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Cell Membranes Osmosis and Diffusion

Cell Membranes Osmosis and Diffusion. This Powerpoint is hosted on www.worldofteaching.com Please visit for 100’s more free powerpoints. Functions of Membranes. 1. Protect cell 2. Control incoming and outgoing substances 3. Maintain ion concentrations of various substances

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Cell Membranes Osmosis and Diffusion

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  1. Cell MembranesOsmosis and Diffusion This Powerpoint is hosted on www.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 • Selectively permeable - allows some molecules in, others are kept out • 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. Fluid Mosaic Model of the cell membrane Polar heads love water & dissolve. Membrane movement animation Non-polar tails hide from water. Carbohydrate cell markers Proteins

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

  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. Simple Diffusion Animation 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

  11. Passive Transport: Osmosis Osmosis animation • 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.

  12. Osmosis

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

  14. Plant and Animal Cells put into various solutions

  15. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions 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)!

  16. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions 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) shrinks Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)!

  17. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions 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)

  18. Types of Transport

  19. Passive Transport: Facilitated Diffusion A B Facilitated diffusion: diffusion of specific particles through transport proteins found 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 • http://bio.winona.edu/berg/Free.htm

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

  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

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