Unit3welcome-reading1.ppt

栏目导引 自学导引 语篇理解 Unit 3　Science and nature 栏目导引 自学导引 语篇理解 Unit 3　Science and nature Unit 3　Science and nature Unit 3　Science and nature 教材背景链接 　　大家对“克隆”这个名词已经不陌生了，可是人们为什么要克隆呢？克隆出另外一个自己，为你做作业，而你去和朋友打球或玩游戏吗？那就读一读下面这篇文章吧！ 　　Research advances over the past decade have told us that，with a little work，we humans can clone just about anything we want，from frogs to monkeys and probably even ourselves! 　　So, we can clone things, but why? Let’s look at some of the reasons. Unit 3　Science and nature 　　Of all the reasons, cloning for medical purposes has the most potential to benefit large numbers of people.Much of what researchers learn about human disease comes from studying animal models such as mice.Often, animal models are genetically engineered to carry disease-causing changes in their genes.Creating these transgenic (转基因的) animals is a process that requires trial-and-error and several generations of breeding.Cloning technologies might reduce the time needed to make a transgenic animal model. Unit 3　Science and nature 　　Stem cells are responsible for developing, maintaining and repairing the body throughout life.Researchers are currently looking up cloning as a way to create genetically defined human stem cells for research and medical purposes. 　　Have you seen Jurassic Park? In this feature film, scientists use DNA preserved for tens of millions of years to clone dinosaurs.Could we really clone dinosaurs? 　　In theory? Yes.A well-preserved source of DNA from the extinct dinosaur, and a closely related species, currently living, that could serve as a surrogate (替代的) mother. Unit 3　Science and nature 　　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. 　　No joke! If you really wanted to, and if you had enough money, you could clone your beloved family cat.At least one biotechnology company