17 Sept

1. 17 Sept • Opener: • What does it mean for a molecule to be polar? • Agenda • Talk about test • Water Stations • Whiteboard Presentations? • Homework • Section 2.8 + gqs

5. 18 Sept • Opener • Which is stronger, a covalent bond, or a hydrogen bond? • What is the difference between the everyday term “theory” & “Scientific Theory” ? • Agenda • Review Water • Unit 2 notes • Homework • Section 3.3 +gqs

6. Today’s terms… Scientific Law = Scientific Theory = 1st law of Thermodynamics = 2nd law of Thermodynamics= Equilibrium = Homeostasis = Diffusion = Osmosis =

7. Scientific Law A description of an observed phenomenon (A statement of what happens) Has no known exception Example: Law of Gravity

8. Scientific Theory A scientific explanation of an observed phenomenon. (explains how something works) Well-documented, well-supported Ties together all the facts about something Example: atomic theory

9. Thermodynamics Law 1 Energy can’t be created or destroyed, but it can be transferred into another form…

10. Thermodynamics Law 2 • Entropy – Energy disperses, leading things to become more disordered and random • This would seem like life would, therefore, become less organized • BUT – Since the Sun is constantly adding energy to our Earth, the dispersed energy (heat) is replaced with new energy (photons) which allow life to occur

11. Homeostasis • Living things need homeostasis, not equilibrium • Homeostasis: Keeping internal conditions constant • Body temperature • Blood glucose levels • Water levels • Mineral, vitamin, electrolyte concentrations

12. Diffusion:The spontaneous movement of a substance from an area of high concentration to an area of low concentration • Osmosis: The diffusion of water • This isn’t always a good thing for living systems…

13. What are they like at the tops of hills? What are they like at the bottom of hills? As the boxes “lose” energy, what happens to the boxes? What does “life” do to the boxes?

14. Equilibrium vs. Homeostasis • TPS: Contrast these terms in your own words • Thought Q: • If equilibrium naturally occurs in non-living systems, what allows living systems to reach homeostasis, essentially often fighting against equilibrium? • Closing Q: • How is equilibrium similar to entropy?

15. 19 Sept • Opener • How does life “get around” the 2nd Law of thermodynamics ? • Agenda • Cell Membrane Structure • Diffusion/Osmosis • Diffusion Lab • Homework • none

16. Cell Membranes& Movement Across Them

17. Building a membrane • How do you build a barrier that keeps the watery contents of the cell separate from the watery environment? FATS LIPIDS Remember: oil & water don’t mix!!

18. inside cell outside cell Lipids of cell membrane • Membrane is made of special kind of lipid • phospholipids • “split personality” • Membrane is a double layer • phospholipid bilayer “attracted to water” phosphate lipid “repelled by water”

19. Semi-permeable membrane • Cell membrane controls what gets in or out • Need to allow some materials — but not all — to pass through the membrane • semi-permeable • only some material can get in or out So what needs to get across the membrane? lipids aa O2 H2O salt sugar waste

20. inside cell outside cell Crossing the cell membrane • What molecules can get through the cell membrane directly? • fats and oils can pass directly through lipid salt waste but… what about other stuff? sugar aa H2O

21. Protein channels • Proteins act as doors in the membrane • channels to move specific molecules through cell membrane HIGH LOW

22. Movement through the channel • Why do molecules move through membrane if you give them a channel? HIGH ? LOW ?

23. Molecules move from high to low • Diffusion • move from HIGH to LOW concentration

24. Diffusion • Move from HIGH to LOW concentration • passive transport • no energy needed diffusion of water diffusion osmosis

25. Diffusion • Move from HIGH to LOW concentration • directly through membrane • simple diffusion • no energy needed • help through a protein channel • facilitated diffusion (with help) • no energy needed HIGH LOW

26. Active transport • Cells may need molecules to move against concentration “hill” • need to pump “uphill” • from LOW to HIGHusing energy • protein pump • requires energy • ATP ATP

27. Transport summary simplediffusion facilitateddiffusion ATP activetransport

28. 20 Sept • Opener • Why do your hands get wrinkly after being in water for a while ? • Agenda • Talk about agar lab • Osmosis notes • Osmosis Lab • Homework • none

29. OsmosisMovement of Water Across Cell Membrane

30. Osmosis • Water is very important, so we talk about water separately • Osmosis • diffusion of water from HIGH concentration of water to LOW concentration of water • across a semi-permeable membrane

31. Keeping water balance • Cell survival depends on balancing water uptake & water loss freshwater balanced saltwater

32. 1 Keeping right amount of water in cell • Freshwater • a cell in fresh water • high concentration of water around cell • cell gains water • example: Paramecium • problem: cells gain water,swell & can burst • water continually enters Paramecium cell • solution: contractile vacuole • pumps water out of cell freshwater

33. Controlling water • Contractile vacuole in Paramecium

34. 2 Keeping right amount of water in cell • Saltwater • a cell in salt water • low concentration of water around cell • cell loses water • example: shellfish • problem: cell loses water • in plants: plasmolysis • in animals: shrinking cell • solution: take up water saltwater

35. 3 Keeping right amount of water in cell • Balanced conditions • no difference in concentration of water between cell & environment • cell in equilibrium • example:blood • problem: none • water flows across membrane equally, in both directions • volume of cell doesn’t change balanced

36. 21 Sept • Opener • What type of osmotic problems does this barracuda have? • Agenda • Plasmolysis • Osmosis Worksheet/ Whiteboard • Participation Quiz • Introduce potato lab • Homework • none – potato lab tomorrow

37. Participation Quiz • Living things tend towards which state: equilibrium or homeostasis? • A scientific __________ is a well-documented, well-supported explanation of how something works. • Fill in the missing parts of the 1st law of thermodynamics: Energy can’t be or , but it can be . • Define diffusion: • What is required in order to move a substance from low concentration to high concentration(uphill)?

38. 24 Sept • Opener • You have a small balloon that is made with a semi-permeable membrane (let’s say water can move in and out but sugar can’t). You add pure water into the balloon, then place the balloon into a beaker that contains a Kool-aid (sugar+water). Which way will water flow: IN or OUT of the balloon? Will the mass of the balloon, therefore, get BIGGER or SMALLER? Explain. • Agenda • Set-up potato lab • Homework • none

40. The Potato Challenge Intro: Finding a food source that is easy to grow and high in nutrition is a high priority for scientists who hope to alleviate hunger in poorer countries. Your challenge: Determine the sucrose levels in potatoes to determine if they would be a good option for this purpose.

41. The Potato Challenge Design an experiment to determine sucrose levels in potatoes. Write your procedures step by step. Also, explain how you’ll be able to use your data to infer the sucrose levels in potatoes. You will be given: • 10 potato pieces • Sucrose solutions: OM, 0.2M, 0.4M, 0.6M, 0.8M • Digital balance • 5 cups

42. 25 Sept • Opener • Why is it important to graph the % change in potato pieces instead of the actual change? • Agenda • Finish potato lab • Homework • none

43. Calculate the % change • % Change change in mass of pieces = ----------------------------------- x 100 initial mass

44. 26 Sept • Opener So, how did you figure out the approximate sucrose concentration in the potato? • Agenda • Wrap-up Potato Lab • Study Guide for formative tomorrow • Homework • Study! • Quiz Tomorrow

45. 27 Sept • Opener • Agenda • Formative Quiz 1 • Homework

46. 28 Sept • Opener • Agenda • Movie Day • Homework • None

47. 1 Oct • Opener • What do you know about Proteins? • Agenda • Intro Proteins • Homework • 3.1

48. Proteins

49. What do you know about proteins?

50. Protein Structure • Made of long chains of amino acids… Amino Acid