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CELL MEMBRANES AND TRANSPORT
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HOW DO CELLS GET NUTRIENTS AND WATER? HOW DO CELLS RELEASE WASTES?
Moving substances across the selectively permeable membrane Selectively permeable = allowing some substances to pass through
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CELL MEBRANE Gatekeeper of the cell
Fence to keep substances not needed out of the cell A fence to move in important substances into the cell CELL MEBRANE
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FLUID MOSAIC MODEL OF CELL MEMBRANE
Composed of proteins, carbohydrates, lipids; proteins move in the membrane; not rigid; flexible
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TYPES OF MOVEMENT OF SUBSTANCES ACROSS THE MEMBRANE
A. PASSIVE TRANSPORT B. ACTIVE TRANSPORT
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PASSIVE TRANSPORT a. Diffusion; b. Osmosis, and
= the movement of molecules across the cell membrane and does not require energy. = dependent on the permeability of the cell membrane. 3 main kinds of passive transport – a. Diffusion; b. Osmosis, and c. Facilitated Diffusion.
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Facilitated diffusion
hill.com/sites/ /student_view0/chapter2/anima tion__how_facilitated_diffusion_works.html . Osmosis hill.com/sites/ /student_view0/chapter2/anima tion__how_osmosis_works.html
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OSMOSIS Net movement of water molecules from an area of high free water concentration ( hypotonic) to an area of less free water concentration ( hypertonic) across a membrane until the concentration of free water is equal on both sides ( isotonic). =results in increase of water level
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OSMOSIS http://www.stjohn.ac.th/Department/school/bio_pix/osmosis.gif
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ACTIVE TRANSPORT Use of energy (ATP) to move substances across the membrane From lower concentration area to high concentration (= against concentration gradient) ml hill.com/sites/ /student_view0/ch apter2/animation/
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ACTIVE TRANSPORT Sodium – potassium pump Endocytosis Exocytosis Phagocytosis
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CELL MEMBRANE http://www.johnkyrk.com/cellmembrane. html
02_int_membraneweb/ enceWork/CellsOrganization.htm CELL MEMBRANE
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http://www.williamsclass.com/SeventhSci enceWork/CellsOrganization.htm
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