Substances that easily pass through membranes

Substances that cannot easily pass through membranes

Concept: Some substances do not need the help of membrane proteins and can diffuse freely along the concentration gradient and pass through the lipid bilayer of the membrane.

two channels

Concept: Material transport mediated by channel proteins is a hydrophilic channel across the plasma membrane that allows water molecules and charged ions to pass along the concentration, including ion channels and water channels

Concept: Some non-lipid-soluble (hydrophilic) substances are transported across the membrane along the electrochemical gradient mediated by specific carrier proteins.

Features: Conformational changes in membrane carrier proteins when transporting substances

Example

ATP drives the pump (ATP directly provides energy)

Co-transport (ATP indirectly provides energy)

endocytosis

exocytosis