專業(yè)英語(yǔ)分析和總結(jié)

resultinproducingnewproteinseachofwhichhasaspecificfunctionneededforcellsurvival(growth,metabolism,replication,andothers).導(dǎo)致產(chǎn)生新的蛋白質(zhì)和所需的每一種都有一個(gè)特定的功能對(duì)于細(xì)胞的生存(生長(zhǎng)、新陳代謝、復(fù)制和其他人)。Thefollowingstatementiscrucialtounderstandingtheprocessofinteipretationoccurringwithinacell.LetageneGintheDNAcomponentberesponsibleforproducingaproteinPInterpretersIcapableofprocessinganygenemaywellutilizePasoneofitscomponents.ThisimpliesthatifPhasnotbeenassembledintothemachineryofInointerpretationtakesplace.下面的語(yǔ)句至關(guān)重要的解釋發(fā)生在一個(gè)細(xì)胞中的過(guò)程。讓基因DNA組件負(fù)責(zé)生產(chǎn)蛋白質(zhì)P翻譯處理任何基因很可能利用P作為它的一個(gè)組件。這意味著如果我沒(méi)有組裝的機(jī)器沒(méi)有辦法去解釋。AnotherinstanceinwhichPcannotbeproducedisthealreadymentionedfactthatanotherproteinP'maypositionitselfatthebeginningofgeneGand(temporarily)preventthetranscription.另一個(gè)實(shí)例中,P不能產(chǎn)生已經(jīng)提到這樣一個(gè)事實(shí):另一種蛋白質(zhì)P可能定位基因G和初(暫時(shí))阻止轉(zhuǎn)錄。Theinterpreterinthebiologicalcaseiseitheronethatalreadyexistsinagivencell(priortocellreplication)orelseit譯員在生物的情況下是一個(gè)已經(jīng)存在于一個(gè)給定的細(xì)胞(細(xì)胞復(fù)制之前)或其他generatedbyspecificgenes(e.g.,ribosomalgenes).Inbiologytheinterpretercanbeviewedasamechanicalgadgetthatismadeofmovingpartsthatproducenewcomponentsbasedongiventemplates(DNAorRNA).Theconstructionofnewcomponentsismadebysubcomponentsthathappentobeinthevicinity.Iftheyarenot,interpretationcannotproceed.由特定的基因(如生成的：核糖體基因)。在生物學(xué)解釋器可以被視為一個(gè)機(jī)械裝置，是由移動(dòng)部件生產(chǎn)新組件基于給定的模板(DNA或RNA)。建設(shè)新組件是由子組件，在附近。如果他們不是這樣的，則不能進(jìn)行解釋。Onecanimagineasimilarsituationwheninterpretingcomputerprograms(althoughitisunlikelytooccurinactualinterpreters).AssumethatthecomponentsofIarefirstgeneratedontheflyandonceIisassembled(asdata),controlistransferredtotheexecutionofI(asaprogram).你可以想象一個(gè)類似的情況，解釋計(jì)算機(jī)程序(雖然不太可能發(fā)生在實(shí)際翻譯中)。假設(shè)我是第一的組件生成的動(dòng)態(tài)和一個(gè)組裝(數(shù)據(jù)),控制轉(zhuǎn)移到我的執(zhí)行(程序)。Theabovesituationcanbesimulatedinactualcomputersbyutilizingconcurrentprocessesthatcompriseamultitudeofinterruptstocontrolprogramexecution.Thiscouldbeimplementedusinginterpretersthatfirsttestthatallthecomponentshavebeenassembled:executionproceedsonlyifthatisthecase;otherwiseaninterrupttakesplaceuntiltheassemblyiscompleted.Alternativelyonecanexecuteprogrampartsassoonastheyareproducedandinterruptexecutionifasequelhasnotyetbeenfullygenerated.InSection7.5.1zwewilldescribeonesuchmodelofgeneinteraction.上述情況可以模擬在實(shí)際計(jì)算機(jī)中利用并發(fā)進(jìn)程組成多種中斷控制程序執(zhí)行。這可能是解釋器實(shí)現(xiàn)第一次測(cè)試所有的組件組裝:執(zhí)行,一個(gè)中斷發(fā)生，直到組裝完成。另外一個(gè)可以執(zhí)行程序部分就產(chǎn)生和中斷執(zhí)行如果續(xù)集尚未完全生成。節(jié)中,我們將描述一個(gè)模型的基因的相互作用。4o實(shí)驗(yàn)室的工具確定生物數(shù)據(jù)Westartwithawarningthattheexplanationsthatfollowarenecessarilycoarse.Thegoalofthissectionistoenablethereadertohavesomegraspofhowbiologicalinformationisgatheredandofthedegreeofdifficultyinobtainingit.Thiswillbehelpfulinunderstandingthevarioustypesofdataavailableandtheprogramsneededtoutilizeandinterpretthatdata.我們開始預(yù)示說(shuō)，下面的解釋必然是不準(zhǔn)確的。本節(jié)的目的是使讀者有一些掌握生物信息是如何收集和獲取的理解起來(lái)有一定難度。這將有助于理解各種類型的數(shù)據(jù)和利用所需的程序和解釋這些數(shù)據(jù)。SequencersaremachinescapableofreadingoffosequenceofnucleotidesinastrandofDNAinbiologicalsamples.ThemachinesarelinkedtocomputersthatdisplaytheDNAsequencebeinganolyzed.Thedisplayalsoprovidesthedegreeofconfidenceinidentifyingeachnucleotide.Presentsequencerscanproduceover300kbasepairsperdayatveryreasonablecosts.ltisalsoinstructivetoremarkthattheinverseoperationofsequencingcanalsobeperformedratherinexpensively:itisnowcommonpracticetoorderfrombiotechcompaniesvialscontainingshortsequencesofnucleotidesspecifiedbyauser.測(cè)序機(jī)器是有能力閱讀核甘酸序列在生物樣本的DNA鏈。機(jī)器與電腦顯示的DNA序列分析。顯示還提供了準(zhǔn)確的程度確定每個(gè)核甘酸。目前測(cè)序可以產(chǎn)生超過(guò)300k堿基對(duì)每天花費(fèi)合理的成本。也很有教育意義的話，測(cè)序的逆操作也被執(zhí)行,而且比較廉價(jià):現(xiàn)在是常見的做法，從生物技術(shù)公司瓶包含短序列的核甘酸由用戶指定。Asignificantdifficultyinobtaininganentiregenome'sDNAisthefactthatthesequencesgatheredinawetlabconsistofrelativelyshortrandomsegmentsthathavetobereassembledusingcomputerprograms;thisisreferredtoastheshotgunmethodofsequencing.SinceDNAmaterialcontainsmanyrepeatedsubsequences,performingtheassemblagecanbetricky.Thisisduetothefactthatafragmentcanbeplacedambiguouslyintwoormorepositionsofthegenomebeingassembled.(DNAassemblywillberevisitedinSection7.7.)顯然是困難的要獲得整個(gè)基因組的DNA序列的聚集在一個(gè)濕實(shí)驗(yàn)室由相對(duì)較短的隨機(jī)部分，必須重新使用計(jì)算機(jī)程序;這是稱為獵槍的測(cè)序方法。因?yàn)镈NA材料包含許多重復(fù)的子序列,執(zhí)行組合可能會(huì)非常棘手。這是由于這樣的事實(shí):一個(gè)片段可以含糊不清地放置在兩個(gè)或兩個(gè)以上的基因組組裝的位置。(DNA組裝將在7.7節(jié)被重提。)Recently,therehasbeenatrendto。甘empttoidentifyproteinsusingmassspectroscopy.Thetechniqueinvolvesdetermininggenesandobtainingthecorrespondingproteinsinpurifiedform.Thesearecutintoshortsequencesofaminoacids(calledpeptides)whosemolecularweightscanbedeterminedbyamassspectrograph.Itisthencomputationallypossibletoinfertheconstituentsofthepeptides最近,有一種趨勢(shì)試圖使用質(zhì)譜法識(shí)別蛋白質(zhì)。技術(shù)涉及到確定基因和獲得相應(yīng)的蛋白純化的形式。這些切成短的氨基酸序列(稱為肽)的分子量可以由質(zhì)譜儀。然后計(jì)算可能推斷出多肽的成分yieldingthosemolecularweights.Byusingexistinggenomicsequences,onecanattempttoreassemblethedesiredsequenceofaminoacids.產(chǎn)生這些分子量。通過(guò)使用現(xiàn)有的基因組序列，可以嘗試重新組裝所需的氨基酸序列。The3DstructureofproteinsismainlydeterminedbyX-raycrystallographyandbynuclearmagneticresonance(NMR).Boththeseexperimentsaretimeconsumingandcostly.InX-raycrystallography,oneattemptstoinferthe3Dpositionofeachoftheprotein'satomsfromaprojectionobtainedbypassingX-raysthroughacrystallizedsampleofthatprotein.Oneofthemajordifficultiesoftheprocessistheobtainingofgoodcrystals.X-rayexperimentsmayrequiremonthsandevenyearsoflaboratorywork.蛋白質(zhì)的三維結(jié)構(gòu)主要是由x射線晶體學(xué)、核磁共振(NMR)。這些實(shí)驗(yàn)都需要耗費(fèi)大量的時(shí)間和成本。在x射線晶體學(xué)，一個(gè)試圖推斷出的3d位置每個(gè)蛋白質(zhì)的原子從一個(gè)投影得到的x射線穿過(guò)固定樣本的蛋白質(zhì)。過(guò)程的主要困難之一是獲得良好的晶體。x射線實(shí)驗(yàn)可能需要幾個(gè)月甚至幾年的實(shí)驗(yàn)室工作。IntheNMRtechnique,oneobtainsanumberofmatricesthatexpressthefactthattwoatoms—thatarenotinthesamebackbonechainoftheprotein—arewithinacertaindistance.Onethendeducesa3Dshapefromthosematrices.TheNMRexperimentsarealsocostly.Agreatadvantageisthattheyallowonetostudymobilepartsofproteins,ataskwhichcannotbedoneusingcrystals.在核磁共振技術(shù),獲得大量的矩陣表達(dá)的事實(shí)，兩個(gè)原子并不在同一個(gè)主鏈的責(zé)任應(yīng)在一定的距離。然后推導(dǎo)出3d從這些矩陣形狀。核磁共振實(shí)驗(yàn)也是昂貴的。一大優(yōu)勢(shì)是，他們讓一個(gè)研究蛋白質(zhì)的移動(dòng)部分,任務(wù)不能使用晶體。TheprecedingparagraphsexplainwhyDNAdataissomuchmoreabundantthan3Dproteindata.前面的段落解釋DNA數(shù)據(jù)比3d蛋白質(zhì)豐富得多的數(shù)據(jù)。AnothertypeofvaluableinformationobtainablethroughlabexperimentsisknownasESTsorexpressedsequencetags.TheseareRNAchunksthatcanbegatheredfromacellinminutequantities,butcaneasilybeduplicated.Thosechunksareveryusefulsincetheydonotcontainmaterialthatwouldbepresentinintrons(seetheAppendixforadefinition).TheavailabilityofESTdatabasescomprisingmanyorganismsallowsbioinformaticianstoinferthepositionsofintronsandevendeducealternatesplicing.另一種類型的有價(jià)值的信息通過(guò)實(shí)驗(yàn)獲得被稱為est或表達(dá)序列標(biāo)簽。這些RNA的塊可以在一個(gè)中微量細(xì)胞聚集，但可以很容易地復(fù)制。這些塊非常有用，因?yàn)樗鼈儾话牧?，將出現(xiàn)在內(nèi)含子的定義（見附錄）。EST數(shù)據(jù)庫(kù)的可用性包括許多有機(jī)體允許bioinformoticions推斷內(nèi)含子的位置甚至演繹交替剪接。Apowerfulnewtoolavailableinbiologyismicroarrays.TheyallowdeterminingsimultaneouslytheamountofmRNAproductionofthousandsofgenes.Asmentionedearlier,thisamountcorrespondstogene-expression;itispresumedthattheamountofRNAgeneratedbythevariousgenesofanorganismestablishesanestimateofthecorrespondingproteinlevels.一個(gè)強(qiáng)大的新工具是可用的生物芯片。他們?cè)试S同時(shí)確定mRNA的數(shù)量生產(chǎn)成千上萬(wàn)的基因。正如前面提到的，此金額對(duì)應(yīng)的基因表達(dá)，它是假定的數(shù)量的RNA產(chǎn)生的各種基因的生物體建立估計(jì)相應(yīng)的蛋白質(zhì)水平。Microarrayexperimentsrequirethreephases.Inthefirstphaseoneplacesthousandsofdifferentone-strandedchunksofRNAinminusculewellsonthesurfaceofasmallglasschip.（Thistaskisnotunlikethatdonebyajetprinterusingthousandsofdifferentcolorsandplacingeachofthemindifferentspotsofasurface.）ThechunkscorrespondtotheRNAknowntohavebeengeneratedbyagivengene.The2Dcoordinatesofeachofthewellsareofcourseknown.Somecompaniesmassproducecustompreloadedchipsforcellsofvariousorganismsandsellthemtobiologicallabs.微陣列實(shí)驗(yàn)需要三個(gè)階段。在第一階段一個(gè)地方成千上萬(wàn)的不同的RNAone-stranded塊小玻璃晶片表面上的小凹陷。（這一任務(wù)是不像,通過(guò)噴墨打印機(jī)使用成千上萬(wàn)的不同的顏色，并讓他們每個(gè)人都在不同的地方的表面）。塊對(duì)應(yīng)于給定生成的RNA已知基因。每個(gè)凹陷的2d坐標(biāo)當(dāng)然知道。一些公司大規(guī)模生產(chǎn)自定義加載芯片的細(xì)胞各種生物和賣給生物實(shí)驗(yàn)室。Thesecondphaseconsistsofspreading—onthesurfaceoftheglass-geneticmaterial（againone-stranded第二階段由spr一oding-on玻璃表面的遺傳物質(zhì)（再次one-stronded）RNA）obtainedbyacellexperimentonewishestoperform.ThosecouldbetheRNAsproducedbyadiseasedcell,orbyacellbeingsubjectedtostarvation,hightemperature,etc.TheRNAalreadyintheglasschipcombineswiththeRNAproducedbythecellonewishestostudy.ThedegreeofcombinedmaterialobtainedbycomplementingnucleotidesisanindicatorofhowmuchRNAisbeingexpressedbyeachoneofthegenesofthecellbeingstudied.RNA）細(xì)胞實(shí)驗(yàn)獲得的一個(gè)愿望來(lái)執(zhí)行。那些可能產(chǎn)生的RNA病變細(xì)胞，或由一個(gè)細(xì)胞遭受饑餓、高溫等。已經(jīng)在玻璃芯片的RNA結(jié)合產(chǎn)生的RNA研究細(xì)胞一個(gè)祝愿。結(jié)合材料的程度得到補(bǔ)充多少RNA的核甘酸是一個(gè)指標(biāo)表達(dá)的每一個(gè)細(xì)胞的基因的研究。Thethirdphaseconsistsofusingalaserscannerconnectedtoacomputer.The