英语听力文摘 English Digest 608、大自然中的DNA交易

 　　Wouldn’t it be great if we could trade genes¹ with other species? For example, suppose you could trade the family cat your genes for intelligence for its genes for physical coordination²! Well, okay, that’s not likely to happen anytime soon. But DNA³ trading really does happen in nature!

 

　　The real DNA traders are bacteria. Unlike more complex organisms, most bacteria reproduce asexually–that is, they just copy their own DNA, and then split in half, leaving one copy of the DNA in each half.

 

　　Asexual reproduction can be a big advantage, since one bacterium⁴ doesn’t need another one around to reproduce. But, on the other hand, the bacterium doesn’t get the benefit of genetic⁵ diversity.

 

　　In order to add some variety to their genetic makeup⁶, bacteria swap⁷ genes with other bacteria. They trade tiny loops of DNA called plasmids. A bacterium makes a plasmid by copying part of its DNA.

 

　　Then it trades its plasmid for one from another bacterium–in fact, just about any other bacterium! That’s right–the trading partners don’t need to be the same kind of bacteria, or even related kinds! Just about any two bacteria can swap plasmids.

 

　　That’s great for bacteria, but not always so great for everyone else. It can be a big problem if a traded plasmid carries genes for drug resistance. If just one type of bacteria–even a harmless type–develops resistance to a drug, it can pass on that resistance to other types of bacteria that aren’t so harmless! That’s the magic, and the menace, of bacterial⁸ “insider trading.”

1 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

2 coordination   

n.协调，协作

参考例句：

• Gymnastics is a sport that requires a considerable level of coordination.体操是一项需要高协调性的运动。
• The perfect coordination of the dancers and singers added a rhythmic charm to the performance.舞蹈演员和歌手们配合得很好，使演出更具魅力。

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 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。

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 makeup   

n.组织；性格；化装品

参考例句：

• Those who failed the exam take a makeup exam.这次考试不及格的人必须参加补考。
• Do you think her beauty could makeup for her stupidity?你认为她的美丽能弥补她的愚蠢吗？

7 swap   

n.交换；vt.交换，用...作交易

参考例句：

• I will swap you my bicycle for your radio.我想拿我的自行车换你的收音机。
• This comic was a swap that I got from Nick.这本漫画书是我从尼克那里换来的。

8 bacterial   

a.细菌的

参考例句：

• Bacterial reproduction is accelerated in weightless space. 在失重的空间，细菌繁殖加快了。
• Brain lesions can be caused by bacterial infections. 大脑损伤可能由细菌感染引起。