6.2 Water and Diffusion Diffusion - PowerPoint Presentation

1. 6.2 Water and Diffusion

2. DiffusionMovement of particles from an area of higher concentration to an area of lower concentration.Brownian motion - random motion of atoms/moleculesExamples: food coloring in water, perfume, tea

3. Rate of diffusion What can speed up diffusion?Concentration- more particles (#1 factor)Temperature- particles move fasterPressure- accelerates particles

4. Importance of DiffusionOxygenNutrientsWaste enter and exit cells by diffusion

5. 7.2 Plasma MembraneSemipermeable, flexible boundary between the cell and its environmentCell Functions: - Need food - Need O2 ; Give off CO2 - Use energy - Send messages - Give off waste - Maintain homeostasis * All must pass through a membrane

6. Selective PermeabilityMembrane allows some molecules to pass through; keeping others outWater, Oxygen, CO2, Nitrogen move freelySugars, amino acids, and fats cannot pass freely

7. Structure: Phospholipid BilayerTwo layers:Each composed of lipidsProtein molecules embedded in layerPhosphate group instead of 3rd fatty acidAttracts water

8. Structure: Phospholipid BilayerPhospholipid contains: polar head  attracts water non-polar tails  repels water

9. Fluid Mosaic ModelPhospholipids are free to move sidewaysLike ping-pong balls in a bucket of water

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11. Saturated vs. Unsaturated Fatty AcidsThe more unsaturated fatty acids, the more fluid the membrane.Caribou example

12. CholesterolStrengthens the fluid mosaicKeeps tails separated

13. Membrane/Transport ProteinsMay extend through one or both layersDetermine which particles can passMarkers- recognize chemicals/fight disease

14. 8.1 Cellular TransportOsmosisdiffusion of water across a membranehelps to maintain homeostasisWhy should I avoid drinking sea water?Isn’t some water better than no water?

15. SaltwaterThe saltwater is 4 times more salty than your blood. The water from your blood passes into your stomach to dilute the salt concentration causing diarrhea. The water from your body cells pass into the blood to dilute the rising salt concentration causing hallucinations, seizures, and heart problems.

16. Which way will the water cross?Since the particles cannot cross, the water will crossHigh to low concentrationRight to Left  dilutes solute concentration

17. Types of SolutionsIsotonic - equal concentrationsHypotonic - solute conc. is lower outsideHypertonic - solute conc. is higher outside

18. Isotonic SolutionConcentration of dissolved substance (solute) is the same inside as it is outside of the cellDynamic equilibrium- no net movement of water “changing” “same”

19. Hypotonic SolutionConcentration of solute is lower outside the cell as it is inside the cellWater moves into the cellTurgor pressure- pressure inside a cellIncreases in a hypotonic solutionEx: Grocery store, House plants

20. Hypertonic SolutionConcentration of solute in higher outside the cell than inside the cellWater moves out of the cellAnimal cells shrivel or crenateDo not salt meat before cooking!

21. Passive vs. Active TransportPassive does not require energy Active requires energy

22. Passive TransportMovement of particles across a membrane by diffusion.No energy requiredFacilitated diffusion- enter by transport proteinEx: sugar and amino acids

23. Active TransportMovement of materials against a concentration gradient requiring energy (lowhigh)How active transport occurs:Particle binds with proteinUses energy to change the shape of the proteinParticle is released to the other side

24. Transport of large particlesEndocytosis- cell surrounds materialForms a vacuole using the plasma membraneExocytosis-Reverse process for expelling wastesBoth use energy to move masses of material

25. Fish: Saltwater vs. Freshwater

26. 8.1 Section Review 1-5 p.200