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Osmosis and Diffusion
 

Osmosis and Diffusion

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    Osmosis and Diffusion Osmosis and Diffusion Presentation Transcript

    • Chapter 8Chapter 8 Cell MembraneCell Membrane
    • HomeostasisHomeostasis  Maintenance of stable internalMaintenance of stable internal conditions (“inside different fromconditions (“inside different from outside”outside”  Cell membrane controls movementsCell membrane controls movements of substancesof substances
    • Structure of the MembraneStructure of the Membrane  Mainly a lipidMainly a lipid bilayerbilayer  HydrophilicHydrophilic phospholipidphospholipid “heads” point out“heads” point out and inand in  HydrophobicHydrophobic phospholipidphospholipid “tails” point“tails” point towards interiortowards interior
    • Structure of the MembraneStructure of the Membrane  Only small, non-Only small, non- chargedcharged molecules canmolecules can pass throughpass through the membranethe membrane  Examples:Examples:  OxygenOxygen  Carbon DioxideCarbon Dioxide
    • Structure of the MembraneStructure of the Membrane  ProteinsProteins embedded inembedded in membranesmembranes have manyhave many functionsfunctions 1.1. Cell-surfaceCell-surface markers act asmarkers act as “ID” tags“ID” tags
    • Structure of the MembraneStructure of the Membrane 2.2. ReceptorReceptor proteins receiveproteins receive signals from outsignals from out of the cellof the cell 3.3. Enzymes causeEnzymes cause chemicalchemical reactions toreactions to occuroccur
    • Structure of the MembraneStructure of the Membrane 4.4. Transport proteins move substancesTransport proteins move substances across membraneacross membrane
    • Cell ProcessesCell Processes
    • Cell ProcessesCell Processes  2 major ways of passing2 major ways of passing within/between cellswithin/between cells  Both rely on concentration ofBoth rely on concentration of solute.solute.
    • Important TermsImportant Terms  Solute: type of molecule dissolved inSolute: type of molecule dissolved in another type of substance; that substanceanother type of substance; that substance is called a…is called a…  Solvent: substance that dissolves theSolvent: substance that dissolves the solutesolute
    • ExamplesExamples  Put onePut one tablespoon oftablespoon of sugar into asugar into a glass of waterglass of water and stir.and stir.  Solute = sugarSolute = sugar  Solvent = waterSolvent = water
    • ExamplesExamples  Fish use gills to extract oxygen dissolved inFish use gills to extract oxygen dissolved in seawaterseawater  Solute = oxygenSolute = oxygen  Solvent = waterSolvent = water
    • CONCENTRATIONCONCENTRATION  Concentration refers to howConcentration refers to how much of some substance ismuch of some substance is present, compared to anotherpresent, compared to another substance.substance.
    • CONCENTRATIONCONCENTRATION EXAMPLESEXAMPLES  High soluteHigh solute concentration: lotsconcentration: lots of sugar dissolved inof sugar dissolved in a relatively smalla relatively small amount of wateramount of water  Low soluteLow solute concentration: littleconcentration: little sugar dissolved in asugar dissolved in a relatively highrelatively high amount of wateramount of water
    • REMEMBER!REMEMBER!  Solutes can be many differentSolutes can be many different kinds of molecules (sugars,kinds of molecules (sugars, gases, nutrients, proteins, andgases, nutrients, proteins, and lipids)lipids)  Solvents can vary as wellSolvents can vary as well (solids, liquids, or gases), but(solids, liquids, or gases), but are usually Hare usually H22OO
    • DIFFUSIONDIFFUSION
    • DiffusionDiffusion  Diffusion is the process byDiffusion is the process by which solute passes throughwhich solute passes through pores in a cell membranepores in a cell membrane  Diffusion also occurs within oneDiffusion also occurs within one area (no membrane) as solutearea (no membrane) as solute travels from one area of spacetravels from one area of space to anotherto another
    • DiffusionDiffusion  NET FLOW OF SOLUTES ISNET FLOW OF SOLUTES IS ALWAYS FROM AREAS OFALWAYS FROM AREAS OF HIGHER CONCENTRATIONHIGHER CONCENTRATION TO AREAS OF LOWERTO AREAS OF LOWER CONCENTATION!CONCENTATION!
    • DiffusionDiffusion  Molecules ALWAYS diffuse inMolecules ALWAYS diffuse in both directions at once (into andboth directions at once (into and out of a cell)out of a cell)  NET FLOW is from greaterNET FLOW is from greater concentration to lesserconcentration to lesser concentrationconcentration
    • bbbb
    • DiffusionDiffusion  MoleculesMolecules diffuse throughdiffuse through a solvent asa solvent as wellwell  Example:Example: aromasaromas
    • OSMOSISOSMOSIS
    • OsmosisOsmosis  Osmosis is the process by whichOsmosis is the process by which WATER passes through a cellWATER passes through a cell membranemembrane  NET FLOW OFNET FLOW OF WATERWATER IS ALWAYSIS ALWAYS FROM AREAS OF LOWER SOLUTEFROM AREAS OF LOWER SOLUTE CONCENTRATION TO AREAS OFCONCENTRATION TO AREAS OF HIGHER SOLUTEHIGHER SOLUTE CONCENTRATIONCONCENTRATION
    • OsmosisOsmosis  Water molecules always flow inWater molecules always flow in both directions at once (into andboth directions at once (into and out of a cell)out of a cell)  NET FLOW is from lowerNET FLOW is from lower concentration (of solute) toconcentration (of solute) to greater concentration (of solute)greater concentration (of solute)
    • CELLULARCELLULAR TRANSPORTTRANSPORT
    • PASSIVE vs. ACTIVEPASSIVE vs. ACTIVE TRANSPORTTRANSPORT  Diffusion and osmosis areDiffusion and osmosis are examples ofexamples of passive transportpassive transport,, which occurs without a cellwhich occurs without a cell using energy.using energy.  Cells can move molecules in theCells can move molecules in the opposite direction by utilizingopposite direction by utilizing energy. This is calledenergy. This is called activeactive transporttransport..
    • Important Terms • Equilibrium • Concentration Gradient • Diffusion • Osmosis • Concentration of a substance is the same throughout • Difference in concentration across a membrane • Process by which molecules move from areas of high to low concentration • Transport of water across a membrane
    • Other Important TermsOther Important Terms  Passive TransportPassive Transport  Movement across aMovement across a membrane withoutmembrane without using energyusing energy (diffusion and(diffusion and osmosis)osmosis)  Active TransportActive Transport  Movement across aMovement across a membrane usingmembrane using energyenergy
    • Active TransportActive Transport
    • Passive TransportPassive Transport
    • Other Important TermsOther Important Terms  HomeostasisHomeostasis  Stable internalStable internal conditions of aconditions of a living thingliving thing  This is anotherThis is another characteristic of allcharacteristic of all living thingsliving things  Living thingsLiving things actively keep theiractively keep their “insides” different“insides” different than theirthan their “outsides”“outsides”
    • Cellular Transport Passive Transport Active Transport Diffusion Osmosis Example: Sodium/Potassium Pump Maintain Homeostasis by…
    • Sodium/PotassiumSodium/Potassium Ion PumpIon Pump
    • Sodium/Potassium Ion PumpSodium/Potassium Ion Pump  Sodium = NaSodium = Na++  Potassium = KPotassium = K++  Ions are electrically charged atomsIons are electrically charged atoms
    • Sodium/Potassium Ion PumpSodium/Potassium Ion Pump  Pump is a protein in the membrane of cells.Pump is a protein in the membrane of cells.  Example of ACTIVE TRANSPORT (pumpsExample of ACTIVE TRANSPORT (pumps AGAINST the concentration gradient)AGAINST the concentration gradient)
    • Sodium/Potassium Ion PumpSodium/Potassium Ion Pump  Pumps 3 NaPumps 3 Na++ ionsions out of the cell and 2out of the cell and 2 KK++ ions into the cell.ions into the cell. (Uses ATP, a(Uses ATP, a molecule with lotsmolecule with lots of stored energy)of stored energy)  Which sideWhich side becomes morebecomes more positively charged?positively charged? Which sideWhich side becomes morebecomes more negativelynegatively charged?charged?
    • Importance of NaImportance of Na++ /K/K++ PumpPump  MaintainsMaintains electricalelectrical gradientgradient (different(different charges insidecharges inside and out)and out)  Essential toEssential to pass signalspass signals through nervousthrough nervous systemsystem