大学生物专业英语lesson_six_图文.ppt

* * The probable next step toward life was the spontaneous linking of such monomers into polymers such as proteinoids and nuclei acids. 这些单体自发的连接成多聚体，如类蛋白和核酸，使进入生命状态成为可能。（使进入生命状态成为可能的下一个步骤） Current research suggests that likely sites for this polymerization were clay or rock surfaces. 目前的研究认为这些聚合作用可能发生在泥土或岩石表面。 * * Researchers have found that, when energy is available to a system, they can generate three kinds of organic molecular aggregates. 研究发现当一个系统获得能量时，可能发生3种有机分子的聚集体。 The Russian Aleksandr Oparin obtained polymer-rich droplets, called coacervates, from solutions of polymers. 俄国科学家从多聚物的溶液中获得了富含多聚物的小液滴，即凝聚物。 * * Sidney Fox generated proteinoid microspheres from mixtures of amino acid and water. Fox从氨基酸和水的混合液中获得了类蛋白微球体。 A third laboratory structure is the liposome, a spherical lipid bilayer that forms from phospholipids. 实验室第三个结构物质是脂质体，即由磷脂形成的球形液体脂双层结构。 * * A structure similar to one or more of these aggregates may have been the precursor of true cells. 与这些聚集体类似的结构可能是生命细胞的前体. * * Further steps in the appearance of cells on the earth included the development of RNA and DNA as biological information molecules. 地球上生命发生的下一阶段就是作为生物信息分子的 RNA 和 DNA的形成。 Evidence suggests that RNA, which can form spontaneously under conditions mimicking those of the early earth, was the first information molecule. 有证据表明,在实验室模拟早期地球自然条件下自发生成的RNA是最早的信息分子 。 * * The discovery of RNA ribozymes—RNA that can act as an enzymelike catalyst—suggests that such catalytic RNA also could have assembled new RNAs from early nucleotides. RNA核酶- RNA可以作为类似酶的催化剂 - 的发现表明它可以催化早期核甘酸形成新的RNA。 Certain catalytic RNAs can also carry out sexlike exchanges of pieces of RNA. 某些催化性的RNA分子也能进行RNA片段间性交换的。 核酶的发现说明它可以催化早期核酸形成新的RNA。对于RNA物种而言，某些催化RNA具备类似于性交换的功能。 * * Following the development of a lipid-protein surface layer and replicating RNA and DNA informational molecules, the even