BSC-2010 Lecture Notes - Lecture 9: Dynamic Equilibrium, Stoichiometry, Pseudopodia
2 Dec 2016
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Document Summary
Molecules tend to spread out in available space. Driven by kinetic energy (thermal motion or heat) Net movement of molecules from regions of high concentration to low concentration Rate of di usion depends on concentration gradient and molecular size. Simpli ed example: permeable membrane separates dye solution from pure water. At dynamic equilibrium: as many molecules pass one way as other cross in the other direction. In the absence of other forces, substance di uses from regions of high concentration to low concentration. In general, each substance independently di uses down its own concentration gradient. Osmosis di usion of water across a selectively permeable membrane. Di erences in solute concentration can lead to movement of water molecules. Lysed cell very full until it bursts. H2o molecules move through selectively permeable membrane from hypotonic solution to hypertonic solution. Two types of membrane transport proteins require facilitated di usion of solutes. H2o moves through the bilayer, bu there are h2o channels too.
