There are two main types of membrane transport - passive transport and active transport. Passive transport does not require energy and involves the movement of molecules down their concentration gradient through simple diffusion, facilitated diffusion, or ion channels. Active transport requires energy and transports molecules against their concentration gradient using pumps such as the sodium-potassium pump. Bulk transport is needed for large molecules and involves endocytosis to bring substances into the cell or exocytosis to expel them.

1. Passive vs. Active Transport

6. Facilitated Diffusion Diagram

7. Passive Transport Simple Diffusion Facilitated Diffusion Facilitated Diffusion diffuses molecules faster than simple diffusion.

9. Ion Channels

17. Membrane Transport Active Transport Protein channels Certain Ions Non-polar molecules Water Facilitated Diffusion Simple Diffusion Passive Transport Endocytosis Pumps Cotransport Large Molecules Pinocytosis Phagocytosis Exocytosis