Types of Cellular Transport Animations of Active Transport & Passive Transport Passive Transport cell doesn’t use energy Diffusion Facilitated Diffusion Osmosis Active Transport cell does use energy Protein Pumps Endocytosis Exocytosis high low Weeee!!! high low This is gonna be hard work!!
Movement of molecules Cell membranes only allow some molecules across w/out help: • Small, non-polar molecules OK ex. steroids, O2, CO2 • No charged, polar, or large molecules ex. sugars, ions, water*
Movement of molecules Simple Diffusion: most basic force to move molecules • Disperse until concentration equal in all areas
Transport Across Membranes Types of transport: Passive transport - Simple diffusion - Facilitated diffusion - Osmosis B. Active transport C. Bulk transport • Energy Required? • Directionality?
Passive Transport - Simple Diffusion • NO ENERGY required - non-polar molecules (steroids, O2, CO2) • DOWN concentration gradient • molecules equally distribute across available area by type
Passive Transport – Facilitated Diffusion • NO ENERGY required • DOWN concentration gradient • molecules equally distribute but cross membrane with the help of a channel (a) or carrier (b) protein.
Passive Transport - Osmosis • osmosis – movement of water across cell membrane • water crosses cell membranes via special channels called aquaporins • moves into/out of cell until solute concentration is balanced
Passive Transport - Osmosis Paramecium example • regulate water balance • pond water hypotonic • water into contractile vacuole – water expelled
Passive Transport - Osmosis Scenario: in movie theater, watching a long movie. You are: drinking water What happens to your blood? You are: eating popcorn What happens to your blood?
Active Transport • Ex. Na-K ion pump • ENERGY IS required - Na+ ions: inside to out • UP/AGAINST concentration gradient - K+ ions: outside to in • transport proteins a. ion pumps (uniporters) • antiporter: two molecules move opposite directions (UP gradient) b. symporter/antiporter c. coupled transport