Concept 7.2: Membrane structure results in selective permeability

Flashcards from Concept 7.2 of Pearson's Campbell Biology, Twelfth Edition.

Selective permeability

Plasma membrane property that allows substances to cross more easily than others as part of material control

• Dependent on the lipid bilyer and specific transport proteins contained

Hydrophobic molecules

Nonpolar molecules that dissolve in the lipid bilayer and pass through the membrane easily; includes hydrocarbons and gasses like CO₂ and O₂

Hydrophilic molecules

Polar molecules where passage through the membrane is impeded; includes sugars, water, and ions

• Requires transport proteins that enable faster transport

Transport proteins

Proteins that function in the transport of hydrophilic molecules across the cell membrane, includes:

• Channel proteins (tunneling proteins)

• Carrier proteins (polymorphic proteins)

These proteins are molecule-specific, affecting overall selective permeability alongside the membrane

Channel proteins

Proteins that have a hydrophilic channel that certain molecules or ions can use a tunnel

Carrier proteins

Proteins that bind to molecules and change shape to shuttle them across the membrane

Aquaporins

Channel proteins that greatly increase the rate of passage of water molecules

• Over 3 billion pass through per second