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Biology 1201 Exam 2 (scored 92%)

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Biological Sciences
BIOL 1201
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Biology 1201 Exam 2CHAPTER 7membrane functionMembranes and Why are membranes called phospholipid bilayersoBecause they are made up of two layers of phospholipids a hydrophilic head and a hydrophobic tailWhat is meant by fluid mosaicoA mosaic of proteins drifting laterally in a fluid bilayer of phospholipidsHow are membranes adjusted for different temperaturesoThey are adjusted by changing the ratios of unsaturated to saturated fatsHow do the relative amounts of saturated and unsaturated fats change in various temperaturesoLower temperaturesmore fluid due to unsaturated fats with kinksoHigher temperaturesmore stable due to less unsaturated fats so they stay closer togetherWhat is meant by membrane fluidityoNot too solid not too fluidable to move aroundWhy is this an important propertyoIt preserves membrane functionHenrique and Hanson performed experiments with pigs and examined the effects on the relative amounts of saturated and unsaturated fats What did they findoThat membrane fluidity can acclimate to temperature pigs that were raised wearing underwear in a hot room had subcutaneous fats with higher melting points oOne can see similar patterns comparing species with different body temperature of cells grown at different culture temperaturesTransport of materials across the membrane what types of molecules can more easily across the membrane oSmall nonpolar steroid hormones gases waterTransport processesWhat is simple diffusionoDown the concentration gradient high to lowoDepends on molecular movementoDoes not require supplied energyoDoes not use a carrier moleculeWhat is facilitated diffusionoDown the concentration gradientoDepends on molecular movementoDoes not require supplied energyoEmploys uses a carrier moleculeWhat is active transportoWork must be done oAgainst concentration gradientoEnergy must be expendedFor which processes are carrier molecules involvedoFacilitated diffusion and active transportWhich processes require the input of additional energyoActive transportWhat is a semipermeable barrieroOnly some types of molecules can pass through When equilibrium is reached in diffusion does the movement of molecules stopoNODoes the net movement of molecules stopoYESTonicity one solution relative to another and aquatic organismsIn lecture we presented examples of aquatic animals from freshwater and seawaterBony fish sharks and invertebratesHow do they compare to their environmentsoThey are hypotonic to seawater the sea is saltier than the fishoSharks are isotonic in seawateroBony fresh water fish hypertonic to water gain wateroBony marine fish hypotonic to sea water lose watermnb What is meant by hyper hypo and isotonicIn which direction does water flowoHypertoniclower water potential more solute lose wateroHypotonichigher water potential less solute gain wateroIsotonicequal water potential equal solute no net movement of waterWhat would happen to red blood cells if they were place in a hypotonic solutionoThey would explode or lyse
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