Movement of molecules across membranes 4 mechanisms 1. Diffusion directly through the lipid bilayer 2. Transport via carrier proteins facilitated Passive diffusion fransport 3. Transport through ion channels 4. Active transport ATPases Co-transportMovement of molecules across membranes 4 mechanisms 1. Diffusion directly through the lipid bilayer 2. Transport via carrier proteins 3. Transport through ion channels 4. Active transport - ATPases - co-transport facilitated diffusion Passive transport