万物简史 第580期:生命的物质(6)

DNA¹ didn't do anything at all, as far as anyone could tell. It just sat there in the nucleus², possibly binding³ the chromosome⁴ in some way or adding a splash of acidity⁵ on command or fulfilling some other trivial task that no one had yet thought of. The necessary complexity⁶, 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 esteemed⁷ 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 bacterium⁸ and another involving bacteriophages (viruses that infect bacteria), DNA betrayed an importance that could only be explained if its role were more central than prevailing⁹ 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 incompatible¹⁰ codes, as if one spoke¹¹ Spanish and the other Hindi. To communicate they need a mediator¹² 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。

1 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

2 nucleus   

n.核，核心，原子核

参考例句：

• These young people formed the nucleus of the club.这些年轻人成了俱乐部的核心。
• These councils would form the nucleus of a future regime.这些委员会将成为一个未来政权的核心。

3 binding   

有约束力的，有效的，应遵守的

参考例句：

• The contract was not signed and has no binding force. 合同没有签署因而没有约束力。
• Both sides have agreed that the arbitration will be binding. 双方都赞同仲裁具有约束力。

4 chromosome   

n.染色体

参考例句：

• Chromosome material with exhibits of such behaviour is called heterochromatin.表现这种现象的染色体物质叫做异染色质。
• A segment of the chromosome may become lost,resulting in a deletion.染色体的一个片段可能会丢失，结果产生染色体的缺失。

5 acidity   

n.酸度，酸性

参考例句：

• This plant prefers alkaline soil,though it will readily tolerate some acidity.这种植物在酸性土壤中也能生存，但硷性土壤更加适宜。
• Gastric acidity would not prevent the organism from passing into the gut.胃的酸度不能防止细菌进入肠道。

6 complexity   

n.复杂(性)，复杂的事物

参考例句：

• Only now did he understand the full complexity of the problem.直到现在他才明白这一问题的全部复杂性。
• The complexity of the road map puzzled me.错综复杂的公路图把我搞糊涂了。

7 esteemed   

adj.受人尊敬的v.尊敬( esteem的过去式和过去分词 )；敬重；认为；以为

参考例句：

• The art of conversation is highly esteemed in France. 在法国十分尊重谈话技巧。 来自《简明英汉词典》
• He esteemed that he understood what I had said. 他认为已经听懂我说的意思了。 来自《简明英汉词典》

8 bacterium   

n.(pl.)bacteria 细菌

参考例句：

• The bacterium possibly goes in the human body by the mouth.细菌可能通过口进入人体。
• A bacterium is identified as the cause for his duodenal ulcer.一种细菌被断定为造成他十二指肠溃疡的根源。

9 prevailing   

adj.盛行的；占优势的；主要的

参考例句：

• She wears a fashionable hair style prevailing in the city.她的发型是这个城市流行的款式。
• This reflects attitudes and values prevailing in society.这反映了社会上盛行的态度和价值观。

10 incompatible   

adj.不相容的，不协调的，不相配的

参考例句：

• His plan is incompatible with my intent.他的计划与我的意图不相符。
• Speed and safety are not necessarily incompatible.速度和安全未必不相容。

11 spoke   

n.（车轮的）辐条；轮辐；破坏某人的计划；阻挠某人的行动 v.讲，谈（speak的过去式）；说；演说；从某种观点来说

参考例句：

• They sourced the spoke nuts from our company.他们的轮辐螺帽是从我们公司获得的。
• The spokes of a wheel are the bars that connect the outer ring to the centre.辐条是轮子上连接外圈与中心的条棒。

12 mediator   

n.调解人，中介人

参考例句：

• He always takes the role of a mediator in any dispute.他总是在争论中充当调停人的角色。
• He will appear in the role of mediator.他将出演调停者。