高中人教版英语选修8教学案：Unit 2 Section Ⅰ Warming Up Rea

Have you ever wished you could have a clone of yourself to do your homework while you went out to play with your friends? Imagine if you could really do that, where would you start?

What exactly is cloning?

Cloning is a way of making an organism (有机体) that is an exact genetic (基因的) copy of another. This means that every single bit of DNA is the same between the two!

You might not believe it, but there are human clones among us right now. They weren't made in a lab, though. They're identical (同样的) twins, created naturally. Below, we'll see how natural identical twins relate to modern cloning technologies.

How is cloning done?

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.

How does one go about making an exact genetic copy of an organism? There are a couple of ways to do this：artificial embryo twinning (人工胚胎双生) and somatic cell nuclear transfer (体细胞核移植). How do these processes differ?

1．Artificial Embryo Twinning

Artificial embryo twinning is the relatively low-tech version of cloning. As the name suggests, this technology mimics the natural process of creating identical twins.

2．Somatic Cell Nuclear Transfer

Somatic cell nuclear transfer (SCNT), uses an approach different from artificial embryo twinning, but it produces the same result: an exact clone，or a genetic copy, of another. This was the method used to create Dolly the sheep.

Section_

ⅠWarming Up & Reading — Pre-reading [原文呈现] [读文清障]

CLONING：WHERE IS IT LEADING

US?

Cloning has always been with us and is here to stay. It is a way of making an exact①copy of② another animal or plant. It happens in plants when gardeners take cuttings③from growing plants to make new ones. It also happens in animals when twins④identical⑤in sex and appearance are produced from the

①exact/Iɡ'zækt/adj.精确的；准确的

②make a copy of (＝copy)复制

of making ...作way的定语。

③cutting/'k?tI?/n.剪枝；剪报；剪纸

④twin/twIn/n.双胞胎之一；孪生儿之一adj.成对的；成双的

⑤identical/aI'dentIkl/adj.同一的；一模一样的

⑥The fact is that ...中，that引导表

same original egg. The fact is that these are both examples of natural clones ⑥.

语从句。

Cloning has two major uses. Firstly, gardeners use it

all the time ⑦ to produce

commercial ⑧ quantities of ⑨ plants.

Secondly, it is valuable for research on new plant species and for medical research on animals. Cloning plants is straightforward ⑩while ? cloning animals is very complicated ?. It is a difficult task to undertake ?. Many attempts to clone

mammals ? failed. But at last ? the

determination and patience of the scientists

paid off ? in 1996 with a breakthrough ? —

the cloning of Dolly the sheep. The procedure ? works like this ：

1 Female sheep A provides an egg

cell.

2 The nucleus ? is removed from ?

the egg cell.

3 The egg cell is ready for a new

nucleus. 4 Female sheep B provides a ⑦all the time 一直 ⑧commercial /k ?'m ???l/adj .商业的；贸易的 ⑨quantities of “大量的”；修饰可数名词复数或不可数名词

⑩straightforward /?streIt'f??w?d/adj .简单的；直接的；坦率的 ?while 在此表示“而；却”，是并列连词，表对比关系。 ?complicated /'k ?mplIkeItId/adj .复杂的；难懂的 ?undertake /??nd ?'teIk/v t .(undertook; undertaken)着手；从事；承担

不定式短语to undertake 作定语，修饰task 。

?不定式短语to clone mammals 作定语，修

饰attempts 。

?Firstly ... Secondly ... But at last ... “首

先……其次……最后……”，表示论述顺序。

?pay off 得到好结果；取得成功；偿清 ?breakthrough /'breIkθru?/n .突破 ?procedure /pr ?'si?d??/n .程序；步骤；手续 ?nucleus /'nju?klI?s/n .原子核；中心 ?remove ... from ... 将……从……移走 ○

21somatic /s ??'mætIk/adj .躯体的；肉体的；细胞体的

somatic○21cell for the clone. The nucleus of this cell contains all the genes needed to produce a new sheep○22.

5The nucleus is taken out of the somatic cell.

6The nucleus from sheep B and the egg cell from sheep A are joined using electricity○23.

7The cell divides and grows into an embryo○24.

8The embryo is put into female sheep C, who becomes the carrier○25of the clone○26.

9The lamb is the clone of the donated○27cell from Sheep B which provided the nucleus○28.

○22过去分词短语needed to ...作定语，修饰genes。

○23现在分词短语using electricity作方式状语。

○24embryo/'embrI??/n.胚；胚胎；萌芽时期○25carrier/'kærI?/n.携带者；搬运工；运输工具

○26who引导非限制性定语从句，修饰先行词female sheep C。

○27donate v t.捐赠；捐献

○28which引导定语从句，修饰Sheep B。

On the one hand○29，the whole scientific world followed the progress of the first successful clone, Dolly the sheep. The fact that she seemed to develop normally○30was very encouraging. Then came the disturbing news that Dolly had become seriously ill○31. Cloning scientists were castdown○32to find that Dolly's illnesses were more appropriate to○33 a much older animal. Altogether○34 Dolly lived six and a half years, half the length of the life of the original sheep. Sadly the same arbitrary○35fate○36affected other species, such as cloned mice. The questions that concerned all scientists○37were：“Would this be a major difficulty for all cloned animals? Would it happen forever? Could it be solved if corrections○38were made in their research procedure？”,○29On the one hand ... On the other hand ...一方面……，另一方面……

○30that she seemed to develop normally是fact的同位语。

○31Then came the disturbing news that ...中，then位于句首引起完全倒装。本句中的news与that Dolly had become …… 此处隐藏：4979字，全部文档内容请下载后查看。喜欢就下载吧 ……