molecules to pass through the membrane

because they are surrounded by a hydration shell and struggle to pass through the hydrophobic region of the bilayer

what do transport proteins do

allow passage of hydrophilic substances across the membrane

channel protein

a type of transport protein that has a hydrophilic channel that certain molecules or ions can use as a tunnel and allows them to bypass the hydrophobic region of the phospholipid bilayer

aquaporins

channel proteins that facilitate the passage of water molecules

carrier proteins

bind to molecules and the carrier protein changes to shuttle the bound molecules across the membrane

what is transport protein specific to

it is specific to the substance it moves