首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
The Cloning Technology I. The difference between a 【T1】______colony and 【T1】______ cloning a mammal A. Clarify the illusion: sc
The Cloning Technology I. The difference between a 【T1】______colony and 【T1】______ cloning a mammal A. Clarify the illusion: sc
admin
2020-06-04
30
问题
The Cloning Technology
I. The difference between a 【T1】______colony and 【T1】______
cloning a mammal
A. Clarify the illusion: scientists have been cloning
genes for years.
B. Definition of clone: a clone is population of
cells produced by 【T2】______; all the cells in 【T2】______
a clone have exactly the 【T3】______, using 【T3】______
a process known as "recombinant 【T4】______ 【T4】______
technology".
C. Clone a mammal: "nuclear transfer".
II. Genes, chromosomes and the genome
A. Genes
- DNA—its 【T5】______makes it divide 【T5】______
easily.
- 【T6】______of chemical groups within DNA 【T6】______
form genes.
- Genes determine what 【T7】______a given 【T7】______
cell will have.
B. Chromosomes: genes are linked together to form
chromosomes.
C. Genome: the entire collection of chromosomes
in each cell.
D. 【T8】______genes enables scientists 【T8】______
to mass-produce proteins that can be used to
【T9】______.【T9】______
III. The process of cloning a gene
A. Remove DNA from the cell.
B. DNA is cut into pieces using 【T10】______. 【T10】_____
C. To replicate DNA, attach them to non-
mammalian DNA.
D. Plasmids are easily incorporated into 【T11】______ 【T11】______
and multiply by themselves.
E. The plasmid carries the gene into a 【T12】______ 【T12】______
cell.
F. The gene 【T13】______a plasmid and some 【T13】______
proteins.
G. The plasmid 【T14】______. 【T14】______
H. Copies passed to the cell’s 【T15】______. 【T15】______
I. Each cell contains one or more copies of the
recombinant DNA molecule. The gene is now
considered cloned.
【T3】
The Cloning Technology
Today, we are going to talk about the cloning technique. First, we will see the difference between a single cell colony and cloning a mammal. Then we will focus on cell cloning process and its scientific use.
In March 1997, the world said "hello" to Dolly, the first mammal to be cloned from an adult cell. We asked ourselves: Would the world soon be populated with human clones? Did you know that cloning isn’t new? In fact, scientists have been cloning genes for many years in laboratories around the world. Of course, cloning a gene and cloning a whole mammal are quite different in terms of process and product. But just how do you get from a single cell to a clone?
We generally think of cloning as producing a duplicate of something. Scientists, however, usually use the term clone in referring to cells. A clone is population of cells produced by one ancestor. Because of the way cells multiply, all the cells in a clone have exactly the same genetic makeup. Gene cloning uses a process known as "recombinant DNA technology". By contrast, cloning a mammal, such as the sheep Dolly, involves a technology known as "nuclear transfer". Although the end result is the same, the actual processes of gene cloning and mammalian cloning are quite different. But we need to start from the beginning to understand how these complicated and amazing bioengineering technologies evolved.
Now, we will study on what genes, chromosomes, and the genome are.
Within the body of a mammal, tissues are made of cells. Inside each cell is a long molecule called DNA. Its shape enables it to divide easily. Arrangements of chemical groups within DNA form genes. Genes direct cells to produce proteins, and thus determine what function a given cell will have. For example, skin cells produce proteins which are present in skin tissue, and blood cells produce a protein present in blood. Genes essentially tell each cell what type it is. Genes are linked together to form chromosomes. The entire collection of chromosomes in each of your cells is called genome. All the cells in your body contain the same genome. Once you realize that all cells contain the information for making the whole organism, you know that cloning is theoretically possible.
But what makes a skin cell different from a blood cell? The chromosomes within the nucleus of each cell are folded in various ways. Genes that are buried within the chromosomes are inactive, or switched off, while genes on the surface of the chromosomes are active. In a skin cell, the genes for producing skin proteins are active, while in a blood cell, the gene is active. Gene cloning is the process of producing a population of cells all of which contain a specific gene. Using these identical cells, scientists can study the entire genome and obtain clues to how genes are switched on and off.
Cloning genes also enables scientists to mass-produce proteins that can be used to treat a variety of diseases. For example, the cells in the pancreas produce a protein called insulin which is important in helping the body maintain appropriate blood sugar levels. Some people have a disease called diabetes because their cells don’t produce enough insulin. Cloning the insulin gene has provided a way of producing large amounts of human insulin which is used to treat diabetes.
Then, we are going to disclose the mystery of cloning a gene. To clone a gene, scientists remove the DNA from a cell, isolate the specific gene of interest, and then get it to multiply. Sound simple? Not so fast. Let’s look at each step.
First the DNA must be removed from the cell. Over the years scientists have perfected chemical methods for doing this, based on the physical properties of DNA molecules. The DNA is then cut into pieces using special proteins. You may think of these special proteins as little knives programmed to cut the DNA in specific places. By using the correct special proteins, scientists can isolate whatever gene they want.
Once the gene is isolated, it can then be duplicated. Mammalian genes do not reproduce by themselves, however. To replicate them, scientists attach them to pieces of non-mammalian DNA that do replicate on their own. The most common procedure uses small circular pieces of DNA called plasmids that come from bacteria. Plasmids have two useful characteristics. They are easily incorporated into bacteria; they multiply by themselves inside bacteria. The gene of interest is combined with a plasmid and some proteins. The proteins open the plasmid circle and stitch in the new gene. The result is a recombinant DNA molecule. The plasmid carries the gene into a host cell. Once inside the host, the plasmid multiplies, making lots of copies of itself and the gene it contains.
When the host cell divides, copies of the recombinant DNA molecule are passed to the cell’s offspring. As the bacterial cells continue to divide, a colony of identical cells is produced. Each cell contains one or more copies of the recombinant DNA molecule. The gene is now considered cloned.
Let’s go back now to the example of the insulin gene. Prior to cloning this gene, scientists purified insulin from animal sources, like pigs or cows. Scientists isolated the insulin gene from the DNA of human pancreatic cells. Then they attached the insulin gene to a plasmid and were able to get bacterial cells to incorporate the recombinant DNA. The result was a colony of bacteria that continually produced human insulin—a little insulin producing factory!
选项
答案
saint genetic makeup
解析
根据讲座原文“Because of the way cells multiply, all the cells in a clone have exactly the same genetic makeup.”即可得出答案。
转载请注明原文地址:https://kaotiyun.com/show/6cbK777K
0
专业英语八级
相关试题推荐
A、Bygettinginvolvedincharities.B、Byparticipatingtheirparties.C、Bylookingforcommoninterests.D、Bybeingavolunteer
HowtoWriteaThesisI.Introduction—writethissectionafter【T1】______therestofthepaper【T1】______—includea(an)【T2】_
HowtoWriteaThesisI.Introduction—writethissectionafter【T1】______therestofthepaper【T1】______—includea(an)【T2】_
A、Becausemoremoneymeansmoretrouble.B、Becausepeopledon’tknowhowtoenjoythemselveswithmoney.C、Becausemoneyhasnot
HowtoDoWellonaJobInterviewAtypicalinterview—confusing,humiliating,andnerve-racking—【T1】______inthesameroomw
A、BycomparingpeoplewithIADtoalcoholics.B、BycomparingpeoplewithIADtosmokers.C、BycomparingpeoplewithIADtocoffe
ThePurposesofLiteraryAnalysisI.IntroductionLiteraryanalysisisinitselfauniversalnecessity.—reason1:enablesrea
ThePurposesofLiteraryAnalysisI.IntroductionLiteraryanalysisisinitselfauniversalnecessity.—reason1:enablesrea
ThePurposesofLiteraryAnalysisI.IntroductionLiteraryanalysisisinitselfauniversalnecessity.—reason1:enablesrea
A、Shedeclinedalotofinterviews.B、Shehadlittleideaoftheprotagonist.C、Shehasrevisedthenovelmanytimes.D、Shemet
随机试题
________运用于行政、执行、技术、军事等性质的事务,________运用于顾问、讨论、立法、决策、调节等性质的工作。________倾向于在行政组织中实施首长制。
不属于病理性脉象的是
下面哪项不是原发性下肢静脉曲张的病因
脑疝形成时,为减轻颅内压,可以进行腰椎穿刺放出脑脊液减压。()
黄风村毗邻松花河,村民以养鱼为生。凯南石化要扩建,将厂址选在黄风村松花河中游,并在村民的强烈要求下修建管道将污水废气排走以防污染松花河。2005年夏天,凯南石化突然发生爆炸,不久以后松花河下游村民发现所养的鱼一夜之间全部死光。原来是石化厂爆炸后的废水废气流
1982年国务院发布《村镇建房用地管理条例》之前,农村居民建房占用宅基地,超过当地政府规定的面积,《村镇建房用地管理条例》施行后未经拆迁、改建、翻建的,可()确定集体建设用地使用权。
纳税人转让土地使用权,不能向()申报纳税。
学生是学校的主体,是具有能动性的教育对象。()
一、注意事项1.申论考试是对应考者阅读能力、综合分析能力、提出和解决问题能力、文字表达能力的测试。2.参考时限:阅读资料40分钟,参考作答110分钟。3.仔细阅读给定资料,按照后面提出的“作答要求”作答。二、给定资料1.
根据下表回答下面问题2007年居民消费价格变动情况(上年=100)注:1.指数=今年值/上年值×1002.表中数据均为指数
最新回复
(
0
)