英語聽力文摘 克隆為什么不是副本

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Why Clones Aren’t Copies

克隆是英文"clone"或"cloning"的音譯，而英文"clone"則起源于希臘文"Klone"，原意是指以幼苗或嫩枝插條，以無性繁殖或營養(yǎng)繁殖的方式培育植物，如扦插和嫁接。在大陸譯為“無性繁殖”在臺灣與港澳一般意譯為復(fù)制或轉(zhuǎn)殖或群殖。 中文也有更加確切的詞表達克隆，“無性繁殖”、“無性系化”以及“純系化”?？寺∈侵干矬w通過體細(xì)胞進行的無性繁殖，以及由無性繁殖形成的基因型完全相同的后代個體組成的種群。通常是利用生物技術(shù)由無性生殖產(chǎn)生與原個體有完全相同基因組織后代的過程。

Last time we were talking about how cloned animals, to some people’s surprise, aren’t just copies of their parent animals. In cloned pigs, for example, some come out bristly-haired, some smooth; some are shy, others aggressive.

How can animals share all the same genes and yet be so different?

Geneticists aren’t sure yet. One possibility is that chemical conditions inside the uterus affect how the fetus develops. But there’s also gene expression to consider. Gene expression refers to which genes are turned on and which are turned off.

Every gene in your body comes in duplicate. You get one from your mother and one from your father. Let’s simplify the situation and pretend there’s just one gene that gives you your sparkling personality.

For example, let’s say your mother was a jewel and that your dad was a crank.

In this instance, presuming you’re an angel, we can imagine that the “personality gene” your father gave you is in the “off” position, while the personality gene your mother gave you is in the “on” position. Would your clone have your same personality?

We don’t know, because we don’t know what position that switch will be in. In reality, there are many, many switches, leading to many possible combinations. A clone is a duplication of the genes, but not of the gene expression.

In other words, a clone could share genes and still look and act differently. They aren’t carbon copies–they are separate organisms all to themselves.