1、Chapter 6 Translation /翻译翻译Chapter 6 Translation /翻译翻译6.1 The Genetic Code6.2 Mechanism of Translation in Prokaryotes6.3 Translation in Eukaryotes6.4 tRNA Structure and Wobble6.5 Experiments6.1 遗传密码遗传密码6.2 原核生物翻译机理原核生物翻译机理6.3 真核生物翻译真核生物翻译6.4 tRNA结构与摇摆结构与摇摆6.5 实验研究实验研究6.1 The Genetic Code/遗传密码遗传密码Tra
2、nslation:synthesis of a protein using an mRNA as the template.Transcription tRNA:the converter tRNA:the converter4 bases vs.20 amino acidsUCAG GlyAla Ile Leu Met Phe Trp Pro Val SerThr Asn Gln Cys Tyr AspGlu Arg HisLys1 base 1 amino acidUCAG GlyAla Ile Leu Met Phe Trp Pro Val SerThr Asn Gln Cys Tyr
3、AspGlu Arg HisLys2 bases 1 amino acidUUUCUAUGGlyAla Ile Leu Met Phe Trp Pro Val SerThr Asn Gln Cys Tyr AspGlu Arg HisLysCUCCCACGAUACAAAGGUGCGAGG3 bases 1 amino acidThe genetic code /遗传密码遗传密码6.2 Mechanism of Translation in Prokaryotes原核生物翻译机理原核生物翻译机理6.2.1 Initiation /起始起始6.2.2 Elongation /延伸延伸6.2.3 T
4、ermination /终止终止Composition of prokaryotic ribosome原核生物核糖体的组成原核生物核糖体的组成6.2.1 Initiation /起始起始IF-1DissociationIF-3No reassociationSeparation of 30S and 50S subunitsSD sequence:the translation start signal16S rRNA3 endThe 30s initiation complex30S起始复合体起始复合体The collection of the 30S subunit,the mRNA,an
5、d the initiator tRNA is called the 30S initiation complex.The initiator tRNAThe 70S initiation complexThe 70S ribosome6.2.2 Elongation /延伸延伸1)tRNA entering2)Peptidyl transfer3)Translocation4)tRNA leaving1)tRNA entering /tRNA进入进入2)Peptidyl transfer /肽基转移肽基转移3)Translocation /移位移位4)tRNA leaving /tRNA离开
6、离开Elongation factors /延伸因子延伸因子Weaver,Molecular Biology,Chapter 18Elongation factors /延伸因子延伸因子Weaver,Molecular Biology,Chapter 186.2.3 Termination /终止终止Translation terminates when ribosome reaches a stop codon,because there is no tRNA being able to bind to the stop codon.Now showingTranslation:the th
7、ree stepsFile:biophoto7 Introduction to Genetic Analysis Translation:the three steps of translation(5)6.3 Translation in Eukaryotes真核生物翻译真核生物翻译Composition of eukaryotic ribosome真核生物核糖体的组成真核生物核糖体的组成Differences in Translation Initiation翻译起始的不同点翻译起始的不同点1)Initiator tRNA/其始其始tRNA2)The scanning model /扫描模
8、型扫描模型1)Initiator tRNA/其始其始tRNACAUAAnticodonfMet-tRNAfMet Formyl Met A C C5 AC AG CA*Alkylated adenosineAnticodonMet-tRNAMet Met A C C5 AG CG CAG-引自：引自：Turner,P.C.et al.分子生物学精要速览分子生物学精要速览（影印版），科学出版社，（影印版），科学出版社，1999，p.249CAUProkaryotic initiator tRNAEukaryotic initiator tRNAProkaryotic initiator tRNA
9、 70S ribosomeEukaryotic initiator tRNA 80S ribosomeCH3Yeast 80S ribosomeFile:Yeast 80S ribosome 1S1I.val 2)The scanning model /扫描模型扫描模型Prokaryotes:SD sequenceEukaryotes:Scanning modelThe scanning model /扫描模型扫描模型Translation initiated by entering IRES site directly通过直接进入通过直接进入IRES位点启动翻译位点启动翻译IRES:inte
10、rnal ribosome entry sequencePicornavirus /小核糖核酸病毒小核糖核酸病毒 www.uniklinikum-giessen.de/./res_ires.htm Internal entryAUGTranslation initiation in eukaryotes(1/4)eIFeukaryotic initiationfactorTranslation initiation in eukaryotes(2/4)Translation initiation in eukaryotes(3/4)Translation initiation in eukar
11、yotes(4/4)6.4 tRNA Structure and WobbletRNA结构与摇摆结构与摇摆6.4.1 Anti-codons /反密码子反密码子Three-dimensional structure of a tRNAAminoacyl-tRNA synthetase:a kind of enzyme that can recognize a tRNAs anticodon and match it with the correct amino acid.Aminoacyl-tRNA synthetase 氨酰氨酰tRNA合成酶合成酶Aminoacyl-tRNA synthet
12、ase53mRNACodonShow 3D:synthetase-tRNA complexFile:E coli Thr-tRNA Synthetase Complex 1QF6.valAnti-codonAmino acid6.4.2 Wobble /摇摆摇摆Wobbling is possiblemRNAtRNADNA5555Wobbled base pairsBase at the first positionin the anticodonBases at the third positionin the codon U A,GG C,UI A,U,CTable 6.2 Allowed
13、 base pairings from wobble hypothesis表表6.2 摇摆假说允许的碱摇摆假说允许的碱基配对基配对Wobbled base pairs6.5 Experiments /实验研究实验研究6.5.1 Deciphering the genetic code 破译遗传密码破译遗传密码6.5.2 Direction of translation 翻译的方向翻译的方向6.5.1 Deciphering the genetic codeNow showingDeciphering the Genetic CodeFile:biophoto7 Life Deciphering the genetic code(15)6.5.2 Direction of translation /翻译的方向翻译的方向
