Diffusion and Osmosis How can matter get in and out of cells?

Diffusion  Watch this! Watch this! Watch this!  So.. because molecules are moving with kinetic energy, when they are close together they will bump into each other more, so…  Diffusion is the process where solutes move from an area of HIGH CONCENTRATION to an area of LOW CONCENTRATION.

Diffusion and Osmosis: Some special terms:  Solution When something is dissolved in another When something is dissolved in another  Solvent The thing that dissolves (like water that dissolves sugar) The thing that dissolves (like water that dissolves sugar)  Solute The thing that is dissolved (like the sugar put in water) The thing that is dissolved (like the sugar put in water)  Hypertonic Hyper = “Above”. A solution with a higher concentration of solutes than a cell A solution with a higher concentration of solutes than a cell  Hypotonic (Hypo = “Below”. ) A solution with a lower concentration of solutes than a cell A solution with a lower concentration of solutes than a cell  Isotonic(Iso = “same”) A solution with equal amounts of solute as the cell A solution with equal amounts of solute as the cell

What happens when we place cells into solutions with various concentrations? Hypotonic: Less solutes than cell like pure water Isotonic: Same concentration inside and out Hypertonic: More solutes than cell like syrup or highly salty water

Osmosis  Watch this! Watch this! Watch this!  So, because water is so special to life it gets a special name for its diffusion… OSMOSIS  Water molecules will move from an area of HIGH CONCENTRATION TO AN AREA OF LOW CONCENTRATION

Diffusion/Osmosis and Cells  How does material get in and out of cells?  Size of most cells?  Largest common cell?  Build Model Cell to see: TODAY: Each lab group needs 2 eggs (partners take care of one) TODAY: Each lab group needs 2 eggs (partners take care of one) Find the initial mass (record all digits) Find the initial mass (record all digits) Label with Period #, Lab Group #, Date, Initials & MASS!! Label with Period #, Lab Group #, Date, Initials & MASS!! Cover with vinegar and store in indicated location Cover with vinegar and store in indicated location

Osmosis through an egg cell membrane  Which egg is in a hypotonic solution?  Which egg is in a hypertonic solution? Hypotonic solution The water has LESS solutes than the egg (more water) Hypertonic solution The syrup has MORE solutes than the egg (less water)

Diffusion Lab Part II  Hypothesis:  IF…(MV?)…………  THEN we will see..(RV what should the lab look like?).. BECAUSE..(this logical reason)….  24 Hour Prediction Stamp (where are the molecules?) GET STAMP TIME LIMIT Formula Water? Formula Water? H 2 OH 2 O Formula Glucose? Formula Glucose? C 6 H 12 O 6C 6 H 12 O 6 Formula Starch? Formula Starch? C 150 H 250 O 125C 150 H 250 O 125

Diffusion Part 1  Record 24Hr ACTUAL RESULTS Speculate with your group about what happened! Be ready to be called upon to explain! Speculate with your group about what happened! Be ready to be called upon to explain! STARCH? (how do we know?) GLUCOSE? (how do we know?) WATER? (how do we know?) IODINE?(how do we know?)

Diffusion Part III: Solution Concentration on Cells  Problem: How do different concentrations of solutions affect the mass of a raw egg (cell)?  Complete the Variables Table Manipulated? Manipulated? Responding? Responding? Controlled (at least 3) Controlled (at least 3)  Hypothesis: Consider what you know about osmosis!  CAREFULLY rinse and mass your egg. Record mass AND observations.  Return to cup, add new tag and carefully pour assigned solution. Store.  Pick up Conclusion Sheet and do questions 1,2,3

Diffusion Part III: Solution Concentration on Cells  1. Carefully rinse your egg, mass and record in the appropriate spot on your data table. Clean up  2. Share data with your lab partner  3. Calculate % change in mass (demonstrate one problem on the bottom)  4. Answer the Analysis Questions  5. Write your Conclusion *Answer the question/hypothesis. *Answer the question/hypothesis. *Give evidence, including high, medium and low points. *Give evidence, including high, medium and low points. *Explain the pattern. *Explain the pattern. *Give logical scientific explanations for what happened. *Give logical scientific explanations for what happened. Be prepared to share and explain 6. GET STAMP

Diffusion and Osmosis  Do all substances diffuse through cell membranes? Semi-permeable Semi-permeable  Why is diffusion useful to cells? NO ENERGY NEEDED! NO ENERGY NEEDED! Food in! Oxygen in! Waste out! Food in! Oxygen in! Waste out!  Challenges? Animal Cell in hypotonic solution? OSMOSIS Animal Cell in hypotonic solution? OSMOSIS Animal Cell in hypertonic solution? OSMOSIS Animal Cell in hypertonic solution? OSMOSIS

What if cell NEEDS large molecules? Or keep a low concentration?  Active Transport Use energy (ATP) to “pump” molecules in or out “against the gradient” Use energy (ATP) to “pump” molecules in or out “against the gradient” In other words, use energy to go from low to high concentration. In other words, use energy to go from low to high concentration. How? Proteins in membranes How? Proteins in membranes  Build Membrane EACH PERSON MUST CONSTRUCT ONE MODEL, BRING TO FRONT WHEN DONE. EACH PERSON MUST CONSTRUCT ONE MODEL, BRING TO FRONT WHEN DONE.

So what does the cell membrane have to do with this?  “Fluid Mosaic”: Phospholipid bilayer (2 layers of lipids) Phospholipid bilayer (2 layers of lipids) Things like proteins and carbohydrates float around in it Things like proteins and carbohydrates float around in it 1. Materials get in and out! Water, Food, Waste 2. Recognize “self” with proteins and carbs 3.Specific “docking” station exploited by viruses. Protein Phospholipid Bilayer Protein w/ Carbohydrates

Why are cells small?

Why Are Most Cells Small?  Part I Cell Structure: Per Lab Group: Complete Part I Data Table and turn in to me Complete Part I Data Table and turn in to me  Part II Cell Function: Per Lab Group (Start by…)  Procedure: 1. Pick up one agar block on a paper towel 1. Pick up one agar block on a paper towel 2. CAREFULLY cut a 3x3x3, 2x2x2 and 1x1x1cm cubes 2. CAREFULLY cut a 3x3x3, 2x2x2 and 1x1x1cm cubes AVOID HANDLING WITH HANDS (WASH) AVOID HANDLING WITH HANDS (WASH) 3. Place beaker and just cover with vinegar 3. Place beaker and just cover with vinegar 4. Time until one cell is all diffused about 5-8 minutes… immediately 4. Time until one cell is all diffused about 5-8 minutes… immediately 5. Cut in half measure & record depth of change in mm 5. Cut in half measure & record depth of change in mm 6. Clean lab (waste in containers) Wash hands/counter 6. Clean lab (waste in containers) Wash hands/counter 7. Analysis and Conclusion Get Stamp! 7. Analysis and Conclusion Get Stamp!

Total percent diffused  Do this!  Total length – length not diffused x 100 = Total length

So, better to be big or small?  How did vinegar get in?  What does diffusion do for cells?  What happens to the surface area to volume ratio as cells get bigger?  Diffusion faster in small?  Better to be big or small?  What if you want to be big? big?

MAXIMIZE SURFACE AREA!  Many small cells, not one big one! 3x3x3 Cell 3x3x3 Cell Surface Area (3x3) x 6 = 54 cm 2Surface Area (3x3) x 6 = 54 cm 2 Volume (3x3x3) = 27 cm 3Volume (3x3x3) = 27 cm 3 Surface Area to Volume = 54:27 or 2:1Surface Area to Volume = 54:27 or 2:1 BUT build same size out of 27 little cubes BUT build same size out of 27 little cubes Surface area (1x1) x 6 = 6 BUT have 27 of them so…Surface area (1x1) x 6 = 6 BUT have 27 of them so… Surface area is 6 x 27 = 162 cm 2Surface area is 6 x 27 = 162 cm 2 Volume still 27 cm 3Volume still 27 cm 3 So surface area to volume = 162:27 or 6:1So surface area to volume = 162:27 or 6:1

Structure and Function: MAXIMIZE SURFACE AREA!

SA to V ratios of real cells:  Red blood cells: 600:1 600:1

Transport in Cells (POGIL) Hold your wee and win a Wii contest. Paramecium using contractile vacuole What happens if the contractile vacuole stops working?

Cell Membranes A membrane in action

Meet a Channel Protein!  Check out Aquaporin Check out Aquaporin Check out Aquaporin The channel protein that allows water through the membrane! The channel protein that allows water through the membrane! The channel protein that allows water through the membrane! The channel protein that allows water through the membrane! Water CAN go through the cell membrane (small and polar), but because it is POLAR, it is slowed somewhat by the lipids – NONPOLAR!! Water CAN go through the cell membrane (small and polar), but because it is POLAR, it is slowed somewhat by the lipids – NONPOLAR!! Aquaporin allows water to move much more rapidly in cells that need this rapid diffusion. Plant cells and human kidney cells have aquaporins. Aquaporin allows water to move much more rapidly in cells that need this rapid diffusion. Plant cells and human kidney cells have aquaporins.

Meet the Cell Theory (a theory is a hypothesis that has been supported by MOUNTAINS of evidence.  All living things are composed of CELLS  Cells are the basic units of structure and function in all living things  New cells come from existing cells (no spontaneous life forms!!)