BIOS 10161 Lecture Notes - Lecture 7: Exocytosis, Hydrolysis, Uniporter
7 Sep 2016
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Document Summary
Membranes are selectively permeable some things can pass through but some others cannot: types of transport. Passive transport energy comes from the concentration gradient: conc gradient the difference in concentration between one side of the membrane and the other. Salt sucks: particles in a solution move randomly until they are evenly distributed, at equilibrium the particles continue to move but there is no net change in distribution, diffusion process of random movement towards equilibrium. Net movement is directional until equilibrium is reached. Diffusion net movement from regions of greater concentration to regions of less concentration. Cells are small, so it works well in cells. Membrane properties affect the diffusion of solutes. Membrane is permeable to solutes that can move across it, and impermeable to those that cannot. Small molecules pass through the lipid bilayer. These molecules include water and lipid soluble molecules. Electrically charged and polar molecules cannot pass through via simple diffusion: osmosis the diffusion of water.
