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Biology Exam 2 Notes (aced the test and got 96%)

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Biological Sciences
BIOL 1201
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Biology120107022012155500The problema cell and its environmentThe interior of the cell is different than its environmentHow to defend the internal environment but still communicate with the external environmentTransport materials across the barrierFigure 72 73Integral Membrane ProteinsAmphipathicHydrophobic regions nonpolarHydrophilic regions polarFluidityNot too solid but not much of a liquidPreserves membrane functionoAt the cellbody temperatureSimilar fluidity in different speciesSpecies with a body temperature of 10 C will have a fluidity similar to a species with a body temperature of 20 CHenrique and Hansen 1901Raised pigs wearing underwear in a hot roomChanged the properties of the subcutaneous fatsLipids had a higher melting point Membrane fluidity can acclimate12Membrane fluidity adjusted by changing the ratio of unsaturated fatty acidsIncrease Unsaturated FatsIncrease the fluidity of the membraneFunctional evidence for the fluidity of Membranes Figure 75 77 79 710 712Direction of MovementExpectdown the concentration gradientWhat about against the gradientoEx sodium 515 mM in the cell 154 mM outside oEnergy must be provided What kind of molecules would pass through a membrane phospholipid bilayerSmall and Nonpolar Have to pass through hydrophobic tails so they must be nonpolar with no charge or they could be repelledExamples that pass easilyoGasesoSteroid HormonesoWaterTransport Processesthe movement of molecules and materials into and out of the cell oActive Transport figure 718 720Against concentration gradientRequires supplied energy ATPform of energywork must be done23Energy is expendedCarrier molecules proteins involved in the movement of moleculesoPassive TransportDown concentration gradientsFrom high concentration to low concentration Does not require supplied energy Diffusion simple or facilitatedFacilitatedmolecules involved in the transport process but energy does not have to be suppliedDown concentration gradientDepends on molecular movementDoes not require supplied energyEmploys a carrier molecule SimpleDown concentration gradientDepends on molecular movement No required supplied energyDoes not use a carrier moleculeWhen concentrations on both sides of the barrier are equaloMolecules keep moving at any given temperatureoThere is no net change in solute concentration Semipermeable Barrier figure 7133
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