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Unformatted text preview: TA: Clarissa Chan OH: Tues 10-11a Section: Wed 1-2p Mandeville Coffee Cart Handout #1 (through 1/10) Movement of Molecules Across Cell Membranes Molecules can move across cell membranes by concentration gradients or electrical gradients ________Concentration Gradients_______ occur via diffusion of molecules from areas of ____________high conc_____ to _______low conc_______. However, molecules can move in both directions but it is the NET movement of molecules that is important. An example of diffusion is Osmosis. Osmosis is the diffusion of water down its concentration gradient. The Molarity of water is: U-tube Diagram: ____Electrical Gradients_____________ occur when cations move towards a negative electric field or vice versa. The movement of ions down concentration gradients can be changed by electric fields. Pathways : Method: Molecules Diffusion lipid soluble molecules Down concentration gradients through the lipid bilayer Gasses Hormones Vitamins Channels water soluble molecules ** All channels work by diffusion Protein sugars, aa, iron Protein channels (hold water molecules for transport down concentration gradients), non specific channels (gap junctions, for larger molecules) ion specific channels (specific to a certain ion) leak channels (steady leak of ion) Gated Channels (gates that are opened by electric fields such as in AP or ligands, mechano receptors, or temperature) Non specific nucleotides Ion specific Na, K, Cl Leak K leak Gated Na channels in AP...
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This note was uploaded on 03/10/2011 for the course BIPN 100 taught by Professor French during the Winter '07 term at UCSD.
- Winter '07