名人轶事:People in America–Barbara McClintock

Written by - George Grow 

(THEME)

VOICE ONE:

I’m Doug Johnson.

VOICE TWO:

Barbara McClintock      

And I’m Barbara Klein with PEOPLE IN AMERICA in VOA Special English. Today,

we tell about Barbara McClintock. She was one of the most important

scientists of the twentieth century. She made important discoveries about

genes¹ and chromosomes³.

(THEME)

VOICE ONE:

Barbara McClintock was born in nineteen-oh-two in Hartford, Connecticut.

Barbara was the third of four children. Her family moved to the Brooklyn area

of New York City in nineteen-oh-eight. Barbara was an active child with

interests in sports and music. She also developed an interest in science.

She studied science at Cornell University in Ithaca, New York. Barbara was

among a small number of undergraduate students to receive training in

genetics in nineteen twenty-one. Years later, she noted⁵ that few college

students wanted to study genetics.

VOICE TWO:

In the early nineteen-twenties, genetics had not received widespread

acceptance as a subject. Only twenty years had passed since scientists re-

discovered the theories of heredity. Gregor Mendel proposed these ideas after

completing a series of experiments with plants. His experiments helped

scientists better understand how genes operate. They showed how genetic⁴

qualities are passed to living things from their ancestors.

VOICE ONE:

Barbara McClintock decided⁶ to study botany, the scientific study of plants,

at Cornell University. She completed her undergraduate studies in nineteen

twenty-three. McClintock decided to continue her education at Cornell. She

completed a master’s degree in nineteen twenty-five. Two years later, she

finished all her requirements for a doctorate⁷ degree.

In the late nineteen-twenties, McClintock joined several other students in a

group that studied genetics. The students included a future winner of the

Nobel Prize, George Beadle. Another was Marcus Rhoades. Years later, he would

become a leading expert in genetics.

McClintock said both men recognized the importance of exploring the

connection between genes and chromosomes.

McClintock stayed at Cornell after she completed her education. She taught

students botany. She also supervised genetic studies of the corn plant, or

maize⁸. She studied chromosomes, which are lines of genes. She made several

discoveries about genes and chromosomes.

VOICE TWO:

The nineteen thirties were not a good time to be a young scientist in the

United States. The country was in the middle of the great economic

depression. Millions of Americans were unemployed⁹. Male scientists were

offered jobs.  But female geneticists were not much in demand.

McClintock received two offers to travel and carry out research projects. The

first came from America’s National Research Council. She worked at several

places, including Cornell and the University of Missouri in Columbia. Later,

a group called the Guggenheim Foundation provided financial aid for her to

study in Germany. McClintock went to Berlin, but returned to Cornell the

following year. Her skills and work were widely praised. But she still was

unable to find a permanent job.

(MUSIC)

VOICE ONE:

For years, scientists had been using x-rays to study genetic material in

plants and other organisms. They found that x-rays caused genes to change.

Sometimes, the x-rays physically¹⁰ broke the chromosome². Genetic researchers

looked for changes in the organism. Then they used this information to

produce a map linking the changes to a single area of the chromosome.


McClintock became interested in the way genes reacted to unusual events. She

formed a successful working relationship with Lewis Stadler of the University

of Missouri. He had demonstrated the effects of x-rays on corn.


Stadler sent maize treated with radiation to McClintock. She identified

unusual areas she called ring chromosomes. She believed they were chromosomes

broken by radiation. The broken ends sometimes joined together and formed a

circle, or ring. This led her to believe that a structure at the end of the

chromosome prevents chromosomes from changing. She called this structure the

telomere.

1 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

2 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。

3 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》

4 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。

5 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

6 decided   

adj.决定了的，坚决的；明显的，明确的

参考例句：

• This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
• There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。

7 doctorate   

n.(大学授予的)博士学位

参考例句：

• He hasn't enough credits to get his doctorate.他的学分不够取得博士学位。
• Where did she do her doctorate?她在哪里攻读博士？

8 maize   

n.玉米

参考例句：

• There's a field planted with maize behind the house.房子后面有一块玉米地。
• We can grow sorghum or maize on this plot.这块地可以种高粱或玉米。

9 unemployed   

adj.失业的，没有工作的；未动用的，闲置的

参考例句：

• There are now over four million unemployed workers in this country.这个国家现有四百万失业人员。
• The unemployed hunger for jobs.失业者渴望得到工作。

10 physically   

adj.物质上，体格上，身体上，按自然规律

参考例句：

• He was out of sorts physically,as well as disordered mentally.他浑身不舒服，心绪也很乱。
• Every time I think about it I feel physically sick.一想起那件事我就感到极恶心。

11 kernels   

谷粒( kernel的名词复数 )； 仁； 核； 要点

参考例句：

• These stones contain kernels. 这些核中有仁。
• Resolving kernels and standard errors can also be computed for each block. 还可以计算每个块体的分辨核和标准误差。

12 molecular   

adj.分子的；克分子的

参考例句：

• The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
• For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时，分子的碰撞就停止了。

13 physiology   

n.生理学，生理机能

参考例句：

• He bought a book about physiology.他买了一本生理学方面的书。
• He was awarded the Nobel Prize for achievements in physiology.他因生理学方面的建树而被授予诺贝尔奖。