BI111 Lecture Notes - Lecture 6: Root Nodule, Bradyrhizobium, Nitrification
Document Summary
Simple diffusion is simplest form of passive transport: requires no metabolic energy, substance moves down concentration or electrochemical gradient. But how efficient is it: not very long distances, 10 m in 0. 1 sec; 100 m in1 sec; 1 mm in 100 sec. Active transport requires metabolic energy (atp: based on h+ pumps, h+ gradient maintained through atp use, h+ diffusion into cell power uptake of solutes. Symport: material transported in same direction as movement of h+ and solute, organic uptake. Antiport: material transported in opposite direction to movement of h+ and solute, na+ export. Diffusion: spontaneous movement of molecules or particles along a concentration gradient. Osmosis: special case of diffusion: water molecules diffuse across selectively permeable membrane from an area of higher water concentration (low solute concentration), to a lower water concentration (high solute concentration) In plants, the cell swells and swells but does not explode.
