BIO130H1 Lecture Notes - Lecture 8: Passive Transport, Active Transport, Lipid Bilayer
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BIO130H1 Full Course Notes
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Week 2 membrane transport of small molecules. Diffusion = passive process where high-conc of molecules moves to low conc: happens down a gradient , spontaneous, eventually eliminates conc ration of concentration difference btwn 2 regions. See droplet of dye in aq solution diffuses as it evenly distributes throughout solution. Diffusion across membrane: eventually get equal concentration. Get diffusion as long as membrane is permeable. Lipid bilayer permeable to: hydrophobic molecules (o2, co2, n2, small uncharged polar molecules (h2o, urea, glycerol) Permeable to these b/c they can pass through hydrophobic core. Move from high conc to low conc: They move via simple diffusion through lipid bilayer: down the conc gradient. More hydrophobic/non-polar the molecule = faster diffusion across lipid bilayer: b/c hydrophobic core prevents larger ones to pass quickly. Lipid bilayer impermeable to: large polar molecules (glucose, sucrose) Want to keep glucose and sucrose in the cell, don"t want to leak it out: ions (h+, na+, k+)
