高二英語(yǔ)教案：《Unit 2 Cloning. 克隆》教學(xué)設(shè)計(jì)（二）

高二英語(yǔ)教案：《Unit 2 Cloning. 克隆》教學(xué)設(shè)計(jì)（二）

　　
　　Unit 2 Cloning

　　Step I Lead-in

　　This topic is difficult for students. So teacher should help the students learn more about it. Do this in the way of asking and answering questions.

　　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?

　　T: Reproductive cloning is a technology used to generate an animal that has the same nuclear DNA as another currently or previously existing animal. Dolly was created by reproductive cloning technology. She was the first mammal to be cloned from adult DNA taken from an adult cell. Previously, animals had only been cloned using embryo cells which already have the potential to become a complete embryo in its own right. The big breakthrough with Dolly was to make a clone from an ordinary, adult cell ? in this case from a female goat’s udder.

　　S: Have you seen Jurassic Park? In this feature film, scientists use DNA preserved for tens of millions of years to clone dinosaurs. They find trouble, however, when they realize that the cloned creatures are smarter and fiercer than expected. Could we really clone dinosaurs.

　　T: In theory? Yes. What would you need to do this? A well-preserved source of DNA from the extinct dinosaur, and a could serve as a surrogate mother. In reality? Probably not. It’s not likely that dinosaur DNA could survive undamaged for such a long time. However, scientists have tried to clone species that became extinct more recently, using DNA from well-preserved tissue samples.

　　More questions about cloning are given in the appendix. The information above is for reference only. Or you can choose several students and ask them to act out a short play whose main topic is as follows:

　　An old man who was dying left all his fortune to his own son. But the did not know that his son was cloned. So two same young men both claimed that they were the old man’s son. They quarreled and fought with each other; at last they went to the judge. The judge let them check DNA. The result was that their DNA was the same. Now even the judge did not know what to do.

　　In this part the teacher can give the students some advice to act out. According to this play teacher ask the students several questions:

　　1. Do you want to be cloned or not? Why?

　　2. If you are the judge what will you do?

　　3. Can you tell me the advantages of cloning?

　　4. And what is the disadvantage?