1. Cell Membranes Osmosis and Diffusion This Powerpoint is hosted on www.worldofteaching.comwww.worldofteaching.com Please visit for 100’s more free powerpoints

2. Functions of Membranes 1. Protect cell 2. Control incoming and outgoing substances 3. Maintain ion concentrations of various substances 4.Selectively permeable - allows some molecules in, others are kept out 5.ALL THIS MAINTAINS HOMEOSTASIS (internal balance)

3. Phospholipid Bilayer

4. Fluid Mosaic Model

5. Methods of Transport Across Membranes 1. Diffusion 2. Osmosis 3. Facilitated Diffusion 4. Active Transport

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

7. Types of Cellular Transport Passive Transport cell doesn’t use energy 1.Diffusion 2.Facilitated Diffusion 3.Osmosis Active Transport cell does use energy 1.Protein Pumps 2.Endocytosis 3.Exocytosis high low This is gonna be hard work!! high low Weeee!! ! Animations of Active Transport & Passive TransportAnimations

8. Diffusion Movement of molecules from an area of high concentration to an area of low concentration. Movement from one side of a membrane to another, un-facilitated

9. Diffusion

10. Passive Transport: Diffusion Diffusion: random movement of particles from an area of high concentration to an area of low concentration. (High to Low) Diffusion continues until all molecules are evenly spaced (equilibrium is reached)-Note: molecules will still move around but stay spread out. http://bio.winona.edu/berg/Free.htm Simple Diffusion AnimationSimple Diffusion Animation

11. Osmosis: diffusion of water through a selectively permeable membrane Water moves from high to low concentrations Water moves freely through pores. Solute (green) too large to move across. Osmosis Osmosis animation Passive Transport: Osmosis

12. Osmosis

13. Tonicity is a relative term Hypotonic SolutionHypotonic Solution - One solution has a lower concentration of solute than another. Hypertonic SolutionHypertonic Solution - one solution has a higher concentration of solute than another. Isotonic SolutionIsotonic Solution - both solutions have same concentrations of solute.

14. Plant and Animal Cells put into various solutions

15. Hypotonic Solution Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water) Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)! Osmosis Animations for isotonic, hypertonic, and hypotonic solutionsOsmosis

16. Hypertonic Solution Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water) Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)! Osmosis Animations for isotonic, hypertonic, and hypotonic solutionsOsmosis shrinks

17. Isotonic Solution Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell. Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium) Osmosis Animations for isotonic, hypertonic, and hypotonic solutionsOsmosis

18. Types of Transport

19. Facilitated diffusion: diffusion of specific particles through transport proteins found in the membrane a.Transport Proteins are specific – they “select” only certain molecules to cross the membrane b.Transports larger or charged molecules Facilitated diffusion (Channel Protein) Diffusion (Lipid Bilayer) Passive Transport: Facilitated Diffusion Carrier Protein AB http://bio.winona.edu/berg/Free.htm

20. High Concentration Low Concentration Cell Membrane Glucose molecules Protein channel Passive Transport: Facilitated Diffusion Go to Section: Transport Protein Through a  Cellular Transport From a- High Low Channel Proteins animationsChannel Proteins

21. Types of Active Transport Endocytosis: taking bulky material into a cell Uses energy Cell membrane in-folds around food particle “cell eating” forms food vacuole & digests food This is how white blood cells eat bacteria!

22. Types of Active Transport Exocytosis: Forces material out of cell in bulk membrane surrounding the material fuses with cell membrane Cell changes shape – requires energy EX: Hormones or wastes released from cell