Wouldn't it be great if we could trade genes with other species? For example, suppose you could trade the family cat your genes for intelligence for its genes for physical coordination! Well, okay, that's not likely to happen anytime soon. But DNA trading really does happen in nature!如果我们能和其他物种进行基因交易的话,岂不妙哉?例如,假设把你可以和家猫交换,用你的智力基因换家猫的灵敏基因!当然,短时期内还不可能实现.但是,DNA的交易却真的存在于大自然中! _______________________.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.与更复杂的生物体不同,大部分细菌能无性繁殖--也就是说,它们只复制自己的DNA,再分裂成两半,每一半都留有一份DNA.