生物化學(xué)

信息代謝生物代謝信息代謝能量代謝物質(zhì)代謝生物代謝

ThereforeitmustReplicatefaithfully.Havethecodingcapacitytogenerateproteinsandotherproductsforallcellularfunctions.“Ageneticmaterialmustcarryouttwojobs:duplicateitselfandcontrolthedevelopmentoftherestofthecellinaspecificway.”-FrancisCrickDNAistheGeneticMaterialDNAReplicationApril25,1953

WatsonandCrick:

"Ithasnotescapedournoticethatthespecific(base)pairingwehavepostulatedimmediatelysuggestsapossiblecopyingmechanismforthegeneticmaterial."TheDawnofMolecularBiologyThehypothesisofsemiconservativereplicationproposedbyWatsonandCrickin1953.OldstrandNewstrand第一節(jié)DNA的復(fù)制

ReplicationofDNADNA半保留復(fù)制DNA在提取過(guò)程中已經(jīng)被斷裂成許多片段,因此,只涉及DNA復(fù)制前和復(fù)制后的狀態(tài)后隨鏈(thelaggingstrand)的Okazaki片斷只有在一個(gè)新的片斷合成后，才能被連接成大的片斷。只有在復(fù)制叉附近有相當(dāng)長(zhǎng)的單鏈區(qū)時(shí)，一個(gè)后隨鏈才能啟動(dòng)復(fù)制。由于有后隨鏈的出現(xiàn)，使得DNA的復(fù)制并不是連續(xù)的，而是半不連續(xù)的復(fù)制。前導(dǎo)鏈→連續(xù)后隨鏈→不連續(xù)岡崎片斷不是一個(gè)復(fù)制子，岡崎片斷的合成起始點(diǎn)不是DNA的復(fù)制起始點(diǎn)。DNA半不連續(xù)復(fù)制DNAreplicationissemi-discontinuousContinuoussynthesisDiscontinuoussynthesis1.5TheEnzymology

ofDNAReplicationDNAIsSynthesizedbyDNAPolymerasesDNA聚合酶IbyArthurKornbergin1955原核生物中。DiscoveryofhowDNAisassembledhelpedignitethebiotechnologyrevolution以DNA為模板的DNA聚合酶模板鏈結(jié)合部位引物鏈結(jié)合部位dNTP專一性結(jié)合部位多種酶活性催化部位識(shí)別并結(jié)合模板識(shí)別并結(jié)合引物識(shí)別并結(jié)合4種dNTP三種酶活性酶活性部位的復(fù)雜性DNA聚合酶DNA復(fù)制過(guò)程及相應(yīng)酶類Topoisomerase以DNA為模板的RNA合成nNTP(NMP)n+nPPi

RNA聚合酶模板、Mg2+RNA的轉(zhuǎn)錄合成

SynthesisofRNAbytranscriptionRNApolymeraseperformsmultiplefunctions:SearchesforinitiationsitesontheDNAmoleculeandunwindsashortstretchofDNA(起始);SelectsthecorrectNTPandcatalyzestheformationofphosphodiesterbonds(延伸);DetectsterminationsignalsforRNAsynthesis(終止).RNA聚合酶RNA生物合成過(guò)程及其酶類轉(zhuǎn)譯或翻譯（translation）：按照轉(zhuǎn)錄產(chǎn)生的mRNA中的信息，合成蛋白質(zhì)的過(guò)程。也稱之為表達(dá)(expression)。翻譯translationAll64

genetic

codes密碼表是按照mRNA的順序編制的Firstletterofcodon(5’end)TheNobelPrizeinphysiologyormedicine1968FortheirinterpretationofthegeneticcodeanditsfunctioninproteinsynthesisEstablishedtheChemicalstructureoftRNAEstablishedthe