1. All organisms and their cells respond to external conditions to maintain a stable internal condition. They are maintaining Homeostasis. To understand how this works we need to first discuss the Plasma Membrane.

5. Membrane movement animation Polar heads love water Non-polar tails fearwater (Hydrophobic) (Hydrophilic)

10. II. Movement of Substances Into and Out of Cells 2 types of transport across membranes: Passive- tranport that does not require any energy. (moves from high to low concentration) Active- transport that requires energy. (moves from low to high concentration)

11. Cell doesn’t use energy Molecules spread out from an area of high concentration to an area of low concentration. (High  Low) 3 types of Passive transport 1.Diffusion 2.Facilitated Diffusion-diffusion with the help of transport proteins 3.Osmosis-diffusion of water high low Weeee!! ! Passive Transport

12. A. Passive Transport: 1.Diffusion: random movement of molecules down a concentration gradient, from high to low concentrations (High to Low) Diffusion continues until all molecules are evenly spaced (equilibrium is reached)-Note: molecules will still move around but stay spread out. http://bio.winona.edu/berg/Free.htm Simple Diffusion AnimationSimple Diffusion Animation

13. 2.Facilitated diffusion: diffusion of specific particles through transport proteins found in the membrane a.Transport Proteins are specific – they “select” only certain molecules to cross the membrane b.Transports larger or charged molecules Facilitated diffusion (Channel Protein) Diffusion (Lipid Bilayer) A. Passive Transport: AB

14. High Concentration Low Concentration Cell Membrane Glucose molecules Protein channel Passive Transport: 2. Facilitated Diffusion Go to Section: Through a  Protein Transport Channel Cellular Transport From a- High Low Channel Proteins animationsChannel Proteins

15. 3.Osmosis: diffusion of water through a selectively permeable membrane Water moves from high to low concentrations Water moves freely through pores. Solute (green) is too large to move across. Osmosis Osmosis animation A. Passive Transport: A solution is a mixture of solutes (things being dissolved) and a solvent (things doing the dissolving). Water is typically the solvent. (i.e. sugar cube in water, the sugar is the solute)

16. Solutes = ___________________________& __________ Solvent = ____________ Koolaid drink = ______________ Use new vocab to make Koolaid sugarKoolaid powder http://www.makash.ac.il/h_school/hst/hstsb/chem/luach/dissolve.jpg Water solution

17. Water Balance in a Cell A Simple rule to remember is: Salt is a solute, when it is concentrated inside or outside the cell, it will draw the water in its direction. SALT SUCKS

18. Types of Solutions 1. Hypertonic: solution with a greater concentration of dissolved particles than its surroundings. 2. Hypotonic: solution with a lower concentration of dissolved particles than its surroundings. 3. Isotonic: solution concentration is equal to its surroundings.

19. Hypertonic 1.Cells placed in a hypertonic solution (environment like salt water) will shrink or shrivel. Remember – Salt sucks!

20. Hypertonic Solution Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water) Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)! This is why you get thirsty after eating something salty. Osmosis Animations for isotonic, hypertonic, and hypotonic solutionsOsmosis shrinks

21. Hypotonic Cells placed in a hypotonic solution (environment like fresh water) will swell and could burst. Think hypo - hippo

22. Hypotonic Solution Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water) Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)! Osmosis Animations for isotonic, hypertonic, and hypotonic solutionsOsmosis

23. Isotonic Cells placed in an isotonic solution (environment) will remain the same size. ISO = Equal or same

24. Isotonic Solution Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell. Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium) Osmosis Animations for isotonic, hypertonic, and hypotonic solutionsOsmosis

25. What type of solution are these cells in ? A CB HypertonicIsotonicHypotonic

27. VACUOLES store WATER ________________________________________ = Pressure exerted by the movement of water during osmosis OSMOTIC PRESSURE

28. How Organisms Deal with Osmotic Pressure Paramecium (protist) removing excess water videoParamecium (protist) removing excess water video Bacteria and plants have cell walls that prevent them from over-expanding. In plants the pressure exerted on the cell wall is called turgor pressure. A protist like paramecium has contractile vacuoles that collect water flowing in and pump it out to prevent them from over-expanding. Salt water fish pump salt out of their specialized gills so they do not dehydrate. Animal cells are bathed in blood. Kidneys keep the blood isotonic by remove excess salt and water.

29. Grocery stores spray water on their veggies to “plump them up” http://www.painetworks.com/photos/gt/gt0461.JPG

30. SO WHAT?

31. This is why it is dangerous to drink sea water-it’s also a myth that drinking sea water will cause you to go insane, but people marooned at sea will speed up dehydration (and death) by drinking sea water. This is also why “salting fields” was a common tactic during war, it would kill the crops in the field, thus causing food shortages

32. Molecules need to move across membranes in cells

33. PROBLEM for CELLS? Diffusion only moves molecules from high concentration to low concentration.

34. What if cell needs to move a molecule _________ the CONCENTRATION GRADIENT? _______________ Cell example: Want to put MORE glucose into mitochondria when there is already glucose in there (LOWER  HIGHER) Image from: http://www.biologyclass.net/mitochondria.jpg AGAINST

35. DIFFUSION automatically moves oxygen from HIGHER concentration (in lungs) to a LOWER concentration (in blood) http://www.le.ac.uk/pa/teach/va/anatomy/case2/2_2.html CELL EXAMPLE: CO 2 automatically moves from where there is a HIGHER concentration (in blood) to where there is a lower concentration (in lungs)

36. PROBLEM for Cells? Cell membranes are SELECTIVELY PERMEABLE See a movie Video from: http://www.southtexascollege.edu/tdehne/BC_ShockwaveAnimations/08SWF-MembraneStructureAndFunct/08-02-MembraneStructure.swf

37. What if a cell needs to move _____ or ______ molecules that can’t get through the membrane? http://www.d.umn.edu/~sdowning/Membranes/membraneImages/jpegimages/diffusionmedium.jpg LARGEPOLAR

38. PROBLEM for CELLS? Diffusion happens very slowly

39. What if cell needs to move molecules really _______? (can’t wait for it to diffuse) Cell example: Movement of Na + & K + ions required to send nerve signals http://www.steve.gb.com/images/science/neuron.png FAST

40. Cells need a ____ to ____ molecules across cell membranes that _______ across by ___________ WAY HELP can’t go themselves

41. Cells use energy to transport materials that cannot diffuse across a membrane.

42. Passive transport requires no energy from the cell. Active transport is powered by chemical energy (ATP). Active transport occurs through transport protein pumps. Cells use active transport to maintain homeostasis.

43. A cell can import and export large materials or large amounts of material in vesicles during the processes of endocytosis and exocytosis. Cells use energy to transport material in vesicles. Endocytosis is the process of taking material into the cell. Phagocytosis is a type of endocytosis.

44. A cell can import and export large materials or large amounts of material in vesicles during the processes of endocytosis and exocytosis. Cells use energy to transport material in vesicles. Exocytosis is the process of expelling material from the cell.

45. Kidspiration by: Riedell

46. Active Transport cell does use energy 1.Protein Pumps 2.Endocytosis 3.Exocytosis high low This is gonna be hard work!!

47. Protein Pump EndocytosisExocytosis

48. Active Transport cell uses energy actively moves molecules to where they are needed Movement from an area of low concentration to an area of high concentration (Low  High) Three Types:

49. Types of Active Transport 1. Protein Pumps - transport proteins that require energy to do work Example: Sodium / Potassium Pumps are important in nerve responses. Sodium Potassium Pumps Sodium Potassium Pumps (Active Transport using proteins) Protein changes shape to move molecules: this requires energy!

50. Types of Active Transport 2. Endocytosis: taking bulky material into a cell Uses energy Cell membrane in-folds around food particle “cell eating” forms food vacuole & digests food This is how white blood cells eat bacteria!

51. Types of Active Transport 3. Exocytosis: Forces material out of cell in bulk membrane surrounding the material fuses with cell membrane Cell changes shape – requires energy EX: Hormones or wastes released from cell Endocytosis & Exocytosis Endocytosis & Exocytosis animations

53. Animations of Active Transport & Passive TransportAnimations

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