BIOL 1201 : Biology Exam 2 Notes
Document Summary
Integral membrane proteins: amphipathic, hydrophobic (non polar) regions, hydrophilic (polar) regions. When concentrations on both sides of a barrier are equal: molecules keep moving, there is no change. Semi-permeable barrier: only some types of molecules pass through. Diffusion: movement of molecules down concentration gradient, from regions of high concentration to low concentration regions, physical property of matter. Individual molecules move randomly, but the net effect is non-random. Movement of water across membranes: from high to low water potential. Membrane permeability: size and shape of molecules, solubility in lipids, net electric charge, other chemical properties, water always freely permeable, aquaporins channel protein which facilitate water diffusion through the membrane. Osmosis: the net movement of water across (through) a semi-permeable membrane, diffusion of water, from higher (fewer solutes) water potential to lower water potential. Hypertonic: lower water potential, more solutes dissolved, hypertonic solutions will tend to gain water. Hypotonic: high water potential, fewer solutes dissolved, hypotonic solutions will tend to lose water.
