Archetypes and Ancestors: The Quest for the Bilaterian Ground PlanGoalReduce the observed diversity of organisms to a more general abstraction The archetypeContains essential properties of many organisms, not unique to only 1Final archetype=ground plan of the groupCuvier 1 archetypeGeoffrey 4 archetypes (Articulata and Vertebrata archetypes)Rational/Transcendental MorphologyVon Baer’s LawGeneral archetype characteristics of an organism to which a group belongs to develop before specific characteristics.Evolution MorphologyPresent techniqueHomeotic MutationsBithorax Duplication of Mesothorax regionAntennapedia antennae expressed as legsHomeotic Vertebrate Extra lumbar/sacral vertebrate in mouseHomeobox GenesMost mutations in animals caused here180 base region coding for 60 base aa (homeodomain)HomeodomainRegulates transcription of specific developmental genesDetermines fate of cells…structures and body regions during developmentHox genesType of homeobox genes that occur in clusters along a chromosome and differentiate regions of the body on the longitudinal axis.Conserved sequences within an organism and orthologsClustering almost always happensHomologs from some organisms can be inserted into other organisms with lethal mutants in certain Hox genesProperties of Hox GenesSpatial ColinearityOrder of Hox genes along a chromosome determine the their expression along the anterior (head) posterior axis.Temporal ColinearityOrder of Hox genes in chromosomes determine their temporal sequence of expression in the embryo.Temporal time of expression during embryogenesis.ExamplesVertebrate Hox genes show both temporal and spatial colinearityFlies show only spatial colinearity Hox genes expressed at the same time.ReasoningUnknown, but upstream Hox genes may try to protect from alterations by downstream genes to maintain the polarity of the anterior-posterior axis.ExamplesChordin (chd) in vertebrates and short gastrulation (sog) in arthropodsBoth function as establishing dorsal-ventral axis of body.Pax 6 (Vertebrates) and eyeless (ArthropodsEstablishes light receptor fieldMutations in Pax 6 may lead to cataractsAmphioxus engrailed (AmphiEn) (Chordate) and engrailed (en) ArthropodSegmentationNkx-25 (vertebrates) and tinman (arthropods)Heart morphogenesis, mesoderm formationDistal-less (Dlx) Chordate and distal-less (dll) ArthropodProximo-distal axis of appendagesNutrient Assimilation (you are what you eat!)Major aspects of Complex OrganismsGathering and ingesting nutrientsBreak down complex moleculesTransport simple molecules into the cells of organismCellular TransportWhy does it reach equilibrium?Equal concentrations in and out (probably by diffusion)Feedback mechanism in cellsDetermining Rate of Solute TransportMeasured in micromoles/minLinear GraphNo transport sites, simple diffusion across membraneGraph with limit (exponential)Cell possesses specific transport sites that are limiting movementFacilitated DiffusionExhibits a measurable rate of affinity for solute and maximum rate of transportAffinityKa = 1/2 Tmax = [x]Measured in mMKa = 1/affinityDiffusion of Glucose via GLUT-1 proteinGlut 1 inactivated by high intracellular ATPIon ChannelsArtificial channels by antibiotics such as Gramicidin (Alpha-helix)Potassium Channel is voltage gated to allow K+ into the cell.Active TransportRequires energy because is independent of concentration or electrochemical gradientsDirect use of ATPNa+ - K+ ATPase in cell membranesIndirect use of ATPCo-transported ionNa+ gradient for transport of glucose and aaSodium gradient is an example of co-transport or symport (Sodium and glucose going in same direction)Oil/Water Partition Coefficient = [S]oil/[S]waterPermeability ChartAquaporinsAllow only water to travel through cell membraneHydro-phyllic on inside, hydrophobic on outside facing the hydrophobic tails of phospholipid bilayer.More than 16 discovered as of 2009First noted in 1995 by Peter AgreOnly accommodates H2O in single file mannerOsmosisWater moves from areas of high concentration to low concentrationRemember water movement goes in OPPOSITE direction as solute!!!p = RT DCp = Osmotic pressure in Osmolar (OsM)R = gas constant (typically 8.315 J K-1 mol-1)T = temperature in degrees KDC = concentration gradient of non-permeable solute moleculesOsmolesTotal number of solute particles in solutions (all species)1mM glucose = 1mOsM solution1 mM NaCl = 2 mOsM solutionTonicity of a solutionHypertonic environment water rushes out (shrinks)Hypotonic environment water rushes in (lyse)Isotonic environment no net movementBasic Trends for water balanceTerrestrialWater loss and MUST GAIN SODIUMAquaticWater Gain and MUST ACCUMULATE SOLUTE IONSMarineWater loss and MUST REMOVE SOLUTES GAINED FROM SEA WATERSingle-celled OrganismsFresh WaterPump out water and use membrane ion pumps to accumulate ionsContractile VacuolesSea WaterPump out salt and prevent leakage of waterFresh WaterSea WaterSeparated Body Fluid CavitiesAround 300 mOsM for most vertebratesOsmoconformersInternal body fluid p is equal to that of environment but do regulate solutes & ions (not same solute concentration as environment!!)Usually requires formation or loss of non-toxic soluteAmino acids, amino acid metabolites, urea, etc.Adjustable solute molecules must be non-toxic and minimally interactive with proteins.OsmoregulatorsInternal p is regulated independent of environmentMust pump water and/or solutesStenohalineOrganisms that cannot handle the wide fluctuations in salt concentration of waterEuryhalineAble to adapt to a wide variety of salinities.Freshwater Osmoregulators (body fluids tend to dilute)ProblemsGain waterLost salt via diffusionSolutionPump in saltMinimize water diffusionSaltwater Osmoregulators (body fluids tend to concentrate)ProblemsGain salt from waterLose water via osmosisSolutionsPump out saltMinimize water diffusionAnadromous fish deal with both hypo and hypertonic environments (Salmon)Shark Rectal GlandExcrete salt from the body fluidsAccomplished by transporting Sodium and Chlorine ions from body fluid into urine.Use urea as osmotic solute!!!Nitrogenous WastesAmmoniaMost aquatic animalsVery toxicSoluble in water (lots of water needed to remove)Uric AcidLow toxicityNot soluble in waterBirds and reptiles (hard-shelled)Terrestrial insects and spidersUreaToxicSoluble in waterNeeds lots of water to removeMammals and sharksHow do you minimize water loss?External covering (Skin or
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