2. 2006-2007 http://www.simpletruths.tv/store/movies.php?movie=race

3. Homeostasis Maintaining a balance of conditions within the cell (or organism). maintaining pH (cells need pH of 6.8-7.2) Neutral pH Scale Acid Base 1 2 3 4 5 6 7 8 9 10 11 12 13 14 most cells Lemon juice Soap Vinegar Hydrogen peroxide

4. Lab: pH and Buffers pH = potential hydrogen (meaning the ability of a solution to attract hydrogen ions) Buffers and pH Virtual Activity http://www.mhhe.com/physsci/chemistry/essenti alchemistry/flash/buffer12.swf H+ OH- Acidic solutionBasic solution

5. Homeostasis Maintaining a balance of conditions within the cell (or organism). maintaining temperatures (humans 98.6 o F) – shiver/sweat metabolism = sum total of the body’s chemical activities Metabolic Rate: how fast an organism uses up its stored energy. High metabolism uses energy FAST Low metabolism uses energy SLOWLY

6. Homeostasis (cont.) Maintaining a balance of conditions within the cell (or organism). maintaining blood sugar levels Person eats food containing glucose Blood sugar levels rise FEEDBACK: Insulin is released to control the incoming glucose and maintain blood sugar levels Blood sugar levels lower HSW: Simply Science: Equilibrium

7. Diffusion Move from HIGH to LOW concentration passive transport no energy needed diffusion SuperQuick Demo: Colored water into water. High Concentration Low Concentration

8. H 2 O (water) Na+ (sodium) Higher concentration of molecules. Lower concentration of molecules. Molecules will always go from high to low. Concentration Gradient

9. Molecules move from high to low Diffusion (substances move) move from HIGH to LOW concentration across the concentration gradient. Membrane High Low Concentration gradient

10. Cell Homeostasis Remember that the cell membrane controls what enters and leaves the cell IN food - sugars - proteins - fats salts O2O2 H2OH2O OUT waste - ammonia - salts - CO 2 - H 2 O products - proteins Cell needs materials in & products or waste out

11. Remember… Membrane is made of special kind of lipid phospholipids “split personality” Membrane is a double layer phospholipid bilayer inside cell outside cell lipid “repelled by water” “attracted to water” phosphate

12. 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 (semi – partly) only some materials can get in or out aa H2OH2O sugar lipidssalt waste So what needs to get across the membrane? O2O2

13. Crossing the cell membrane What molecules can get through the cell membrane without doors or help? fats and oils can pass directly through inside cell outside cell lipid salt aa H2OH2O sugar waste but… what about other stuff?

14. Cell membrane protein channels Need to make “doors” through membrane protein channels allow substances in & out specific channels allow specific material in & out H 2 O channel, salt channel, sugar channel, etc. inside cell outside cell waste salt H2OH2O aasugar

15. Channels are made of proteins proteins both “like” water & “like” lipids bi-lipid membrane protein channels in bi-lipid membrane

16. Protein channels (cont.) Proteins act as open doors in the membrane channels to move specific molecules through cell membrane HIGH LOW Concentration gradient Sugar molecules

17. Movement through the channel Why do molecules move through the membrane if they find a channel? ? ? HIGH LOW

18. Simple Diffusion Move from HIGH to LOW inside cell outside cell Which way will these fat molecules move? fat LOW HIGH

19. Facilitated Diffusion Move from HIGH to LOW through a channel inside cell outside cell sugar Which way will sugar move? sugar LOW HIGH

20. Simple vs. facilitated diffusion inside cell outside cell lipid inside cell outside cell H2OH2O simple diffusionfacilitated diffusion H2OH2O protein channel HIGH LOW

21. Active transport Cells may need to move molecules against concentration gradient need to pump “uphill” from LOW to HIGH using energy protein PUMP Requires ATP Low High Notice the direction of Amino Acid movement and the concentrations! Na+ activates the pump. ATP

22. Quick Review… simple diffusion facilitated diffusion active transport ATP

23. When Surface Area Counts: Intestinal Folds increase the surface area through which substances can pass. Villi = folds in the intestine that allow for more absorption area. What is the purpose of folds in the intestinal lining?

24. Osmosis Osmosis and the Egg Demonstration

25. Osmosis Water is so important that we discuss it separately Osmosis diffusion of water from high concentration of WATER to low concentration of water across a semi-permeable membrane

26.  Osmosis  diffusion of water from high concentration of WATER to low concentration of water  across a semi-permeable membrane High Low

27. Keeping water balance ( Homeostasis) Cell survival depends on balancing water uptake & water loss freshwaterbalancedsaltwater

28. Keeping right amount of water in cell Cells in 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 Hypotonic

29. Controlling water Contractile vacuole in Paramecium

30. Cells in Saltwater a cell in salt water low concentration of water around cell cell loses water example: shellfish problem: cell loses water plasmolysis in plants shrinking cell solution: take up water Hypertonic

31. Cells in 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 Isotonic

32. BLOOD! Animated Cell Responses to Solution Concentrations: http://www.phschool.com/science/biology_place/labbench/lab1/watpot.html

33. Learning through Osmosis?

34. Virtual Lab 4: Osmosis thru a Selectively Permeable Membrane Virtual Lab 5: Onion Cell Plasmolysis Hands-On w/Virtual Lab 3: Diffusion of IKI through Selectively Permeable Membrane DO NOT TOUCH LAB ITEMS!

35. Cells need ENERGY to power biochemical reactions.

36. How does a biochemical reaction work? Product Reactant Reactants ENTER the reaction. Products are PRODUCED by the reaction. Energy is absorbed or released by the reaction. Endo – inside Exo – outside

37. EXOTHERMIC Product Reactant Reactants ENTER the reaction. Products are PRODUCED by the reaction. E n e r g y i s R E L E A S E D b y t h e r e a c t i o n. EXOthermic Reaction = RELEASES energy

38. Product Reactant Reactants ENTER the reaction. Products are PRODUCED by the reaction. Energy is ABSORBED by the reaction. ENDOthermic Reaction = ABSORBS energy ENDOTHERMIC

39. ENERGY TIME Exothermic Reaction = Releases Energy ACTIVATION ENERGY = energy required to cause the reaction to occur. Energy RELEASED

40. ENERGY TIME Endothermic Reaction = Absorbs Energy ACTIVATION ENERGY = energy required to cause the reaction to occur. Energy ABSORBED

41. Any Questions?