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1. Name the three basic parts of a cell and describe the functions of each.
2. Why do phospholipids organize into a bilayer – tail-to-tail – in a watery environment?
Hypertonic, isotonic, or hypotonic?1. What type of fluid might be infused into
the bloodstream of a patient who needs fluid drawn out from swollen tissues?
2. What type of fluid might be used (carefully) to rehydrate the tissues of extremely dehydrated patients?
3. In a U-tube separated by a selectively permeable membrane, there is .2 M glucose in Side A, and .4 M glucose in Side B. Side A is ____ compared to Side B, and Side B is ____ compared to Side A.
4. If the membrane in #3 is only permeable to water, what will happen?
Part 2: Membrane Transport
Interstitial fluidInterstitial fluid: Fluid outside cells Rich, nutritious “soup” – amino acids,
sugars, fatty acids, vitamins, hormones, salts, wastes
Selective PermeabilitySelective Permeability: Plasma membrane only allows some
substances to enter cell Nutrients in, wastes out By passivepassive or activeactive transport
No energy (ATP) needed Molecules move down concentration down concentration
gradientgradient from HIGH LOW concentration
Types: diffusion, filtration
Nonpolar & lipid-soluble Nonpolar & lipid-soluble substancessubstances diffuse directly through lipid bilayer
Eg. O2, CO2, fat-soluble vitamins
Transport proteins Transport proteins (carrier or channel proteins) assist molecules across membrane
Eg. glucose, amino acids, H2O, ions
Water-filled channels Eg. ions
Binds to molecule, changes shape, ferries it across membrane
Eg. glucose transporter
Diffusion of H2O Aquaporins: Aquaporins: channel proteins for H2O
passage
Ability of solution to change shape or tone of cells by changing water volume
IsotonicIsotonic = equal concentration solutes HypertonicHypertonic = higher conc. of solutes HypotonicHypotonic = lower conc. of solutes
Energy (ATP) is needed!! Move molecules against concentration against concentration
gradientgradient from LOW HIGH concentration
Types: Primary and Secondary
Directly uses ATPATP to drive transport
Eg. Ca2+ pump, H+ pump, Na+-K+ pump
Sodium-Potassium PumpSodium-Potassium Pump
Move more than 1 substance at a time SymportSymport: 2 substances moved in same direction AntiportAntiport: 2 substances cross in opposite
directions Eg. cotransport of sugars, animo acids, ions
Fluid & large particles transported across membranes in vesiclesvesicles (sacs)
ExocytosisExocytosis: “out of cell” – eject substances
EndocytosisEndocytosis: “within the cell”- ingest substances
PhagocytosisPhagocytosis: (cell eating) – engulf large or solid materialeg. WBC engulf
bacteria
PinocytosisPinocytosis: (cell drinking) – fluid w/dissolved moleculesEg. intestinal
cells
Receptor-Receptor-mediated mediated endocytosisendocytosis: concentrate specific substances (ligandsligands) that bind to receptor receptor proteinsproteinsEg. insulin, iron,
cholesterol