Biological membranes and transport part I Dunging pei, Ph D 裴端卿 Tsinghua University Cell phone:1368301-7108 peixx003oumn edu
Biological Membranes and Transport part II • Duanqing Pei, Ph.D. • 裴 端 卿 • Tsinghua University • Cell phone: 136-8301-7108 • peixx003@umn.edu
Biological Membranes and transport part II Passive transport: with the gradient Water transport--aquaporins Glucose transporters Co-transport of chloride and bicarbonate Active transport: against the gradient Transport ATPases Ion channels
Biological Membranes and Transport part II • Passive transport: with the gradient – Water transport—aquaporins – Glucose transporters – Co-transport of chloride and bicarbonate • Active transport: against the gradient – Transport ATPases – Ion channels
Simple diffusion across permeable membranes ●● @● 。g 1 Before equilibrium At equilibrium Net flux No net flux
Simple diffusion across permeable membranes
Electrochemical Potentials: chemical gradient/electric potential G G ⊙ ⊙ ⊙ ⊙ V>0 V=0 Before equilibrium At equilibrium (b)
Electrochemical Potentials: chemical gradient/electric potential
Selectively permeable barriers Hydrated of living organisms: all solute membranes- intracellular and pl dasma Simple diffusion--virtuall Simple diffusion without transport impermeable to polar and charged species (too slow to be Diffusion meaningful); permeable for with transporter usIon certain gases- molecular oxygen, nitrogen, methane and △ Transport water(huge concentration) Passive transport(facilitated diffusion)-passage of polar compounds and ions aided by membrane proteins that lowers Transporter the activation energy Transporter or permeases
Selectively permeable barriers of living organisms: all membranes—intracellular and plasma Simple diffusion—virtually impermeable to polar and charged species (too slow to be meaningful); permeable for certain gases- molecular oxygen, nitrogen, methane and water (huge concentration) Passive transport (facilitated diffusion)—passage of polar compounds and ions aided by membrane proteins that lowers the activation energy Transporter or permeases