MATTER ENERGY AND LIFE.docx

MATTER ENERGY AND LIFE.docx

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MATTERENERGYANDLIFE

Chapter3MATTER,ENERGYANDLIFE

Everyorganismusesmatterandenergyfromitsenvironmentandtransformsthemintostructuresandprocessesthatmakelifepossible.

Thephysicalandchemicalprinciplesthatgoverntheuniversealsogovernthecompositionandmetabolicprocessesoflivingorganisms.

Organismsaremadeofinorganiccompoundsandorganiccompounds.

MATTERANDFUNDAMENTALPARTICLES

Matterisanythingthathasmassandtakesupspace.

WeightisameasurementofthepulloftheEarth'sgravityonanobject.

∙Weightchangeswithdistance.

∙Massofanobjectisconstantregardlessofdistance.

Matteristransformedandrecombinedbutitdoesn’tdisappear.Thisistheprincipleofconservationofmatter.

Elementsarethesimplestsubstances.Theycannotbebrokendownintosimplersubstancebychemicalreactions.

Anatomisthesimplestportionofanelementthatretainsitschemicalproperties.

Eachelementhasitsowncharacteristicatomrepresentedbyachemicalsymbol.

Subatomicparticles:

protons,neutronsandelectrons.

Thenumberofprotons,atomicnumber,identifiestheatom.

Protonscarryapositiveelectricalcharge;neutronsareelectricallyneutral,andelectronsarenegative.

Thenumberofprotonsandneutronsdeterminesthemassoftheatom,atomicmass.

Themassoftheelectronis1/1800ofthemassofaprotonorneutron,anditisdisregardedincalculatingtheatomicmassofanatom.

Isotopesofanelementareatomsthathavethesamenumberofprotonsanddifferentnumberofneutrons.

Someisotopesareradioactiveandarecalledradioisotopes.

CHEMICALBONDS

Atomsmaycombinechemically,bond,toformmolecules.

Moleculesofanelementhaveatomsofthesamekind,e.g.H2,N2.

Achemicalcompoundismadeofdifferenttypeatoms,e.g.H2O,Ca（OH）2.

Molecularformulasdescribetheatomiccompositionofonemoleculeofthecompound.

Theforcesthatholdatomstogetherarecalledchemicalbonds.

Eachbondcontainscertainamountofenergycalledchemicalenergy.Thisenergycanbereleasedincertainchemicalreactions.

Bondsvaryinstability.Somearestableandformstrongbondsthatrequirealotofenergytobreakapart.Othersareweakandbreakwithverylittleenergy.

Atomsshareelectronswhentheyformcovalentbonds.

Thecarbonatomcanformfourcovalentbondsmakingitpossibletomakethemanycomplexmoleculesfoundinlivingorganisms.

Atomswithequalnumberofprotonsandneutronsareelectricallyneutral.

IONS,ACIDSANDBASES

Atomscanlooseorgainelectronsandbecomeelectricallychargedintheprocess.Theseelectricallychargedatomsormoleculesarecalledions.

∙Atomsthatgainanelectronbecomenegative,1-charge,andarecallednegativeions.Wesaythisatomisreduced.

∙Atomsthatlooseanelectronbecomepositive,1+charge,andarecalledpositiveions.

Wesaythisatomisoxidized.

Example:

HClcansplitintoH+andCl-.

Herethehydrogenatomgaveuponeelectrontothechlorineatomandbecamepositive,whichis1+orH+;thechlorineatomgainedoneelectronanditsnegativechargeswentupbyone.Itisnow1-orCl-.

Compoundsthatreleasehydrogenionsarecalledacidsandthosethatcombinereadilywithhydrogenionsarecalledbases.

ThepHscaledescribesthenumberoffreehydrogenionsinasolution.

∙ApHof7isneutral;apHlessthan7isacidicandabove7isbasic.

∙Thescaleislogarithmic,whichmeansthatapH6representtentimesmorehydrogenionsinsolutionthanpH7.

SomeionslikethoseofNa+andCl-canattracteachotherandformionicbonds.Thesebondscouldbeverystronglikethoseformedbysodiumchloride,tablesalt.

Watermoleculesformhydrogenbonds.Thesebondsgivewatersomeofitsimportantchemicalandphysicalcharacteristics.

Substancesthatreleasehydrogenions（H+）inwaterarecalledacids.

Substancesthatreadilybondwithhydrogenions（H+）arecalledbasesoralkalinesubstances.

ThepHscalemeasurestheconcentrationofhydrogenions（protons）inasolution.

ItisbasedonthenegativelogarithmofitsconcentrationofH+.

Example:

10-6concentrationofH+hasapHof6;aconcentrationof10-5hasapHof5,whichistentimesstrongerthanpH6.

NoticethattheconcentrationofH+increasesaspHdeclines.

ApHof10hasanacidconcentrationof10-10andahydroxideconcentrationof10-4.Thisisabasicoralkalinesolution.

7isneutral.Below7isacidandabove7isbasicoralkaline.

ORGANICCOMPOUNDS

Organiccompoundsaresonamedbecausetheywerethoughttobeproducedonlybylivingorganisms.

Organiccompoundscontaincarbon.

Therearesimplecarboncompoundsthatareconsideredinorganicespeciallyiftheydonotcontainhydrogen,e.g.CO,CO2.

Carbonatomsformchainsandringsthatformdifferentorganicmoleculesfoundinthebodyofplantsandanimals.Thesearecalledbiomolecules.

Lipids,proteins,carbohydratesandnucleicacidsaretheprincipalbiomolecules.

∙Lipids（fatsandoils）areimportantcomponentsofcellmembranes.

∙Carbohydratesaresourcesofenergyandalsoformpartofsupportingstructures,e.g.celluloseformsthecellwallofplants.

∙Proteinsareinvolvedinthestructureandfunctionofcells,e.g.structureofcellmembrane;enzymesareproteins.

∙Nucleicacidsareverycomplexmolecules.Theystoregeneticinformationanddirectthelifeprocesses.

CELLS

1.Cellsarethebasicunitofstructureandfunctionofalllivingthings.

2.Allcellscomefrompreexistingcells.

Allcellshaveasimilarorganization:

∙semipermeableplasmamembranethatsurroundsthecell

∙internalstructurescalledorganelles.

∙DNAthatcontainsthegeneticmaterial..

Organismsmaybeunicellularormulticellular.

Amembrane,theplasmamembrane,surroundscells.

Theplasmamembraneismadeoflipids,proteinsandafewcarbohydrates.

Theplasmamembraneregulateswhatentersandleavesthecell.

Insidethecellsthereare"organelles"thatperformdifferentfunctionsandpermitthecelltooperate.

Enzymesareproteinsthatactascatalysts.Thesecatalystsarespecializedandpermitlifefunctionstotakeplace.

Metabolismisthesumofalltheenzymaticreactionstakingplaceinthebodyofanorganism.

ENERGY

Basicconcepts

Energyisthecapacitytodowork.

∙Energyismeasuredinjoules.Onejoulecanmoveonekilogramonemeter.

∙1kg=2.2.pounds.

Workisanychangeinthestateormotionofanobject.

Energycanchangeform.

Kineticenergyistheenergyofmotion.

Potentialenergyisstoredenergy.Itdependsonthelocationandstructureofmatter.

∙Chemicalenergystoredisfood（e.g.sugars）isaformofpotentialenergy.

Heatistheenergythatcanbetransferredbetweenobjectsofdifferenttemperature.Itisthetotalamountofkineticenergyinasubstancethatitsbulkisnotmoving.

Temperatureisthemeasureoftheenergyofmotionofmolecules.

∙Asubstancecanhavehighheatcontentandlowtemperature!

∙Lowaveragemolecularspeed.

∙Largemasswithmanymovingmoleculesandatoms.

Thermodynamics

Thermodynamicsregulatesenergytransfer.

Matterisrecycled.Itchangesformsbutitisneithercreatednordestroyed.

1.Firstlawofthermodynamics.

∙Energyoftheuniverseisconstant.

∙Energy-masscannotbecreatednordestroyed.

∙Energymaybetransformed,e.g.fromaenergyinachemicalbondtoheatenergy.

2.Secondlawofthermodynamics.

Whenenergyisconvertedfromoneformtoanother,someoftheusableenergyisconvertedtoheatandisdispersedinthesurroundings.

Ateverystepofenergytransformationthereisalossofenergycapabletodowork.

Nooneprocessthatrequiresenergyconversionis100%efficient.

Allnaturalsystemsthentogofromastateofordertotowardastateofincreasingdisorder.

Entropyoramountofdisorderincreasesreflectingthelossofenergy.

Thereislessenergyavailableattheendofaprocessthanatthebeginning.

APPLICATIONTOORGANISMS:

Organismsarehighlyorganizedbothstructurallyandfunctionally.

Constantmaintenanceisrequiredtokeepthisorganizationandaconstantsupplyofenergyisrequiredtomaintaintheseprocesses.

Energyisusedbythecelltodowork.

Iftheenergysupplyisdepletedthecellwilldie.

ENERGYFORLIFE

Thesunistheultimatesourceofenergyforlivingorganisms.

Afewecosystemsarebasedonenergyderivedfrominorganicsubstancesandtheearthmolteninterior.

Extremophiles

Extremophilesareorganismsthatliveinsevereconditions.

Deep-seahydrothermalventsprovideenergytoanecosystemthatlivesintotaldarknessandundertremendouspressure.

Theenergysourceforthisecosystemisprovidedbyinorganicmoleculeslikehydrogensulfideandhydrogengasthroughaprocesscalledchemosynthesis.

Mostoftheseextremophilesaresinglecelledorganismscalledarchaea.

Archaeaareconsideredtobeveryprimitiveorganismsandtheconditionsunderwhichtheylivearethoughttobesimilartothoseinwhichlifefirstevolved.

Greenplantsgetenergyfromthesun

Thesunproduceswarmthandlight,bothofwhichareneededforlivingorganisms.

∙Mostorganismslivewithinanarrowtemperaturerange.

∙Lightiscomposedofparticlesofenergythattravelaswaves.

∙Lightispartoftheelectromagneticspectrum,theentirerangeofelectromagneticradiation.

Ofthesolarradiationthatreachestheearth’ssurface,45%isvisiblelight,45%isinfraredradiationand10%isultravioletradiation.

∙30%isreflectedbackintospace.

∙20%isabsorbedbytheatmosphere.

∙50%isabsorbedbyground,waterandvegetation.

Lessthan1%oftheabsorbedenergyisusedinphotosynthesis.Thissmallpercentageistheenergybaseforalllifeonthebiosphere.

HOWPHOTOSYNTHESISCAPTURESENERGY

Photosynth