Slide 1Slide 2The phospholipid bilayer is a dynamic structureHow do molecules move across the membrane?DiffusionOsmosisSlide 7Effect of tonicity on the cellSlide 9Plant Cells Prefer to Live in a Hypotonic EnvironmentOsmosisSome important termsMembrane proteins and the fluid mosaic modelSlide 14Slide 15Slide 16How do membrane proteins affect ions and molecules?Let’s see again what happens to ions in the membrane bilayerSlide 19Slide 20Passive and facilitated diffusionCarrier ProteinsActive TransportActive TransportCotransportActive Transport and PumpsSummary of Mechanisms of membrane transportThe Cell Membrane1Movement of molecules and ions across the cell membraneDiffusion, osmosis, tonicity.2The phospholipid bilayer is a dynamic structure•The movement and fluidity of the bilayer is affected by temperature and the composition of the membrane. 3How do molecules move across the membrane?•Solvent- the substance in which the solute dissolves; it is usually found in a larger quantity.•Solute- the component in a solution which changes state upon dissolving; it is found in a smaller quantity.•Concentration gradient- the difference in solute concentration between two areas4DiffusionDiffusion- spontaneous movement of molecules from an area of high concentration to low concentration (i.e., down a concentration gradient).5Osmosis67Effect of tonicity on the cell89Plant Cells Prefer to Live in a Hypotonic Environment10Osmosis•Is the diffusion of water across a selectively permeable membrane from a region of high water concentration (low solute concentration) to a region of low water concentration (high solute concentration).11Some important terms •Hypotonic- In comparing two solutions, referring to the one with the lower solute concentration (thus, higher water concentration).•Hypertonic- In comparing two solutions, referring to the one with the higher solute concentration (thus, lower water concentration).•Isotonic- Having the same solute concentration (thus, same water concentration) as another solution.12Membrane proteins and the fluid mosaic model131415The role of proteins in the movement of ions and other molecules.Facilitated diffusion16How do membrane proteins affect ions and molecules?•Researchers have identified three broad groups of transmembrane proteins.–Channel proteins–Transporters –pumps17Let’s see again what happens to ions in the membrane bilayer18Membrane channel protein are highly selective and highly regulated19Membrane channel protein are highly selective and highly regulated. (second example)20Passive and facilitated diffusion•Passive transport:– is produced by diffusion along an electrochemical gradient.– doesn’t require an expenditure of energy.•Facilitated diffusion:– is the passive transport of substances that otherwise would cross a membrane.21Carrier Proteins22Active Transport•The movement of substance across a cell membrane against the concentration of an electrochemical gradient.–with an expenditure of energy (ATP)–specific transport molecules23Active Transport24Cotransport255. Unbound protein6. Potassium binding7. Shape change8. ReleaseActive Transport and Pumps•The movement of substance across a cell membrane against the concentration of an electrochemical gradient.–with an expenditure of energy (ATP)–specific transport molecules26Summary of Mechanisms of membrane
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