bio910

bio910 - Water spontaneously moves across the membrane...

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Biology 9/10 Cholesterol fills spaces between phospholipids o Hydrophobic interactions increase and bilayer permeability decreases Membrane “fluidity” also decreases with decreasing temperature because molecules in the bilayer move more slowly Diffusion across a lipid bilayer (diagram in book p.120) Simple Diffusion is Solute Movement o Molecules or ions in high concentration on one side of a membrane tend to diffuse thru the membrane to an area of lower concentration = down their concentration gradients Osmosis is water movement o Osmosis occurs when solutions of a different concentration (cont.) o
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Unformatted text preview: Water spontaneously moves across the membrane toward the solution with the higher solute (lower water) concentration • Tonicity o A hyper tonic solution has a higher solute concentration (lower water concentration) relative to another solution. o A hypo tonic solution has a lower solute concentration (higher water concentration) relative to another solution • Water moves by osmosis into a hypertonic solution • Water moves by osmosis out of a hypotonic solution • Isotonic solution o Same on both sides, water flows in and out equally o Equilibrium o Net movement = 0 •...
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