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Transport through the Cell Membrane

Transport through the Cell Membrane. Passive Transport. Movement across a cell membrane that does not require energy 2 examples: Diffusion Osmosis. Diffusion. Movement of a substance from areas of higher concentrations to areas of lower concentrations Ex. Food coloring in water.

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Transport through the Cell Membrane

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  1. Transport through the Cell Membrane

  2. Passive Transport • Movement across a cell membrane that does not require energy • 2 examples: • Diffusion • Osmosis

  3. Diffusion • Movement of a substance from areas of higher concentrations to areas of lower concentrations • Ex. Food coloring in water

  4. Concentration Gradient • Difference in the concentration of a substance

  5. Equilibrium • Concentration of a substance is equal throughout an area

  6. Facilitated Diffusion • Type of passive transport that uses proteins to move substances down their concentration gradient. • Ex: There are specific proteins that help move sugars into the cell

  7. Ion Channels

  8. Osmosis • Diffusion of water • http://www.watchknow.org/Video.aspx?VideoID=5165 - Osmosis in lettuce • Why should you gargle with salt water when you have a sore throat?

  9. Answer • Pain caused by swelling of throat tissues (these contain water) • Salt water has a lower concentration of water than the throat tissues. • When a person gargles with salt water, the water from the throat tissues moves to the salt water. • Loss of water from throat tissue results in less swelling and pain.

  10. Question • Why do plants along side of the road die after a winter where roads were heavily salted? Explain in terms of osmosis.

  11. Answer • The higher than normal amount of salt in the plants’ environment causes their cells to lose water through osmosis. • Their leaves begin to look they have been through a very hot, dry summer. • Eventually the plants die because they do not have enough water to live.

  12. Question • Why do wooden drawers of a dresser become sticky after a rain storm or a high humidity day? Explain in terms of osmosis.

  13. Answer • On very wet days, wooden drawers in dressers absorb water from the air because of osmosis. This absorption warps the wood, making the opening and closing of drawers difficult. In drier weather water is lost from the wood, and the drawers return to their normal size.

  14. Movement of Water • Solute: the substance that is dissolved in a solution, the smaller amount. • Solvent: dissolves the solute in a solution, the larger amount • Ex: Make a solution of saltwater. • Solute: Salt • Solvent: Water Water is the universal solvent.

  15. Hypertonic solution: solution is more concentrated (more solute), water moves out of the cell

  16. Hypotonic solution: solution has a lower concentration (less solute) water moves into the cell

  17. Isotonic: concentration is equal (equal amts of solute), no water movement

  18. Questions • Why are green leafy vegetables sprinkled with water at the supermarket? • Why is salt sometimes used to preserve food? • Why should you not drink sea water?

  19. Answers • This prevents them from wilting due to water loss • Because a salt solution is hypertonic , the microorganisms present on the foods shrink and die. • Sea water contains high concentrations of solutes. Cells in the body lose water because of osmosis, possibly causing death.

  20. http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.htmlhttp://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.html

  21. Active Transport Chapter 4.2

  22. Active Transport • Transport of substances against their concentration gradient, uses energy • Energy is in the form of ATP • Adenosine Triphosphate • Carrier proteins help move substances

  23. Sodium-Potassium Pump • Transports sodium and potassium Ions against their concentration gradient

  24. Chapter 4 Cells and Their Environment Sodium-potassium pump pumps three pumps two sodium ions potassium ions out of the cell into the cell

  25. Sodium Potassium Pump • http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120068/bio03.swf::Sodium-Potassium%20Exchange%20Pump

  26. Movement in Vesicles • Many substances, such as proteins and polysaccharides, are too large to be transported by carrier proteins. • These substances are moved across the cell membrane by vesicles.

  27. Movement in Vesicles • Endocytosis: movement of a substance into the cell. • Cell membrane forms a pouch and pinches off • Exocytosis: movement of a substance out of the cell • Vesicles fuse with the cell membrane and empty their contents outside the cell.

  28. Endocytosis

  29. Exocytosis

  30. Review of Cell Processes • http://highered.mcgraw-hill.com/olc/dl/120068/bio02.swf Exo and Endo animation • http://www.classzone.com/cz/books/bio_07/get_chapter_group.htm?cin=2&rg=animated_biology&at=animated_biology&var=animated_biology • http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.html

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