万物简史 第580期:生命的物质(6)（在线收听）

DNA didn't do anything at all, as far as anyone could tell. It just sat there in the nucleus, possibly binding the chromosome in some way or adding a splash of acidity on command or fulfilling some other trivial task that no one had yet thought of. The necessary complexity, it was thought, had to exist in proteins in the nucleus.

就大家所知，DNA根本不做任何事情，它只是静静地待在细胞核中。它可能以某种方式约束染色体，也可能根据指令增加一点酸度，或者完成一些不得而知的其他微不足道的任务。据认为，复杂的东西非得存在于蛋白质之中。

There were, however, two problems with dismissing DNA. First, there was so much of it: two yards in nearly every nucleus, so clearly the cells esteemed it in some important way. On top of this, it kept turning up, like the suspect in a murder mystery, in experiments. In two studies in particular, one involving the Pneumonococcus bacterium and another involving bacteriophages (viruses that infect bacteria), DNA betrayed an importance that could only be explained if its role were more central than prevailing thought allowed. The evidence suggested that DNA was somehow involved in the making of proteins, a process vital to life, yet it was also clear that proteins were being made outside the nucleus, well away from the DNA that was supposedly directing their assembly.

然而，如果将DNA的作用忽略不计，会引发两个问题。首先，DNA数量是如此之多，几乎每个细胞核里都有将近2米长的DNA，显然它在细胞中起着某种非同小可的作用。最重要的是，它在实验中频频露面，犹如一起神秘的凶杀案中的嫌疑人。尤其是在与肺炎球菌和噬菌体（感染性细菌病毒）有关的两项研究中，DNA所扮演的重要角色说明它的角色远远被低估了。实验表明，DNA在制造蛋白质这样对生命至关重要的物质方面起着某种作用，不过人们也很清楚，蛋白质是在细胞核外生成的，与据测对它们聚合施加影响的DNA相距甚远。

No one could understand how DNA could possibly be getting messages to the proteins. The answer, we now know, was RNA, or ribonucleic acid, which acts as an interpreter between the two. It is a notable oddity of biology that DNA and proteins don't speak the same language. For almost four billion years they have been the living world's great double act, and yet they answer to mutually incompatible codes, as if one spoke Spanish and the other Hindi. To communicate they need a mediator in the form of RNA.

过去，没有人能够弄明白DNA是怎样将信息传递给蛋白质的。我们现在知道，是RNA，也就是核糖核酸在这两者中间起到了一种翻译作用。DNA和蛋白质操的不是同一种语言，这是生物学里一件引入注目的奇事。在将近40亿年的时间里，它们在生命世界中扮演了至关重要的双簧角色，然而它们各自操的是彼此不能相容的密码，就好比一个说的是西班牙语，另一个说的是印地语。要想相互交流，它们就得有一个中介，而这个中介就是RNA。