LIFE 102 1st Edition Lecture 3Outline of Last Lecture I. Went over test and introduction to diffusion in a cellOutline of Current Lecture II. Passive TransportIII. Phospholipid BilayerIV. OsmosisV. Facilitate Diffusion Current Lecture-Passive Transport-Always via diffusion from high to low concentration-Molecules spread out evenly (equilibrium)-Different molecules diffuse independently-Phospholipid bilayer -Selectively permeable -Hydrophilic head and hydrophobic tails -Molecules that can diffuse across lipid bilayeroNon polar molecules -i.e. O2, CO2, hydrocarbonsoSmall uncharged polar molecules -i.e. H2O -Transport ProteinsoLarger polar molecules or Ions need to get across membrane -Osmosis: passive movement of water across a membrane-What causes osmosis?oSolutes that don't cross the membrane -Water diffuses towards highest solute concentration -Both # of particles and H2O concentration impact water movement-Hypotonic- lower concentration solute-Hypertonic – higher concentration of solute-Isotonic – equal concentrations of solute on each side of membrane-Water balance of cells without walls oTonicity is the ability of a surrounding solution to cause a cell to gain or lose wateroIsotonic solution: Solute concentration is the same as that inside the cell; no net water movement across the plasma membraneoHypertonic solution: Solute concentration is greater than that inside the cell; cell loses waterHypotonic solution: Solute concentration is less than that inside the cell; cell gains waterThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-Implications of osmosis for cells (.3M= total solute concentration in cell)ohypertonic solution – cell loses wateroisotonic solution – no net movement of water(equilibrium)-Animals prefer an isotonic environment ohypotonic solution – cell absorbs water-Plant cells prefer a hypotonic environment -Facilitated Diffusion: passive transport (does not require energy like active transport)-Faster than Diffusion across plasma membrane-Can move ions and large polar molecules across -Channel diffusion through proteins (like an open door)oSpecific hydrophilic tunnel across membraneoMany are gated (Mostly ion channels)-Open/Close by stimulusoExample: aquaporin-water channel -retain water in kidneys-Carrier Proteins (like a revolving door)oPass specific substances down concentration gradients through changes in membrane protein shapeoshifts binding site (translocates) across membrane-Unbound- open to one side of membrane-Bound-open to other sideoSubstance released-Active Transport -move molecules against concentration gradient – requires energy (ATP)-All Carrier Proteins-Transfers terminal phosphate to membrane protein-Induces change in protein shape moving molecule across membrane -Membrane potential -Ion pumps generate membrane potential - voltage difference across a membrane- Animals: Na+/K+ ATPase-Plants, Fungi, Bacteria: Proton Pump-Also called electrogenic pumps-creates electrochemical Gradient – 2 forces acting on ions-Chemical Force : Concentration Gradient-Electrical Force: Difference in Electrical Charge Across Membrane -Cotransportergradient created by active transport of one molecule can move second moleculeup its concentration gradientcotransporter – Transport of two different molecules at the same time by one carrierPlants: load glucose into the veins of leavesAnimals: Na+/Glucose costransporter – keeps Na levels up diarrheadoctors replace Na+ by mixing with