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Designing Model Membranes

Designing Model Membranes. Day 2: Nature of Science and Engineering NSE 3-6 MSTP Region 11 Teacher Center Today’s Trainers: Tamara Moore and Selcen Guzey. Engineering Design. Goals 1. Teachers will connect engineering activities across the standards.

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Designing Model Membranes

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  1. Designing Model Membranes Day 2: Nature of Science and Engineering NSE 3-6 MSTP Region 11 Teacher Center Today’s Trainers: Tamara Moore and Selcen Guzey

  2. Engineering Design Goals 1. Teachers will connect engineering activities across the standards. 2. Teachers will experience an integrated engineering and life science lesson

  3. Agenda • Engineering Standards • Engineering is Elementary (EiE) • Just Passing Through: Designing Model Membranes • Correlating the EiE unit to State Standards

  4. Connecting to the Standards • What standards were covered in the “save the penguins” activity? • How well did this activity address the engineering standards? Which specific standards were addressed?

  5. Connecting to the Standards

  6. Connecting to the Standards

  7. Connecting to the Standards Nature of Science & Engineering

  8. Pre-Assessment • Complete Pre-test

  9. EiE-Engineering is Elementary EiE was developed by the Museum of Science in Boston in 2003. Funded by NSF grant. • Integrate engineering and technology into science lessons that you currently teach. • Does not explicitly teach the science, adds on to deepen knowledge by combining one field of engineering with science content. • The units are not built upon each other; so they can be taught as a stand alone or in any order. • http://www.mos.org/EiE

  10. EiE-Engineering is Elementary The main goal of EiE: • Increase children’s technological literacy. • Increase elementary educators’ abilities to teach engineering and technology to their students. • Modify the educational systems to include engineering at the elementary level. • Conduct research and assessment to further the first three goals and contribute knowledge about engineering teaching and learning at the elementary level.

  11. An Overview of EiE Kits for grade 3-5

  12. EiE Story Books

  13. Teacher Guide Each EiE Unit includes: • Lesson plans • Duplication Masters (e.g., student handouts) leveled for Basic and Advanced abilities. • Assessment materials • References for background resources

  14. Teacher Guide Structure • Overview • Prep Lesson • Lesson 1: Engineering Story • Lesson II: A broader view of an engineering field • Lesson III: Scientific data inform engineering design • Lesson IV: Engineering design challenge • Assessment

  15. More on EiE Story books: $6.99 Teacher guides: $45 Materials kits: most around $300 EiE Educator Resources: search for content connections, multimedia tools, and supporting documents

  16. Technology in a Bag Activity • In your group, discuss what comes to mind when you hear the word “technology.” • Come and grab your mystery bag! • Identify a technology in your bag! • What material is it made of? • What problem does it solve? • How else could you use it? • What other materials could it be made of?

  17. Overview of “Just Passing Through: Designing Model Membranes” 1. Juan Daniel’s Futbol Frog (Prep: 10-15 min., lesson: 90-120 min.) 2. Biology Meets Technology (Prep: 10-25 min., lesson: 45-50 min.) 3. Exploring Membranes (Part I: Prep: 10-15 min., lesson: 45-50 min., Part II: Prep: 15-20 min., lesson: 55-60 min.) 4. Designing Model Membrane (Part I: prep: 10-15 min. lesson: 55-60 min., Part II: prep: 10-15 min. lesson: 45-50 min.)

  18. Lesson I: Story of Juan Daniel’s Futbol Frog Goals of the Story Book: • The story presents context for relevant science content and engineering design challenge. • It introduces science and engineering vocabulary and field of engineering.

  19. Story of Juan Daniel’s Futbol Frog Read the story and then answer the following questions individually: • What part of the story did you like most? • Why was it important that Juan Daniel learn about membranes and how they work? Share your responses with someone next to you!

  20. Kristin Peters, the Bioengineer What does Kristin Peters do? • As a team discuss about bioengineering and the roles of bioengineers.

  21. Bioengineering Many bioengineers , instead of creating new devices or materials, focus on learning just how that living tissue work. UCSD senior Lisa Serventi (pictured left) works in a lab studying the fluid that lubricates joints, figuring out how different molecules in the fluid help to lower friction.

  22. Engineering Design Cycle • What process did Ms. Peters teach Juan Daniel about to help him solve his problem?

  23. Introducing the EDP • Individually complete the “Juan Daniel and the Engineering Design Process” worksheet.

  24. Lesson II: Biology Meets Technology Guiding question: How do bioengineers use natural objects to inspire human-made technologies? 1) As a team discuss the following questions: • What technology did Juan Daniel design? • What inspired his design? 2) Card game time!!! 3) Individually complete the “Technology Match-up worksheet.”

  25. Membrane • Why is it important for Juan Daniel to keep his frog’s skin moist? • When Juan Daniel sees the waterfall, what does he realize about his design? • Why can’t Juan just fill the bowl with water and leave it covered?

  26. Membrane • As a team define the word “membrane” and discuss how membranes help organisms meet their basic needs. A membrane is a structure that….

  27. Definition • A membrane is a structure that organizes and maintains cells as separate and distinct molecular environments.

  28. Membrane All cells are surrounded by a cell membrane!

  29. Membrane • Epithelial tissue covers all external surfaces, internal cavities, and organs • What are the functions of epithelial tissue? • Protection • Absorption • Secretion

  30. Membrane Models • Simple Epithelium vs. Stratified Epithelium Single layer (frog skin) Multiple layers (human skin)

  31. Lesson III: Exploring Membranes Guiding question: What are some properties of natural membranes and what materials might be good choices for designing a model membrane? Part I: • Raisin demonstration • Egg demonstration • Iodine-cornstarch demonstration

  32. Lesson III: Exploring Membranes • Raisin Demonstration Observing: • Dried raisins • Raisins that have been submerged in water for 24 hours • Raisins that have been submerged in a mixture of sand and water for 24 hours • Raisins that have been submerged in water for 3 hours Documenting: Individually complete the “Exploring Membranes: Raisin Skin” worksheet

  33. Raisin Demonstration • What are your observations of the soaked raisins? • Why do the raisins swell when soaked in water? • Raisin skin acts as a membrane and allows water to pass through. • How does the water travel across the raisin membrane?

  34. Membrane Structure • All cell membranes share a common structural organization: Bilayers of phospholipids Hydrophilic head Hydrophobic tail The fluid mosaic model by S. J. Singer and G. L. Nicolson (1972).

  35. Membrane Lipids Membrane Lipids are the building blocks of the membrane, they provide the basic structure. Lipids include fat and cholesterol and do not dissolve in water. A phospholipid is a lipid that contains phosphorus. The lipid composition of different cell membranes varies! In addition to the phospolipids, animal cell membranes contain glycolipids and cholesterol.

  36. Passive Transport-Diffusion • Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration.

  37. Diffusion Passive Diffusion: A molecule simply dissolves in the phospholipid bilayer. Direction to transport is determined by the concentrations (number of molecules per unit volume) of the molecule inside and outside. Ex: gases such as oxygen

  38. More on Raisin Demonstration • What will happen when you put a raisin in pure water for 48 hours? • What will happen when you put a fresh grape in salt water? • Membranes have holes that are too small to see! • The high concentration of sugar molecules inside the raisin creates a concentration gradient. Water flows insidewhen the raisin in placed in water. • Membranes control the rate at which things pass through

  39. Osmosis with Egg Step 1: Obtain two eggs and two beakers Step 2: Pour vinegar into each beaker and add one egg to each beaker of vinegar - leave them overnight. Step 3: Remove the eggs and rinse with water and weigh each egg. Step 4: Pour distilled water into the Egg #1 beaker and pour corn syrup into the Egg # 2 beaker Step 5: After 24 hours, observe each egg and measure the mass of each egg. • What is the purpose of step 2? • What do you think Egg #1 will look like at step 5? Why? • What do you think Egg #2 will look like at step 5? Why? • What will be the relative masses of the eggs at step 5?

  40. Osmosis-The diffusion of the water! • Osmosis is the movement of water across the membrane. Although water molecules are polar, they are small enough to pass the membrane! http://www.youtube-nocookie.com/watch?v=sdiJtDRJQEc&feature=related

  41. When you put a cell into a solution 3 things can happen: More water Fewer dissolved substances Less water More dissolved substances

  42. The Cell Membrane is Semipermeable • Only certain molecules can pass through the membrane since it is semipermeable. Small uncharged molecules can diffuse freely through lipid barriers. The bilayer is impermeable to large molecules (e.g., glucose, ions)

  43. Osmosis with Egg What we have learned: • An egg is a large single cell surrounded by membranes that lie just inside the shell. • The egg membrane behaves the same as the raisin membrane • An egg in distilled water will gain water by osmosis (diffusion) • An egg in corn syrup will lose water by osmosis (diffusion) and thus mass and circumference!

  44. Lesson III:Iodine – Cornstarch Demo What happens when iodine and cornstarch mix? • Iodine plus cornstarch is blue in color • What do you think you will observe after six hours? Explain your prediction. Fill cup 1 with cornstarch and then fill a baggie with a mixture of water and a few drops of iodine. Place the bag into cup 1 and wait 6 hours. Fill cup 2 with a mixture of water and iodine and then fill a baggie with a mixture of water and a tablespoon of cornstarch. Place the bag into cup 2 and wait 6 hours.

  45. More on Membrane Structure The cell membrane controls materials going into and out of the cell.

  46. Membrane Proteins Membrane Proteins carry out specific functions. Some of the proteins control the movement of the materials into and out of the cell.

  47. Membrane Proteins Facilitated Diffusion: A molecule is carried by carrier or channel proteins via a concentration gradient. Ex: carbohydrates, amino acids. Channel proteins form open pores Carrier proteins selectively bind the molecules

  48. Transport Across Cell Membranes Passive Transport: The movement of particles across a cell membrane without the use of energy by the cell is called passive transport. Active Transport: A process of transporting particles that requires the cell to use energy is called active transport.

  49. Active Transport • If molecules are transported in an energetically unfavorable direction across membranes this process is called active transport. http://www.youtube-nocookie.com/watch?v=STzOiRqzzL4&feature=related

  50. Iodine/starch Demonstration • What we have learned: • Membranes are semi-permeable – they have small holes and molecules pass through them based on size (and charge). • The cornstarch cannot pass through the holes in the dialysis tube since it is a big molecule. Iodine is a small molecule relative to cornstarch easily pass through the membrane (dialysis tube) • Human engineered structures can behave like cell membranes

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