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
There have been several claims to have cloned humans over the past few years. Most have been bogus. But the announcement made th
There have been several claims to have cloned humans over the past few years. Most have been bogus. But the announcement made th
admin
2014-03-22
28
问题
There have been several claims to have cloned humans over the past few years. Most have been bogus. But the announcement made this week by Woo Sur Hwang, of Seoul National University in South Korea, and his colleagues, is serious. It is the first to achieve the accolade of publication in a peer-reviewed scientific journal. Dr. Hwang’s work appears in Science.
The terminology of human development has become slippery over the past few years, in the hands of both "life-begins-at-conception" propagandists who want to stop this sort of research, and publicity-seeking scientists who have claimed more than they have really achieved. What Dr. Hwang and his team have created is not what developmental biologists would normally refer to as an embryo. But it is a genuine scientific advance. South Korea’s researchers have taken egg cells from volunteer women, removed the nuclei from those cells (which contain only half of the genetic complement required to make a human being, since the other half is provided by the sperm), and replaced each nucleus with one taken from one of the volunteer’s body cells (which contains a full genetic complement). Given a suitable chemical kick-start, such re-nucleated cells will begin dividing as though they were eggs that had been fertilised in the more traditional manner. Since they have all of the mother’s genes, they count as clones.
Then the team cultured the dividing eggs until they had formed structures called blastocysts, with a few dozen cells each. This is the significant advance. At this stage the structure, though still just a featureless ball of cells, has started to differentiate into the body’s three basic cell types (known as endoderm, mesoderm and ectoderm). The researchers were able to extract cells from some of their blastocysts, and grow tissues containing all three cell types.
These are so-called stem cells, which can be directed to form a wide variety of the specialised cells from which organs are built. That, not the creation of new human beings, is the stated reason for this sort of research, since specialised cells made this way might be used to replace the cells lost in diseases such as Parkinson’s and type-I diabetes. This process is known as therapeutic cloning.
No doubt Dr Hwang’s scientific success will sharpen the debate between those who see therapeutic cloning as a potential force for good, and those who see it as a step on the road to a cloned human being. The former have been queuing up to praise the scientist’s work. It is "a major medical milestone" that could help spur a "revolution", said Robert Lanza, a cloning expert.
But opponents of therapeutic cloning should not worry too much yet. The road from a blastocyst to a baby is a long and complex one. Nevertheless, the South Korean breakthrough make’s it more urgent than ever that legislation be passed differentiating clearly between therapeutic and reproductive cloning—permitting the former and prohibiting the latter.
The team’s claimed objective of its cloning research is to______.
选项
A、develop fertilized eggs with all mother’s genes
B、form body structures with all three basic cell types
C、obtain specialised cells from which organs are built
D、create new human beings
答案
C
解析
细节题。在第四段中,干细胞通过培养形成各种用于构建器官的特殊细胞(即C),是韩国研究人员宣称的进行研究的原因,而不是创造新人类(D)。A和B都与原文意思不一致。所以C是本题正确答案。
转载请注明原文地址:https://kaotiyun.com/show/3lXO777K
0
在职攻硕英语联考
相关试题推荐
Theeldestchildisthoroughlybecausetheyalwaysgivehimwhateverhewants.
Inthepastfewdecades,remarkablefindingshavebeenmadeinethology,thestudyofanimalsocialbehavior.Earlierscientists
Iwaiteduntilhehad()beforeItoldhimIwasleavingandheadedforthefrontdoor.
"Before,weweretooblacktobewhite.Now,we’retoowhitetobeblack."Hadija,oneofSouthAfrica’s3.5mColoured(mixedr
Inrecentyearstherehasbeena______increaseinthecostofliving;manyfamilieshavetodependonthefederalaids.
Weareenteringaperiodinwhichrapidpopulationgrowth,thepresenceofdeadlyweapons,anddwindlingresourceswillbringin
Humorisamosteffective,yetfrequentlyneglected,meansofhandlingthedifficultsituationsinourlives.Itcanbeusedfor
Thebestthingsinlifearefree,andthatincludesairandwater.Swimmingandbreathingusuallydon’tcostanything,butneith
Thereligionsoftheworldhaveproducedgreatbooks,withgreatlessonstoteach.Ifwefollowed(36)iswritteninthebooks
Long-termeffectsinclude________(3words),heartfailure,hypertensionandevenobesity.
随机试题
饮料中果汁含量的测定中,测定总黄酮时,橙、柑、橘中的黄烷酮类与()作用,开环生成2,6-二羟基4-环氧基苯丙酮和对甲氧基苯甲醛,遇碱缩合生成黄色橙皮素查耳酮,比色测定。
企业战略决策的任务,就是_____________,_____________,并_____________。
由政策的间接主体构成的子系统是()
土地转让的发包方和承包方应当订立承包合同,约定双方的权利和义务。土地承包经营的期限为()。
较大质量事故指对工程造成较大经济损失或延误较短工期,经处理后()的事故。
下列关于内部控制的说法,不正确的是()。
下列各项中,构成企业留存收益的有()。
下面各序列中,只有(60)不是小顶堆。
A、Localstories.B、Englishscenery.C、Anexcursion.D、Scottishfolklore.A
修正
最新回复
(
0
)