02 nucleic acid structure and feature

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1、Chapter02:nucleicacidsstructureandproperties1Overview1.1.1DNAdeoxyribonucleicacid;function:Thegeneticinformationcarrier,responsibleforthegeneticinformationstorageandtransmission；distribution：Eukaryotes:nucleus（98%）,organelle（2%）；prokaryotes:nucleoid、plasmids

2、viruses1.1typeanddistributionofnucleicacid1.1.2RNAribonucleicacid；Function:mainlyparticipatetheexpressionofgeneticinformationType:rRNA（ribosomalRNA）mRNA（messengerRNA）tRNA（transferRNA）distribution:cytoplasm(90%),nucleus(10%)；virusesmRNArRNAtRNA1.1.2.1mRNA种类最多

3、，比例最低，寿命最短；EachpolypeptidehascorrespondingmRNA，thedifferenceamongdifferentmRNAisquitebig(inlengthandmolecularweight)；Functions:asintermediaries,carryinggeneticinformationfromgenestoribosomes,wherethecorrespondingproteinscanbesynthesized(astemplates).1.1.2.2t

4、RNA分子量最小；Functions:asadaptermolecules(transportaminoacids),thatfaithfullytranslatetheinformationinmRNAintoaspecificsequenceofaminoacids；每个Aa至少有一个对应的tRNA（如丙氨酸tRNA、tRNAAla）。不同tRNA分子的大小很相似，73-78Nts1.1.2.3rRNA比例最大，分子量最大；Functions:structuralcomponentsofribosomes,

5、thecomplexesthatcarryoutthesynthesisofproteins已经发现的RNA种类名称缩写功能核糖体RNArRNA核糖体组成成分信使RNAmRNA蛋白质合成模板转运RNAtRNA转运活化氨基酸不均一核RNAhnRNA成熟mRNA的前体核内小RNAsnRNA参与hnRNA的剪接转运核仁小RNAsnoRNA参与rRNA的加工和修饰胞质小RNAscRNA蛋白质内质网定位合成信号的识别组分summary核酸是生命遗传信息的携带者和传递者（生命的延续、遗传特性的保持、生长发育、细胞分化）Th

6、eRNAworld，theDNAcorenucleicacidnucleotidephosphoricacidnucleosidepentosebase1.2thecomponentsofnucleicacidmeanspentose,DNAhasdeoxyribose,RNAhasribose；meansnitrogenousbasesmeansphosphatenucleotide1.2.1pentoseribose（inRNA）2’-deoxyribose（inDNA）1.2.2basepurinerin

7、gNN6543219NNNN12346587PyrimidineringDNARNAModifiedbasesThechemicalmodificationofbasesiswidespread,andhasanumberofspecificroles.Suchas:themethylationoftheN-6positionofA、the4-aminogroupandthe5-positionofC1.2.3nucleosideandnucleotide2.3.1nucleoside：DNA:2’-deoxy

8、ribose+A、T、C、GRNA:ribose+A、U、C、GThebaseislinkedtoposition1onapentosebyaglycosidicbondfromN1ofpyrimidineorN9ofpurineH2OH2ObasephosphoricacidpentoseglycosidicbondPhosphatebond1.2.3.2nucleotide2Nuc