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Cellular Energetics Notes: Enzymes, Photosynthesis, Respiration
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APBiounit3 CellularEnergetics Énz mTTainjobis tospeedupchemicalreactionwithin our bodiesbyloweringactivation energy shapedeterminesthefunction ActivesitelocationonanenzymewherethesubstrateattachesVeryspecific forthesubstratereactionoccurshere isnotdamagedduringthereactionandcanbeusedoverandoveragaincreatedbythefoldingupoftheaminoacidRgroup substratethereactantsin anenzymecatalyzedreaction Leiiii Enzyme ofthereaction Productstheendresults Enzymesubstratecomplex whenthesubstrateattachestotheenzyme foranenzymemediated chemicalreactiontooccurtheshape thechargeofthesubstratemustbecompatiblewiththe oftheenzyme activesite 3.2EnzymeInhibitors thereactionbycompetingwiththesubstratefortheactivesite competitiveinhibitor inhibits getintotheactivesiteoverthecompetitiveinhibitor Allostericinhibitornon competitive when moleculesattachtotheenzymeandchangethe shapeoftheactivesite increasetheamountofsubstrate so itsmorelikelyto reactionisnowinhibited sometimesthisis permenantandothertimes it isreversible 3.3 Factorsthateffectenzymereaction Temperture whenthetemp the increased energylevelofmoleculesdisruptsthebonds in theenzymeAND thebondsbetweentheenzymeandsubstrate onlyhydrogen ionicbondsare disrupted leadingtodenaturation PHthepowerofhydrogenmoreacidic lowPH howtheionsaffectthesecondaryandtertiarystructures Enzymeconcentration increasingenzymeconcentrationwillincreasetherateofreactionbutthiswilleventually offsincetherewon'tbeenoughsubsratesfortheenzymetoattach tomakingthesubstratethelimiting level factor enzychcentration Ef.TTtotalityof anorganism'schemicalreactions Metabolicpathway beginswitha specificmoleculeandendswith aproduct catabolicpathway releaseenergy breakingdowncomplexmoleculesintosimplercompounds by Anabolicpathway consumeenergy tobuildcomplexmoleculesfromsimplerones Reactions ExergonicReaction energyreleasedspontaneous ofpotentialenergyremainingislessthanwhatit wasintheproduct AGCO amount spontaneous EndergonicReaction energyrequirednon oftheproducts is greater so o potentialenergy ATP Adenosine triphosphate atsb he thigh TastePileetathstan ofabsorbanceoflightvswavelength sowhenthegra isat a peak it suggestlotsofphotosynthesis is is goingon at lowpeaklowamountoflight beingabsorbed lowphotosynthesis whichisprobab Greenpigment Phosphorylation whenyouadd a phosphate grouptoanything madefromADPby adding one phosphate group Eeased's ADP Ftp THE's 3 5 LightReactionof Photosynthesis Plantsneedtobeableto collectsolar orlightenergyandtransform itintochemicalusableenergyThentheywill need tostore theenergyandbeabletomove it aroundin astableformTheyalsoneedtobeacquirethebuilding blocksfororganicmoleculesfromtheir environment Ontheleavesofplantsthereareopeningscalledstomata whereCO2goesinand02comesout Photosynthesis lights Indent Requires light water Lightindependent Reaction PI.intwill requirecarbondioxide andthechloroplastswill aswellastheATP NADPHtoproduce ProduceOaas awaste YourmacromoleculeslikeG3P Productbutwillalsoconvert thatsolarenergyintotheusuable energycalledATPandNADPH Chloroplast Thylakoid wherethelightreactionhappens Granum stack ofthylakoid Stroma spaceoutside ofthethylakoid wherethe calvincycle ordarkreactionoccurs Photo systems proteinsonthethylakoidthatgatherthe lightandholdthepigments ETC electrontransportchainbetweenthe2 photosystems goal oflightreactionis tocreateNADPH whichwillbethefinalelectronacceptor ultimate ProtonswillflowthroughATPsynthase tomakeATP by photophoshphorylation andnow wehavethatsolarenergy converted to ausabletypesofenergy whichwillbeused in thecalvincyclewhereCoawillbecomereduced meaning it willacceptelectrons hydrogens sosincewearebuilding on to cos it is an anabolicpathaway Incalvincycle itgetsthoseelectronsfromtheNADPHthatwasfromthelightreactionandthenitwillalsorequireATP todrivethesereactions soattheendofthecalvincycleyouwillendwitha 3carbonsugarcalledgap 263psmake a 6 carbon sugar iers incens ofelectronsThereforetherearemoleculescalledelectroncarriersThey energyismovedintheform littlecarryelectronsfromoneplacetoanother Attheendofthelightreaction NADP istheelectroncarrierusedin photosynthesis Soitwillgainelectrons aswell ashydrogensandwillbecomeareducedelectroncarrierthatwillcarrytheelectronsovertothecalvincycle Photosystems proteinswithinthethylakoidmembrane andwithinthesephotosystems wehave chlorophyll A andchlorophyll B which arepigments thatabsorb reflect light so chlorophyllwillactuallydonateelectronsintotheETCof thelightreactionbygetting theelectrons excitedcausingthemtomoveto ahigherstate AttheendoftheETC is an electron carrier NADP which willpullthoseelectronsdowntheETCwhen itgains thoseelectrons itgetsreduced willalsopickup a hydrogen becomeNADPHwhichwill carrythoseelectrons overtothecalvincycle PSI nowdoesnothaveanyelectronssinceitdonatedthem toNADP so PS2willsendelectronsthroughtheETC toPSIAsitdoessotheprotons H thatstartedinthestromawillbepumpedintothethylakoidspacewherethe throughtheETC energy is comingfromtheelectronsmoving Psanow isleftwithnoelectronssowaterwillbeoxidizedheremeaning it donateselectrons sowater will bespiltapartintohydrogenselectronsand Thiswholeprocess iscalledphotolysis fearons andthen it willdonateitselectronsintoPS2 theH ionsarealsostuckinsidethemembranenowbicthethylakoidhas a lipidbilayerwhiletheor willdiffuseoutofthecell ProtonGradient alltheH ionsarenowaccumulatedwithinthe thylakoidspacesoATPsynthasewillspinandtheH ionswillflowthrough itandwillphosphorlyateADPintoATP convertingthesolarenergyintoATP Thiswholeprocess iscalledchemiosmosis diffusionofionsfromhigh tolow Thisentireprocess is calledPhotosphosphorylationsincethewholethingisdrivenbylight whenADPisconverted toATP byusingtheenergyfromATPsynthase TheDarkReaction orcalvincycle Thisiswherethechloroplastisabletobuildmacromolecules or organicmoleculesfromCo2butinorderto buildbondsyou needenergy in theformof ATPand NADPH 1ststepcarbonfixation chloroplastwilltakeCo2fromtheairandwillincorporate it into an actualmolecule theelectrons hydrogensfromthelightreactionwillbeattachedtothecoztoformglucose NADPH NADP Rubisco takesthecozfromtheair incorporate itintoRUBP 5carbonchainmolecule forming a six carbonmolecule thiswillhappen 3time sit spitsinto younowhave 3 chainsof a carbonmoleculesthatquickly 8888 molecules Phase2 Reductionphase investthe energy fromATPas well as theelectronsfrom NADPH andthenoutcomes theG3P investsomeoftheATPfromthelightreaction into aseriesofchemicalreactionsandphosphorylatethose carbonmolecules sothiswill happen 6times Then once a phosphate group is attached toyourcarbon gosomewherenowleftbackto chain NADPH will beoxidized to NADP so the electron hydrogencould nowhave18 thataregonnaleavethecalvin we have 3extracarbonssincewestartedwith is molecules This 3C is our G3P cycleandwillbeused tobuildglocuse othermarco Regeneration Phase brings usback tothestartofthewholecycle fewmoreATPwillbeinvestedandreorganizedbackintoyourfivemoleculesofRUBP iititi.is iiitiiiiiiiiti as memoans respiration downglucose its going to be brokendown into its component part coz water electrons Theelectrons hydrogensfromthebonds will beused in the mitochondria to produce themasority Glycolosis metabolic pathwaythathappens in thecytoplasm of our ATP ofall cells where we endupwith a netgain of 2 ATPmolecules we then add upsplitting thesugar into 2 molecules of pyruvate INwhathappensnextdependson if oxygen is present ornot if oxygen is presentandused in cellularrespiration we call that AerobieRespiration occurs in the Mitochondria The3carbon pyruvate willenterinto themitochondriawheremajorityof thepotential energywillbereleased thepyruvates willbebrokendowntorelease ATP AerobicRespiration Glycolosis oxidation of pyruvate Krebscyclecitricacid oxidative Phosphorylation Anaerobic Respiration no oxygen is available so no mitochondria Glycolosis Pyruvate will beconverted to LacticAcid or Ethanol co Fermentation Oxidized amoleculethatdonates electronsandhydrogenwillbeoxidized charge Reduced a moleculethat is goingtogainelectrons hydrogens contains a Hydrogen NAD electroncarrier moveselectrons movingenergy Glycolosis occurs in thecytoplasm Begins with a glucose molecule 1 a ATPmolecules that aregoing to attach some phosphates to our glucose firststepofglycolosis is endergonic requires energytherest is exergonic 2 An enzymewill comeandbreakthismolecule into a smallerones whereeachhave3 carbons 3 another ezymewillsticktoeachmolecule molecule to an electron carrier NAD alittle bit ofenergy istransferred fromthe 30 The NAD willgainsome electrons and a hydrogen will be reduced Theenzymeaddsanotherphosphorus to our substrate 4total 2 oneach if thecellwereto runout ofNAD allofglycolosis willstop 4 Differentenzymesthancomeandremovethephosphatefromthesubstratewhichleadsto the phosphorylationofADP ATP substrate levelphosphorylation weendwith 4 ATP'sbutthenglycolosis startsagain whichrequires another 2 ATP's so our net gain of ATP is a a reduced electroncarriers NADH 2 pyruvates that each have 3carbons AnaerobicRespiration wedonotusethemitochondria thisallhappens in thecytoplasm doesn'trequire or so itwillonlyuse glycolysis tomake energy so theNADH pyruvates aren'tusedforanythingafterwards However wecan'trunoutof theNADHbic weneedthemforglycolosisso usuallyinAerobicrespiration the NADHwill beoxidized in the ETC toNAD In orderforNADHtonotrun outfermentationhappenswhere we oxidizetheETC Pyruvate is converted tolaticacid endswithNAD so it cancontinuewith glycolosis leavinglacticacidas awasteproductwhereourliver willconvert itbackto pyruvate Anothertypeoffermentation is alcoholfermentationwhereduringthereaction to oxidizeyourelectroncarrier backto NAD so glycolosis cancontinueresults in pyruvateformingethanol co AerobicRespiration The 2pyruvate NADHwillbemovedintothemitochondriasincetherearestillbondsbetweenthe carbonsin pyruvateweneedto fullybreakthosedownandwhenwedoso we'regettingenergyfromourorganicmolecules 1 oxidationofpyruvate when we oxidizeourfoodtakeelectronsfromit theelectroncarrier NAD isreduced formingNADHwhichwillcarrythe electrons totheETC one of thecarbons also came off ofpyruvate whenwe oxidized it in the form of co whichwilldiffuseoutofthecell coenzyme A withattach toouracetyl CC brokenpyruvate whichwillhelpstartthecitricAcidcycleendwithco whichleaves NADH accety Thisalloccursagainfortheotherpyruvate 2 citricAcidcycle happens inthematrix wealreadyhave a reducedelectroncarriersNADH fromglycolosis 2 fromoxidationofpyruvate wehave our acetyl Maingoal is tofullyoxidize ourfoodxt Anenzyme isgoing totakethatacetyl attach it to a 4carbonmoleculecalled oxaloacetateformingcitricacid acarbon Anotherenzymeisgoingtocome breakthebonds takethe reduce an electroncarrierThe 6Cmolecule isoxidizedreleasing a coz reducinganelectron electrons carrierA semolecule remains as coaleavesThishappensagain endingwith a 4carbonglucosewhichis whatwestartedwith andalsoend withanother 2 NADH Wealsoget 1ATPproducedbysubstrate levelphosphorylation reallyGtpismade convertedintoATP AnotherelectroncarriercalledFAD willbereducedtoformFADH carrier isgoingtobeformed NADH TheprocessgoesalloveragainfortheotherAccetyI thenonemoreelectron we endwith4NADH 2 Atp Bytheendofthecyclewehavefullybrokenthefoodintocoz have alotofEC 3 oxidative Phosphorylation Alongthe innermembrane is the ETC Oxygen will pulltheelectronsdownthe etc bic it is veryelectronegative NADH is oxidizes to NAD and or pulls the electrons while pumping H proton intothe inner membrane spacewhile the oxygenbecomesreduced The NAD can now be used in glycolosis on Krebscycle over time a proton gradient of H have a charge is built in the innermembranespace since they can'tpassthroughwhich also creates a moreacidic environment ATPsynthase within the membrane whichallows protons topass through as it turns performing phosphorylation producing ATPfromADPthe hydrogen ions that flow through ATP synthase are attracted to the negative oxygen water is formed chemiosmosis diffusion of ions down a concentration gradient ATP was created not by substrate level phosphorylation but phosphorylation by oxidative Eˢm Ihe position ofsaturatedvs unsaturated fattyacids in alipidbilayerinfluences the findityofthe membrane Plants iftheyhada high ofsaturatedfattyacids in winter theircellmembranes wouldsolidifythereforethey havetheability toincreasethe i ofunsaturated fattyacidstoensuretheirmembranes maintainfluidity ofsaturatedfattyacid Theability tochangethecomposition oftheircellmembraneshelpthemrespond to avariety of foreasierpassivetransport In summertheycan theunsaturated the environmentalstimuli variation in the types ofmoleculeswithincellsprovides organisms a greaterability to survive reproduce in differentenvironments the 2 different chlorophyllmolecules specialize in absorbing differentwavelengths oflightwhich increasethe ability toabsorb solarenergy drivethelightReactions
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