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1、,Welcome to our class!,Ready to have fun learning English?,cloning,Reading,Where is it leading us?,Book 8 unit 2,is one that occurs in a natural form of cloning without human help.,is one that is produced through human intervention(介入) .,Warming up,Two kinds of clones:,Natural clone,Man-made clone,I
2、n pairs, look at these pictures and discuss which ones are natural clones and which ones are man-made. Explain how they differ.,discussion,A strawberry plant,The new plants that grow from the runners are exact copies of the original plant.,Natural clone,一株草莓依靠它沿地“爬走”的匍匐茎,一年内就能长出数百株草莓苗,A strawberry p
3、lant,The plant produces its own runners.,Growing new plants,Man-made clone,A stem Take cuttings from growing plants to make new ones.,富贵竹插枝即活,The gardener cuts the plant ,and then the cutting produces another new plant.,Man-made clone,富贵竹插枝即活,仙人掌每块落地就生根,Twins,They are born naturally and identical in
4、 sex and appearance.,Natural clone,Dolly是世界上第一例用体细胞乳腺上皮细胞,通过细胞核移植技术,在复杂的人工操作下,得到的一只小绵羊 。,She was cloned while the others were born naturally. Dolly was a _ sheep.,cloned,How does Dolly differ from other sheep?,Man-made clone,In 1996, a sheep called Dolly was born. It is the first mammal to be cloned
5、. It is considered to be the greatest success in the development of cloning.,The following are some photos about cloning. See how much you know about it.,2001 cloning cattle,2003 Cloning horse,cloning rabbits,2002 cloning cats,2005 cloning dogs,克隆的荧光小猪(左)和正常小猪(右),In pairs discuss what you understand
6、 about cloning. Then list the questions you want to find out. Share your lists with one another.,Pre-reading,Questions about cloning,1. What is a clone?,A clone is group of cells or organisms that are genetically identical and have been produced asexually (无性生殖 /繁殖) from the same original cell. They
7、 include natural and man-made clones.,Clone, also called reproduce asexually (无性生殖 /繁殖), is the creation of cells or whole animals using DNA from a single “parent”, without using the normal reproductive (有性生殖) process. The clone has the exactly same DNA to the parent. It includes natural and man-mad
8、e clone.,克隆,是Clone的译音,意为生物体通过细胞进行的无性繁殖形成的基因型完全相同的后代个体组成的种群,简称为“无性繁殖”。 “克隆”一词于1903年被引入园艺学,以后逐渐应用于植物学、动物学和医学等方面。但克隆与无性繁殖是不同的。无性繁殖是指不经过雌雄两性生殖细胞的结合、只由,一个生物体产生后代的生殖方式,常见的有孢子生殖、出芽生殖和分裂生殖。由植物的根、茎、叶等经过压条或嫁接等方式产生新个体也叫无性繁殖。绵羊、猴子和牛等动物没有人工操作是不能进行无性繁殖的。科学家把人工遗传操作动物繁殖的过程叫克隆,这门生物技术叫克隆技术。,克隆的基本过程是先将含有遗传物质的供体细胞的核移植到
9、去除了细胞核的卵细胞中,利用微电流刺激等使两者融合为一体,然后促使这一新细胞分裂繁殖发育成胚胎,当胚胎发育到一定程度后,再被植入动物子宫中使动物怀孕,便可产下与提供细胞者基因相同的动物。这一过程中如果对供体细胞进行基因改造,那么无性繁殖的动物后代基因就会发生相同的变化。,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 i
10、ts own runners (natural cloning). The cloning of animals is more complicated. It was not achieved until 1996 and is fully explained in the first reading.,3. What benefits can humans gain from cloning?,1) Medical cloning can help cure serious illnesses that ruin ones quality of life (such as Parkinso
11、ns disease帕金森症 or Alzheimers disease老年痴呆症). 2) It can help infertile people have babies.,4. What problems may arise when humans are cloned?,1) People may want to clone themselves so they can live forever. 2) People may want to clone dead children. 3) People may want to clone their favorite pets.,Ski
12、mming,Please read the passage quickly and get the main idea, and then finish the following exercises in groups.,The main idea of the text is_ A. animal cloning is very valuable and can benefit the world. B. animal cloning could be misused by bad people so it must be forbidden C. animal cloning is we
13、ll developed because Dolly the sheep was born. D. animal cloning raised arguments and scientists are not sure about its future.,主旨大意,2. The cloning of Dolly the sheep succeeded because_. A. its easier to clone a sheep than other animals B. the scientists were determined and worked hard with patience
14、 C. the scientists were rewarded and got lots of money D. many other attempts to clone mammals failed,B,细枝末节,3. What is peoples fear about human cloning. Which of the following is wrong? A. Cloned Hitlers would do harm to the world. B. Cloned people may be killed at will for medical aid. C. A woman
15、would have difficulty recognizing her real husband. D. Men will die out because a woman can give birth to a baby without a husband.,4. The sheep that donated the somatic cell most probably lived _ years. A. 3 B. 6 C. 9 D. 13,推理判断,5. We can infer from the last three paragraphs that _. The normal deve
16、lopment of Dolly had no effect on the cloning of other species. B. Dollys serious disease and final death disturbed the whole world. C. There were arguments about animal cloning and concerns about the future of cloning. D. Dolly successfully cloned a new lamb with the help of cloning scientists.,Reading
