1、Nucleic acids:the information carrierInformation for making proteins is stored in nucleic acids.ProteinsNucleic acids(mainly DNA)Chapter 2 Nucleic acids2.1 Properties of a Genetic Material2.2 Nucleic Acids and DNA structure2.3 DNA as the Genetic Material2.4 DNA in the Cell2.5 RNA(Ribonucleic Acid)2.
2、6 Experiments2.1 遗传物质的性质遗传物质的性质2.2 核酸与核酸与DNA结构结构2.3 DNA作为遗传物质作为遗传物质2.4 细胞中的细胞中的DNA2.5 RNA（核糖核酸）（核糖核酸）2.6 实验研究实验研究2.1 Properties of a Genetic Material1.It must be able to hold information for how to make proteins.2.It must be stable.3.It must have some capacity for change.4.It must be able to be copi
3、ed.1.它必须能够保持如它必须能够保持如何生产蛋白质的信何生产蛋白质的信息。息。2.它必须是稳定的。它必须是稳定的。3.它必须具有容忍变它必须具有容忍变化的能力。化的能力。4.它必须能够被复制。它必须能够被复制。1.It must be able to hold information for how to make proteins 1它必须能够保持如何生产蛋白质的信息它必须能够保持如何生产蛋白质的信息2.It must be stable /2它必须是稳定的它必须是稳定的Lizard:1,000,000 B.C.Lizard:2008 A.D.No change!It must be s
4、table /它必须是稳定的它必须是稳定的Age:15 Age:45 Age:75 No change!No change!3.It must have some capacity for change3它必须具有容忍变化的能力它必须具有容忍变化的能力It must have some capacity for change它必须具有容忍变化的能力它必须具有容忍变化的能力MUTAtiOn4.It must be able to be copied4它必须能够被复制它必须能够被复制2.2 Nucleic Acids and DNA structure2.2 核酸与核酸与DNA结构结构2.2.1
5、Nucleotides/2.2.1 核苷酸核苷酸Nucleotides are composed of three parts:1)a nitrogenous base,2)a sugar,and 3)a triphosphate.N-glycosidic bond1)Nitrogenous base /含氮碱基含氮碱基2)Sugar /糖糖No oxygen here!Ribonucleotides and deoxyribonucleotides核糖核苷酸核糖核苷酸 与与 脱氧脱氧核糖核苷酸核糖核苷酸3)Triphosphate/三磷酸三磷酸2.2.2 General Structure
6、of Nucleic Acids2.2.2 核酸的一般结构核酸的一般结构deoxyribonucleic acid(DNA)ribonucleic acid(RNA)Phosphodiester bond /磷酸二酯键磷酸二酯键Three prime end and five prime end三一撇末端三一撇末端 与与 五一撇末端五一撇末端Sugar-phosphate backbone/糖糖-磷酸骨架磷酸骨架NegativechargesNucleosome /核小体核小体Chapter 72.2.3 Structure of DNA /2.2.3 DNA的结构的结构Double-stra
7、nded DNAHydrogen bonds Base pair /碱基对碱基对Complementary base pairsAntiparallel DNA strands反向平行的反向平行的DNA链链The DNA double Helix /DNA双螺旋双螺旋MinorgrooveMajorgroove2 nanometers1 turn=10 bases=3.4 nanometersBase stackingDenaturation of DNA /DNA变性变性Light absorbance by DNADNA对光的吸收对光的吸收=260nm=260nmssDNAdsDNANow
8、 showingMacromolecules Nucleic AcidsFile:biophoto7 Life Macromoleculs Nucleic Acids(3)2.3 DNA as the Genetic Material2.3 DNA作为遗传物质作为遗传物质StoreinformationStableAllowmutationEasyreplication1.Storing information /保存信息保存信息2.Stability /稳定性稳定性2)Covalentbonds arevery strong4)Doublehelix3)Manyhydrogenbonds1)
9、Bases areprotected3.Allowing mutation /允许突变允许突变Chapter 9Allowing mutation /允许突变允许突变Attack!Allowing mutation /允许突变允许突变Evolution4.Easy replication /容易复制容易复制2.4 DNA in the Cell2.4 细胞中的细胞中的DNAProkaryotic Chromosome /原核生物的染色体原核生物的染色体Eukaryotic chromosomes /真核生物染色体真核生物染色体Nucleus2.5 RNA(Ribonucleic Acid)2.
10、5 RNA（核糖核酸）（核糖核酸）RNADNARNA is less stable than DNARNA不如不如DNA稳定稳定RNA is usually in a single-stranded form.RNA通常以单链的形式存在通常以单链的形式存在RNA as the genetic materialRNA用作遗传物质用作遗传物质Single-strandedRNARNA is also importantRNA也很重要也很重要2.6 Experiments /实验研究实验研究 Conclusion from studies in 19th century:Chromosomes ca
11、rry the genetic material!But what is a chromosome made of?Chromosome /染色体染色体They found that the chromosome is:60%protein40%DNAWhich one is the genetic material?The transformation experiment /转化实验转化实验The Hershey-Chase experimentWhat is injected?/注射的是什么？注射的是什么？Only DNA is injected!How did they know?/他们是怎么知道的？他们是怎么知道的？How did they know?/他们是怎么知道的他们是怎么知道的DNA was the genetic materialDNA是遗传物质是遗传物质DNAProtein
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