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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 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 Active Transport Movement of molecules across a semi-permeable membrane against a concentration gradient with a protein ENERGY required

5 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) 2 3 1 4

6 Equilibrium Reached Low Concentration High Concentration

7 Osmosis [concentration]
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 Osmosis Sucrose will not move but water will

10

11 Dialysis Bag Experiment
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 Iodine Glucose Starch Dialysis bag

12 Osmosis in Living Cells
Cellulose in cell wall plasmolyzed flaccid Normal turgid

13 RED BLOOD CELLS

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

15 Recall the Cell Membrane

16 Proteins in the Plasma (cell) Membrane

17 Proteins are Specific to certain Solutes

18 Active Transport

19 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.

20 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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