第一篇：高中選修7英語課后題

高中選修7英語課后題一

一、單詞拼寫

1.All of us should be concerned with public _____（事務(wù)）to make our society a better one.2.Nowadays people have to pass various tests for professional _____（證書）so that they can be qualified for a well-paying job.3.He may be good at football, but he is very _____(笨拙)on the dance floor.4.When human friends desert us, good books are always ready to give us friendship, sympathy and e_____.5.The foundation would like to launch programs for providing _____(援助)for poor areas and for disease control and prevention in Africa.6.I hope we will have the strength to bear the difficulties and disappointments and bear them with _____(尊嚴(yán))and without self-pity.7.He is a well-edacuted man and behaves _____(高雅).8.Do you believe that the photo-electric reader be capable of s_____ characters at the rate of two thousand a second?

9.Not everyone think it is ridiculously _____(荒謬的)to predict that the sun will not rise tomorrow.10.It is reported that a couple who separated after 40 years of m_____ split their house in two.11.I want an e_____ for why you have refused to eat these nice fresh cod.12.---I heard that your brother got d_____.Is that true?

---Not so bad,but he dose have problems with his wife.13.F_____ Germany, Einstein went first to France, then to Belgium, and then to Britain.14.In my opinion,this journey, like all the ones mentioned above, was _____(純粹)imaginary.15.The poor old couple began to regret the _____(購買)of such a large house at so high a price.16.Who will in charge of the distribution of food and clothing to the flood vivtims?

17.We all think that the repairs to the school will be _____(提供資金)by the local educational department.18.Many people thought he should remain and _____(講課)in Europe to influence society.19.My new boss used to be a travel _____(代理人)in a famous city.20.Life can be compared to a journey with an unknown _____(目的地).二、詞語填空

1.This novel,____ TV from the American original, is very popular among young students.2.I know the warning systerm will work well because we have ____ it ____ many times.3.Take heart and wee are sure to ____ these difficulties sooner or later.4.I ____ to see if you were at work but no one answered my phone.5.Just then I heard my name called.____, I found my former English teacher similing at me.6.You must always keep your mind fresh by ____ some time for exercise.7.Hearing the news that he was fired , the young man ____ despair.8.It is time that we ____ and got ready to start out.9.The old man on duty ____ having seen the accused enter the building.10.I don't really work here;I am just ____ until the new secretary arrives.11.It is necessary for us to ____the likely result before we decide to do anything.12.We had several anxious hours waiting for our wet clothes to _____.13.She ____her head from the window and called for help.14.The doctor's advice was that the patient ____ at once.15.I have never done this type of work before;I'm not sure how I will ____.16.It is you teachers’s duty to make the new students ____in your school.17.Here are my reasons for believing I am ____ the position of branch manager

18.At first man ____the places where the food and water were plentiful.19.Why did the president refuse to comment on the election results at the news conference?The symptom of jetlag often persists for several days while the internal body clock slowly ____ the new time zone.三、單句改錯

1.The truth is that she did everything she could save her sons from the big fire but in vain.2.We have no choice but work hard to try to find a solution to make sure that we save our economy.3.My English teacher is said to be studying abroad, but I don’t know what country he studied in.4.The doctor noted that the oral drug would significantly reduce the amount of time patients needed being treated.5.As we had had a long walk through one of the markets of Old Delhi, we stopped having a rest at a square.6.I wonder whether the way you thought of making the water clean makes any sense.7.Having stood with great difficulty from the ground, the wounded soldier rushed in the war, never being heard from again.8.On Monday, former Prime Minister Nawaz Sharif also said he wants the vote holding next week.9.The introduction of modern equipment to the company led to a great many workers laid off.10.Tim Bemers-Lee is generally considered to set up the World Wide Web, on which all theinformation is shared by all．

11.Caught cheating in the exam cost him the chance to be promoted.12.He escaped punishing by taking advantage of his position,which caused a bad influence among the citizens.13.We have long known that the reasons why President Bush and his team gave for going to war in Iraq were false

14.The couple saw a new movie at the theatre, after that they had dinner at a Chinese restaurant.15.There is very strong evidencethat the degree in which you maintain your mental faculties depends on a handful of quite simple environmental factors

高中選修7英語課后題二

一、補全句子

1.The young man _____（一心想成為）the general manager of a great enterprise.2.The manager needs an assistant that he can count on to take care of problems _____(在他不在場的情況下).3.The visiting Minister _____(對……表示滿意)the talks, _____(補充說)that he had enjoyed his stay here.4.She discovered that there were _____(一堆堆)empty wine bottles _____(形狀各導(dǎo)、大小不一)in the corner.5.The young girl _____(險勝)her great rival(對手)in the tennis competition.6.Don’t be angry with them.They only said such unkind things about you _____（出于忌妒）.7.Once he was run after by a seal that was like _____(長著鋒利牙齒的巨人)and he was almost _____（當(dāng)場嚇?biāo)溃?8.This business invitation is _____(出租或出售)of electronic production workshops and related buildings in the IT industry park.9.The moment the 28th Olympic Games _____(宣布開幕), the whole world cheered.10.It is said that dogs will _____(陪伴你)for as long as you want when you are feeling lonely.11.They got home after work only to find the whole house had _____（被弄得亂七八糟）.12.Mary ceremonies will be held to _____（慶祝中華人民共和國成立60周年）next year.13.I hope we can live_____(舒服地)and happ ss in the countryside after we retire.14.The students who fail to _____(符合這些要求)will not be admitted to the famous university.15.It has not been decided _____r(誰接替史密斯先生做我們的導(dǎo)師)?

二、句型轉(zhuǎn)換

1.The new medicine proved beneficial to the patient's skin problems.----The new medicine proved to _____ _____ _____to the patient's skin problems.2.I have neither brothers nor sisters.That is to say, I'm an only child.---I have neither brothers nor sisters—_____ _____ _____, I'm an only child

3.Li Ming has his faults, but, on the whole, he is a good helper

--Li Ming has his faults, but, _____ _____ _____, he is a good helper.4.The manager is busy at his desk.You'd better disturb him.---The manager is busy at his desk.You'd better _____ _____ _____.5.As a matter of fact, my boss is thr years younger than me.--As a matter of fact, my boss is thr years _____ _____ me.6.All we could see in front of us was 200 km of nothing but sand.--All we could see _____ _____ us was 200 km of nothing but sand.7.Did you rewalize that Joe had this problem with his knee?

--____ you ___ that Joe had this problem with his knee?

8.I haven't received any letter from myfather working abroad so far.---I haven't _____ _____ myfather working abroad up to the present.9.We have arranged for her to be treated by a famous doctor of our city.---We have_____ _____ _____ her to be treated by a famous doctor of our city.10.We have become accustomed to the way of living in such a crowded place.---We have _____ _____ _____ the the way of living in so crowded a place.11.It is difficult to imagine that he accepted the decision without any hesitation.---It is hard to imagine _____ _____ the decision without any hesitation.12.The famous scientist will arrive soon and a party will be held in honour of him.---The famous scientist , _____ _____ _____ a party will be held, is to arrive soon.13.It is reported that the floods have left about two thousand people homeless.---The floods _____ _____ _____ _____ _____ about two thousand people homeless.14.It may rain tomorrow．In that case，we'll have to put off the sports meet till next Saturday．

---It may rain tomorrow, _____ _____ _____，we'll have to put off the sports meet till next Saturday．

15.We've replaced the old adding machine with a computer.---We've _____ the old adding machine _____ a computer.三、翻譯

1.我以為他在取笑我,就越發(fā)跑得快起來,到達(dá)學(xué)校時我都上氣不接下氣了。（make fun of;out of breath）

2.我們許多人很少或沒有與殘疾人工作或交往的經(jīng)驗，因此可能意識不到他們的需求。（disability;aware）

3.就我而言，這兩個設(shè)計中的后者比前者實際的多。（as far as one is concerned;latter）

4.這位年輕的作家沒有文學(xué)理論知識，只有吸引觀眾的愿望。（desire）

5.她年齡還太小，不能不依賴父母；她依靠他們給她提供衣服和食物。（independent；depend）

6.十位專家組成的訪問團預(yù)定星期四到達(dá)，這期間我們該做些什么呢?（due to；in the meantime）

7.我發(fā)郵件祝賀他考入清華大學(xué),攻讀經(jīng)濟專業(yè)。（congratulate；majorg in）

8.有時我們會發(fā)現(xiàn)面對面的交流可能是人很尷尬。（embarrass）

9.我確信那兒的自然之美將會給你留下極好的印象。（beauty）

10.我們班所有的學(xué)生都渴望參加下月舉行的演講比賽。(be dying to;participate in)

11.人們期待這些年輕人去適應(yīng)過去幾代人從未處理過的社會環(huán)境的變化。(adapt to)

12.每年我們都向紅十字會捐部分錢以幫助那些貧困中的人。（donate;in need）

13.孩子們在房間里很安靜。我納悶他們在干什么。（up to）

14.在準(zhǔn)備發(fā)射神舟七號的過程中，科學(xué)家需要了解天氣變化。(preparation;knowledge)

15.我們不知道那些建筑工人遇到了困難，要不然我們會幫他們的。（otherwise）

第二篇：高二英語選修七課后題

一、單詞拼寫(20)

1.All of us should be concerned with public _____（事務(wù)）to make our society a better one.2.Nowadays people have to pass various tests for professional _____（證書）so that they can be qualified for a well-paying job.3.He may be good at football, but he is very _____(笨拙)on the dance floor.4.When human friends desert us, good books are always ready to give us friendship, sympathy and e_____.5.The foundation would like to launch programs for providing _____(援助)for poor areas and for disease control and prevention in Africa.6.I hope we will have the strength to bear the difficulties and disappointments and bear them with _____(尊嚴(yán))and without self-pity.7.He is a well-edacuted man and behaves _____(高雅).8.Do you believe that the photo-electric reader be capable of s_____ characters at the rate of two thousand a second?

9.Not everyone think it is ridiculously _____(荒謬的)to predict that the sun will not rise tomorrow.10.It is reported that a couple who separated after 40 years of m_____ split their house in two.11.I want an e_____ for why you have refused to eat these nice fresh cod.12.---I heard that your brother got d_____.Is that true?

---Not so bad,but he dose have problems with his wife.13.F_____ Germany, Einstein went first to France, then to Belgium, and then to Britain.14.In my opinion,this journey, like all the ones mentioned above, was _____(純粹)imaginary.15.The poor old couple began to regret the _____(購買)of such a large house at so high a price.16.Who will in charge of the distribution of food and clothing to the flood vivtims?

17.We all think that the repairs to the school will be _____(提供資金)by the local educational department.18.Many people thought he should remain and _____(講課)in Europe to influence society.19.My new boss used to be a travel _____(代理人)in a famous city.20.Life can be compared to a journey with an unknown _____(目的地).二、詞語填空(20)

根據(jù)句意，選擇詞語，并用其適當(dāng)?shù)男问教羁铡?/p>

This novel,____ TV from the American original, is very popular among young students.2.I know the warning systerm will work well because we have ____ it ____ many times.3.Take heart and wee are sure to ____ these difficulties sooner or later.4.I ____ to see if you were at work but no one answered my phone.5.Just then I heard my name called.____, I found my former English teacher similing at me.6.You must always keep your mind fresh by ____ some time for exercise.7.Hearing the news that he was fired , the young man ____ despair.8.It is time that we ____ and got ready to start out.9.The old man on duty ____ having seen the accused enter the building.10.I don't really work here;I am just ____ until the new secretary arrives.11.It is necessary for us to ____the likely result before we decide to do anything.12.We had several anxious hours waiting for our wet clothes to _____.13.She ____her head from the window and called for help.14.The doctor's advice was that the patient ____ at once.15.I have never done this type of work before;I'm not sure how I will ____.16.It is you teachers’s duty to make the new students ____in your school.17.Here are my reasons for believing I am ____ the position of branch manager

18.At first man ____the places where the food and water were plentiful.19.Why did the president refuse to comment on the election results at the news conference?The symptom of jetlag often persists for several days while the internal body clock slowly ____ the new time zone.三、單句改錯（15題）

下面句子中，各有一處錯誤，請改正。

1.The truth is that she did everything she could save her sons from the big fire but in vain.2.We have no choice but work hard to try to find a solution to make sure that we save our economy.3.My English teacher is said to be studying abroad, but I don’t know what country he studied in.4.The doctor noted that the oral drug would significantly reduce the amount of time patients needed being treated.5.As we had had a long walk through one of the markets of Old Delhi, we stopped having a rest at a square.6.I wonder whether the way you thought of making the water clean makes any sense.7.Having stood with great difficulty from the ground, the wounded soldier rushed in the war, never being heard from again.8.On Monday, former Prime Minister Nawaz Sharif also said he wants the vote holding next week.9.The introduction of modern equipment to the company led to a great many workers laid off.10.Tim Bemers-Lee is generally considered to set up the World Wide Web, on which all theinformation is shared by all．

11.Caught cheating in the exam cost him the chance to be promoted.12.He escaped punishing by taking advantage of his position,which caused a bad influence among the citizens.13.We have long known that the reasons why President Bush and his team gave for going to war in Iraq were false

14.The couple saw a new movie at the theatre, after that they had dinner at a Chinese restaurant.15.There is very strong evidencethat the degree in which you maintain your mental faculties depends on a handful of quite simple environmental factors

答案

一、單詞拼寫(20)

1.affairs 2.certificates 3.clumsy 4.encouragement 5.assistance 6.dignity 7.elegantly

8.scanning 9.absurd 10.marriage 11.explanation 12.divorced 13.Fleeing

14.purely 15.purchase 16.distribution 17.financed 18.lecture 19.agent 20.destination

二、詞語填空(20)

1.adapted for 2.tested;out 3.smooth away 4.rang up 5.Turning aroud 6.setting aside 7.abandoned himself to.8 packed up 9.witnessed to 10.helping out

11.reflect on 12.dry out 13.stuck out 14.be operated on 15.fit in 16.feel at home

17.qualified for 18.settled in 19.comment on 20.adjusts to

三、單句改錯（15題）

1.save改為 to save 2.work 改為 to work

3.be studying 改為 have studied 4.being改為to be

5.having 改為 to have 6.making 改為 to make

7.never being 改為never to be 8.holding 改為 to be held

9.workers后加being 10.to set 改為 to have set

11.Caught改為Being caught 12.punishing 改為 punished

13.why 改為 that 14.that 改為 which 15.in改為to

第三篇：高中人教版生物選修3前兩章課后題答案

專題1 基因工程 1.1 DNA重組技術(shù)的基本工具

一、思考與探究

1.限制酶在DNA的任何部位都能將DNA切開嗎？以下是四種不同限制酶切割形成的DNA片段：

(1)?CTGCA(2)?AC(3)GC?（4）?G(5)G?(6)?GC(7)GT?(8)AATTC?

?G ?TG CG? ?CTTAA ACGTC? ?CG CA? G? 你是否能用DNA連接酶將它們連接起來？ 答：

2和7能連接形成?ACGT? 4和8能連接形成?GAATTC? ?TGCA?； ?CTTAAG?； 3和6能連接形成?GCGC? 1和5能連接形成?CTGCAG?

?CGCG?； ?GACGTC?

2.聯(lián)系你已有的知識，想一想，為什么細(xì)菌中限制酶不剪切細(xì)菌本身的DNA？

提示：迄今為止，基因工程中使用的限制酶絕大部分都是從細(xì)菌或霉菌中提取出來的，它們各自可以識別和切斷DNA上特定的堿基序列。細(xì)菌中限制酶之所以不切斷自身DNA，是因為微生物在長期的進(jìn)化過程中形成了一套完善的防御機制，對于外源入侵的DNA可以降解掉。生物在長期演化過程中，含有某種限制酶的細(xì)胞，其DNA分子中或者不具備這種限制酶的識別切割序列，或者通過甲基化酶將甲基轉(zhuǎn)移到所識別序列的堿基上，使限制酶不能將其切開。這樣，盡管細(xì)菌中含有某種限制酶也不會使自身的DNA被切斷，并且可以防止外源DNA的入侵（本題不要求學(xué)生回答的完全，教師可參考教師用書中的提示，根據(jù)學(xué)生的具體情況，給予指導(dǎo)。上述原則也應(yīng)適用于其他章節(jié)中有關(guān)問題的回答。3.天然的DNA分子可以直接用做基因工程載體嗎？為什么？

提示：基因工程中作為載體使用的DNA分子很多都是質(zhì)粒（plasmid），即獨立于細(xì)菌擬核處染色體DNA之外的一種可以自我復(fù)制、雙鏈閉環(huán)的裸露的DNA分子。是否任何質(zhì)粒都可以作為基因工程載體使用呢？其實不然，作為基因工程使用的載體必需滿足以下條件。（1）載體DNA必需有一個或多個限制酶的切割位點，以便目的基因可以插入到載體上去。這些供目的基因插入的限制酶的切點所處的位置，還必須是在質(zhì)粒本身需要的基因片段之外，這樣才不至于因目的基因的插入而失活。

（2）載體DNA必需具備自我復(fù)制的能力，或整合到受體染色體DNA上隨染色體DNA的復(fù)制而同步復(fù)制。

（3）載體DNA必需帶有標(biāo)記基因，以便重組后進(jìn)行重組子的篩選。

（4）載體DNA必需是安全的，不會對受體細(xì)胞有害，或不能進(jìn)入到除受體細(xì)胞外的其他生物細(xì)胞中去。

（5）載體DNA分子大小應(yīng)適合，以便提取和在體外進(jìn)行操作，太大就不便操作。實際上自然存在的質(zhì)粒DNA分子并不完全具備上述條件，都要進(jìn)行人工改造后才能用于基因工程操作。

4.網(wǎng)上查詢：DNA連接酶有連接單鏈DNA的本領(lǐng)嗎？

提示：迄今為止，所發(fā)現(xiàn)的DNA連接酶都不具有連接單鏈DNA的能力，至于原因，現(xiàn)在還不清楚，也許將來會發(fā)現(xiàn)可以連接單鏈DNA的酶。

二、尋根問底

1.根據(jù)你所掌握的知識，你能分析出限制酶存在于原核生物中的作用是什么嗎？ 提示：原核生物容易受到自然界外源DNA的入侵，但是，生物在長期的進(jìn)化過程中形成了一套完善的防御機制，以防止外來病原物的侵害。限制酶就是細(xì)菌的一種防御性工具，當(dāng)外源DNA侵入時，會利用限制酶將外源DNA切割掉，以保證自身的安全。所以，限制酶在原核生物中主要起到切割外源DNA、使之失效，從而達(dá)到保護(hù)自身的目的。2.DNA連接酶與DNA聚合酶是一回事嗎？為什么？

答：不是一回事?；蚬こ讨兴玫倪B接酶有兩種：一種是從大腸桿菌中分離得到的，稱之為E·coli連接酶。另一種是從T4噬菌體中分離得到，稱為T4連接酶。這兩種連接酶催化反應(yīng)基本相同，都是連接雙鏈DNA的缺口（nick），而不能連接單鏈DNA。DNA連接酶和DNA聚合酶都是形成磷酸二酯鍵（在相鄰核苷酸的3位碳原子上的羥基與5位碳原子上所連磷酸基團的羥基之間形成），那么，二者的差別主要表現(xiàn)在什么地方呢？

（1）DNA聚合酶只能將單個核苷酸加到已有的核酸片段的3′末端的羥基上，形成磷酸二酯鍵；而DNA連接酶是在兩個DNA片段之間形成磷酸二酯鍵，不是在單個核苷酸與DNA片段之間形成磷酸二酯鍵。

（2）DNA聚合酶是以一條DNA鏈為模板，將單個核苷酸通過磷酸二酯鍵形成一條與模板鏈互補的DNA鏈；而DNA連接酶是將DNA雙鏈上的兩個缺口同時連接起來。因此DNA連接酶不需要模板。

此外，二者雖然都是由蛋白質(zhì)構(gòu)成的酶，但組成和性質(zhì)各不相同。

三、模擬制作討論題 1.你模擬插入的DNA片段能稱得上一個基因嗎？ 提示：不能。因為一般基因有上千個堿基對。

2.如果你操作失誤，堿基不能配對?？赡苁鞘裁丛蛟斐傻模?提示：可能是剪切位點或連接位點選得不對（也可能是其他原因）。

四、旁欄思考題

想一想，具備什么條件才能充當(dāng)“分子運輸車”？

提示：能自我復(fù)制、有一個或多個切割位點、有標(biāo)記基因位點及對受體細(xì)胞無害等。

1.2 基因工程的基本操作程序

一、思考與探究

1.作為基因工程表達(dá)載體，只需含有目的基因就可以完成任務(wù)嗎？為什么？

答：不可以。因為目的基因在表達(dá)載體中得到表達(dá)并發(fā)揮作用，還需要有其他控制元件，如啟動子、終止子和標(biāo)記基因等。必須構(gòu)建上述元件的主要理由是：

（1）生物之間進(jìn)行基因交流，只有使用受體生物自身基因的啟動子才能比較有利于基因的表達(dá)；

（2）通過cDNA文庫獲得的目的基因沒有啟動子，只將編碼序列導(dǎo)入受體生物中無法轉(zhuǎn)錄；（3）目的基因是否導(dǎo)入受體生物中需要有篩選標(biāo)記；

（4）為了增強目的基因的表達(dá)水平，往往還要增加一些其他調(diào)控元件，如增強子等；（5）有時需要確定目的基因表達(dá)的產(chǎn)物存在于細(xì)胞的什么部位，往往要加上可以標(biāo)識存在部位的基因（或做成目的基因與標(biāo)識基因的融合基因），如綠色熒光蛋白基因等。2.根據(jù)農(nóng)桿菌可將目的基因?qū)腚p子葉植物的機理，你能分析出農(nóng)桿菌不能將目的基因?qū)雴巫尤~植物的原因嗎？若想將一個抗病基因?qū)雴巫尤~植物，如小麥，從理論上說，你應(yīng)該如何做？

提示：農(nóng)桿菌可分為根瘤農(nóng)桿菌和發(fā)根農(nóng)桿菌，在植物基因工程中以根瘤農(nóng)桿菌的Ti質(zhì)粒介導(dǎo)的遺傳轉(zhuǎn)化最多。根瘤農(nóng)桿菌廣泛存在于雙子葉植物中。據(jù)不完全統(tǒng)計，約有93屬643種雙子葉植物對根瘤農(nóng)桿菌敏感。裸子植物對該菌也敏感。當(dāng)這些植物被該菌侵染后會誘發(fā)腫瘤。近年來，也有報道該菌對單子葉植物也有侵染能力。

根瘤農(nóng)桿菌侵染植物是一個非常復(fù)雜的過程。根瘤農(nóng)桿菌具有趨化性，即植物的受傷組織會產(chǎn)生一些糖類和酚類物質(zhì)吸引根瘤農(nóng)桿菌向受傷組織集中。研究證明，主要酚類誘導(dǎo)物為乙酰丁香酮和羧基乙酰丁香酮，這些物質(zhì)主要在雙子葉植物細(xì)胞壁中合成，通常不存在于單子葉植物中，這也是單子葉植物不易被根瘤農(nóng)桿菌侵染的原因。近年來還發(fā)現(xiàn)一些中性糖，如L-阿拉伯糖、D-木糖等也有誘導(dǎo)作用。酚類物質(zhì)和糖類物質(zhì)既可以作為根瘤農(nóng)桿菌的趨化物，又可以作為農(nóng)桿菌中Ti質(zhì)粒上Vir區(qū)（毒性區(qū)）基因的誘導(dǎo)物，使Vir區(qū)基因活化，導(dǎo)致T-DNA的加工和轉(zhuǎn)移，從而侵染植物細(xì)胞。

需要注意的是農(nóng)桿菌中不同的菌株，侵染能力有差別，在基因工程中需要加以選擇使用。利用農(nóng)桿菌侵染單子葉植物進(jìn)行遺傳轉(zhuǎn)化時，是需要加上述酚類物質(zhì)的，同時單子葉植物種類不同，農(nóng)桿菌侵染進(jìn)行遺傳轉(zhuǎn)化的效果也有很大差異。

如果想將一個抗病毒基因轉(zhuǎn)入小麥，也可以用農(nóng)桿菌，但要注意兩點：①要選擇合適的農(nóng)桿菌菌株，因為不是所有的農(nóng)桿菌菌株都可以侵染單子葉植物；②要加趨化和誘導(dǎo)的物質(zhì)，一般為乙酰丁香酮等，目的是使農(nóng)桿菌向植物組織的受傷部位靠攏（趨化性）和激活農(nóng)桿菌的Vir區(qū)（誘導(dǎo)）的基因，使T-DNA轉(zhuǎn)移并插入到染色體DNA上。

3.利用大腸桿菌可以生產(chǎn)出人的胰島素，聯(lián)系前面有關(guān)細(xì)胞器功能的知識，結(jié)合基因工程操作程序的基本思路，思考一下，若要生產(chǎn)人的糖蛋白，可以用大腸桿菌嗎？

提示：有些蛋白質(zhì)肽鏈上有共價結(jié)合的糖鏈，這些糖鏈?zhǔn)窃趦?nèi)質(zhì)網(wǎng)和高爾基復(fù)合體上加工完成的，內(nèi)質(zhì)網(wǎng)和高爾基復(fù)合體存在于真核細(xì)胞中，大腸桿菌不存在這兩種細(xì)胞器，因此，在大腸桿菌中生產(chǎn)這種糖蛋白是不可能的。

4.β-珠蛋白是動物血紅蛋白的重要組成成分。當(dāng)它的成分異常時，動物有可能患某種疾病，如鐮刀形細(xì)胞貧血癥。假如讓你用基因工程的方法，使大腸桿菌生產(chǎn)出鼠的β-珠蛋白，想一想，應(yīng)如何進(jìn)行設(shè)計？ 提示：基本操作如下：

（1）從小鼠中克隆出β-珠蛋白基因的編碼序列（cDNA）。

（2）將cDNA前接上在大腸桿菌中可以適用的啟動子，另外加上抗四環(huán)素的基因，構(gòu)建成一個表達(dá)載體。

（3）將表達(dá)載體導(dǎo)入無四環(huán)素抗性的大腸桿菌中，然后在含有四環(huán)素的培養(yǎng)基上培養(yǎng)大腸桿菌。如果表達(dá)載體未進(jìn)入大腸桿菌中，大腸桿菌會因不含有抗四環(huán)素基因而死掉；如果培養(yǎng)基上長出大腸桿菌菌落，則表明β-珠蛋白基因已進(jìn)入其中。

（4）培養(yǎng)進(jìn)入了β-珠蛋白基因的大腸桿菌，收集菌體，破碎后從中提取β-珠蛋白。

二、求異思維

你能推測出由mRNA反轉(zhuǎn)錄形成cDNA的過程大致分為哪些步驟嗎？ 提示：1970年，特明（H.M.Temin）和巴爾的摩（D.Baltimore）證實了RNA病毒中含有一種能將RNA轉(zhuǎn)錄成DNA的酶，這種酶被稱為依賴RNA的DNA聚合酶，由于與中心法則中的從DNA到RNA的轉(zhuǎn)錄是反向的，所以稱為反轉(zhuǎn)錄酶（reverse transcriptase）。

反轉(zhuǎn)錄酶既可以利用DNA又可以利用RNA作為模板合成與之互補的DNA鏈。像其他DNA聚合酶一樣，反轉(zhuǎn)錄酶也以5′→3′方向合成DNA（圖1-3）。

圖1-3 由mRNA反轉(zhuǎn)錄形成cDNA的過程

cDNA合成過程是：第一步，反轉(zhuǎn)錄酶以RNA為模板合成一條與RNA互補的DNA單鏈，形成RNA-DNA雜交分子。第二步，核酸酶H使RNA-DNA雜交分子中的RNA鏈降解，使之變成單鏈的DNA。第三步，以單鏈DNA為模板，在DNA聚合酶的作用下合成另一條互補的DNA鏈，形成雙鏈DNA分子。

三、尋根問底

1.為什么要構(gòu)建基因文庫？直接從含有目的基因的生物體內(nèi)提取不行嗎？

提示：構(gòu)建基因文庫是獲取目的基因的方法之一，并不是惟一的方式。如果所需要的目的基因序列已知，就可以通過PCR方式從含有該基因的生物的DNA中，直接獲得，也可以通過反轉(zhuǎn)錄，用PCR方式從mRNA中獲得，不一定要構(gòu)建基因文庫。但如果所需要的目的基因的序列完全不知，或只知道目的基因序列的一段，或想從一種生物體內(nèi)獲得許多基因，或者想知道這種生物與另一種生物之間有多少基因不同，或者想知道一種生物在個體發(fā)育的不同階段表達(dá)的基因有什么不同，或者想得到一種生物的全基因組序列，往往就需要構(gòu)建基因文庫。2.將目的基因直接導(dǎo)入受體細(xì)胞不是更簡便嗎？如果這么做，結(jié)果會怎樣？

提示：有人采用總DNA注射法進(jìn)行遺傳轉(zhuǎn)化，即將一個生物中的總DNA提取出來，通過注射或花粉管通道法導(dǎo)入受體植物，沒有進(jìn)行表達(dá)載體的構(gòu)建，這種方法針對性差，完全靠運氣，也無法確定什么基因?qū)肓耸荏w植物。此法目前爭議頗多，嚴(yán)格來講不算基因工程。

1.3 基因工程的應(yīng)用

思考與探究

根據(jù)所學(xué)內(nèi)容，試概括寫出基因工程解決了哪些生活、生產(chǎn)中難以解決的問題。提示：基因工程可以生產(chǎn)人類需要的藥物，如胰島素、干擾素等。我們吃的某些食品如番茄、大豆等也可以是基因工程產(chǎn)品。農(nóng)業(yè)生產(chǎn)中的抗蟲棉、抗病毒煙草、抗除草劑大豆等都已進(jìn)入商品化生產(chǎn)，上述產(chǎn)品有些是常規(guī)方法難以生產(chǎn)的或者生產(chǎn)成本過高。

1.4 蛋白質(zhì)工程的崛起

一、思考與探究

1.蛋白質(zhì)工程是應(yīng)怎樣的需求而崛起的？

提示：蛋白質(zhì)工程的崛起主要是工業(yè)生產(chǎn)和基礎(chǔ)理論研究的需要。而結(jié)構(gòu)生物學(xué)對大量蛋白質(zhì)分子的精確立體結(jié)構(gòu)及其復(fù)雜的生物功能的分析結(jié)果，為設(shè)計改造天然蛋白質(zhì)提供了藍(lán)圖。分子遺傳學(xué)的以定點突變?yōu)橹行牡幕虿僮骷夹g(shù)為蛋白質(zhì)工程提供了手段。

在已研究過的幾千種酶中，只有極少數(shù)可以應(yīng)用于工業(yè)生產(chǎn)，絕大多數(shù)酶都不能應(yīng)用于工業(yè)生產(chǎn)，這些酶雖然在自然狀態(tài)下有活性，但在工業(yè)生產(chǎn)中沒有活性或活性很低。這是因為工業(yè)生產(chǎn)中每一步的反應(yīng)體系中常常會有酸、堿或有機溶劑存在，反應(yīng)溫度較高，在這種條件下，大多數(shù)酶會很快變性失活。提高蛋白質(zhì)的穩(wěn)定性是工業(yè)生產(chǎn)中一個非常重要的課題。一般來說，提高蛋白質(zhì)的穩(wěn)定性包括：延長酶的半衰期，提高酶的熱穩(wěn)定性，延長藥用蛋白的保存期，抵御由于重要氨基酸氧化引起的活性喪失等。

下面舉一個如何通過蛋白質(zhì)工程來提高重組β-干擾素專一活性和穩(wěn)定性的例子。干擾素是一種抗病毒、抗腫瘤的藥物。將人的干擾素的cDNA在大腸桿菌中進(jìn)行表達(dá)，產(chǎn)生的干擾素的抗病毒活性為10 U/mg，只相當(dāng)于天然產(chǎn)品的十分之一，雖然在大腸桿菌中合成的β-干擾素量很多，但多數(shù)是以無活性的二聚體形式存在。為什么會這樣？如何改變這種狀況？研究發(fā)現(xiàn)，β-干擾素蛋白質(zhì)中有3個半胱氨酸（第17位、31位和141位），推測可能是有一個或幾個半胱氨酸形成了不正確的二硫鍵。研究人員將第17位的半胱氨酸，通過基因定點突變改變成絲氨酸，結(jié)果使大腸桿菌中生產(chǎn)的β-干擾素的抗病性活性提高到10 U/mg，并且比天然β-干擾素的貯存穩(wěn)定性高很多。

在基礎(chǔ)理論研究方面，蛋白質(zhì)工程是研究多種蛋白質(zhì)的結(jié)構(gòu)和功能、蛋白質(zhì)折疊、蛋白質(zhì)分子設(shè)計等一系列分子生物學(xué)基本問題的一種新型的、強有力的手段。通過對蛋白質(zhì)工程的研究，可以深入地揭示生命現(xiàn)象的本質(zhì)和生命活動的規(guī)律。2.蛋白質(zhì)工程操作程序的基本思路與基因工程有什么不同？

答：基因工程是遵循中心法則，從DNA→mRNA→蛋白質(zhì)→折疊產(chǎn)生功能，基本上是生產(chǎn)出自

86然界已有的蛋白質(zhì)。蛋白質(zhì)工程是按照以下思路進(jìn)行的：確定蛋白質(zhì)的功能→蛋白質(zhì)應(yīng)有的高級結(jié)構(gòu)→蛋白質(zhì)應(yīng)具備的折疊狀態(tài)→應(yīng)有的氨基酸序列→應(yīng)有的堿基排列，可以創(chuàng)造自然界不存在的蛋白質(zhì)。

3.你知道酶工程嗎？絕大多數(shù)酶都是蛋白質(zhì)，酶工程與蛋白質(zhì)工程有什么區(qū)別？

提示：酶工程就是指將酶所具有的生物催化作用，借助工程學(xué)的手段，應(yīng)用于生產(chǎn)、生活、醫(yī)療診斷和環(huán)境保護(hù)等方面的一門科學(xué)技術(shù)。概括地說，酶工程是由酶制劑的生產(chǎn)和應(yīng)用兩方面組成的。酶工程的應(yīng)用主要集中于食品工業(yè)、輕工業(yè)以及醫(yī)藥工業(yè)中。α-淀粉酶、葡萄糖淀粉酶和葡萄糖異構(gòu)酶這三個酶連續(xù)作用于淀粉，就可以代替蔗糖生產(chǎn)出高果糖漿；蛋白酶用于皮革脫毛膠以及洗滌劑工業(yè)；固定化酶還可以治療先天性缺酶病或是器官缺損引起的某些功能的衰竭等。至于我們?nèi)粘Ｉ钪兴姷降募用赶匆路?、嫩肉粉等，就更是酶工程最直接的體現(xiàn)了。通常所說的酶工程是用工程菌生產(chǎn)酶制劑，而沒有經(jīng)過由酶的功能來設(shè)計酶的分子結(jié)構(gòu)，然后由酶的分子結(jié)構(gòu)來確定相應(yīng)基因的堿基序列等步驟。因此，酶工程的重點在于對已存酶的合理充分利用，而蛋白質(zhì)工程的重點則在于對已存在的蛋白質(zhì)分子的改造。當(dāng)然，隨著蛋白質(zhì)工程的發(fā)展，其成果也會應(yīng)用到酶工程中，使酶工程成為蛋白質(zhì)工程的一部分。

二、正文中討論題

某多肽鏈的一段氨基酸序列是：?—丙氨酸—色氨酸—賴氨酸—甲硫氨酸—苯丙氨酸—? 討論：（1）怎樣得出決定這一段肽鏈的脫氧核苷酸序列？請把相應(yīng)的堿基序列寫出來。（2）確定目的基因的堿基序列后，怎樣才能合成或改造目的基因（DNA）？

答：（1）每種氨基酸都有對應(yīng)的三聯(lián)密碼子，只要查一下遺傳密碼子表，就可以將上述氨基酸序列的編碼序列查出來。但是由于上述氨基酸序列中有幾個氨基酸是由多個三聯(lián)密碼子編碼，因此其堿基排列組合起來就比較復(fù)雜，至少可以排列出16種，可以讓學(xué)生根據(jù)學(xué)過的排列組合知識自己排列一下。首先應(yīng)該根據(jù)三聯(lián)密碼子推出mRNA序列為GCU（或C或A或G）UGGAAA（或G）AUGUUU（或C），再根據(jù)堿基互補配對規(guī)律推出脫氧核苷酸序列：CGA（或G或T或C）ACCTTT（或C）TACAAA（或G）。

（2）確定目的基因的堿基序列后，就可以根據(jù)人類的需要改造它，通過人工合成的方法或從基因庫中獲取。

三、異想天開

能不能根據(jù)人類需要的蛋白質(zhì)的結(jié)構(gòu)，設(shè)計相應(yīng)的基因，導(dǎo)入合適的細(xì)菌中，讓細(xì)菌生產(chǎn)人類所需要的蛋白質(zhì)食品呢？ 提示：理論上講可以，但目前還沒有真正成功的例子。一些報道利用細(xì)菌生產(chǎn)人類需要的蛋白質(zhì)往往都是自然界已經(jīng)存在的蛋白質(zhì)，并非完全是人工設(shè)計出來而自然不存在的蛋白質(zhì)。主要原因是蛋白質(zhì)的高級結(jié)構(gòu)非常復(fù)雜，人類對蛋白質(zhì)的高級結(jié)構(gòu)和在生物體內(nèi)如何行使功能知之甚少，很難設(shè)計出一個嶄新而又具有生命功能作用的蛋白質(zhì)，而且一個嶄新的蛋白質(zhì)會帶來什么危害也是人們所擔(dān)心的。

四、旁欄思考題

1.你知道人類蛋白質(zhì)組計劃嗎？它與蛋白質(zhì)工程有什么關(guān)系？我國科學(xué)家承擔(dān)了什么任務(wù)？

提示：人類蛋白質(zhì)組計劃是繼人類基因組計劃之后，生命科學(xué)乃至自然科學(xué)領(lǐng)域一項重大的科學(xué)命題。2001年，國際人類蛋白質(zhì)組組織宣告成立。之后，該組織正式提出啟動了兩項重大國際合作行動：一項是由中國科學(xué)家牽頭執(zhí)行的“人類肝臟蛋白質(zhì)組計劃”；另一項是以美國科學(xué)家牽頭執(zhí)行的“人類血漿蛋白質(zhì)組計劃”，由此拉開了人類蛋白質(zhì)組計劃的帷幕?！叭祟惛闻K蛋白質(zhì)組計劃”是國際上第一個人類組織／器官的蛋白質(zhì)組計劃，由我國賀福初院士牽頭，這是中國科學(xué)家第一次領(lǐng)銜的重大國際科研協(xié)作計劃，總部設(shè)在北京，目前有16個國家和地區(qū)的80多個實驗室報名參加。它的科學(xué)目標(biāo)是揭示并確認(rèn)肝臟的蛋白質(zhì)，為重大肝病預(yù)防、診斷、治療和新藥研發(fā)的突破提供重要的科學(xué)基礎(chǔ)。人類蛋白質(zhì)組計劃的深入研究將是對蛋白質(zhì)工程的有力推動和理論支持。

2.對天然蛋白質(zhì)進(jìn)行改造，你認(rèn)為應(yīng)該直接對蛋白質(zhì)分子進(jìn)行操作，還是通過對基因的操作來實現(xiàn)？

答：毫無疑問應(yīng)該從對基因的操作來實現(xiàn)對天然蛋白質(zhì)改造，主要原因如下：

（1）任何一種天然蛋白質(zhì)都是由基因編碼的，改造了基因即對蛋白質(zhì)進(jìn)行了改造，而且改造過的蛋白質(zhì)可以遺傳下去。如果對蛋白質(zhì)直接改造，即使改造成功，被改造過的蛋白質(zhì)分子還是無法遺傳的。

（2）對基因進(jìn)行改造比對蛋白質(zhì)直接改造要容易操作，難度要小得多。

專題2 細(xì)胞工程 2.1 植物細(xì)胞工程 2.1.1植物細(xì)胞工程的基本技術(shù)

一、思考與探究

1.為什么“番茄—馬鈴薯”超級雜種植株沒有如科學(xué)家所想像的那樣，地上長番茄、地下結(jié)馬鈴薯？

提示：1978年，梅爾徹斯（Melchers）等人首次獲得了馬鈴薯與番茄的屬間體細(xì)胞雜種。他們將培育的二倍體馬鈴薯品系和番茄葉片細(xì)胞進(jìn)行融合，所產(chǎn)生的雜交株被稱為“馬鈴薯番茄”。像大多數(shù)雜種一樣，雜交株同時具有馬鈴薯和番茄的形態(tài)特征。其中一些植株形成了“類似塊莖的生殖根”，但是沒有產(chǎn)生可結(jié)實的花、果實以及真正意義上的塊莖。到目前為止“馬鈴薯—番茄”一類的體細(xì)胞雜交植物還不能產(chǎn)生經(jīng)濟效益，但是其研究價值不可忽視。

至于馬鈴薯—番茄沒有像人們預(yù)想的那樣地上長番茄、地下結(jié)馬鈴薯，主要原因是：生物基因的表達(dá)不是孤立的，它們之間是相互調(diào)控、相互影響的，所以馬鈴薯—番茄雜交植株的細(xì)胞中雖然具備兩個物種的遺傳物質(zhì)，但這些遺傳物質(zhì)的表達(dá)受到相互干擾，不能再像馬鈴薯或番茄植株中的遺傳物質(zhì)一樣有序表達(dá)，雜交植株不能地上長番茄、地下結(jié)馬鈴薯就是很自然的了。

2.自然界中有一種含有葉綠體的原生動物──眼蟲，說明植物的細(xì)胞器同樣可以在某些動物細(xì)胞中存活，請?zhí)接懀簞游锛?xì)胞與植物細(xì)胞之間可以實現(xiàn)雜交嗎？如果理論上可行，請設(shè)計出具體實驗方案。

提示：根據(jù)眼蟲的特點，動物細(xì)胞和植物細(xì)胞之間在理論上是可以實現(xiàn)雜交的。具體的實驗方案可以設(shè)計如下：

二、正文中討論題 【實驗 胡蘿卜的組織培養(yǎng)】

1.在組織培養(yǎng)實驗中，為什么要強調(diào)所用器械的滅菌和實驗人員的無菌操作？

提示：植物組織培養(yǎng)中用到的培養(yǎng)基含有豐富的營養(yǎng)成分，有利于培養(yǎng)物的生長，然而各種雜菌同樣也可以在上面迅速生長，所以植物組織培養(yǎng)過程中污染現(xiàn)象經(jīng)常發(fā)生。培養(yǎng)基一旦被污染，迅速生長的各種雜菌不但會和培養(yǎng)物爭奪營養(yǎng)，而且這些雜菌生長的過程中會生成大量對培養(yǎng)物有害的物質(zhì)，導(dǎo)致培養(yǎng)物迅速死亡。

造成培養(yǎng)基污染的因素有很多，一般包括：外植體帶菌、培養(yǎng)瓶和各種器械滅菌不徹底、操作人員操作不規(guī)范等。所以在組織培養(yǎng)實驗中用到的植物材料和各種器械都要進(jìn)行徹底地滅菌，實驗人員操作一定要規(guī)范，避免帶入雜菌。

2.在本實驗中，切取胡蘿卜塊根時強調(diào)要切取含有形成層部分，原因是這部分容易誘導(dǎo)形成愈傷組織。請思考一下，胡蘿卜的其他部分（如莖、葉、花），是否也能培養(yǎng)成小植株，你能用實驗的方法進(jìn)行驗證嗎？

提示：胡蘿卜的其他部分（如莖、葉、花）也能培養(yǎng)再生形成小植株，只是誘導(dǎo)愈傷組織比較困難。可以讓學(xué)生參考利用胡蘿卜根進(jìn)行組織培養(yǎng)的實驗，嘗試設(shè)計出利用胡蘿卜的莖、葉、花進(jìn)行組織培養(yǎng)的實驗流程。

3.請根據(jù)上面的實驗過程，概括出植物組織培養(yǎng)技術(shù)的流程簡圖。提示：

2.1.2植物細(xì)胞工程的實際應(yīng)用

一、思考與探究

1.通過查閱資料，請你再列舉出植物組織培養(yǎng)技術(shù)在我們生活中的另外一些應(yīng)用。提示：a.拯救瀕危植物； b.提供食品制作的原料； c.利用愈傷組織進(jìn)行轉(zhuǎn)基因操作。

2.請查閱植物人工種子制備技術(shù)的詳細(xì)過程，設(shè)計出制備技術(shù)的主要流程圖。提示：誘導(dǎo)植物愈傷組織→體細(xì)胞胚的誘導(dǎo)→體細(xì)胞胚的成熟→體細(xì)胞胚的機械化包裹

→貯藏或種植

3.請查閱相關(guān)文獻(xiàn)，設(shè)計出一種植物花藥組織培養(yǎng)和染色體加倍的實驗流程。提示：

二、正文中討論題

1.人們利用植物的微型繁殖技術(shù)來進(jìn)行工廠化育苗生產(chǎn)，這是利用了該項技術(shù)的哪些特點？

提示：植物“微型”繁殖技術(shù)具有高效性和可以保持種苗的優(yōu)良遺傳特性的優(yōu)勢。工廠化大規(guī)模育苗生產(chǎn)正是利用了植物“微型”繁殖技術(shù)的這兩方面優(yōu)勢。利用植物“微型”繁殖技術(shù)我們可以在短時間中獲得大量的優(yōu)質(zhì)種苗。

2.人工種子之所以神奇，是由于它具有天然種子不可比擬的特點，想一想它們具有哪些優(yōu)點？

提示：人工種子的優(yōu)點：

（1）天然種子由于在遺傳上具有因減數(shù)分裂引起的重組現(xiàn)象，因而會造成某些遺傳性狀的改變；天然種子在生產(chǎn)上受季節(jié)限制，一般每年只繁殖1～2次，有些甚至十幾年才繁殖一次。而人工種子則可以完全保持優(yōu)良品種的遺傳特性，生產(chǎn)上也不受季節(jié)的限制。（2）試管苗的大量貯藏和運輸也是相當(dāng)困難的。人工種子則克服了這些缺點，人工種子外層是起保護(hù)作用的薄膜，類似天然種子的種皮，因此，可以很方便地貯藏和運輸。3.人工種皮是保證包裹在其中的胚狀體順利生長成小植株的關(guān)鍵部分，請?zhí)接懭斯しN皮中應(yīng)該具有的有效成分是什么？為了促進(jìn)胚狀體的生長發(fā)育，我們還可以向人工種皮中加入哪些物質(zhì)？

提示：針對植物種類和土壤等條件，在人工種子的包裹劑中還可以加入適量的養(yǎng)分、無機鹽、有機碳源以及農(nóng)藥、抗生素、有益菌等。為了促進(jìn)胚狀體的生長發(fā)育，還可以向人工種皮中加入一些植物生長調(diào)節(jié)劑。

4.高效抗癌的藥物紫杉醇，雖然能造福人類，但卻為瀕危的紅豆杉帶來一場滅頂之災(zāi)。以“我們能否利用植物組織培養(yǎng)技術(shù)大量生產(chǎn)紫杉醇，從而拯救紅豆杉”為題，與同學(xué)展開討論，說出植物組織培養(yǎng)技術(shù)在節(jié)約資源、保護(hù)環(huán)境方面的重要意義。

提示：可以利用植物組織培養(yǎng)技術(shù)來大量生產(chǎn)紫杉醇。現(xiàn)在國內(nèi)外的科學(xué)家們正在研究利用植物細(xì)胞培養(yǎng)技術(shù)來大量培育紅豆杉細(xì)胞，希望利用這種方法來大量生產(chǎn)紫杉醇。國內(nèi)外許多實驗室開展了用組織培養(yǎng)法生產(chǎn)紫杉醇的研究，紅豆杉屬的11種植物現(xiàn)都在進(jìn)行組織培養(yǎng)。ESC Agenetics公司宣布他們用細(xì)胞培養(yǎng)法所得紫杉醇的含量是樹皮的2～5倍。國內(nèi)外在分化細(xì)胞株系和培養(yǎng)條件方面做了不少工作，摸索了外植體、光照、培養(yǎng)基組成等因素對細(xì)胞培養(yǎng)及紫杉醇生成的影響?，F(xiàn)在工藝條件已基本摸清，正研究反應(yīng)的放大技術(shù)等，有望實現(xiàn)通過細(xì)胞培養(yǎng)進(jìn)行工業(yè)化生產(chǎn)紫杉醇的目標(biāo)。

2.2 動物細(xì)胞工程

2.2.1動物細(xì)胞培養(yǎng)和核移植技術(shù)

一、思考與探究

1.幼齡與老齡動物的組織細(xì)胞比較，分化程度低的與分化程度高的組織細(xì)胞比較，哪一種更易于培養(yǎng)？思考一下，這是什么道理？

提示：細(xì)胞的衰老與動物機體的衰老有著密切的關(guān)系，細(xì)胞的增殖能力與供體的年齡有關(guān)，幼齡動物細(xì)胞增殖能力強，有絲分裂旺盛，老齡動物則相反。所以，一般來說幼年動物的組織細(xì)胞比老年動物的組織細(xì)胞易于培養(yǎng)。同樣，組織細(xì)胞的分化程度越低，則增殖能力越強，所以更容易培養(yǎng)。

2.動物細(xì)胞培養(yǎng)要經(jīng)過脫分化的過程嗎？為什么？

提示：脫分化又稱去分化，是指分化細(xì)胞失去特有的結(jié)構(gòu)和功能變?yōu)榫哂形捶只?xì)胞特性的過程。植物的任何一部分，甚至單個細(xì)胞都具有長成完整植株的能力。但要發(fā)育成完整植株，必須先脫分化，脫分化的細(xì)胞具有發(fā)育成任何組織的能力，然后進(jìn)行再分化，形成完整植株。植物細(xì)胞培養(yǎng)主要用于農(nóng)林生產(chǎn)中的作物、苗木育種，快速繁育種苗、培育無病毒植株等，這就要求植物的組織或細(xì)胞先進(jìn)行脫分化。動物細(xì)胞的培養(yǎng)有各種用途，一般而言，動物細(xì)胞培養(yǎng)不需經(jīng)過脫分化過程。因高度分化的動物細(xì)胞發(fā)育潛能變窄，失去了發(fā)育成完整個體的能力，所以，動物細(xì)胞也就沒有類似植物組織或細(xì)胞培養(yǎng)時的脫分化過程了。要想使培養(yǎng)的動物細(xì)胞定向分化，通常采用定向誘導(dǎo)動物干細(xì)胞，使其分化成所需要的組織或器官。3.1997年，美國威斯康星州的一個奶牛場有一頭名叫盧辛達(dá)（Lucinda）的奶牛，年產(chǎn)奶量為30.8 t，創(chuàng)造了世界奶牛產(chǎn)奶量最高新紀(jì)錄。目前世界各國高產(chǎn)奶牛場奶牛，年平均產(chǎn)奶量一般為十幾噸，而我國奶牛產(chǎn)奶量年平均水平僅為3～4 t。（1）能利用體細(xì)胞核移植技術(shù)克隆高產(chǎn)奶牛盧辛達(dá)嗎？請說明理由。

提示：可以用體細(xì)胞核移植技術(shù)克隆高產(chǎn)奶牛盧辛達(dá)。盧辛達(dá)的產(chǎn)奶量很高，說明它有高產(chǎn)奶的遺傳基礎(chǔ)，利用盧辛達(dá)的體細(xì)胞克隆的奶牛其遺傳物質(zhì)基本上全部來自該奶牛，其克隆牛具有高產(chǎn)的遺傳基礎(chǔ)，如果精心培育和飼養(yǎng)，有可能在世界范圍內(nèi)推廣，克隆牛再與高產(chǎn)的公牛自然繁殖，可得到很多高產(chǎn)的后代，從而加快奶牛改良進(jìn)程。

但同時需注意，該克隆牛不能無限制地推廣，其數(shù)量不宜過多，尤其是在小范圍內(nèi)不能無限的繁殖，以避免奶牛群出現(xiàn)近親繁殖而引起種質(zhì)衰退。

（2）如果將克隆高產(chǎn)奶牛盧辛達(dá)的任務(wù)交給你，你將如何對它進(jìn)行克?。?/p>

提示：首先從盧辛達(dá)耳朵（也可用別的組織、器官，耳朵在活體上容易?。┥霞羧∫恍K組織，在體外培養(yǎng)獲得該組織（如軟骨組織）的細(xì)胞。從屠宰場取廢棄的牛卵巢，抽取卵母細(xì)胞體外培養(yǎng)成熟。用顯微針去除卵母細(xì)胞的核，再將耳細(xì)胞注入卵母細(xì)胞，用電刺激方法使卵母細(xì)胞與體細(xì)胞融合，這時供體核就進(jìn)入了受體卵母細(xì)胞，再用電刺激或化學(xué)物質(zhì)激活注入了體細(xì)胞核的卵母細(xì)胞，使其完成減數(shù)分裂和發(fā)育過程。核移植胚胎在體外短時間培養(yǎng)后，挑選正常卵裂的胚胎植入經(jīng)同期發(fā)情處理的受體母牛體內(nèi)。

4.體細(xì)胞核移植技術(shù)在研究和應(yīng)用上還存在什么問題？請你查閱資料，了解這方面的前沿動態(tài)。

提示：在研究方面，克隆動物基因組重新編程的機制尚不清楚，克隆技術(shù)效率低，克隆動物畸形率高、死亡率高、易出現(xiàn)早衰等問題。這些問題尚在研究中。在應(yīng)用上，生產(chǎn)克隆動物費用昂貴，距大規(guī)模應(yīng)用還有一定距離。

二、正文中討論題 【討論1】

多細(xì)胞動物和人體的細(xì)胞都生活在內(nèi)環(huán)境中，根據(jù)你所學(xué)的內(nèi)環(huán)境的知識，思考并討論以下問題：

1.體外培養(yǎng)細(xì)胞時需要提供哪些物質(zhì)？

提示：充足的營養(yǎng)供給、適宜的溫度、適宜的pH和氣體環(huán)境。2.體外培養(yǎng)的細(xì)胞需要什么樣的環(huán)境條件？ 提示：無菌、無毒的環(huán)境。【討論2】

1.在體細(xì)胞的細(xì)胞核移植到受體卵母細(xì)胞之前，為什么必須先去掉受體卵母細(xì)胞的核？ 提示：為使核移植的胚胎或動物的遺傳物質(zhì)全部來自有重要利用價值的動物提供的體細(xì)胞，在供體細(xì)胞的細(xì)胞核移至受體細(xì)胞之前，必須將受體細(xì)胞的遺傳物質(zhì)去掉或?qū)⑵淦茐摹?.用于核移植的供體細(xì)胞一般都選用傳代10代以內(nèi)的細(xì)胞，想一想，這是為什么？ 提示：培養(yǎng)的動物細(xì)胞一般當(dāng)傳代至10～50代左右時，部分細(xì)胞核型可能會發(fā)生變化，其細(xì)胞遺傳物質(zhì)可能會發(fā)生突變，而10代以內(nèi)的細(xì)胞一般能保持正常的二倍體核型。因此，在體細(xì)胞核移植中，為了保證供體細(xì)胞正常的遺傳基礎(chǔ)，通常采用傳代10代以內(nèi)的細(xì)胞。3.你認(rèn)為用上述體細(xì)胞核移植方法生產(chǎn)的克隆動物，是對體細(xì)胞供體動物進(jìn)行了100%的復(fù)制嗎？為什么？

提示：克隆動物絕大部分DNA來自于供體細(xì)胞核，但其核外還有少量的DNA，即線粒體中的DNA是來自于受體卵母細(xì)胞。所以，用教材中所述的方法克隆的動物不是供核動物完全相同的復(fù)制。

此外，即便動物的遺傳基礎(chǔ)完全相同，但動物的一些行為、習(xí)性的形成與所處環(huán)境有很大關(guān)系，核供體動物生活的環(huán)境與克隆動物所生活的環(huán)境不會完全相同，其形成的行為、習(xí)性也不可能和核供體動物完全相同，從這一角度看，克隆動物不會是核供體動物100%的復(fù)制。

三、尋根問底

胰蛋白酶真的不會把細(xì)胞消化掉嗎？為什么？

提示：胰蛋白酶除了可以消化細(xì)胞間的蛋白外，長時間的作用也會消化細(xì)胞膜蛋白，對細(xì)胞有損傷作用，因此必須控制好胰蛋白酶的消化時間。

四、旁欄思考題

1.進(jìn)行動物細(xì)胞傳代培養(yǎng)時用胰蛋白酶分散細(xì)胞，說明細(xì)胞間的物質(zhì)主要是什么成分？用胃蛋白酶行嗎？

提示：用胰蛋白酶分散細(xì)胞，說明細(xì)胞間的物質(zhì)主要是蛋白質(zhì)。胃蛋白酶作用的適宜pH約為2，當(dāng)pH大于6時，胃蛋白酶就會失去活性。胰蛋白酶作用的適宜環(huán)境pH為7.2～8.4。多數(shù)動物細(xì)胞培養(yǎng)的適宜pH為7.2～7.4，胃蛋白酶在此環(huán)境中沒有活性，而胰蛋白酶在此環(huán)境中活性較高，因此胰蛋白酶適宜用于細(xì)胞培養(yǎng)時的消化。2.為什么對動物細(xì)胞進(jìn)行培養(yǎng)時通常要添加血清？ 提示：血清中含有蛋白質(zhì)、氨基酸、葡萄糖、激素等，其中蛋白質(zhì)主要為白蛋白和球蛋白。氨基酸有多種，是細(xì)胞合成蛋白質(zhì)的基本成分，其中有些氨基酸動物細(xì)胞本身不能合成（稱為必需氨基酸），必須由培養(yǎng)液提供。血清激素有胰島素、生長激素等及多種生長因子（如表皮生長因子、成纖維細(xì)胞生長因子、類胰島素生長因子等）；血清還含有多種未知的促細(xì)胞生長因子、促貼附因子及其他活性物質(zhì)，能促進(jìn)細(xì)胞的生長、增殖和貼附。因此，細(xì)胞培養(yǎng)時，要保證細(xì)胞能夠順利生長和增殖，一般需添加10%～20%的血清。

2.2.2動物細(xì)胞融合與單克隆抗體

思考與探究

1.植物體細(xì)胞雜交技術(shù)與動物細(xì)胞融合技術(shù)有什么不同？

提示：植物體細(xì)胞雜交技術(shù)與動物細(xì)胞融合技術(shù)基本相同，不同的是植物體細(xì)胞融合前需去掉細(xì)胞壁，然后再融合；動物細(xì)胞融合是兩個體細(xì)胞直接融合。

2.制備單克隆抗體時，為什么要選用B淋巴細(xì)胞和骨髓瘤細(xì)胞融合形成雜交瘤細(xì)胞？ 提示：哺乳動物感染抗原后，其體內(nèi)會形成相應(yīng)的B淋巴細(xì)胞，B淋巴細(xì)胞能分泌相應(yīng)的抗體凝聚或殺死這些抗原。動物在免疫反應(yīng)的過程中，每一種B淋巴細(xì)胞能分泌一種特異性抗體，要想獲得大量的特異性抗體，必須使能分泌該單一抗體的B淋巴細(xì)胞大量增殖。B淋巴細(xì)胞具有產(chǎn)生單一抗體的能力，但不能在體外增殖；骨髓瘤細(xì)胞是一種癌細(xì)胞，它能在體外培養(yǎng)條件下無限增殖，但不能產(chǎn)生抗體。因此，把一種B淋巴細(xì)胞與骨髓瘤細(xì)胞進(jìn)行細(xì)胞融合，產(chǎn)生雜交瘤細(xì)胞，它會兼有兩個親本細(xì)胞的特性──在體外培養(yǎng)條件下能不斷增殖，同時能產(chǎn)生出某種特異性的抗體。

第四篇：英語課后翻譯題

Unit 1 1.當(dāng)今的大學(xué)生，盡管他們努力地想使自己成才，但對未來還是很模糊的。（establish oneself）

Today's university students are struggling to establish themselves, but they still have ambiguous feelings about their future.2.一個人如果不能找到自我以外的中心，就不能實現(xiàn)他的自我價值。所以，理想的本科教育必須使學(xué)生超越自我。(transcend)A man cannot realize his values without finding a center beyond him.So the idealistic of the undergraduate experience must help the student transcend himself.3.我們強烈地希望在大學(xué)所學(xué)到的知識在今后的工作與學(xué)習(xí)中能起到重要的作用。（reveal oneself）We eagerly hope that the lessons leaned in the university will reveal themselves in our performance in the workplace and further education.4.四年的本科學(xué)習(xí)是走向成功生活的唯一道路，這種說法是無法接受的。（go unchallenged）It cannot go unchallenged to say that the 4-year undergraduate experience is the only path to success in life.5.在對一個關(guān)鍵的問題做結(jié)論時，如果只相信所謂的專家而不相信自己，不根據(jù)調(diào)查的結(jié)果，不根據(jù)實驗的數(shù)據(jù)，那是在冒險。（run the risk of;blind faith in）

We run the risk of making critical decisions, not on the basis of what we know, the findings of investigations, and the data of experiments, but on the basis of blind faith in professed experts.6.我們的事業(yè)需要一批受過良好教育又能關(guān)心他人的年輕人，他們能團結(jié)一致，相互學(xué)習(xí)，積極參加四化建設(shè)。（band together;participate in）

Our task needs a large group of well-informed, caring young people who can band together, learn from each other, and actively participate in the four modernizations.7.如果這所新學(xué)校要有生命力的話，它培養(yǎng)的學(xué)生不僅要有扎實的基礎(chǔ)和熟悉的專業(yè)技能，還要有奉獻(xiàn)精神。（be to endure;commit oneself）

If it is to endure, the new school should help the students not only acquire a solid basic education and become competent in a specific field, but also be ready to commit themselves to others.8.如果大學(xué)生對考試過于投入，就有可能把能力與風(fēng)險放到次要的地位，這樣說一點也不過分。（push to the fringes）

It is not too much to say that if undergraduates excessively devote themselves to examinations, they will push competence and commitment to the fringes.9.我甚至沒有跟他說話，當(dāng)然更不用說與他討論有關(guān)你們學(xué)校的改建問題。（much less）I didn't even speak to him, much less discuss the reconstruction of your school with him.10.有人認(rèn)為考試是很重要的，但也有人認(rèn)為考試有不少弊端。所以考試留下了一個未能解決的問題——考試對教育有什么影響？（open question）

Some people think examinations are second to none, but some think examinations have a lot of disadvantages.Examinations leave us an open essential question---what influence do examinations exert on education?

Unit 2 1.他不但是位出色的銀行家和公認(rèn)的貿(mào)易專家，而且還是位經(jīng)驗豐富的企業(yè)主管。(not to mention)He is an experienced banker and an acknowledged trade expert, not to mention an excellent managing director.2.意大利一個和平組織的志愿者不顧危險，已開赴伊拉克首都巴格達(dá)，組成“人體盾牌”，以阻止美國轟炸該地。（regardless of）

Regardless of danger, volunteers from an Italian organization for peace have gone to Baghdad, the capital of Iraq, to form a “body shield” for the purpose of preventing the U.S.from bombing the place.3.在這個家庭里，沒有人比朱蒂更能致力于經(jīng)營房地產(chǎn)生意。（be dedicated to）Nobody in the family is more dedicated to operating the real estate business than Judy.4.由于經(jīng)濟不景氣，房地產(chǎn)經(jīng)紀(jì)人正處于或降低房價或減少銷售量的兩難境地。(dilemma)Because of the economic depression, real estate agents are in the dilemma of whether to lower prices or let sales fall off.5.史密斯先生往往靠慎重投資而獲取巨額利潤。(more ofen than not)More often than not, Mr.Smith earns great profits by careful investment of his capital.6.約翰在學(xué)校里各門功課的成績都不怎么樣，但在體育方面倒是身手非凡。(excel at)John did not make much of a mark in his studies at school, but he excelled at sports.7.有條不紊的職責(zé)交接是家庭企業(yè)長期繁榮的一個條件。(transition;longrange)Orderly transition of responsibilities is a condition for the long-range prosperity of a family business.8.在制定投資計劃之前，你最好對投資前景有個清楚地了解。(have a clear picture of)You had better have a clear picture of prospects before formulating a plan for investment.9.盡管雕塑費時，但是仍有一些人以雕塑為職業(yè)。(timeconsuming)Although sculpture is a time-consuming art, there are still some people following it as a profession.10.這家電腦軟件公司正處于從獨資經(jīng)營到合資經(jīng)營的轉(zhuǎn)化過程中。(in the midst of)The software company is in the midst of being transformed from an individual proprietorship to a joint venture.Unit 3

1.汽車誕生后發(fā)展很快，不就就替代了馬。(displace)The automobile was improved very rapidly after it was invented and soon displaced horses.2.由于汽車污染環(huán)境并嚴(yán)重傷害人體，甚至殺人，我們可能不得不削減私人擁有汽車的數(shù)量而更多地依賴公共交通系統(tǒng)。(mass transit systems)We may have to cut down on the number of privately owned cars and depend more on mass transit systems because cars pollute and maim or even kill people.3.汽車輪子給我們帶來了更好、更為便利的交通時，它也應(yīng)對諸如空氣污染、交通事故、交通擁擠之類的許多問題負(fù)責(zé)。(be guilty of)While wheels(automobiles)have brought with them better or more convenient transportation, they are guilty of many sins, such as air pollution, traffic accidents and traffic congestion.4.美國人對汽車的熱愛以及他們較大的工作流動性是出了名的。(be noted for)Americans are noted for their love for cars and great job mobility.5.要是燃料質(zhì)量和效率的提高和技術(shù)的進(jìn)步能大大減少汽車的排放量，那該多好啊。(if only)If only advances in fuel quality and efficiency and in technology would radically reduce the emissions from automobiles.6.在美國，高速發(fā)達(dá)的公路網(wǎng)使在各地之間來來往往成為可能。(from coast to coast)A highly developed highway network has made possible the easy movement from coast to coast in the United States.7.一想到這條林蔭大道的建設(shè)速度，參觀者都感到很吃驚：這條路不久前還在開挖及鋪設(shè)排水管。(the very thought of;tear up)The very thought of the speed at which the beautiful avenue was constructed electrified every visitor;the road had only recently been torn up to lay drain-pipes not long ago.8.環(huán)境保護(hù)主義者嚴(yán)厲譴責(zé)了汽車，認(rèn)為汽車是產(chǎn)生空氣污染的主要因素。(denounce)Environmentalists have denounced automobiles, believing they are a major factor in the production of dirty air.9.由于有便利的公共交通，在大都市的市郊，許多新建的住宅群拔地而起。(rise up,complex)Many new residential complexes have risen up in the suburbs of metropolitan cities because of the availability of convenient public transportation.10.盡管非常喜歡汽車，許多人還是相信廣泛的使用公共交通系統(tǒng)能緩解交通擁擠。（lend credence to）

Despite their love for cars, many people lend credence to the extensive use of the public transport system, which can cut down on traffic congestion.Unit 4 1.一些職業(yè)觀察家認(rèn)為，現(xiàn)在的年輕人不再對政治和事業(yè)感興趣，他們越來越關(guān)注與他們自身關(guān)系更為密切的問題。(preoccupied with)Some professional observers believe that young people today are no longer interested in politics and causes, but rather, have become increasingly preoccupied with issues closer to themselves.2.一個婦女所獲得的教育程度越高，就越有可能走出小家庭這個環(huán)境，到社會上去實現(xiàn)自我。（be likely to,realize oneself）

The higher a woman’s educational attainment, the more likely she is to go out of the private setting of the nuclear family and to realize herself in the community.3.就我而言，一些已婚夫婦做出選擇不要小孩的真正原因是他們非常自戀，以至于他們沒有多余的愛給別人。(start a family,lie behind,have no margin of,spare)As far as I am concerned, what really lies behind the decision of some married couples not to start a family is that they are so narcissistic and have no margin of love to spare others.4.這家公司甚至在未征求發(fā)明人同意的情況下，就將其一項注冊過的新發(fā)明投放市場。這一行為違反了專利法。(go against)The company put on the market a registered invention even without asking the inventor’s permission, which goes against the patent law.5.在一些國家的敦促下，聯(lián)合國對該國施加壓力，迫使其放棄研制和使用核武器。（pressure sb to do）Urged by some other countries, the United Nations has pressured the country to give up developing and using nuclear weapons.6.按照每個會員必須是無子女的這一規(guī)定，懷特先生及其太太只好退出Non-Parent協(xié)會，因為他們很快就要當(dāng)父母了。(alternative,parenthood)According to the rule that every member should remain childless, Mr.And Ms.white have no alternative but to withdraw from the Non-Parent Association, for they will attain parenthood soon.7.他期望通過上演一部肥皂劇來揭示現(xiàn)實生活所固有的復(fù)雜性。(implicit)He expects to reveal, by presenting a soap opera, the complexity implicit in real life.8.幾乎在每個國家，嗜用麻醉品，酗酒和摧殘兒童都有變?yōu)樽盍钊松钏嫉纳鐣栴}的趨勢。(loom as)In virtually every country, drug abuse, alcohol abuse and child abuse loom as most challenging social problems.9.在接受來訪時，這些老年人合理地解釋了為什么會對當(dāng)今青年人產(chǎn)生矛盾心理的原因。(be ambivalent about,rationalize)When interviewed, these elderly people rationalized why they were ambivalent about today’s young people.10.不少大學(xué)生更關(guān)心怎樣在畢業(yè)后謀得一份報酬優(yōu)厚工作，怎樣在這個充滿競爭的社會里迅速得到提升。(be concerned with)Many college students are far more concerned with how to get a highly-paid job on graduation and how to receive a quick promotion in the competitive society.Unit 5

1.總的來說，人變得越來越有同情心；不少家庭收養(yǎng)了來自市孤兒院的孤兒。(take in,orphanage)Generally, people have become more compassionate and quite a few families have taken in an orphan from the municipal orphanage.2.一個有工作的婦女既要照顧她的孩子和和老人，又要設(shè)法保有這份工作，是一件非常困難的事情。(hold down)It is a demanding task for a workingwoman to look after her parents and her children while holding down a job.3.起先，我們對他們初次在異國他鄉(xiāng)生活感到擔(dān)憂，但是結(jié)果他們在那個國家生活得相當(dāng)不錯。(work out)At first we were worried about their first stay in a foreign country, but things there worked out much better for them.4.今天，中年人的孩子比他們父母的孩子要少得多；40年后人口老化問題可能成為他們孩子的沉重負(fù)擔(dān)。(weigh on)Today's middle-aged people have fewer children than their parents did, and the aging population problem may weigh on them in about 40 years.5.希望目前的教育改革能為學(xué)生更好地迎接社會的挑戰(zhàn)做好準(zhǔn)備。(set up)It is hoped that the current reform in education will better set students up to meet the challenges from society.6.政府想把一部分健康護(hù)理的負(fù)擔(dān)轉(zhuǎn)嫁給個人；但是家庭成員并不總是有空的，因為他們不能離開工作來照顧生病的老人。(break away from)The government intends to transfer some of the health-care burden to the individual family;but family members are not always available for the task because they cannot break away from their jobs to look after the sick elderly.7.對養(yǎng)老院床位的需求越來越大，我們不得不想盡一切辦法騰出床位。(free up)There is an increasing demand for beds in the nursing home, and we have to try every possible means to free them up.8.隨著該國老年人的日益增多，為醫(yī)療保健和養(yǎng)老金提供資金可能使政府感到恐懼。(scare the devil out of)With the increase of elderly population in this country, financing health care and pensions could scare the devil out of the government.9.這對年輕夫婦不得不做出犧牲，以避免使他們年邁的慈父傷心。（let down）The young couple has to make some sacrifice to avoid letting their old beloved father down.10.他們在照顧年邁多病的老父時所經(jīng)歷的一切使他們更具有同情心并向養(yǎng)老院捐了款。(go through)What they had gone through in looking after their sick old father made them more compassionate, and they made a donation to the nursing home

第五篇：英語課后題翻譯

第一單元

1.這種植物只有在培育它的土壤中才能很好地成長。(other than)

The plant does not grow well in soils other than the one in which it has been developed.2.研究結(jié)果表明，無論我們白天做了什么事情，晚上都會做大約兩個小時的夢。(may have done)

Research findings show that we spend about two hours dreaming every night, no matter what we may have done during the day.3.有些人往往責(zé)怪別人沒有盡最大努力，以此來為自己的失敗辯護(hù)。(justify sth.by)Some people tend to justify their failure by blaming others for not trying their best.4.我們忠于我們的承諾：凡是答應(yīng)做的，我們都會做到。(remain true to)We remain true to our commitment: Whatever we promised to do, we would do it.5.連貝多芬的父親都不相信自己兒子日后有一天可能成為世界上最偉大的音樂家。愛迪生也同樣如此，他的老師覺得他似乎過于遲鈍。(discount;be true of)

Even Beethoven's father discounted the possibility that his son would one day become the greatest musician in the world.The same is true of Edison, who seemed to his teacher to be quite dull.6.當(dāng)局控告他們威脅國家安全。(accuse sb.of sth.)

They were accused by the authorities of threatening the state security.第二單元

1.要是這部喜劇中的人物更幽默些的話，就會吸引更多的觀眾。(if...had + past participle, would + have + past participle)

If the characters in this comedy had been more humorous, it would have attracted a larger audience.2.她從未對自己的能力失去信心，因此她有可能成為一名成功的演員。(it is a possibility to)She has never lost faith in her own ability, so it is a possibility for her to become a successful actress.3.我從未受過正式培訓(xùn)，我只是邊干邊學(xué)。(go along)

I never had formal training, I just learned as I went along.4.隨著產(chǎn)品進(jìn)入國際市場，他們的品牌知名度越來越高了。(find one's way into)

As their products find their way into the international market, their brand is gaining in popularity.5.她可以編造一個故事，說自己被竊賊打昏，所有的錢都沒了，但她懷疑自己是否能讓這故事聽起來可信。(make up)

She could make up a story by saying she was knocked unconscious by thieves and that all her money was gone, but she doubted whether she could make it sound believable.6.誰都不清楚他是否故意推遲了這次訪問，可是這引起了對他更多的批評。(on purpose)No one was certain whether he postponed the visit on purpose, but this brought more criticism of him.第三單元

1.據(jù)報道有七八位官員收受賄賂，市長決定親自出馬調(diào)查這件事。(be reported to;look into)Seven or eight officials are reported to have taken bribes and the mayor has decided to look into the affair in person.2.這些工人后悔當(dāng)時接受管理部門的意見重新回去工作。現(xiàn)在他們再次面臨失業(yè)的危險了。(regret doing sth.;yield to;be faced with)

These workers regret yielding to the management's advice and going back to work.Now they are again faced with the threat of losing their jobs.3.你只需填寫一張表格就可取得會員資格，它可以使你在買東西時享受打折的優(yōu)惠。(fill out)

You only need to fill out a form to get your membership, which entitles you to a discount on goods.4.不知為什么他們的汽車在半路壞掉了，結(jié)果他們比原計劃晚到了三個小時。(break down)Their car broke down halfway for no reason.As a result they arrived three hours later than they had planned.5.那位官員卷入了一場丑聞，數(shù)周后被迫辭職。(get involved in)

The official got involved in a scandal and was forced to resign weeks later.6.這個靠救濟過日子的人開始慢慢地建立起自己的市場，生意日漸興隆。(build up;one step at a time)

The man living on welfare began to build up his own market, one step at a time and his business is thriving.第四單元

1.我父母不是對我的教育投資，而是把錢花在了買新住房上。(rather than)

Rather than invest in my education, my parents spent their money on a new house.2.如今，人們用于休閑娛樂的開支是過去的兩倍。(twice as...as)

Today, people are spending twice as much on entertainment and relaxation as they did in the past.3.一家公司要成功，它必須跟上市場的發(fā)展。(keep pace with)

In order to be successful, a business must keep pace with developments in the marketplace.4.與申請這個職位的其他女孩相比，她流利的英語是個優(yōu)勢。(give an advantage over)Her fluency in English gave her an advantage over other girls for the job.5.對于學(xué)生而言，沒有任何地方比圖書館更好了，在那里所有的圖書都任由他們使用。(at one's disposal)

For students, nowhere is better than the library, where all the books are at their disposal.6.我們要充分利用好這個平臺，加強交流，拓展合作領(lǐng)域，共謀發(fā)展大計。(make use of)We should make full use of the platform to strengthen communication, expand cooperation in more areas and seek further development through joint efforts.第五單元

1.這位小個子男子并不如他看上去那么單純。(not so...as)

This little man is not so innocent as he appears.2.對這個問題我已束手無策了，所以你不妨去求助于王教授吧。(might as well)

There's nothing I can do about the problem, so you might as well turn to Professor Wang for help.3.雙方高度評價了在不同領(lǐng)域合作取得的成果，并希望合作進(jìn)一步加深。(speak highly of)Both sides speak highly of the fruits in their cooperation in different areas, and hope that the cooperation can be furthered.4.一方面，親民形象能使新政策更易于被民眾接受，另一方面，它也能“廣直言之路，啟進(jìn)善之門”。(on the one hand, on the other hand)

On the one hand, an image of being close to the people can get a new policy more easily accepted.On the other hand, it will “encourage people to speak their minds and come up with constructive suggestions”.5.他孤獨的感覺時起時落，他有時會對自己、對寵物、對電視機嘮叨不休。(rise and fall, at length)

His sense of loneliness rose and fell and he sometimes would talk at length to himself and his pets and the television.6.畢竟，金錢不是萬能的，最富有的人不一定是最幸福的。(after all)

After all, money is not everything.The richest people are not necessarily the happiest.第六單元

1.假設(shè)你發(fā)現(xiàn)了你自己的同事受賄，你會不會無動于衷呢？(Use “suppose” as a conjunction.)

Suppose you found out that your colleague takes bribes, would you just ignore it?

2.他如此固執(zhí)，我們已對他失望了。跟他爭論一點意義都沒有。(give up on;it is + adjective + to do/that-clause)

We've given up on him because he is so stubborn.It is pointless to argue with him.3.他突然想到了一個加速實驗進(jìn)程的好辦法，但組里的成員卻對此意見不一。(hit upon;speed up)

He hit upon a good method to speed up the progress of the experiment, but opinions differed among members of the group on it.4.今天我能夠使自己的職業(yè)與興趣相符，之前我是做不到的。(square...with)Today I'm able to square my profession with my interest, which I wasn't able to do before.5.要成為一名駕駛員，視覺上分辨紅色與綠色的能力是必不可少的。(distinguish between)The ability to visually distinguish between red and green is essential to becoming a driver.6.這個組由七個人組成，他們經(jīng)常見面，分享彼此的信息。(consist of)

The team consisted of seven people who met on a regular basis to share their information with each other.第七單元

1.這些科學(xué)家在創(chuàng)建基因圖譜的過程中體會到：合作不僅僅是一種有吸引力的選擇，它還是一種責(zé)任。(more than)

In the process of creating the genetic map, these scientists realized that cooperation was more than an attractive option;it was a responsibility.2.他們的研究發(fā)現(xiàn)簡直就是一個奇跡。由于他們的發(fā)現(xiàn)，人們對人類基因的歷史有了新的了解。(nothing less than;shed light on)

Their research findings were nothing less than a miracle.As a result of their findings, new light has been shed on the history of human genes.3.事實上，只有勤奮加方法得當(dāng)才能使你在學(xué)習(xí)上比他人有優(yōu)勢。(in combination with;give an advantage over)

In fact, only hard work in combination with proper methods will give you an advantage over others.4.法官說這種懲罰將起到殺一儆百的作用。(serve as)

The judge said the punishment would serve as a warning to others.5.感染的危險只限于那些與病人有親密接觸的人。(be confined to)

The risk of infection is confined to those who have close contact with the patients.6.從這一分析中我們可以更好地知道發(fā)生了什么以及要做些什么。(in a better position to do)From such an analysis we are in a better position to understand what has happened and what to do about it.第八單元

1.只要他守規(guī)矩，我倒不在乎他晚上在外呆得這么晚。(mind + V-ing)

I don't mind his staying out so late as long as he behaves himself.2.與其他計劃相比，我更喜歡他的計劃，因為我覺得沒有任何一個計劃比他的計劃更實際。(no + singular nouns or plural nouns;in that)

I prefer his plan to others in that I think no plan is more practical than his.3.他們與那家公司中斷了生意來往，因為那家公司上一個財政損失慘重，已經(jīng)破產(chǎn)了。(break off)

They broke off business relations with that company as it suffered huge losses in the last fiscal year and went bankrupt.4.既然你不喜歡他，當(dāng)初為什么還要邀請他參加你的生日晚會呢？(now that;in the first place)

Now that you don't like him, why did you invite him to your birthday party in the first place?

5.雖然知道獲勝的可能性不大，但比賽失敗后，我們多少還是有點沮喪。(more or less)Though we knew our chances to win were slim, we were more or less depressed when we lost in the game.6.也許這是為進(jìn)步而付出的代價，誰知道呢?(pay the price)

Perhaps this was the price that has to be paid for progress—who knows?

第九單元

1.盡管他們做出了巨大的努力，但目前為止，博物館每天的參觀者仍然還是很少。(for all;so far)

For all their great efforts, the museum's daily attendance has so far still been very low.2.作為對政府檢查員批評的回應(yīng)，公司改變了一些做法，而不是放棄自己的規(guī)定。(in response to;rather than)

In response to criticism by government inspectors, the company changed some of its practices rather than gave up its rules.3.警方提醒乘客，不要將錢和貴重物品放在提包里，以防被盜。(warn against)

The police warned the passengers against putting money and precious things in bags lest they should be stolen.4.調(diào)查應(yīng)集中于父母和孩子們?nèi)绾慰创龑W(xué)校滿足他們需求的那些辦法。(focus on)

Surveys ought to focus on how parents and children perceive the ways in which the school satisfies their needs.5.一瞬間，特斯（Tess）由一個天真的女孩變成了一個成熟、受過良好教育的女子。(in a flash)

In a flash, Tess changed from an innocent girl to a mature and well-educated woman.6.我能證實200列新火車正在制造中，第一批將在今年五月投入運營。(come into service)I can confirm that 200 new trains are being manufactured and that the first of those trains will come into service in May this year.第十單元

1.無論你的智商有多高，你的看法都受到個人經(jīng)歷的局限，因此要學(xué)會吸納他人有用的觀點。(no matter...)

No matter how high your IQ is, your view is limited by the experience you have had and so you should learn to incorporate the useful perspectives of others.2.這個游戲非常有趣，他們誰也沒有注意到時間的流逝。(Use inverted order of “so...that...”;take note of)

So interesting was the game that none of them took note of the passage of time.3.我一直在整理這些舊文件，看看哪些有用，哪些需要扔掉。(sort through)

I've been sorting through these old documents to see which are useful and which can be thrown away.4.隨著年齡越來越大，你應(yīng)該考慮未來的計劃。(reflect on)

As you get older you should reflect on future plans.5.他在演出中的亮相簡直是個轟動。(nothing less than)

His appearance in the show was nothing less than a sensation.6.他們每個月都從工資中留出一筆錢，用于孩子將來的教育。(set aside)

Every month they set aside a particular amount of money from their salary for the sake of their kid's education in the future.