吉林大学《遗传学》第章 遗传物质的分子基础

1、L/O/G/O 第十章第十章 遗传的分子基础遗传的分子基础 Proof of DNA as Genetic Proof of DNA as Genetic MaterialMaterial Transformation转化转化 in Bacteria ( Frederick Griffith . 1928 ) Characteristics of S.pneumoniae肺炎肺炎(链链) 双球菌双球菌 Strains When Grown on Blood Agar Medium Colony Morphology菌落形态菌落形态 Type Appearance Size Capsule荚膜荚

2、膜 Virulence毒毒 性性 II R Rough Small Absent Avirulent II S Smooth Large Present Virulent Colony Morphology Type Appearance Size Capsule Virulence IIIR Rough Small Absent Avirulent IIIS Smooth Large Present Virulent Reaction with Antiserum Prepared Against Type Type II S Type III S II R None None II S A

3、gglutination凝集凝集 None Reaction with Antiserum Prepared Against Type Type II S Type III S III R None None III S None Agglutination DNA : the Transformation Material ( Oswald Avery and his colleagues 1944) The analytical tools Avery etc. used were the following: 1.Ultra- centrifugation超速离心超速离心 2. Elec

4、trophoresis电泳电泳 3.Ultraviolet Absorption紫外吸收紫外吸收 4. Elementary Chemical Analysis化学化学 元素分析元素分析 The Hershey-Chase Experiment Proof of RNA as Genetic Material A variety of strains of tobacco mosaic virus tobacco mosaic virus (TMV) exist. Many strains cause distinctive symptoms on indicator plants TMV p

5、articles can be dissociated into解离解离 RNA and protein components. The separated RNA and protein can be mixed together to reform infectious viral particles. Experiments with tobacco viruses revealed that RNA, as well as DNA, could carry hereditary information. vulgare masked yellow ribgrass none Mixed

6、 particles, with RNA of one strain and protein of another, can also be formed. Mixed particles are infectious. Note the symptoms they produce (C). C Coat Protein Source vulgara masked yellow ribgrass vulgara masked yellow ribgrass RNA source L/O/G/O 第二节第二节 核酸的化学组成及结构核酸的化学组成及结构 分析分析 Nucleic Acid Chem

7、istry Johann Misecher ( 1844 1895 ) “ nuclein ”. Ribonucleic acids ( RNA ) Deoxyribonucleic acids ( DNA ) 核核 糖糖 核核 苷苷 酸酸 1 23 4 5 脱脱 氧氧 核核 糖糖 核核 苷苷 酸酸 核糖2-脱氧核糖 嘧啶环 嘌呤环 胞嘧啶 尿嘧啶 胸腺嘧啶 鸟嘌呤腺嘌呤 尿苷脱氧腺苷酸 蛋白质生物合成 脂质代谢 能量代谢 3-5磷酸二酯键 DNA Structure Erwin Chargaff and Chargaff rules A+G = T+C The Double Helix Wa

8、tson and Crick ( 1953 ) X-ray diffraction photograph of the B form of purified DNA fibers. The Nobel Prize in Physiology or Medicine 1962 DNA双链构象改变 因素： 1、核苷酸顺序 2、碱基组成 3、盐的种类 4、相对湿度 Tm ( melting temperature解链温解链温 度度 ) The temperature at which a population of double-stranded nucleic molecules is half-

9、 dissociated into single strands. This is taken to be the melting temperature for that species of nucleic acid. Denaturation变性变性 and Renaturation复复 性性 DNA紫外吸收 紫外吸收 RNA 1. 脱氧核糖脱氧核糖核糖；核糖；TU 2. 单链单链 3. 自身互补配对形成双链区。自身互补配对形成双链区。 rRNA ( ribosomal RNA ) mRNA (messenger RNA ) tRNA ( transfer RNA ) snRNA ( s

10、mall nuclear RNA ) antisense RNA telomerase RNA primer ( in vivo ) DNADNA的复制的复制 Replication ( Semiconservative Replication )半保留复制半保留复制 ( Semidiscontinuous Replication )半不连续半不连续 复制复制 The Meselson-Stahl experiment Enzymology酶学酶学 of DNA Replication Helicase解旋酶解旋酶 ( Strand Separation ) Single strand DNA-binding Proteins单链单链DNA 结合蛋白结合蛋白 ( SSBs) Primerase引物酶引物酶 ( primer ) Ligase连接酶连接酶 Telomerase端粒酶端粒酶 Topoisomerases II拓扑异构酶拓扑异构酶 ( r