BCH210H1 Lecture Notes - Lecture 17: Aquaporin, Gtpase, Second Messenger System

• School: UTSG
• Department: Biochemistry
• Course: BCH210H1
• Professor: Stavroula Andreopoulos

Document Summary

Lys216, glu2014+, glu194), order of events, and the role of retinal+ in the process. Membrane transport: essential for life, nutrients in, garbage out. Inorganic ions in and out: some small uncharged molecules freely diffuse across, passive diffusion, most require integral membrane protein transporters, facilitated transport, active transport (uses atp) Some small uncharged molecules can slowly diffuse across the bilayer: most nutrients require membrane proteins that sit in the lipid to get across, forming conduits. Passive diffusion: favours small, uncharged nonpolar molecules, diffuse down their concentration gradient i. e. , [high] [low, no help from any transporter system. Small, uncharged, nonpolar molecules can pass through the membrane down their concentration gradient: don"t need transporter, just diffuse through the lipid if they"re nonpolar enough. It"s a free energy situation, because it wants to reach equilibrium. Bilayer permeability: few molecules cross membranes by passive diffusion, gases can freely pass through the membrane, important for aerobic respiration, without transporters.