万物简史 第577期:生命的物质(3)

The tiny differences in that remaining 0.1 percent — "roughly one nucleotide base in every thousand," to quote the British geneticist and recent Nobel laureate John Sulston — are what endow us with our individuality. Much has been made in recent years of the unraveling of the human genome. In fact, there is no such thing as "the" human genome. Every human genome is different. Otherwise we would all be identical. It is the endless recombinations of our genomes — each nearly identical, but not quite — that make us what we are, both as individuals and as a species.

这千分之一的小小基因差异——用英国遗传学家，最近获得诺贝尔奖的约翰·萨尔斯顿的话说，“每1000个核苷酸基中的约1个”就是赋予我们个性的基础。近年来很重视人类基因组结构的研究。其实根本没有单一的人类基因组这种东西。每一个人的基因组都不相同，否则我们就会完全一样。正是我们基因组的不断重组——每个基因组大体上相同，而又不完全相同，使得我们成为现在这个样，既是许多个体，又是一个物种。

But what exactly is this thing we call the genome? And what, come to that, are genes²? Well, start with a cell again. Inside the cell is a nucleus³, and inside each nucleus are the chromosomes⁴ — forty-six little bundles of complexity⁵, of which twenty-three come from your mother and twenty-three from your father. With a very few exceptions, every cell in your body — 99.999 percent of them, say — carries the same complement⁶ of chromosomes. (The exceptions are red blood cells, some immune system cells, and egg and sperm⁷ cells, which for various organizational reasons don't carry the full genetic¹ package.) Chromosomes constitute the complete set of instructions necessary to make and maintain you and are made of long strands⁸ of the little wonder chemical called deoxyribonucleic acid or DNA⁹ — "the most extraordinary molecule¹⁰ on Earth," as it has been called.

但是究竟什么是基因组？什么又是基因？嗯，让我们再从细胞开始吧。细胞内部是一个细胞核，细胞核内就是染色体——共有46束复杂的物质，其中23束来自你的母亲，23束来自你的父亲。你体内的每一个细胞——它们中的99.9999%——携带同样数量的染色体，只有极少数例外。（这些例外是红细胞、一些免疫系统细胞、卵子和精子细胞；由于不同的组织系统原因，它们不携带完整的基因孢。）染色体包含着一组完整的生成和维持你生命所必需的指令，它们由一长串一长串小而神奇的化学物质——脱氧核糖核酸（俗称DNA）组成。DNA被称为“地球上最非同寻常的分子”。

1 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。

2 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

3 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。

4 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》

5 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。

6 complement   

n.补足物，船上的定员；补语；vt.补充，补足

参考例句：

• The two suggestions complement each other.这两条建议相互补充。
• They oppose each other also complement each other.它们相辅相成。

7 sperm   

n.精子，精液

参考例句：

• Only one sperm fertilises an egg.只有一个精子使卵子受精。
• In human reproduction,one female egg is usually fertilized by one sperm.在人体生殖过程中，一个精子使一个卵子受精。

8 strands   

n.（线、绳、金属线、毛发等的）股( strand的名词复数 )；缕；海洋、湖或河的)岸；（观点、计划、故事等的）部份v.使滞留，使搁浅( strand的第三人称单数 )

参考例句：

• Twist a length of rope from strands of hemp. 用几股麻搓成了一段绳子。 来自《简明英汉词典》
• She laced strands into a braid. 她把几股线编织成一根穗带。 来自《简明英汉词典》

9 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。

10 molecule   

n.分子，克分子

参考例句：

• A molecule of water is made up of two atoms of hygrogen and one atom of oxygen.一个水分子是由P妈̬f婘̬ 妈̬成的。
• This gives us the structural formula of the molecule.这种方式给出了分子的结构式。