Chapter 5

Chapter 5Homeostasis and Cell Transport

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http://ailil.deviantart.com/art/Osmosis-Jones-Strikes-Back-3678440Section 1 Vocabulary PretestPassive TransportDiffusionConcentration gradientEquilibriumOsmosisHypotonicHypertonicIsotonicContractile vacuoleTurgor pressurePlasmolysisCytolysisFacilitated diffusionCarrier proteinIon channelMovement of water from high to low concentrationMovement of molecules from high to low conc.Organelles that remove water from cellsPressure exerted by water molecules on cell wallsProteins that help move molecules through cellsState where molecules are evenly spacedDifference in the concentration of molecules over a distanceBursting of a cellShrinking of a cellAssisted diffusion of moleculesProteins that move ions through a membraneSolution with a low concentration of solute outside a cellSolution with a high concentration of solute outside a cellSolution with an equal concentration of solute inside and outside a cellO. Moving substances without using energy

Answer KeyPassive TransportODiffusionBConcentration gradientGEquilibriumFOsmosisAHypotonicLHypertonicMIsotonicNContractile vacuoleCTurgor pressureDPlasmolysisICytolysisHFacilitated diffusionJCarrier proteinEIon channelK

Types of TransportCells move molecules using different types of passive and active transportThese differ from each other by whether or not cells must use energy.Passive= no energyActive = use energy

Passive TransportPassive transport movement of substances through a membrane that requires NO ENERGYTypes:Diffusion movement of molecules from high to low concentrationOsmosis movement of WATER from high to low concentrationFacilitated Diffusion assisted diffusion of large or insoluble molecules through a cell membrane.Ion Channel Diffusion movement of ions from high to low concentration.DiffusionSimplest type of passive transportMoves molecules from high to low concentrationThey have kinetic energy and are in constant motion.They will spread out simply because they bump into each other.They move away from areas where they are too crowdedThis is called moving down a concentration gradientConcentration gradient is the difference in concentration of molecules across a distanceDiffusion can happen in a gas, liquid or solidIt can happen in a living or nonliving systemIt is how most molecules pass into and out of cell membranes.It continues until equilibrium is reachedEquilibrium the concentration of molecules is the same throughout the space they occupyHow Diffusion Works Animation

Note: Even at equilibrium the random movementof molecules continues but we no longer see anet movement of molecules in one directionCell membranes are semi-permeable: some molecules can pass through and some cannot.Depends on size and chemical nature of the moleculePassing unassisted through the membrane is called simple diffusionExample: CO2 and O2 dissolve in lipids and can pass directly through the phospholipid bilayerExample: Molecules like NH3 and some hormones that cant dissolve in lipids but are small enough can pass through the Channel Protein Pores in the membrane

http://www2.estrellamountain.edu/faculty/farabee/biobk/biobooktransp.htmlOsmosisOsmosis is the diffusion of WATER from high to low concentration.Direction of osmosis (water movement) depends on the relative concentration of solutes inside and outside the cellReview:Solute substance dissolved in water (Ex: sugar, salt)Solvent water

Pay attention!! This getsconfusing!!Hypotonic Solution a solution outside the cell that has a lower concentration of solute molecules than the concentration inside the cell. Ex: (less salt outside the cell)This means that there is a higher concentration of solvent outside the cell. Ex (more water outside the cell)So water will move into the cell by osmosis.

http://www.biologycorner.com/bio1/diffusion.htmlHypo means lessHypertonic Solution a solution outside the cell that has a higher concentration of solute molecules than the concentration inside the cell. Ex: (more salt outside the cell).This means that there is a higher concentration of solvent inside the cell. Ex: (more water inside the cell)So water will move out of the cell by osmosis.

http://www.biologycorner.com/bio1/diffusion.htmlHyper means moreIsotonic Solution concentrations of solute are equal both inside and outside the cell.Water will move in both directions in even amounts.

http://www.biologycorner.com/bio1/diffusion.htmlSome cells control osmosis to some degreeThree methods:Contractile Vacuole structures found in certain cells (usually cells of freshwater organisms that constantly have water moving in) that pump excess water out. Ex. ParameciumSolute Pumps pump out solutes so that water is less likely to move in.Cell Walls support the cell so when water moves in the cell does not burst. Creates turgor pressure which keeps plants upright. Plasmolysis is the shrinking of the cells cytoplasm creating a loss of turgor pressure. Result: plant wilts

http://evervision2.ispace.in.th/contractile-vacuoles-are.htmlContractile Vacuole

Solute Pump

http://botany.thismia.com/2010/02/24/plasmolysis/

http://www.classhelp.info/Biology/AUnit4Cells.htm

http://www.uic.edu/classes/bios/bios100/lecturesf04am/lect09.htmTurgor Pressure and PlasmolysisCytolysis bursting of a cell due to osmosis.

Identify the pictures as a cell in an isotonic solution, hypertonic solution and hypotonic solutionIsotonicHypotonicHypertonicFacilitated DiffusionAssisted diffusion of large or insoluble molecules through a cell membrane.Carrier Proteins help the molecules to move from high to low concentration.Glucose is transported to cells in this way.

http://www.ncbi.nlm.nih.gov/books/NBK9847/Ion Channel DiffusionSeveral ions are vital to cells but cannot pass through the cell membrane because they are not soluble in lipids. They are:Sodium (Na+) Potassium (K+ ) Calcium (Ca2+ ) Chlorine (Cl-)They require specific ion channels to pass through membranes

http://tantalusprime.blogspot.com/2008_02_01_archive.htmlMany ion channels have gates that close or open in response to three stimuli: 1. stretching of cell membrane2. electrical signals3. chemical signals

Section 2 Vocabulary PretestActive TransportSodium-potassium PumpEndocytosisVesiclePinocytosisPhagocytosisPhagocyteExocytosisReleasing large molecules from a cellThe movement of molecules from low to high concentration using energyTaking large molecules into a cellOrganelles that form from the cell membrane and transports molecules within the cellCarrier protein the transports sodium ions out of a cell and potassium ions into a cellType of endocytosis that takes in liquidsType of endocytosis that takes in solidsWhite blood cell

Answer KeyActive TransportBSodium-potassium PumpEEndocytosisCVesicleDPinocytosisFPhagocytosisGPhagocyteHExocytosisA

Active TransportActive Transport movement of substances through a cell membrane that REQUIRES ENERGY.Molecules move from low to high concentration ( up their concentration gradient).The Carrier Proteins involved require energy from ATP and are called Cell Membrane Pumps.Example: Sodium-potassium pump

Importance of the Sodium-potassium pumpThe sodium-potassium pump is important in animals to maintain the normal function of many cells including nerve cells.The exchange of three sodium ions for two potassium ions creates an electrical gradient. The outside of the cell becomes positively charged and the inside becomes negatively charged.This helps nerve cells to conduct electrical impulsesEndocytosisMovement of VERY LARGE PARTICLES into a cell. The cell membrane pinches off to trap the particle inside a vesicle which can then transport the particle throughout the cell.

Two types of endocytosis:Phagocytosismovement of large particles or whole cells

Pinocytosismovement of fluidsExocytosisMovement of VERY LARGE PARTICLES out of a cell. Vesicles bring particles to the cell membrane to be released.