Unit 2 Cloning
Ⅰ. 单元教学目标 技能目标 Skill Goals ▲Talk about cloning ▲Practice expressing and supporting an opinion ▲Use the appositive clause ▲Write a composition about cloning Ⅱ. 目标语言 Express
ing and supporting an opinion I’m happy to accept... but... I would never accept... I’m not bothered about... 功 能 句 式 I don’t mind but... I hope you’ll carry on... Are you sure you want to...? I agree with you that... Is it fair to...? Do you think it is wise to...? I think you should... Well done to you for... I don’t understand why you don’t... I can’t help thinking... I could never agree to... 四会词汇 Differ exact twin procedure object forbid flour commercial carrier straightforward cast altogether obtain attain undertake arbitrary moral opera
breakthrough correction 词 汇 conservative chorus loaf
objection accumulate owe
unable feather turkey claw adore hatch 2． 词组
cast down, object to, the media, in favour of，（be） bound to （do） ..., from time to time, bring back to life, pay off, in vain 结 构 重 点 句 子 It is a way of... P11 The fact is that... P11 The question that occurred ... P12 The advantage is that... P15 Appositive clause — that 可引导同位语从句
Ⅲ. 教材分析和教材重组 1. 教材分析 本单元以 Cloning 为话题，旨在通过单元教学，使学生了解克隆技术的优缺 点，学会表达和支持个人观点，能用所学的有关 Cloning 的词汇去表述自己对这 一新技术的观点和看法。 1.1 Warming Up 提供了四幅有关 Dolly the sheep( 多莉羊 ) ， A strawberry plant(草莓植物)，Identical dogs(克隆狗) ，Twins（双胞胎婴儿）的图片，让学生 用已有的知识和经验讨论对克隆技术的看法与观点。 1.2 Listening 是关于人类克隆的听力材料，难度中等。 1.3 Speaking 根据材料，四人小组合作，要求把自己对克隆婴儿的态度和感 觉用相关的语言表达出来。语言要得体，锻炼语段表达能力。 1.4 Pre-reading 是 Reading 的热身活动， 它要求采用与同学讨论交流的方式谈 论有关克隆的相关知识。 1.5 Reading 是一篇介绍克隆技术的说明文。 1.6 Comprehending 第一题所给出的表格让学生根据课文内容列举克隆技术 的优缺点； 第二题让学生根据所拥有的知识来评价作者的观点；第三题要求学生 用自己的语言阐述对克隆技术的观点并给出理由。 1.7 Learning about Language 分词汇和语法两部分，其中 Discovering useful
words and expressions 是 根 据 语 境 在 运 用 中 掌 握 词 汇 。 Discovering useful structures 是通过阅读和补全句子来练习。 1.8 Using Language 中的 Reading，Discussingand writing 要求学生先读, 然后 再完成四个任务型的作业， 即 1. 讨论并回答三个问题；2. 讨论几种已经灭绝的 动物，并且讨论哪种动物应该被恢复到这个世界上，并且给出理由；3. Listening and speaking 让学生根据所听到的内容选择并列出文中人物观点。 2． 教材重组 2.1 从话题内容上分析，Warming Up 与 Reading 相一致，而从训练目的上分 析 Warming Up 与 TALKING 比较一致。从教材份量来说，可将 Warming Up 和 Reading 整合在一起，设计成一节任务型“阅读课（一） （精读课）”。 2.2 将 Listening 和 Workbook 中的 LISTENING 整合在一起， 设计成一节“听 力课”。 2.3 将 Using Language 与 Workbook 中的 TALKING 和 SPEAKING TASK 结 合在一起，设计成一节“口语课”。 2.4 将 Learning about Language 与 Workbook 中的 USING WORDS AND EXPRESSIONS 整合在一起上一节“语法课”。 2.5 将 Workbook 中 READING TASK 和 PROJECT 以及 WRITING TASK 整 合成一节“泛读与写作课”。 3. 课型设计与课时分配 1st Period 2nd Period 3rd Period 4th Period 5th Period Ⅳ. 分课时教案 The First Period Reading Teaching goals 教学目标 1. Target language 目标语言 a. 重点词汇和短语 clone, commercial, producer, undertake, arbitrary, object, forbid, accumulate, cast Reading Listening Speaking Grammar Extensive reading and writing
down, object to, the media, in favour of b. 重点句子 It is a way of... The fact is that... The question that occurred ... 2. Ability goals 能力目标 Enable the students to describe cloning: What is the advantages of cloning？ What is the problems or dangers of cloning？What is your opinion of cloning？ 3. Learning ability goals 学能目标 Help the students learn how to describe cloning. Teaching important points 教学重点 How to describe cloning. Teaching difficult points 教学难点 Help the students analyze the writing techniques of the article. Teaching methods 教学方法 Skimming, task-based method and debate method. Teaching aids 教具准备 A recorder, a projector and some slides. Teaching procedures && ways 教学过程与方式 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 thing 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 closely related species, currently living, that 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 he 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? Discussion In this part the students will discuss the relationship between the development of technology and social customs. T: As the technology develops day by day, it has a more and more important influence on the whole society. Technology affects social customs and ethics, sometimes technology may go against the conventional thinking, then comes the problem that
whether we should stop the development of research or change the ethics. S1: As technology develops in almost every field, a lot of our original customs and ethics changed, either because they are out of time or not so scientific. For example millions of years ago human ate meat of animals without heating them. Later people used fire and no longer ate raw meat and they also used fire to scare dangerous animals. S2: I think we could not stop the development of technology, for it may develop in the way which is acceptable by social customs. … Look at pictures T: Look at the pictures and discuss which ones are natural clones and which ones are man-made. Then explain how they differ. S: I think the twins are natural clones and the Dolly sheep is man-made. T: You are right! Can you explain how they differ? S: The twins were born at the same time, but the Dolly sheep is man-made. T: Anything else? Who want have a try? S: I think the identical dog is man-made. T: Good job! Step Ⅱ Pre-reading Before class, ask the students to search for some information about this topic. Now show your questions on the screen, and then let them discuss with each other. T: Now please work in pairs and discuss about cloning. Then list the questions you want to find out. Share your list with your partner. Ss: Yes, sir / madam. Questions about cloning: 1. What is a clone? 2. How is a clone produced? 3. What benefits can humans gain from cloning? 4. What problems may arise when humans are cloned? 5. Should we clone human?
6. Could cloning replace sex as the means of creating new human life? 7. Could a parent clone a child who is dying of a terminal illness? After a few minutes. T: Do you have other questions? Volunteer! S: I have! What is the writer ’s opinion? T: Good job! I think many of you have questions, now let us read the article with the questions. Suggest answers: 1. It is a way of making an exact copy of another animal and plant. 2. This happens in plants when gardeners take cuttings from growing plants to make new ones, and when small parts of a plant are taken and gown in a laboratory. It also happens in animals when twins identical in sex and appearance are produced from the same original egg. 3. It can help cure disease and can help couples who have no baby to bear a new baby. 4. There may be more bad people like Hitler. 5. In my opinion, I do not agree, for it may cause many moral problems. 6. No. Because cloned human has the same quality as the real human, natural born baby’s quality is higher than his parents. 7. No. The cloned baby also has the disease. Step Ⅲ While-reading Get the students to comprehend the passage quickly and accurately and meanwhile help the students form a good habit of reading. T: Have you got the answers of your questions? Now please skim the passage fast to obtain a general understanding of the whole passage. While reading, divide the whole passage into several parts and find out the main idea of each part. Show the following. Para. 1 Cloning is a way of making an exact copy of another animal and plant. Para. 2 Cloning has two major uses. Para. 3 The problems of Dolly. Para. 4 The effect of Dolly.
Para. 5 It is forbidden to clone human being. Step Ⅳ Post-reading Ask the students to read the passage again to finish three tasks. T: Now let’s listen to the tape. While listening, pay more attention to the correct pronunciation and tone. Then read the text by yourselves to get the answers to the three tasks. You can work in groups. T: First, what are the problems or dangers of cloning? S: Let me have a try! First, the cloned animals have the same illness of the old animals and the same goes with the other species. Second, the cloned animals have short life and can cause moral questions. T: You are right! And what are the advantages of cloning? S: I know! Firstly, gardeners use it all the time to produce commercial quantities of plants. Secondly, it is valuable for research on new plant species and for medical research on animals. Thirdly, it suddenly opens everyone’s eyes to the possibility of using cloning to cure serious illnesses, and even producing human beings. T: What is the writer ’s opinion? What do you think is the writer ’s point of view in this reading passage? Is it in favour of cloning or against it? S1: I think the writer is in favour of it, because there are many advantages of cloning. It can help people solve many problems in our daily life. S2: I think the writer doesn’t agree with it, because if the cloning technology can be used in an evil way, it can cause much trouble to our society. T: The next question: What is your opinion of cloning? Give the reasons. S1: As a coin has two sides, everything has two aspects. First, if the cloning is used in a correct way it can bring many conveniences to us. Such as: curing serious illnesses and being used to produce commercial qualities of plants. On the other hand, if the cloning is used in an evil way it can cause much troubles: such as moral questions. S2: My view on cloning and nuclear transfer is that it is ethical. So actually I find no reason to clone presently. I have this opinion currently, because scientists are unable to successfully clone using nuclear transfer as of today.
S3: I also have a problem with the possible effects of using nuclear transfer on a large scale. This is because I fear that cloning could greatly reduce genetic diversity. I believe if we were to interfere with the genetic diversity of an entire population we would undoubtedly fail. S4: As you can see I believe cloning using nuclear transfer should not be used on humans for any reason. I think if we were to use cloning it should be closely monitored as to what dangers are involved in having copies of people. I also think this technology should not be used until success. S5: I agree that we should develop cloning. I’m not afraid of cloning Hitlers or excited to clone Einsteins. I would say the time and the environment produced Hitler, not his DNA. So you do not need DNA from Hitler to produce a Hitler. In fact, there are Nazis already present. We should make use of cloning to benefit future generations. You can imagine that how happy the people are if they can recover from the serious illness or get back the son who has just lost his life in an accident by cloning. T: Good job! Yes, if we our human beings use the scientific technology properly it can bring many advantages to us! S: Why did Dolly’s appearance raise a storm of objections and have a great impact on the media and public imagination? T: Because nothing really prepared the world for the 1997 announcement that a group of Scottish scientists had created a cloned sheep named Dolly. Many folks believe that within the next decade, we will hear a more shocking announcement of the first cloned human. Scientists in South Korea have already created human embryonic stem cells through cloning. Until now, the idea of human cloning has only been possible through movie magic, but the natural progression of science is making human cloning a true possibility. We’ve cloned sheep, mice and cows, so why not humans? Some countries have set up laws banning cloning, but it is still legal in many countries. Imagine using a piece of your great-grandmother ’s DNA to create a clone of her. In a sense, you could be the parent of your great-grandmother. This opens the door to many ethical problems, but it’s a door that could soon be opened.
S: So what happens next? T: Whatever the reasons, the new cloning technologies have sparked many ethical debates among scientists, politicians and the general public. Several governments have considered or enacted legislation to slow down, limit or ban cloning experiments outright. It is clear that cloning will be a part of our lives in the future, but the course of this technology has yet to be determined. Cloning could cause birth defects, but it ’s not going to change society. In the absence of any legislation or regulation, cloning attempts will quietly continue. Eventually, cloning will succeed (if it hasn’t happened already), and humankind will have taken another step down the road of biological engineering. You young students are the future of the world. You should study hard today, and you will be able to face this difficult problem and know how to deal with it. Explanation Step Ⅴ Homework Ask the students to do the following. 1. Complete the exercises on page 13. 2. Recite the key sentences in the text. 3. What is Clone? You might not believe it, but there are human clones among us right now. Have you ever wished you could have a clone of yourself to do homework while you hit the skate park or went out with your friends? Imagine if you could really do that. Where would you start? The Second Period Listening Teaching goals 教学目标 1. Target language 目标语言 a. 词汇和短语 cloning, attitude, medicine, organs b. 重点句子 I agree with... How would you do...? Do you think...?
2. Ability goals 能力目标 Let the students focus on the different attitude towards cloning technology. 3. Learning ability goals 学能目标 Teach the students how to get the specific information. Teaching important points 教学重点 Listen to the materials about cloning and choose the correct answers. Teaching difficult points 教学难点 Work together with partners and show their own opinions. Teaching methods 教学方法 Listening and cooperative learning. Teaching aids 教具准备 A tape recorder. Teaching procedures & ways 教学过程与方式 Step I Revision 1. Greetings 2. Revision Step Ⅱ Pre-listening Work in groups to discuss how we should behave towards the human clones. T: Before human clones become part of our life, perhaps we should spend some time thinking about how we should behave towards them. Now, work in groups to discuss the following questions. Show the following. 1. How would you treat human clones? 2. Do you think they should have legal and political rights, such as getting married or voting? 3. Do you think they are separate people or part of the original donor? Sample answers: 1. I will treat them as normal people. 2. Yes, I think they should have the legal and political rights. 3. I think they are separate people.
Step Ⅲ Listening The students are asked to read fast the questions and multiple answers to find out the listening points first, and then listen to the tape twice to choose the best answer. T: Please open your books at page 54. Before you listen to the tape, please read fast the questions and multiple answers to find out the listening points. Pay more attention to these important points while listening. While listening, you’d better make notes of the listening points. A few minutes later. T: Now, I’ll play the tape twice. Please listen carefully and pay more attention to the important points. You may make notes while listening. Notes taking are helpful for you to remember each of the important points. After listening twice, check the answers and explain some difficult listening points if necessary. Step Ⅳ Listening task (P57) (时间不足时改为作业) First, ask the students to read these sentences and then listen to the tape and decide if they are facts or opinions. T: Now turn to page 57, there’re 10 questions. You should form the habit of going through the questions and the answers to get the important listening points. Yes? And make notes if necessary. OK? Play the recording and then check the answers with the class. Sample answers: Arguments for cloning pets: 1. Favorite pets can live forever as clones. 2. It is moral to clone pets for their owners. Arguments against cloning pets: 1. Many people don’t agree with cloning. 2. Some people think that cloning pets is selfish. Step Ⅴ Homework T: Boys and girls, today we have listened to some materials about cloning. I do hope you can listen to the materials again after class so that you can get very familiar with them. Besides, please preview the reading. Now class is over. Goodbye, everyone.
Ss: Goodbye, sir / madam. The Third Period Speaking Teaching goals 教学目标 1. Target language 目标语言 a. 重点词汇和短语 theme，fighting，conflict，argument，destruction，in one’s opinion b. 交际用语 Expressing and supporting an opinion I would never accept... I’m not bothered about... I don’t mind but... I hope you’ll carry on... Are you sure you want to...? I agree with you that... Do you think it is wise to...? I think you should... Well done to you for... I can’t help thinking... I could never agree to... 2. Ability goals 能力目标 Enable the students to express their opinions about cloning using some useful expressions. 3. Learning ability goals 学能目标 Help the students learn how to express their opinions. Teaching important points 教学重点 Learn to use the structures of expressing and supporting an opinion. Teaching difficult points 教学难点 How to give a speech. Teaching methods 教学方法 Cooperative learning.
Teaching aids 教具准备 A computer & a projector. Teaching procedures & ways 教学过程与方式 Step Ⅰ Lead-in T: Good morning / afternoon, boys and girls! Ss: Morning Mr... T: Last class we have talked about clone, we all know it is not a dream. Now everyone, if I give you a chance to clone what will you restore then? S: Edison, dinosaurs, Japanese wolf, Einstein. T: Do you want to clone Hitler? S: No. Hitler is a dangerous person. T: If some terrorists master this clone method, they may bring disasters. All your choices are excellent. Today we will learn another passage about cloning, from which we will know whether we can bring dinosaurs back to life. Ask the students to go through some facts of cloning. T: From these facts we know human beings have achieved great progress in cloning. Now read the text carefully to get the answers for these questions: what animals have people cloned? S: Frogs, mice, cows, sheep, bisons, cats, and dogs. T: Good job. Answer the question: What are the common characteristics of these animals? Ss: They are nowadays animals. T: Yeah, I think you must have seen the film Jurassic Park, in which a scientist clones several different kinds of extinct dinosaurs. Can we really clone dinosaurs now? Let the students turn to page 15 and then read the text quickly. Several minutes later. S: We cannot clone dinosaurs, because it’s difficult for us to get its DNA. T: Good job. It’s only a dream. Dinosaurs disappeared 65,000,000 years ago. So the chance of dinosaurs ever returning to the earth is merely a dream. Step Ⅱ Read and answer (P16) To answer these three questions, teacher can give the students some examples as
explanation, for example, Question 1. T: Now think about this question: if in the world there is only one sheep and human beings want to clone more. Some days later a Dolly appears, then many more. But one day all sheep get the same deadly disease. Now please think about what the results are. S: Maybe they would all die. T: Why? S: Because all sheep have the same arrangement of genes. T: Right. Now can you answer Question 1? Why shouldn’t you clone an extinct animal unless there is enough diversity in the group? S: It is useless to clone an animal if there is not enough diversity in the group for it to overcome illnesses. T: Why is it wrong to clone an extinct animal if it would have to live in a zoo? S: If the cloned animals have to live in the zoo, it is unfair to them. They need freedom. T. Why can’t you clone the DNA of animals that have been extinct longer than 10,000 years? S: Dinosaurs disappeared 65,000,000 yeas ago. So the chance of dinosaurs returning to the earth is merely a dream. Step Ⅲ Discussion (Question 2) This is a speaking task. Ask the students to have a discussion in groups, organize their words properly, and give vivid description of the chosen animals. T: Now look at the table on page 16, discuss in pairs which extinct animals described are worth restoring by means of cloning. Choose one animal and use the information to help you argue why this animal should be restored to the earth. Give the students six minutes to discuss. S1: I think Great Auk is a wonder. Because it is a very large bird that cannot fly. The useful thing about it is that its feather doesn’t absorb water. I think if we wear clothes made of its feather, we will not worry about rain. S2: I agree with you. But I am happy to accept Dodo bird because it is friendly and not harmful. I like gentle animals. It can also lay large eggs and its meat is tasty, but I
don’t think I will eat its meat. … T: From your answers I think these animals are all useful and they all should be restored to the earth. At the same time, we should try our best to protect them. Do you agree with me? S: Yes. Step Ⅳ Writing a report (P17) Deal with Questions three and four. Divide the whole class into four groups. Then they can have a competition. T: Now everyone, imagine all of you are owners of your chosen animal. Now work together, and give us a vivid description of your pet, then I will decide which one is the best to be resorted to the earth. Several minutes later, the students give performances. At the same time, list some major points on the blackboard. T: Well done everyone. It is really hard for me to choose, let us vote OK? Step Ⅴ TALKING (P55) Ask the students to talk about the questions with the teacher ’s help. T: Look at the questions on page 54. Do you know how to show your opinion? You can discuss the following questions with your partner and use these expressions on page 54. 1. How would you feel about having a clone of yourself in the family? 2. What problems did you have growing up and how can you help him / her avoid them. Step Ⅵ Homework T: Write down your feelings and attitudes towards clone. Combine them into a composition. Sample version 1: In my opinion it is wrong to clone human beings. If my parents decide to have a clone made of me, I will feel very sad and I will never accept the clone as a member of my family or as my friend because I think it is unfair to natural things.
We are all sons of nature, birth or death is a natural thing. The day we born, it destined we are independent. Nobody has the right to change ourselves. If one day I were to be cloned to another person, he would kill me, because I lost some original characters. I hope we should respect human beings, and not change any original things. Sample version 2: I think the cloning represents the progress of the mankind. But it still has many problems to work out, the law, the ethic and especially the goals and purposes for cloning. However, we are actually doing much of this research for the improvement of life for humans. We should get benefit from cloning. In China, the government has put out written policy on human cloning. It has officially banned research on human cloning for reproduction purposes, but allows cloning on embryonic stem cells and remedial cloning. As we all known, everything can’t be perfect. We should treat the cloning with correct attitudes. We should know the advantages and disadvantages of cloning. The Fourth Period Grammar Teaching goals 教学目标 1. Target language 目标语言 a. 重点词汇和短语 bother, regulation, resist, unable, argument, reasonable, obtain, be bound to, from time to time, bring back to life, pay off b. 重点句子 Altogether Dolly lived for six years, half the length of the life of the original sheep. The fact that she seemed to develop normally was very encouraging. 2. Ability goals 能力目标 Enable the students to learn the modal verbs must, have to, have got to. 3. Learning ability goals 学能目标 Help the students learn how to use the modal verbs must, have to, have got to. Teaching important points 教学重点 The use of the modal verbs must, have to, have got to.
Teaching difficult points 教学难点 How to teach the students to master the usage of the modal verbs must, have to, have got to. Teaching methods 教学方法 Study independently and practice. Teaching aids 教具准备 A projector and a blackboard. Teaching procedures & ways 过程与方式 Step Ⅰ Revision Check the students’ homework. T: Last class we talked something about cloning. Now, who can show your opinion? S: Let me have a try. In my opinion it is wrong to clone human beings. If my parents decided to have a clone made of me, I would feel very sad and I would never accept the clone as a member of the family or as my friend. T: Good job! Step ⅡGrammar T: Do you know the appositive clauses? Please pick out three more examples from the reading passage. Sample answers: The fact is that they are natural clones of each other. The whole scientific would follow the progress of the first successful clone, Dolly the sheep. Altogether Dolly lived for six years, half the length of the life of the original sheep. T: Now let me explain something about the appositive clauses. The appositive clause is a clause used as an appositive. The clause is an explanation to the noun before. The appositive clause belongs to noun clauses. Most of the appositive clauses may be introduced by the conjunction that. A content clause is frequently in apposition with such nouns as fact, news, idea, thought, question, reply, report, remark, hope, belief, suggestion etc. Some examples:
Nobody shares my belief that he was mad. My suggestion that he was mad was not accepted. They are familiar with the opinion that all matter consists of atoms. Where did you get the idea that I could not come? We haven’t yet settled the question where we are going to spend our summer vacation. The suggestion came from the chairman that the new rule should be adopted. T: The words the fact are often inserted in front of an object clause when the clause cannot be conveniently connected with the verb either directly or by means of the representative it. This cannot hide the fact that he is growing old. We must face the fact that we are living in a revolutionary world. Some supplements: 同位语从句与 that 引导的定语从句 1) 从先行词看 同位语从句与名次之间在逻辑上是“主语+be+表语”的关系。 该名词是需要做特殊 说明的抽象名词。例如： They were delighted at the news that their team had won. The news was that their team had won. 2) 从引导词来看 引导词 that 在同位语从句中是连词，只起连接作用，无具体词，that 不可省略； that 在定语从句中是关系代词，它在从句中充当一定成分--主语或宾语，有具体 词义，作宾语时还可以省略。 The factory (that) we visited yesterday is a chemical one. The news that he will leave for Shanghai is true. 3) 同位语从句的简易判断方法 同位语从句与其先行词在逻辑上是“主语+be+表语”的同位语关系。所以，可以在 名词从句之间加系动词 be，使之构成一个新句子，如果合乎逻辑，句子通顺， 则原句为同位语从句；定语从句是不能够用系表结构把先行词与从句连接起来
的。 The belief that the earth is flat is still held in some countries. The belief is that the earth is flat. 能用于名词性从句的名词有：ability, patience, anxiety, answer, order, report, wish, decision, suggestion, belief, doubt, fact, hope, message, news, promise, question, reply 等等。 学好同位语从句关键应注意下列几点： 一、理解同位语从句的含义，把握同位语从句的实质。 在主从复合句中作同位语的从句称为同位语从句。同位语从句一般用 that, whether 等词引导， 常放在 fact, news, idea, truth, hope, problem, information 等名词 后面，说明该名词的具体内容。换言之，同位语从句和所修饰的名词在内容上为 同一关系。 例：The news that they had won the game soon spread over the whole school. 他们比赛获胜的消息很快传遍了整个学校。 析：they had won the game 说明 The news 的全部内容，因此该句为同位语从 句。 二、正确运用同位语从句的引导词，准确把握同位语从句。 1.如同位语从句意义完整，应用 that 引导同位语从句。 例：The general gave the order that the soldiers should cross the river at once. 将军下达了战士们立即过河的命令。 析： the soldiers should cross the river at once 是 the order 的全部内容， 且意义 完整，因此应用 that 引导同位语从句。 2.如同位语从句意义不完整，需增加“是否”的含义，应用 whether 引导同位 语从句。 例： We’ll discuss the problem whether the sports meeting will be held on time. 我们将讨论运动会是否会如期举行的问题。 析： the sports meeting will be held on time 意义不完整，应加“是否”的含义才 能表达 the problem 的全部内容，因此应用 whether 引导同位语从句。 3.如同位语从句意义不完整，需增加“什么时候”、“什么地点”、“什么方式”
等含义，应用 when, where, how 等词引导同位语从句。 例 1： I have no idea when he will be back. 析： he will be back 意义不完整，应加“什么时候”的含义才能表达 idea 的全 部内容，因此应用 when 引导同位语从句。 例 2： I have no impression how he went home, perhaps by bike. 析： he went home 意义不完整，应加“如何”的含义才能表达 impression 的全 部内容，因此应用 how 引导同位语从句。 三、 把握同位语从句和定语从句的区别， 明确同位语从句和相似从句的界限。 同位语从句和定语从句相似，都放在某一名词或代词后面，但同位语从句不 同于定语从句。同位语从句对名词加以补充说明，是名词全部内容的体现，且名 词和同位语从句的引导词均不在从句中充当任何成分；定语从句对名词加以限 制，是名词内容的修饰性定语，且名词和定语从句的引导词均在从句中作成分。 例 1 Information has been put forward ____ more middle school graduates will be admitted into universities. (2001 上海) A. while B. that C. when D. as 析：答案为 B。more middle school graduates will be admitted into universities 是 Information 的内容，且 Information 不在从句中充当任何成分，所以该句为同 位语从句。应将该句区别于： It is said that more middle school graduates will be admitted into universities， this is the information ____ has been put forward. A. what B. that C. when D. as
析：答案为 B。 that has been put forward 为 information 的修饰性定语，且 information 在从句中作主语，所以该句为定语从句。 例 2 She heard a terrible noise, ____ brought her heart into her mouth. (MET91) A. it B. which C. this D. that
析：答案为 B。分析语境含义、句子结构和句子成分可知，该句为非限制性 定语从句，先行词为 a terrible noise，且它在从句中作主语。应将该句区别于： I can’t stand the terrible noise ____ she is crying loudly. A. it B. which C. his D. that
析：答案为 D。she is crying loudly 是 the terrible noise 的内容，且 the terrible noise 不在从句中充当任何成分，所以该句为同位语从句。 巩固性练习： 1. The fact ____ she works hard is well known to us all. A. that B. what C. why D. which
2. The fact ____ he was successful proves his ability. A. that B. what C. which D. why
3. The news ____ he was kidnapped surprised us greatly. A. what B. that C. why D. when
4. His suggestion ____ the meeting be delayed was turned down. A. which B. that C. / D it
5. I have no idea ____ he will start. A. when B. that C. what D. / 6. I’ve come from the government with a message ____ the meeting won’t be held tomorrow. A. if B. that C. whether D. which
7. The thought ____ he might fail in the exam worried him. A. when B. which C. what D. that
8. The order ____ the prisoner be set free arrived too late. A. which B. whether C. that D. what
9. The nurses are trying their best to reduce the patient’s fear ____ he would die of the disease. A. that B. as C. of which D. which
10. He often asked me the question ____ the work was worth doing. A. whether B. where C. that D. when
Key: 1-5 AABBA 6-10 BDCAA Step III Homework Finish the work on pages 55-57. The Fifth Period Extensive reading and writing
Teaching goals 教学目标 Integrating skills and writing. 1.Target language 目标语言 a. 重点词汇 debate, issue, competition, in charge, topic, argument, reply to, summarize, profitable, donate, existence, embryo, justified, transfer, ethically. b. 重点句子 I suggest that medical cloning is very important of curing serious illnesses that at present have no cure. I would like to suggest that medical cloning is not as simple as issue as my colleague claims. 2. Ability goals 能力目标 Activate the students to show their opinions about the cloning. Enable the students to write an article on this debate. 3. Learning ability goals 学能目标 Help the students learn how to organize a debate and how to write a short composition of the debate. Teaching important and difficult points 教学重难点 How to organize the debating materials. How to write a short composition of the debate. How to write a report. Teaching methods 教学方法 Task-based teaching method. Teaching aids 教学准备 A computer and a projector. Teaching procedures & ways 教学过程与方式 Step Ⅰ Revision Check the homework and ask the students to speak out their opinion about the medical cloning.
Step Ⅱ Reading task T: Homework check is over. Please turn to page 58. Today we will make a debate. To begin with, I want to ask you what your opinion about debate is, have you seen any TV debates? S: Yeah, we have seen college students’ debate on TV. S2: I know in a debate there is one chairperson some-times two, four members each group, two leading debaters. T: You are right. Do you want to know more details about a debate? S: Yeah. Ask the students to read the debate rules. T: OK. Stop reading. Here are some questions for you. Question 1: What is the definition of debate? Ss: A debate is an activity in which students can discuss two sides of an issue. There is a chairperson to charge it. T: Question 2: Tell me the process of a debate in your own words. S: The leading debater who supports the topic speaks first, then another one who disagrees with the topic speaks, then other people take turns to give a free discussion. Towards the end of the debate, the last speaker of each side will summarize the arguments that have been made to support their point of view. T: Excellent, thanks for your answer. In our textbook there is an example of debate, read the topic carefully and discuss the questions with your partner. And I will divide you into two teams. One side agrees with the medical cloning and the other side is against the medical cloning. Then show the questions. Give students 6 minutes to prepare their answers. Team A: 1. What’s their argument? 2. Two reasons for medical cloning. 3. Do you agree with them? Why? Team B: 1. What’s their argument? 2. Two reasons against medical cloning. 3. Do you agree with them? Why?
Sample answers: Team A: Q1: They support the idea that there should be medical cloning. Q2: a. There is no danger of the body refusing to accept the new calls. b. Patients can be treated immediately. Q3. Yes, I agree with them. Because the medical cloning can help our human beings to cure many diseases. With the help of the cloning techniques, people can be restored to perfect health and be able to live a good life. No, I disagree with them. I think all animals including human beings are natural things on the earth. We should not damage this natural rule. Team B: Q1. They disagree that there should be medical cloning. Q2. a. It brings many ethical problems. b. Many scientists are also worried about the efficiency of the system. Q3. Yes, I agree with them. Because the medical cloning brings many serious problems to our human beings. We must be very cautious about cloning until these problems are solved. No, I disagree with them. Because all of us want to lead a meaningful life. We should try our best to realize our dream. Step Ⅲ Speaking task T: Just now, we learned how to organize a debate, now it’s our turn to continue the debate. The topic of our debate is “should we clone?” Now choose the team you agree with. Divide the whole class into four groups, two agree and two disagree. T: To begin this debate, I will give you some information about clone. You can choose what you need. During the speech, you can make notes so that you do not forget what you want to say. In our debate the person who speaks last must summarize your ideas. Here are some tips for you. Show the following. Center on the subject of the debate. Organize main ideas that support your point of view. List your own ideas.
Make a conclusion. Ask the students to read the following information Show the following. Why should we use cloning? The goals and purposes for cloning range from making copies of those that have deceased to better engineering the offspring in humans and animals. Cloning could also directly offer a means of curing diseases or a technique that could extend means to acquiring new data for the sciences of embryology and how organisms develop as a whole over time. Currently, the agricultural industry demands nuclear transfer to produce better livestock. Cloning could massively improve the agricultural industry as the technique of nuclear transfer improves. The goal of transgenic livestock is to produce livestock with ideal characteristics for the agricultural industry and to be able to manufacture biological products such as proteins for humans. Researchers can harvest and grow adult cells in large amounts compared to embryos. Scientists can then genetically alter these cells and find which ones did transform and then clone only those cells. Scientists also ponder the idea of cloning endangered species to increase their population. The possibilities are endless. However, we are actually doing much of this research for the improvement of life for humans. Scientists foresee the cloning of pigs that will produce organs that will not be rejected by humans. Cloning also provides better research capabilities for finding cures to many diseases. There are also possibilities that nuclear transfer could provide benefits to those who would like children. For instance, couples who are infertile, or have genetic disorders, could use cloning to produce a child. Equally important, women who are single could have a child using cloning instead of in-vitro fertilization or artificial insemination. Cloning could also provide a copy of a child for a couple whose child had died. Why should we not use cloning? The biggest problem with the use of cloning on a large scale is the decline in genetic diversity. Think about it, if everyone has the same genetic material, what happens if we lose the ability to clone. We would have to resort to natural
reproduction, causing us to inbreed, which will cause many problems. Also, if a population of organisms has the same genetic information, then the disease would wipe out the entire population. Helping endangered species by cloning will not help the problem. Currently, zoologists and environmentalists trying to save endangered species are not so much having trouble keeping population numbers up, but not having any animals to breed that are not cousins. The technique of nuclear transfer is also early in its developmental stages. Thus, errors are occurring when scientists carry out the procedure. For instance, it took 277 tries to produce Dolly, and Roslin scientists produced many lambs with abnormalities. If we tried to clone endangered species we could possibly kill the last females integral to the survival of a species. This may be the main reason science is holding out on cloning humans. Other arguments for cloning include if we are taking nature into our own hands by cloning animals or people. People question when we will draw the line for getting involved in natural events. Religious organizations consider nuclear transfer to cause men to be reproductively obsolete. This claim was deduced by gathering of the information that cloning requires only oocytes, any cell, and a woman to develop in. They also claim that cloning does not respect the fact that humans have souls. They also consider cloning unnatural, and say we are taking the work of God into our own hands. There is also a debate as to the moral rights of clones. Some say their rights will be defied because clones are not granted the birth of newness. We would not receive clones with such excitement as a child of a couple who conceived naturally. If natural reproduction were to occur, genetic variation would occur. They say cloning would deprive a person of uniqueness. They argue that identical twins are not unique from each other, but that they are new in genetic variation and unique from anything that came before them. People also wonder what mental and emotional problems would result if a clone was to find out that he or she was cloned. Then give students 10 minutes to prepare, everyone finds their roles in the debate. As a chairperson, the teacher is in charge of the debate. Ask the students to do as follows: First leading speaker gives an argument.
Then others give speech freely. Last the fourth speaker gives a summary. Chairperson: From our debate, we really can learn much. All of you have performed well. Whether can we clone? This is a long term argument. To me, if people can use this method properly, it’s really useful, but if we use it in other ways, it can bring us disaster. Sample notes: arguments for cloning 1) Cloning will be beneficial to humans. For example, if a couple can ’t have children, cloning could help give them a child; 2) we could use cloning to cure illnesses. arguments against cloning 1) health risks from mutation of genes; 2) emotional risks; 3) risk of abuse of the technology; 4) against nature; 5) cloned animals get ill and die quite young; 6) people are afraid of that scientists will create thousands of copies of the same person; 7) Cloning is dangerous because scientists my create monsters by mistake. Sample speech 1: The topic of my speech is: Cloning should be banned. If I had the power, I would ban cloning for several reasons. Firstly, it is against nature and dangerous. Any living things have life and death recycle periods, which promote the evolution of life. The cloning technique is extremely risky right now. An abnormal baby would be a nightmare come true. And people are worried about the possibility that the genetic material used from the adult will continue to age so that the genes in a newborn baby clone could be 30 years old or more on the day of birth. Also monsters may be created by mistake. According to a survey, 29 European countries do not permit medical cloning. Secondly, people are
afraid of that scientists will create thousands of copies of the same person. There are powerful leaders in every generation who will seek to abuse this technology for their own purposes. Going ahead with cloning technology makes this far more likely. What would happen if Hitler was cloned? That would mean more severe disasters and destruction upon human civilization. Thirdly, cloning will result in high emotional risks. Just think: a child grows up knowing her mother is her sister, her grandmother is her mother. Her father is her brother-in-law. Every time her mother looks at her she is seeing herself growing up. The family environment and relationship will be totally different. What kind of pressures will the child feel? All in all, I would determinedly ban cloning if I had the power. Sample speech 2: The topic of my speech is: Cloning should be encouraged As for myself, I would encourage cloning. There are several reasons. Firstly, cloning will be beneficial to humans. For example, if a couple can ’t have children, cloning could help give them a child. Secondly, we could use cloning to cure illnesses. For example, if there is something wrong with some part of a human body, we could clone a healthy one to replace it. For another, if a child is seriously ill or disabled, we could clone another one. According to a survey, 67% of over 1,000 people want medical cloning to continue in America. And in Britain and China medical cloning has been allowed. Thirdly, clone technology could be used in other ways. For example, we can save the endangered animals by cloning. In a word, cloning technology has a promising future. I would encourage it if I had enough power. Step Ⅳ Writing T: Imagine that you are the reporter on a local newspaper and you have been asked to write an article on this debate. To do this you must mention both sides of the argument. Remember to make a large main heading and then a small heading below it. Write around 250 words. Organize your writing in this way: Paragraph 1: the topic of the debate and who won Paragraph 2: the ideas of the winning side
Paragraph 3: the ideas of the other side Paragraph 4: conclusion and your reaction to the debate, together with any idea you feel they left out A sample version: Should Medical Cloning be Allowed A debate between Beijing Normal University and Nanjing University In December 26th 2005, there is a debate between Beijing Normal University and Nanjing University. The two teams began their argument about the cloning techniques. The topic of this compotation is: Should medical cloning be allowed? After the fierce debate, Beijing Normal University — the positive side win this compotation. The view of the positive side is: there should be medical cloning. The view of the negative side is: there should not be medical cloning. This debate is very successful. As the coin has two sides, every technology can bring the advantages to our society, and also can bring the negative effects to our human beings. So when we judge a new technology good or not good, we should look at whether there are more advantages than its disadvantages or not. If we use it in a proper way it can benefit our human beings a lot. Step Ⅴ Homework T: Now you’ve known how to make a debate. Why don’t you arrange one with your classmates? Choose whichever topic interests you but make sure that it is popular topic. Organize it as you have been shown in this unit. Enjoy the argument and let the better side win! Teacher can give the students some issues to infer: Should students use phones in schools? Should students wear school clothes? Should senior 3 students have PE class? Protect ourselves first or save others first? Save money or pre-consume? Should students have extra-class during their holiday?
I. Reading comprehension: Hello, Dolly! British scientists have done something that many people thought was impossible: they created the first clone of an adult mammal. The clone, named Dolly, is a seven-month-old sheep, grown from a cell of an adult female sheep. What is a clone? A clone is a copy, a genetic copy. Genes are the instructions for life. They tell a cell what to do and how to do it. Genes make each individual plant or animal different and unique. But a clone has the same genes as the original organism. Cloning is not new. Plants have been cloned for centuries. New plants are often grown from cuttings from another plant. Also, plants like pineapples, strawberries and carnations are sometimes cloned. One benefit of cloning is that we can make many copies of the best and healthiest plants. It has been much more difficult to clone animals. Frogs have been cloned, but they died as tadpoles, never living long enough to become adult frogs. Mice, sheep and cattle have been cloned from embryos. But Dolly is the first healthy clone of an adult mammal. How did they do it? (1) An unfertilized egg was taken from a sheep. (2) The egg nucleus was removed. (3) A cell was taken from the udder of a pregnant sheep. It was “starved”, so that it stopped growing. (4) The two cells were combined into one and then implanted in a third sheep, where it grew normally. (5) The clone was born. It was genetically identical to the pregnant sheep in step (3). This sounds much easier than it actually was. To end up with one clone, the scientists started with 277 udder cells. And they needed in a way to make the egg cell accept a new nucleus. They did that by starving the cell in step (3). It may soon be possible to clone many types of animals. Will we also be able to clone human organs, or even whole human beings? We have only begun to think about the morality of cloning technology. Maybe the question to ask is not whether
we can clone humans, but instead, should we clone humans? 1. Dolly is a sheep because she is grown from a cell of an adult female sheep _____. A. that has not her father B. that has not her mother C. that has no parents D. that has not any tail 2. Tell which of the following statements is TRUE. A. Only plants can be cloned. B. Only strawberries and carnations can sometimes be cloned. C. Animals and plants have quite a long history of cloning. D. Genes can tell a cell what to do and how to do it during cloning. 3. From the fourth paragraph we can know that _____. A. a tadpole is the early stage of a grown-up frog B. a tadpole is a frog without a tail C. a tadpole is a pool where frogs can live D. a tadpole is a clone of an adult mammal 4. What is the right order in the process of the clone of Dolly? a. Taking an unfertilized egg from an adult female sheep. b. Removing the egg’s nucleus. c. Combining the two cells into one and then implanting it in a third sheep. d. Taking a cell from the udder of a pregnant sheep. A. a b c d C. a b d c 答案与分析 本文是科普时文阅读。全文讲述了克隆羊多莉的出生过程。 1. C 从文章中可以看出，多莉是从一只成年羊的细胞中克隆出来的，所以它 根本没有父母，而是那只羊的一个翻版。A 项“它没有父亲”、B 项"它没有母亲" 说得太片面，D 项“它没有尾巴”不符合题意。 2. D 题意为“下面哪句话是对的”，D 项“基因在克隆过程中可以告诉细胞做 B. c a b d D. d c b a
什么及如何去做”，文中第二 段正是说的这个意思。第三段指植物可以克隆，第 四段指动物也可以克隆，所以选项 A“只有植物可以克隆”不正确。从文中第三段 可知菠萝也是可以克隆的，所以 B 项“只有草莓和康乃馨有时可以克隆”不正确。 第三段中指植物已有几个世纪的克隆历史，而没有提到动物的克隆历史，所以与 C 项“动、植物都有一个相当长的克隆历史”与题意不符。 3. A 文中第四段第二句中说：人们曾经克隆过青蛙，但在蝌蚪阶段就死了， 并没有活到成年青蛙阶段，所以我们可以判断，蝌蚪是青蛙的早期形态，故 A 项“蝌蚪是成年青蛙的早期形态”正确。 B 项“蝌蚪是没有尾巴的青蛙”、 C 项“蝌蚪 是青蛙生存的池塘”、D 项“蝌蚪是成年哺乳动物的克隆体”与实际不符。 4. C 题意为“克隆多莉的正确顺序是什么”，从文中第四段后半部分的内容可 知，正确顺序应是 C 项中所说的。 Ⅱ. About Cloning Quite a few people might take a negative attitude towards cloning. They argue that cloning will arouse a lot of moral and ethical problems and that some people would use the technique to develop crime (How will you feel to face a younger but identical twin of you yourself?). All that they worry about are true. But as every coin has two sides, cloning is no exception. Even the father of the world’s first clone Dolly is not for cloning. But he simply goes against cloning people. But what is clone anyway? Up to now Dolly is the only clone in the world. She was created not out of the natural way the union of a sperm and an egg that we are familiar with, but out of the genetic material from an udder cell of a six-year-old sheep. The embryologist Wilmut fused the udder cell with an egg from another sheep, after first removing all genetic material from the egg. The udder cell’s genes took up residence in the egg and directed it to grow and develop and an identical twin of the original sheep, Dolly was resulted. And that is how a clone is born. As cloning is no longer a science fiction, and with the birth of Dolly, the whole world begins to focus on these high technology and that generate a severe argument mentioned at the beginning of the article. Is it that frightening when speaking of cloning? The answer is yes.
I’m not denying that clone has certain disadvantages. Actually clone is a double-edge sword, we have to admit. But we can make the best of its bright side. Will you admire the rose’s beauty as you used to when you discover its thorn? We all know that it is just because the rapid development of economy that has led to the polluted environment and therefore brings a lot of diseases and many an animal’s dying out. Can we just stop modernizing because of this? The answers are certainly no. Such is the case as cloning. We can gain a lot from it if used properly. We can clone organs patients need badly to help reduce their pain and even save their lives because they are the perfect match. We can also make an extinct creation back to live when necessary. The list goes on and on. There are never going be sufficient reasons that we should stop doing research on the field of cloning. Instead, the future of cloning is prosperous. Since the harm can not be avoided, at least we can try to put it to the least. But it turns out to be the government’s duty. In addition, the clone technique has not grown mature yet. What troubles us now is really how to make the program a successful one. Take a second thought, and you might be for cloning too. Ⅲ. Questions about Cloning 1. Why clone? Research advances over the past decade which 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 would we want to? Let’s look at some of the reasons people give to justify cloning. A. Cloning for medical purposes Of all the reasons, cloning for medical purposes has the most potential to benefit large numbers of people. How might cloning be used in medicine? a. Cloning animal models of disease 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 mutations in their genes. Creating these transgenic animals is a time-intensive process that requires trial-and-error and several generations of breeding.
Cloning technologies might reduce the time needed to make a transgenic animal model, and the result would be a population of genetically identical animals for study. b. Cloning stem cells for research Stem cells are the body’s building blocks, responsible for developing, maintaining and repairing the body throughout life. As a result, they might be used to repair damaged or diseased organs and tissues. Researchers are currently looking toward cloning as a way to create genetically defined human stem cells for research and medical purposes. c. “Pharming” for drug production Farm animals such as cows, sheep and goats are currently being genetically engineered to produce drugs or proteins that are useful in medicine. Just like creating animal models of disease, cloning might be a faster way to produce large herds of genetically engineered animals. B. Reviving endangered or extinct species 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? In theory? Yes. What would you need to do this? A well-preserved source of DNA from the extinct dinosaur and a closely related species, currently living, that 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. C. Reproducing a deceased pet 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 in the United States offers cat cloning services for the privileged and bereaved, and they are now working to clone dogs. But don’t assume that your cloned kitty will be exactly the same as the one you know and love. The main reason to clone plants or animals is to mass produce organisms with desired qualities, such as a prize-winning orchid or a genetically engineered animal — for
instance, sheep have been engineered to produce human insulin. If you had to rely on sexual reproduction (breeding) alone to mass produce these animals, and then you would run the risk of breeding out the desired traits because sexual reproduction reshuffles the genetic deck of cards. Other reasons for cloning might include replacing lost or deceased family pets and repopulating endangered or even extinct species. Whatever the reasons, the new cloning technologies have sparked many ethical debates among scientists, politicians and the general public. Several governments have considered or enacted legislation to slow down, limit or ban cloning experiments outright. It is clear that cloning will be a part of our lives in the future, but the course of this technology has yet to be determined. 2. How are clones created? The most common process takes DNA from one cell and puts in a hollowed-out egg. Chemicals and electricity are then used to encourage the new DNA to fuse with the egg and develop into an embryo. This technique is called nuclear transfer. 3. Are clones normal, healthy animals? Dolly is, but scientists do not yet know whether this is the exception or the rule. Some early evidence suggests that clones may have health problems and that they may age prematurely. 4. Could a human clone be born soon? In theory, yes. The techniques used to create Dolly could be applied to humans. But the technology of reproductive cloning is still in its very early stages and there is much that scientists do not understand. It took more than 200 attempts to make Dolly. The other embryos failed to implant in the surrogate mother or were miscarried. Even if a clone makes it to birth, at present it has a very low chance of surviving into adult life. 5. Has anyone said they will make live human clones? A number of people have, including Chicago physicist Dr Richard Seed. However, few experts believe that these people have the skills to succeed. 6. Are there any benefits from cloning?
Yes. The techniques used have already demonstrated benefits. Polly, another sheep clone at the Roslin Institute in Edinburgh has had a human gene inserted so that it produces a blood clotting agent needed by haemophiliacs in its milk. Cloning of human cells in a laboratory could offer perfectly-matched tissue for surgical or genetic repair of humans. 7. Where does the law stand on live human clones? In the UK, human cloning is already banned(禁止) by law. President Bill Clinton has proposed banning research into producing human clones in the US for five years. Some measures have also been made to establish international agreements banning live human clones. 8. What animals have been cloned? Scientists have been cloning animals for many years. In 1952, the first animal, a tadpole, was cloned. Before the creation of Dolly, the first mammal cloned from the cell of an adult animal, clones were created from embryonic cells. Since Dolly, researchers have cloned a number of large and small animals including sheep, goats, cows, mice, pigs, cats, rabbits, and a gaur. All these clones were created using nuclear transfer technology. Hundreds of cloned animals exist today, but the number of different species is limited. Attempts at cloning certain species such as monkeys, chickens, horses, and dogs, have been unsuccessful. Some species may be more resistant to somatic cell nuclear transfer than others. The process of stripping the nucleus from an egg cell and replacing it with the nucleus of a donor cell is a traumatic one, and improvements in cloning technologies may be needed before many species can be cloned successfully. 9. Can organs be cloned for use in transplants? Scientists hope that one day therapeutic cloning can be used to generate tissues and organs for trans-plants. To do this, DNA would be extracted from the person in need of a transplant and inserted into an enucleated egg. After the egg containing the patient’s DNA starts to divide, embryonic stem cells that can be transformed into any type of tissue would be harvested. The stem cells would be used to generate an organ or tissue that is a genetic match to the recipient. In theory, the cloned organ could then
be transplanted into the patient without the risk of tissue rejection. If organs could be generated from cloned human embryos, the need for organ donation could be significantly reduced. Many challenges must be overcome before “cloned organ” transplants become reality. More effective technologies for creating human embryos, harvesting stem cells, and producing organs from stem cells would have to be developed. The scientists then harvested fetal tissue from the clones and transplanted it into the donor cow. In the three months of observation following the transplant, no sign of immune rejection was observed in the transplant recipient. More research is needed to study the transplantation of organs from “knock-out” pigs o other animals. 10. What are the risks of cloning? Reproductive cloning is expensive and highly inefficient. More than 90% of cloning attempts fail to produce viable offspring. More than 100 nuclear transfer procedures could be required to produce one viable clone. In addition to low success rates, cloned animals tend to have more compromised immune function and higher rates of infection, tumor growth, and other disorders. Japanese studies have shown that cloned mice live in poor health and die early. About a third of the cloned calves born alive have died young, and many of them were abnormally large. Many cloned animals have not lived long enough to generate good data about how clones age. Appearing healthy at a young age unfortunately is not a good indicator of long term survival. Clones have been known to die mysteriously. For example, Australia’s first cloned sheep appeared healthy and energetic on the day she died, and the results from her autopsy failed to determine a cause of death. Problems also may result from programming errors in the genetic material from a donor cell. 11. Should humans be cloned? This is a serious topic. I read a report (Reuters, United Nations, October 8, 2004) about the human cloning. A group of scientists, doctors and legal experts asked the United Nations on Wednesday to seek an advisory opinion from the World Court declaring human cloning to be a “crime against humanity.” Physicians from the American Medical Association and scientists with the American Association for the Advancement of Science have issued formal public statements advising against
human reproductive cloning. Currently, the U.S. Congress is considering the passage of legislation that could ban human cloning. In China, the Chinese Government has officially banned research on human cloning for procreation purposes, but allowed remedial cloning. 12. What benefits can humans gain from cloning? 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 would we want to? Let’s look at some of the reasons people give to justify cloning. 1. Cloning for medical purposes 2. Reviving endangered or extinct species 3. Reproducing a deceased pet. Of all the reasons, cloning for medical purposes has the most potential to benefit large numbers of people. 13. How might cloning be used in medicine? Much of what researchers learn about human disease comes from studying animal models such as mice. Cloning technologies might reduce the time needed to make a transgenic animal model, and the result would be a population of genetically identical animals for study. Researchers are currently looking toward cloning as a way to create genetically defined human stem cells for research and medical purposes. Farm animals such as cows, sheep and goats are currently being genetically engineered to produce drugs or proteins that are useful in medicine. Just like creating animal models of disease, cloning might be a faster way to produce large herds of genetically engineered animals. 14. Could humans be cloned now? Unquestionably, yes. Since the first cloned sheep, Dolly, surprised the world back in 1997, the cloning of animals has become almost routine. Companies have been able to churn out cloned cows, goats, and other critters, some of them genetically engineered to make valuable pharmaceutical products. “With cows, it has been very easy to do,” says Princeton biology professor Lee Silver. Human biology is even better understood than that of cows, so the cloning of people is pretty much inevitable. Indeed, the actual procedure is only a small step beyond
what’s already routinely done in test tube baby clinics.
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