首页
登录
职称英语
The Cloning TechnologyI. The difference between a (1)__
The Cloning TechnologyI. The difference between a (1)__
游客
2023-12-11
67
管理
问题
The Cloning Technology
I. The difference between a (1)______colony and cloning a
mammal
clarify the illusion: Scientists have been cloning genes for many years in laboratories
clone a single cell: the term clone refers to (2)______, cells
multiplying, all the cells in a clone have exactly the same genetic makeup, "recombinant (3)______technology"
clone a mammal: "nuclear transfer"
II. Genes, chromosomes, and the genome
Genes: DNA— its (4)______makes it divide easily.
(5)______of chemical groups within DNA form genes.
Genes direct cells to produce proteins, and thus determine
what (6)______a given cell will have.
e.g. skin cells produce proteins present in skin tissue, blood cells produce a protein present in blood Chromosomes: genes are linked together to form chromosomes Genome: the entire collection of chromosomes in each of your cells is called genome.(7)______genes enables scientists to mass-produce
proteins that can be used to treat a variety of diseases, e.g. diabetes: Cloning the insulin gene has provides a way of producing large amounts of human insulin which is used to treat diabetes
III. The process of cloning a gene
1) Remove DNA from the cell.
2) DNA is cut into pieces using (8)______.
3) To replicate DNA, attach them to non-mammalian DNA.
4) Plasmids easily incorporated into bacteria, multiply by themselves inside bacteria.
5) The plasmid carries the gene into a (9)______cell.
6) The gene 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".
7) The plasmid multiplies.
8) Copies passed to the cell’s (10)______.
9) Each cell contains one or more copies of the recombinant DNA molecule. The gene is now considered cloned. [br]
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 genes and cloning a whole mammal are quite different in terms of process and product. (1) But just how do you get from a single cell to a clone?
We generally think of cloning as producing a duplicate of something. (2) 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 multiplying, all the cells in a clone have exactly the same genetic makeup. (3) 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 genome are.
Within the body of a mammal, tissues are made of cells. Inside each cell is a long molecule called DNA. (4) Its shape enables it to divide easily. (5) Arrangements of chemical groups within DNA form genes. Genes direct cells to produce proteins, (6) 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. (8) 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. (9) 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, (10) 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. They then 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
cells
解析
细节题。根据讲座内容“Scientists,however,usually use the term clone in referring to cells”直接拷贝入题即可。
转载请注明原文地址:http://tihaiku.com/zcyy/3264885.html
相关试题推荐
TheGreatCivilWar,asitbecameknown,wasfoughtbetween______.A、Royolistsan
TheInteriorPlainsliebetween______and______.A、theCanadianShield/theAppalac
Theareabetween______and______isnowoftenreferredtoasthe"SiliconGlen".A、
WhichofthefollowingisNOTthecorrectrelationshipbetweenlanguageandcult
Thedistinctionbetweenacquisitionandlearningisputforwardby______.A、Choms
Whatistherelationshipbetween"livestock"and"cattle"?A、Polysemy.B、Antonymy
Therelationshipbetweenwordsandthingsintheworldisestablishedbymeanso
SimilaritiesandDifferencesbetweenPublicSpeakingandConversationⅠB
SimilaritiesandDifferencesbetweenPublicSpeakingandConversationⅠB
SimilaritiesandDifferencesbetweenPublicSpeakingandConversationⅠB
随机试题
Readthearticlebelowaboutforeignlanguageskills.Choosethebestwordtof
ReadthetextbelowaboutAdCompaign.Inmostofthelines34-45thereisonee
()虚拟终端()自动编程[br]()插入粘贴()非法操作N、K
关于期刊使用作品的付酬,说法正确的有( )。A.期刊刊载作品可以比照图书出版的
下列在我国可获得专利授权的有()A.一种发现结核病的诊脉法发明 B.快速检
患者女性,18岁,2日前因游泳呛水后出现高热,食欲减退,伴左耳搏动性耳痛,体检发
有限合伙人不可以用()出资,设立合伙企业。A.实物 B.劳务 C.土
同时具有抑制骨吸收和刺激骨形成作用的药物是A.同化类固醇 B.甲状旁腺素 C
银行承兑汇票的承兑银行,应当按照票面金额向出票人收取()的手续费。A:千分之一
普通螺栓作为永久性连接螺栓时,当设计有要求或对其质量有疑义时,应进行螺栓实物(
最新回复
(
0
)