大学生物专业英语lessonfive.pptVIP

1 Genes Code for Particular Proteins;尿黑酸症（alcaptonuria）：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。 ?　　尿黑酸尿症是常染色体隐性遗传病，由于先天性尿黑酸氧化酶缺乏，因而由酪氨酸分解而来的尿黑酸不能进一步分解为乙酰乙酸，致使过多的尿黑酸由尿排出，并在空气中氧化为黑色。; Thirty years later Beadle and Ephrussi showed a relationship between particular genes and biosynthetic reactions responsible for eye color in fruit flies. 三十年后, Beadle 和Ephrussi(乔治·比德尔和埃弗鲁西，美国 )发现特殊基因与负责果蝇眼睛颜色的生物合成反应有关。; Next, in a series of classic experiments on the effects of mutation 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. 接着, Beadle and Tatum（比德尔和塔特姆）通过一系列经典的面包霉粗糙脉孢菌的突变试验得出一个基因一个酶的假说。; Their work paved the way for other researchers to elucidate [i?lu:s?de?t] the precise way in which enzymes affect complex metabolic pathways. 他们的工作为其他研究者精确阐明 “酶是如何影响复杂新陈代谢途径”铺平了道路。;; In 1949s, in research on the role of hemoglobin [?hi:m??gl??b?n] in sickle cell anemia [?s?k?l s?l ??nimi?], Linus Pauling helped refine the one-gene-one-enzyme hypothesis into the one-gene-one-polypeptide hypothesis. 在1949年， Linus Pauling（莱纳斯·卡尔·鲍林，美国化学家 ）通过研究镰刀状细胞贫血症中血红素的作用,将一个基因一个酶的假说进一步修正为一个基因一个多肽假说。 ; 2 the search for chemistry and molecularstructure of nucleic acids; Nuclei acid, originally isolated by Johann Miescher in 1871, was identified as prime constituent of chromosomes through the use of the red-staining method developed by Feulgen in the early 1900s. 在1871年，核酸最初是由Johann Miescher（约翰拿·米歇尔 瑞士化学家）分离成功的，并通过应用1900年由Feulgen（福尔根 ） 发现的R带技术被证实是染色体组最基本的组成。;　　Frederick Griffith′s experiments with the R and S stains of pneumococci [nju:m?k?ksa?] showed that an as yet unknown material from one set of bacterial could alter the physical traits of a second set. 　　Frederick Griffith（弗雷德里克·格里菲斯 ）对粗糙和光滑的肺炎球菌实验表明，来自一组细菌的某种未知物质可以改变另一组细菌的物理性状。;　　In the 1940s the team of Avery, MacLeod, and McCarty sho