T: You can imagine how rapidly the modern science and technology develop. I think most of you must know something about space traveling, submarine exploration, robot, maglev train, gene engineering etc. But in recent years, a hot topic, cloning is often mentioned, especially when the cloning Dolly the sheep appeared. You may have first heard of cloning when Dolly the Sheep showed up on the scene in 1997. Cloning technologies have been around for much longer than Dolly, though. First things first, what is cloning and a clone? The dictionary says cloning is the technique of producing a genetically identical duplicate of an organism. A clone is said to be all descendants derived asexually from a single individual, as by cuttings, bulbs, by fission, by mitosis, or by parthenogenesis reproduction. It sounds very different and complicated to us. In fact, I mean, in our daily life, this happens often. For example, gardeners take cuttings from growing plants to make new ones. You often see that your mother picks a small branch from a growing plant to make a new one. If she likes this kind of flowers, she can do cloning. Cloning also happens in animals or human beings when twins identical in sex and appearance are produced from the same original egg. The fact is that cloning plants is straightforward but the cloning of animals is more complicated. The possibility of human cloning, raised when Scottish scientists at Roslin Institute created the much-celebrated sheep "Dolly", aroused worldwide interest and concern because of its scientific and ethical implications. You can give your questions if you are interested in this topic. I am here today one of the scientists who work in this field. I am ready to answer any of your questions.

S: Now we know what is cloning. Are there different types of cloning?

T: When the media report on cloning in the news, they are usually talking about only one type called reproductive cloning. There are different types of cloning however, and cloning technologies can be used for other purposes besides producing the genetic twin of another organism. A basic understanding of the different types of cloning is key to taking an informed stance on current public policy issues and making the best possible personal decisions. The following three types of cloning technologies will be discussed: (1) recombinant DNA technology or DNA cloning, (2) reproductive cloning, and (3) therapeutic cloning.

S: Was Dolly created by what cloning? And why was Dolly so important?