生物专业英语第五章基因的化学本质讲述.ppt

Text analysis Genes code for particular proteins The search for the chemistry and molecular structure of nucleic acids The research race for the molecular structure of DNA How DNA replicates 1.Genes code for particular proteins The first scientists to investigate the question of how genes affect phenotype was Sir Archibald Garod , whose studies of alkaptonuria implied a relationship between genes and enzymes. Archibald Garrod是第一个研究基因是如何影响表型的科学家，他对尿黑酸症的研究揭示了基因与酶之间的关系。 Alkaptonuria(尿黑酸尿症 ) 是酪氨酸代谢中缺乏尿黑酸酶引起的代谢遗传病。这种病人的尿中含有尿黑酸，在碱性条件下暴露于氧气中，氧化并聚合为类似于黑色素的物质，从而使尿成黑色。 Thirty years later Beadle and Ephrussi showed a relationship between particular genes and biosynthetic reactions responsible for eye color in fruit flies. Biosynthetic adj. 生物合成的 三十年后，Beadle 和Ephrussi在对果蝇眼睛颜色的研究发现特殊基因与相关反应的生物合成有关。 Next, in a series of classic experiments on the effects of mutations in the bread mold Neurospora crassa, Beadle and Tatum explored the one-gene-one-enzyme hypothesis- the idea that each gene codes for a particular enzyme. bread mold：面包霉菌 接着，通过对面包霉粗糙脉孢菌的一系列经典的突变试验，Beadle 和Tatum得出一个基因一个酶的假说，即每一个基因编码一个特定的酶。 Their work paved the way for other researchers to elucidate the precise ways in which enzymes affect complex metabolic pathways. elucidate [ ilju:sideit ] . v. 阐明,说明 metabolic [ ,met?b?lik ] a. 新陈代谢的 他们的工作为其他工作者铺平了道路，即精确地阐明了酶影响了复杂的新陈代谢途径。 In 1949, in research on the role of hemoglobin in sickle cell anemia, Linus Pauling helped refine the one-gene-one-enzyme hypothesis into the one-gene-one-polypeptide hypothesis. hemoglobin [ ,hi:m?ugl?ubin ] . n. 血红蛋白 anemia [ ?ni:mi? ] n. 贫血,贫血症 在1949年， 通过研究血红蛋白对镰刀状细胞贫血症的影响，Linus Pauling将一个基因一个酶的假说进一步上升为一个基因一个多肽。  决定血红蛋白的基因中一个核酸发生变化，导致血红蛋白的一个氨基酸发生改变，使红细胞变成镰刀状，携带氧气能力降低，因而出现贫血症状。 Nucleic acid, originally isolated by Johann Miescher in 1871, was identified as a prime constituent of chromosomes through the use of the red-staining method developed by Feulgen in the early 1900s. 2.The search for the chemistry and molecular struct