万物简史 第428期:生命的起源(22)

 Mitochondria manipulate oxygen in a way that liberates¹ energy from foodstuffs². 线粒体支配着氧，释放食物中的能量。

Without this niftily facilitating trick, life on Earth today would be nothing more than a sludge of simple microbes. 没有这种很有用处的戏法，今天地球上的生命不过是生活在污泥里的一大堆简单的微生物。

Mitochondria are very tiny—you could pack a billion into the space occupied by a grain of sand—but also very hungry. 线粒体极小——一粒沙子的空间里可以装上10亿个线粒体，而且老是肚子饿，

Almost every nutriment you absorb goes to feeding them. 我吸收的营养到头来都喂养了线粒体。

We couldn't live for two minutes without them, 要是没有线粒体，我们两分钟也活不到。

yet even after a billion years mitochondria behave as if they think things might not work out between us. 然而，即使过了10亿年，线粒体的表现显示，它们似乎依然认为我们之间的问题有可能解决不了。

They maintain their own DNA³. 它们保持了自己的DNA、RNA（核糖核酸）和核蛋白体。

They reproduce at a different time from their host cell. 它们与寄主细胞在不同的时候繁殖。

They look like bacteria, divide like bacteria, and sometimes respond to antibiotics⁴ in the way bacteria do. 它们看上去像细菌，像细菌那样分裂，有时候对抗菌素作出细菌会作出的那种反应。

In short, they keep their bags packed. 总之，它们老是把行李准备停当。

They don't even speak the same genetic⁵ language as the cell in which they live. 它们甚至不说寄主细胞说的那种基因语言。

It is like having a stranger in your house, but one who has been there for a billion years. 这很像是你家里来了个陌生人，而这个陌生人已经在你的家里住了10亿年。

The new type of cell is known as a eukaryote (meaning "truly nucleated"), 新的种类的细胞被称之为真核细胞（意思是“真具有核的”），

as contrasted with the old type, which is known as a prokaryote ("prenucleated"), and it seems to have arrived suddenly in the fossil record. 与之相对的旧的种类的细胞被称之为原核细胞（意思是“在具有核之前的”）。它们似乎突然出现在化石记录里。

The oldest eukaryotes yet known, called Grypania, were discovered in iron sediments⁶ in Michigan in 1992. 已知的最古老的真核细胞，即所谓的卷曲藻，是1992年在密歇根州的铁沉积物中发现的。

Such fossils have been found just once, and then no more are known for 500 million years. 这种化石发现过一次，接着5亿年中杳无踪影。

1 liberates   

解放，释放( liberate的第三人称单数 )

参考例句：

• On the contrary, my caring liberates both of us. 与此相反，我的关心会使我们两个都不受到束缚。
• May cause severe burns. Contact with acids liberates toxic gas. 可导致严重灼伤。与酸接触会释放有毒气体。

2 foodstuffs   

食物，食品( foodstuff的名词复数 )

参考例句：

• Imports of foodstuffs accounted for a small proportion of total imports. 食物进口仅占总进口额的一小部份。
• Many basic foodstuffs, such as bread and milk, are tax-free. 许多基本食物如牛奶和面包是免税的。

3 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。

4 antibiotics   

n.（用作复数）抗生素；（用作单数）抗生物质的研究；抗生素，抗菌素( antibiotic的名词复数 )

参考例句：

• the discovery of antibiotics in the 20th century 20世纪抗生素的发现
• The doctor gave me a prescription for antibiotics. 医生给我开了抗生素。

5 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。

6 sediments   

沉淀物( sediment的名词复数 )； 沉积物

参考例句：

• When deposited, 70-80% of the volume of muddy sediments may be water. 泥质沉积物沉积后，体积的70-80％是水。
• Oligocene erosion had truncated the sediments draped over the dome. 覆盖于穹丘上的沉积岩为渐新世侵蚀所截削。