万物简史 第592期:生命的物质(18)

Ninety-seven percent of your DNA¹ consists of nothing but long stretches of meaningless garble² — "junk," or "non-coding DNA," as biochemists prefer to put it. Only here and there along each strand³ do you find sections that control and organize vital functions. These are the curious and long-elusive genes⁴.

你的DNA的97%是由大量没有任何意义的垃圾（Junk），或生化学家喜欢称之为非编码DNA构成的。每一段里你发现只有部分区段在起着掌控和组织的作用。这是一些行为古怪、难以捉摸的基因。

Genes are nothing more (nor less) than instructions to make proteins. This they do with a certain dull fidelity⁵. In this sense, they are rather like the keys of a piano, each playing a single note and nothing else, which is obviously a trifle monotonous⁶. But combine the genes, as you would combine piano keys, and you can create chords and melodies of infinite variety. Put all these genes together, and you have (to continue the metaphor) the great symphony of existence known as the human genome.

基因就是（不过是）制造蛋白质的指令。它们在完成这一工作时尽职尽责。在这个意义上，它们就像钢琴的键，每一个键只能弹奏出一个音符，仅此而已，这显然有点儿单调。然而，将所有的基因组合在一起，就像你将所有的键组合在一起一样，你就能（继续这个比喻）弹奏出一曲伟大的生命交响乐，这就是人类基因组。

An alternative and more common way to regard the genome is as a kind of instruction manual for the body. Viewed this way, the chromosomes⁷ can be imagined as the book's chapters and the genes as individual instructions for making proteins. The words in which the instructions are written are called codons, and the letters are known as bases. The bases — the letters of the genetic⁸ alphabet — consist of the four nucleotides mentioned a page or two back: adenine, thiamine, guanine, and cytosine. Despite the importance of what they do, these substances are not made of anything exotic. Guanine, for instance, is the same stuff that abounds⁹ in, and gives its name to, guano.

基因组换一种通俗的说法就是一种身体指令的手册。从这个角度来看，可以将染色体想像为一本书的章节，而基因则是制造蛋白质的个别指令。指令中所写的单词被称为密码子，单词中的一个个字母被称为碱基。碱基——基因子母表中的字母——由前面我们提到的腺嘌呤、鸟嘌呤、胞嘧吟和胸腺嘧啶4种核苷酸组成。尽管它们的作用极为重要，这些物质不是什么稀奇的东西组成。例如，鸟嘌呤就是因为在鸟粪层中大量存在而得名。

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 garble   

v.曲解，窜改

参考例句：

• You garble my words from their real meaning.你曲解了我的话的真实含义。
• We must take this report as a whole and not garble any part of it.对这篇报告要全面理解，不能断章取义。

3 strand   

vt.使（船）搁浅，使（某人）困于（某地）

参考例句：

• She tucked a loose strand of hair behind her ears.她把一缕散发夹到了耳后。
• The climbers had been stranded by a storm.登山者被暴风雨困住了。

4 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

5 fidelity   

n.忠诚，忠实；精确

参考例句：

• There is nothing like a dog's fidelity.没有什么能比得上狗的忠诚。
• His fidelity and industry brought him speedy promotion.他的尽职及勤奋使他很快地得到晋升。

6 monotonous   

adj.单调的，一成不变的，使人厌倦的

参考例句：

• She thought life in the small town was monotonous.她觉得小镇上的生活单调而乏味。
• His articles are fixed in form and monotonous in content.他的文章千篇一律，一个调调儿。

7 chromosomes   

n.染色体( chromosome的名词复数 )

参考例句：

• Chromosomes also determine the sex of animals. 染色体也决定动物的性别。 来自《简明英汉词典》
• Each of four chromosomes divide longitudinally. 四种染色体的每一种都沿着纵向分裂。 来自《现代汉英综合大词典》

8 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

9 abounds   

v.大量存在，充满，富于( abound的第三人称单数 )

参考例句：

• The place abounds with fruit, especially pears and peaches. 此地盛产水果，尤以梨桃著称。 来自《现代汉英综合大词典》
• This country abounds with fruit. 这个国家盛产水果。 来自《现代汉英综合大词典》