河北省迁安一中高二英语：book8Unit2《Cloning》warming_up课件（人教版）.pptVIP

金太阳新课标资源网 * 金太阳新课标资源网 老师都说好! Cloning Warming up A clone is an animal or plant produced naturally or artificially from the cells of another animal or plant and is exactly the same as it. Whats a clone? 克隆是英语单词clone的音译，clone源于希腊文klon，原意是指幼苗或嫩枝，以无性繁殖或营养繁殖的方式培育植物，如杆插和嫁接。 如今，克隆是指生物体通过体细胞进行的无性繁殖，以及由无性繁殖形成的基因型完全相同的后代个体组成的种群。克隆也可以理解为复制、拷贝，就是从原型中产生出同样的复制品，它的外表及遗传基因与原型完全相同。 1997年 2月，绵羊“多利”诞生的消息披露，立即引起全世界的关注，这头由英国生物学家通过克隆技术培育的克隆绵羊，意味着人类可以利用动物身上的一个体细胞，产生出与这个动物完全相同的生命体，打破了千古不变的自然规律。 Dolly the sheep A strawberry plant Growing new plants Twins In pairs, look at these pictures and discuss which ones are natural clones and which ones are man-made. Think about how they differ. The first one is a man-made clone, the rest three are natural clones. Natural clone is one that occurs from the “parent ” in a natural form of cloning without human help. Man-made clone is one that produced through human intervention(介入) . 自然克隆:由无性生殖或是由于偶然的原因产生两个遗传上完全一样的个体（就像同卵双生一样）。 人工克隆:通过有意识的设计来产生的完全 一样的复制。  twins More natural cloning examples cucumber pepper red –leave poplar tree More man-made cloning examples 2. How is a clone produced? The cloning of plants is simple and relatively easy. It can be done by taking cuttings (man-made cloning) or letting the plant produce its own runners (natural cloning). The cloning of animals is more complicated. It was not achieved until 1996 . Here is an example to show how a clone is produced. A female sheep provides an egg cell. The nucleus is removed from the egg cell. Step 1 How do scientists clone a sheep? A second female sheep provides a somatic cell. The nucleus is also taken out. Step 2 The egg cell from sheep A and the nucleus from sheep B are joined together using electricity. Step 3 The combined cell divides and grows into an embryo. Step 4 The embryo is then put into female sheep C. Finally a sheep D is cloned. Step 5 3. What benefits can humans gain from cloning? 1) Medical cloning can help cure serious illnesses th