Diffusion and Osmosis

1. Diffusion and Osmosis

2. 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)

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

4. 2 1 1 3 6 4 5 Diffusion Rates of Various Dyes • How do different MW solutions migrate through a colloid? • Colloid – suspension of large, insoluble particles in a fluid medium • Agar plate • Measure the rate of diffusion of various dye (differ in MW) • Measure diameter at T90 (minutes) • 3 known(s) (crystal violet, malachite green, potassium permanganate) • 3 unknowns Part 1 pg. 82

5. Effect of Water on Cells • Hypertonic Environment • High [solute], low [water] • Hypotonic Environment • High [water], low [solute] • Isotonic Environment • [water] = [solute] Hypertonic Hypotonic Isotonic Part 3 pg. 85

6. Cellulose in cell wall Osmosis in Living Cells

7. Isotonic Predictions? Hypertonic Hypotonic Osmosis in Red Blood Cells • Observe sheep RBCs via a wet mount of the sample • Aliquot one drop the following solutions with a ½ drop of RBC to a slide • 0.9% saline • 10% NaCl • Distilled water • Record observation in the table on page 85 Crenation

8. Hypertonic Predictions? Hypotonic Osmosis in Plant Cells Plasmolysis • Observe Elodea leaves via a wet mount of the sample • Aliquot two drops the following solutions with a new Elodea leaf to a slide. Incubate for 10 minutes @ room temp. • 10% NaCl • Distilled water • Record observation in the table on page 85

9. Animations Dialysis Bag Experiment • http://ccollege.hccs.cc.tx.us/instru/Biology/AllStudyPages/Diffusion_Osmosis/Baggif.swf Elodea Cell • http://ccollege.hccs.cc.tx.us/instru/Biology/AllStudyPages/Diffusion_Osmosis/Elodeagif.swf Osmosis • http://ull.chemistry.uakron.edu/genobc/animations/osmosis.mov

10. Transportation of Molecules • Passive Transport • Movement of molecules across a semi-permeable membrane • no energy required • Active Transport • Movement of molecules across a semi-permeable membrane against a concentration gradient with a protein • ENERGY – ATP • Facilitated Diffusion • Movement of molecules across a semi-permeable membrane with a protein • no energy required

11. Effect of Water on RBC