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Transport of Molecules in a Cell

Transport of Molecules in a Cell. Terms to Know. SOLUTE: refers to the substance that is to be dissolved (Salt, Sugar) SOLVENT : responsible for dissolving the solute (Water) SOLUTION : Solvent and solute after combining together ECF : Extracellular Fluid. Surrounds all living cells

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Transport of Molecules in a Cell

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  1. Transport of Molecules in a Cell

  2. Terms to Know • SOLUTE: refers to the substance that is to be dissolved (Salt, Sugar) • SOLVENT: responsible for dissolving the solute (Water) • SOLUTION: Solvent and solute after combining together • ECF: Extracellular Fluid. Surrounds all living cells • CONCENTRATION: mass of solute dissolved in the solvent • SEMI-PERMEABLE (SELECTIVELY-PERMEABLE): a membrane that allows only some substances in or out

  3. Selectively Permeable Membrane

  4. Active Transport Movement of molecules across a semi-permeable membrane against a concentration gradient with a protein ENERGY required Transportation of Molecules • Passive Transport • Movement of molecules across a semi-permeable membrane with the gradient • 3 types: Osmosis,Diffusion + • Facilitated Diffusion • Movement of molecules across a semi-permeable membrane with a protein • NO ENERGY required

  5. 1 4 2 3 Diffusion • Solute molecules moving from an area of high concentration to an area of low concentration • Random motion drives diffusion • Movement is based on kinetic energy (speed), charge, and mass of molecules • Equilibrium is reached when there is an even distribution of solute molecules (water)

  6. Equilibrium Reached Low Concentration High Concentration

  7. Osmosis • Diffusion of water through a semi-permeable membrane • Permeable to solvents (WATER), but not to large molecules • High [water] to low [water] [concentration] • Dissolved molecules (i.e. glucose, starch) are called solutes • REMEMBER: Water = solvent Glucose, Starch, Salt = solutes

  8. Effect of Water on Cells • Hypertonic Environment • High [solute], low [water] • Isotonic Environment • [water] = [solute] • Hypotonic Environment • High [water], low [solute]

  9. OsmosisSucrose will not move but water will

  10. Dialysis bag Glucose Iodine Starch Dialysis Bag Experiment • Dialysis Bag • Semi-permeable membrane • Water, glucose, & starch • What passes through the dialysis bag? • Glucose (Benedict’s Test) • Starch (Iodine Solution) • Time Course Experiment • Every 10 minutes, measure the amount of glucose & starch present in the beaker

  11. Cellulose in cell wall Osmosis in Living Cells plasmolyzed flaccid Normal turgid

  12. RED BLOOD CELLS

  13. Hypertonic Hypotonic Osmosis in Plant Cells Plasmolysis • Observe Elodea leaves via a wet mount of the sample • 10% NaCl • Distilled water

  14. Recall the Cell Membrane

  15. Proteins in the Plasma (cell) Membrane

  16. Proteins are Specific to certain Solutes

  17. Active Transport

  18. ENDOCYTOSIS The general term for bringing bulk chemicals into a cell is endocytosis (endo = inside); the general term for bringing bulk chemicals out of a cell is exocytosis (exo=outside). Moving material into the cell by endocytosis involves the pinching in of a portion of the cell membrane around the material to be transported into the cell. The pinched-in portion eventually breaks free from the cell membrane and forms a vesicle in the cytoplasm.

  19. Homework • Complete your Cheek Cell & Elodea Cell mini-lab • Study for your Microscope quiz • Answer questions on p.25 Q.1-19  Next topic: Cell cycle & cell division

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