MOVEMENT OF SUBSTANCES

1. MOVEMENT OF SUBSTANCES DIFFUSION

2. Learning Outcomes After completing this chapter, you will able to : • Define diffusion as the movement of molecules from a region of their higher concentration to a region of their lower concentration down a concentration gradient

3. Surface area : volume ratio Volume = _______ Surface area = ______ Volume : Surface area ratio = ___________ Volume = _______ Surface area = ______ Volume : Surface area ratio = ___________

4. Passive Transport • Cell uses no energy • Molecules move randomly • Molecules spread out from an area of high concentration to an area of low concentration.

5. 3 Types of Passive Transport • Diffusion • Facilitative Diffusion– diffusion with the help of transport proteins • Osmosis – diffusion of water

6. Diffusion Before After Region of high concentration

7. Diffusion of Liquids

8. Diffusion in Life

9. Diffusion of Bromine

10. Diffusion of Bromine

11. Diffusion in Living Organisms • Diffusion • movement from highlow concentration • 2nd Law of Thermodynamicsgoverns biological systems • universe tends towards disorder (entropy)

12. Diffusion in Living Organisms Diffusion is a PASSIVEprocess which means no energy is used to make the molecules move, they have a natural KINETIC ENERGY

13. Cell Membrane Structure of cell membrane Lipid Bilayer-2 layers of phospholipids • Phosphate head is polar(water loving) • Fatty acid tails non-polar(water fearing) • Proteins embedded in membrane Phospholipid Lipid Bilayer

14. Fluid Mosaic Model of the cell membrane Polar heads love water & dissolve. Non-polar tails hide from water. Carbohydrate cell markers Proteins

15. Structure of the Cell Membrane Outside of cell Carbohydrate chains Proteins Lipid Bilayer Transport Protein Phospholipids Inside of cell (cytoplasm) Go to Section:

16. Cell Membrane is Selectively Permeable

17. inside cell outside cell Diffusion Through PhospholipidBilayer • What molecules can get through directly? • fats & other lipids • What molecules can NOT get through directly? • polar molecules • H2O • ions • salts, ammonia • large molecules • starches, proteins lipid salt NH3 sugar aa H2O

18. Passive Transport: Facilitated Diffusion Glucose molecules Cellular Transport From a- High High Concentration Cell Membrane Low LowConcentration Protein channel Transport Protein Through a 

19. Passive Transport: Facilitated Diffusion A B Facilitated diffusion: diffusion of specific particles through transport proteinsfound in the membrane • Transport Proteins are specific– they “select” only certain molecules to cross the membrane • Transports larger or charged molecules Facilitated diffusion(Channel Protein) Diffusion (Lipid Bilayer) Carrier Protein

20. Diffusion in Living Organisms Diffusion of digested food through the cell lining the small intestine and into the blood Diffusion of oxygen into a root hair cell

21. Summary No energy needed Passive transport Molecules move from area of high to low concentration Diffusion is a passive transport Diffusion in living organism Across cell membrane