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Bellringer

Bellringer. List the two things that make up the cell membrane. What does it mean to be selectively permeable?. From the lab, Order of the items…. Biggest: ? Smallest: ? Where do the pores fit in?. Sizes of Molecules…. Water (H 2 O) Iodine (I 2 K) Glucose (C 6 H 12 O 6 )

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Bellringer

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  1. Bellringer • List the two things that make up the cell membrane. • What does it mean to be selectively permeable?

  2. From the lab, Order of the items… • Biggest: ? • Smallest: ? • Where do the pores fit in?

  3. Sizes of Molecules… • Water (H2O) • Iodine (I2K) • Glucose (C6H12O6) • Food Coloring (~450 atoms) • Starch (~1000 atoms) So…how big are the pores of the membrane? Make an estimate (with an explanation) on the back side of your questions!!!

  4. Fluid Mosaic Model • http://www.susanahalpine.com/anim/Life/memb.htm • http://www.youtube.com/watch?v=ULR79TiUj80

  5. Role of the membrane? • Selective permeability

  6. Roles of the membrane proteins • Move stuff across the membrane that can’t get across on its own • Recognition – like nametags • Receptors – trigger cellular responses • Enzymes

  7. How does the membrane regulate movement of molecules? • It’s structure dictates!!

  8. Cell Transport

  9. Cell Membrane • Cell Membrane Animation • Made of phospholipids and proteins • Molecules move into and out of a cell through the cell membrane • The cell membrane is selectively permeable • How certain molecules move through the cell is called cell transport • Passive Transport • Active Transport

  10. Questions • What happens when you spray air freshener or perfume? • What happens when you put food coloring in water? • THIS IS DIFFUSION!!!! Diffusion is also one way things are transported across the cell membrane

  11. What is concentration? • Amount of solute in a certain amount of solvent…think about kool-aid… • Solvent – what does the dissolving (liquid) • Solute – what is dissolved in the solvent • Which is more concentrated?

  12. Passive Transport • Particles move from high concentration to low concentration • Does NOT require extra cell energy • Includes simple diffusion, osmosis, facilitated diffusion

  13. SIMPLE DIFFUSION • Movement of molecules from areas of high concentration to areas of low concentration • Does not require energy (PASSIVE) • Because molecules are in constant, random, motion! • Will diffuse until reaches equilibrium (equal concentrations) • Dynamic equilibrium (still moving!)

  14. Diffusion Dynamic Equilibrium

  15. For lab… • To the tube, add: • Glucose solution • Starch • To the beaker, add: • Water • Iodine

  16. Make a hypothesis…. • Will the glucose move? Which way? Why or why not? • Will the iodine move? Which way? Why or why not? • Will the starch move? Which way? Why or why not?

  17. Flea Diffusion Analogy

  18. Flea Diffusion Analogy

  19. Flea Diffusion Analogy

  20. Dynamic Equilibrium

  21. Simple Diffusion in Cells Diffusion Animation Diffusion Across a Membrane

  22. PROBLEM BREAK

  23. OSMOSIS • The diffusion of water across a membrane from an area of high concentration to low concentration • No energy required (PASSIVE TRANSPORT) • Occurs until reaches DYNAMIC EQUILIBRIUM • Equal concentrations on both sides of the membrane

  24. Tonicity of solutions • Used to compare the relative concentrations • Hypertonic • solution with a higher concentration of solute • So lower water concentration • Hypotonic • solution with a lower concentration of solute • So higher water concentration • Isotonic • solutions with equal concentrations of solute • Water diffuses from hypotonic solutions to hypertonic solutions!

  25. http://www.linkpublishing.com/video-transport.htm#Brownian_Movementhttp://www.linkpublishing.com/video-transport.htm#Brownian_Movement What About Cells?

  26. Cells in Hypertonic Solution HYPERTONIC • Water moves out of the cell • Cell shrivels Low Hi

  27. Hypotonic Solution • Water moves into the cell • Cell swells • Animal cell – can burst • Plant cell – builds up pressure on cell wall, but rigid cell wall keeps it from bursting HYPOTONIC Hi Lo

  28. Isotonic Solution • Water moves in and out of the cell • Cell stays the same size • Dynamic Equilibrium ISOTONIC

  29. Osmosis Animations http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

  30. What happens to slugs in salt? • Dead bodies in the river?

  31. FRAYER MODEL BREAK! Draw example define Passive transport Explain your example Does it require energy? Examples

  32. Starter • Consider the following information: • Water, oxygen, and CO2 all readily move across a membrane • Glucose, proteins and small ions (like Na+ or Cl-) cannot pass on their own • Considering this information, devise a rule that describes what CAN and CANNOT pass through the membrane via SIMPLE DIFFUSION

  33. Pumping Water • Some organisms have vacuoles that pump out excess water that enters the cell • Too much water in the cell = vacuole works hard pumping out water! • http://www.linkpublishing.com/video-transport.htm#Brownian_Movement

  34. FACILITATED DIFFUSION • Particles move from high concentration to low concentration • No energy needed (PASSIVE) • Cells use proteins to “help” • Transport Proteins • Channel proteins http://www.stolaf.edu/people/giannini/biological%20anamations.html

  35. FRAYER MODEL BREAK! Draw example define Facilitated Diffusion Explain your example Does it require energy?

  36. Review passive transport

  37. Active Transport • Particles move from low concentration to high concentration (against the concentration gradient) • DOES REQUIRE ENERGY!! • Requires transport proteins • Includes pumps, endocytosis, exocytosis, etc.

  38. The sodium-potassium pump • Active Transport = requires energy! • Sodium is pumped out • Potassium is pumped in • Animation

  39. Active transport • Examples: Pumping Na+ (sodium ions) out and K+ (potassium ions) in against strong concentration gradients. • Called Na+-K+ Pump

  40. Sodium-Potassium Pump 3 Na+ pumped in for every 2 K+ pumped out; creates a membrane potential

  41. Pumps • Some animals use salt pumps to maintain a constant concentration of salt in their bodies • This requires energy! ACTIVE TRANSPORT!

  42. Pom-Pom Potential • Modeling passive and active transport along a cell membrane in a NERVE CELL • What do nerves do? • How do they do it?

  43. Questions • How did this activity model passive transport? • How did this activity model active transport? • Why do the membranes “work” to keep the charges on either side of the membrane “balanced”?

  44. FRAYER MODEL BREAK! Draw example define Active transport Explain your example Does it require energy? Examples

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