2 Cell Barriers Cell membranes Structure: contain a flexible lipid bilayer with imbedded protein molecules and carbohydrate moleculesFunction: Substances move across the cell membrane throughA.) lipid bilayerB.) protein channelsC.) assistance of proteinmoleculesD.) Processes of endocytosisand exocytosis
3 Cell Barriers Cell Walls Structure: made mostly of tough carbohydrate fiber called celluloseFunction: Cell walls support and protect cells; cell walls are porous and allows substances to move through easily
4 Types of Movement Through Cells A.) Diffusion B.) Osmosis C.) Facilitated Diffusion D.) Active Transport
5 DiffusionSubstances move across the cell membrane from areas of high solute concentration to areas of low solute concentration until equilibrium is reachedNo energy requiredSubstances continue to move back and forth across the membrane once equilibrium is reached
6 Osmosis The diffusion of water across a cell membrane Types of osmotic solutionsHypotonicIsotonicHypertonic
7 ConcentrationConcentration of a solution is the mass of solute in a given volume of solution, or mass/volume A Solute is a substance that is dissolved in a solvent to make a solution
10 Hypotonic SolutionAnimal Cellthe solution has a lower solute concentration than the cell so water moves into the cell causing plant cells to swell and animal cells to swell and burstLower solute concentration outside cellLower solute concentrationPlant CellLower solute concentration outside cell
11 Isotonic SolutionAnimal CellThe concentration of solutes is equal inside and outside the cell so water moves across the membrane in both directions maintaining cell sizeEqual solute concentration inside and outside cellPlant CellEqual solute concentration inside and outside cell
12 Hypertonic SolutionAnimal CellThe solution has a higher solute concentration than the cell so water moves out of the cell and into the solution causing the cell to plasmolyzehigher solute concentration outside cellPlant Cellhigher solute concentration outside cell
14 Facilitated Diffusion A) Substance specific protein channels allow movement of molecules such as glucose to move across the membrane in either directionB) Substances still move high concentration to low concentration and no energy is required
15 REMEMBER: Requires ATP Energy! Active Transport Characteristics: Movement of substances is against the concentration gradientEnergy is required !Types of Active TransportMolecular transportEndocytosisExocytosisREMEMBER:Requires ATP Energy!
16 Active Transport – Molecular Transport Molecular transport: Protein molecules act like energy requiring pumps to move molecules and ions across membranes
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