Nearly all living organisms have parents in which they were reproduced and born through various stages of the life cycle. Whether it is a human being with a mother and a father or a chicken hatching from an egg, most living organisms have male and female parents. Some living organisms also form from one parent such as when a single-celled amoeba splits into two to reproduce offspring.
几乎所有的生命体在生命周期的不同阶段都有双亲孕育和培养。无论是有父母双亲的人类还是从一只从鸡蛋孵化而成的鸡,大部分生命体有两性亲代。也有一些生物体形成于单一亲代,例如单细胞变形虫分裂成两个从而繁衍后代。
However, there is a process which is much different in producing offspring called cloning. Cloning is the process when scientists take DNA from an animal cell and then place it or implant it into an egg cell taken from another animal. Before placing though, the DNA from the cell receiving it is removed.
然而,克隆这种繁殖后代的方法大相径庭。克隆是科学家在动物细胞提取DNA然后将其放入或植入其他动物卵细胞的过程。在植入之前,受体细胞内的DNA被移除。
An example of cloning, which made history in 1997, was when scientists successfully cloned a sheep. The new sheep's name was Dolly, and she was not born in the usual manner. Instead, she became an exact copy of her mother, similar to an identical twin. It would be nearly the same as taking the DNA from the son of a mother, placing the DNA in the egg cell of another woman, but first removing the woman's own DNA, and then allow the growth of the new cell in the woman. Nine months later there would be an exact copy of the mother's son born to the woman.
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2020-09-15
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