托福听力中生物类讲座的逻辑结构---解题的金钥匙

 　　TPO12 Lecture 1

　　6. What does the professor mainly discuss?（主旨题）

　　A. How genes² control human development.

　　B. Why various types of human cells divide at different rates.

　　C. How human chromosomes⁴ differ from one another.

　　D. Why most human cells cannot keep dividing successfully.

　　7. The professor discusses research about the percentage of a chromosome³’s DNA⁵ that contains genetic⁶ information. How did she feel about this research?（态度题）

　　A. She doubted its accuracy.

　　B. She was surprised by its conclusion.

　　C. She was concerned about its implications.

　　D. She thought it was unnecessary.

　　8. What does the professor say about the DNA in a telomere?（细节加推断题，易错点）

　　A. It causes a cell to begin dividing.

　　B. It separates one gene¹ from another.

　　C. It is genetically⁷ meaningless.

　　D. It has no function.

　　9. Why does the professor mention shoelaces?（修辞目的题）

　　A. To point out that chromosomes are arranged in pairs.

　　B. To describe the coiled shape of a chromosome.

　　C. To illustrate⁸ how chromosomes are protected from damage.

　　D. To explain how chromosomes are joined before dividing.

　　10. What does the professor imply about the length of the telomeres on a cell’s chromosomes?（推断题）

　　A. Longer telomeres allow the cell to divide more times.

　　B. Longer telomeres contain more genetic information.

　　C. Shorter telomeres are wound into tighter coils.

　　D. Shorter telomeres are less likely to break.

　　11. According to the professor, how is the chemical telomerase related to the telomere?（细节题）

　　A. It resembles the telomere in structure.

　　B. It helps repair broken telomeres.

　　C. It is produced at the end of telomere.

　　D. It prevents telomeres from becoming too long.

　　生物类常见的逻辑结构：在课堂演讲中，教授常常会就某一生物现象或者生物特征进行讲解，并举出相应的例子进行证明，期间往往会有老师的自问自答和已经和学生之间的讨论。

　　本文的逻辑结构：背景引入式开头，以一个重要的observation开头，实验室里的细胞在分裂特定的次数之后会死亡------But转折之后引出今天的课堂的重点，所有细胞最终不会renew而是走向死亡-----人体细胞是怎么分裂的，引出染色体概念---人体有23对染色体46条DNA----meaningful genetic information20%和junk DNA占据的比例70%----JUNK DNA有其他的用途，如它的典型代表telomere以及特征-----telomere在细胞每次分裂之后会变短，这是它的一个缺点，使得染色体失去重要基因信息，失去功能，也是细胞最终会死亡的原因-----telomerase新概念的提出，关于telomerase的作用，telomerase 可以修复telomere------the use of telomerase的发展前景

　　一句话概括：Human cell division before they die------how it happens---why it happens

　　长难句跟读练习：

　　1 then may be we can explain a very important observation,that when we try to grow most human cells in libratory, they seem programmed to divide only a certain number of times before they die

　　2 You see that it sort of looks like, well actually it’s much more complex than this but it reminds us a couple of springs linked together to coil up(盘卷成) pieces of DNA. （将DNA类比成弹簧。）

　　3 Now a telomere is a highly repetitious and genetically meaningless sequence of DNA,what we were calling JUNK DNA. But it does have any important purpose;

　　4 it is sort of like the plastic tip on each end of shoe lace.It means not help you tie your shoe but that little plastic tip keeps the rest of the shoelace, the shoe string from unraveling into weak and useless threads.

　　5 Someday we may be able to take any cell and keep it alive functioning and reproducing itself essentially⁹ forever through the use of telomerase.

1 gene   

n.遗传因子，基因

参考例句：

• A single gene may have many effects.单一基因可能具有很多种效应。
• The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。

2 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

3 chromosome   

n.染色体

参考例句：

• Chromosome material with exhibits of such behaviour is called heterochromatin.表现这种现象的染色体物质叫做异染色质。
• A segment of the chromosome may become lost,resulting in a deletion.染色体的一个片段可能会丢失，结果产生染色体的缺失。

4 chromosomes   

n.染色体( chromosome的名词复数 )

参考例句：

• Chromosomes also determine the sex of animals. 染色体也决定动物的性别。 来自《简明英汉词典》
• Each of four chromosomes divide longitudinally. 四种染色体的每一种都沿着纵向分裂。 来自《现代汉英综合大词典》

5 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

6 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

7 genetically   

adv.遗传上

参考例句：

• All the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
• Genetically modified foods have already arrived on American dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物

8 illustrate   

v.举例说明，阐明；图解，加插图

参考例句：

• The company's bank statements illustrate its success.这家公司的银行报表说明了它的成功。
• This diagram will illustrate what I mean.这个图表可说明我的意思。

9 essentially   

adv.本质上，实质上，基本上

参考例句：

• Really great men are essentially modest.真正的伟人大都很谦虚。
• She is an essentially selfish person.她本质上是个自私自利的人。