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
考研
Cancer arises when the descendants of just one of our more than ten thousand billion cells proliferate out of control, eventuall
Cancer arises when the descendants of just one of our more than ten thousand billion cells proliferate out of control, eventuall
admin
2015-03-25
69
问题
Cancer arises when the descendants of just one of our more than ten thousand billion cells proliferate out of control, eventually interfering with normal body functions. Since so many cells are at risk, the most amazing thing about cancer to me is how many years it usually takes to develop the disease. One major obstruction to the proliferation of cancerous cells is the phenomenon of
apoptosis
, which causes nearly all of our cells to kill themselves whenever they start to behave aberrantly.
A complicated cellular signaling network determines the balance between the pro-apoptotic and anti-apoptotic proteins inside animal cells. Each of our many cells is constantly sensing its external and internal environment and will sacrifice itself(for our own good)if it is either not correctly located or not behaving normally. Without mechanisms of this type, the evolution of large complex organisms such as ourselves would probably not have been possible, because the tumors caused by cancerlike diseases would have overtaken us early in life.
Tumors arise after a long process of random mutation followed by multiple rounds of selection for those cells able to proliferate best. One change selected for is in apoptotic mechanisms, which will be altered in different ways in different tumors. Imagine that we could determine why the cells in an individual’s tumor incorrectly compute that they need not kill themselves, as normal cells would do in their condition. If we understood the fundamental mechanisms by which cells make these decisions, we would stand an excellent chance of creating a tailored mixture of drugs that causes the tumor cells to compute differently, so that they commit suicide without harming normal cells.
Another promising strategy takes advantage of the fact that essentially all cancer cells have acquired a defect in some aspect of their "DNA metabolism" , often some aspect of DNA repair that causes them to become highly mutable. This genetic instability of cancer cells is selected for early in tumor development, because only such cells can evolve the multiple additional changes, including defects in apoptosis, that are necessary for most cell types to become malignant.
Cells that are too genetically unstable will die. Therefore, a treatment that blocks a particular DNA repair process can be lethal for a cancer cell, while sparing normal cells. If we could determine why the cells in a particular individual tumor are genetically unstable, we might be able to design drugs that kill the cells in that cancer highly selectively, with little harm to normal cells.
These examples of rational approaches to cancer therapy were only a dream until recently. But by targeting these types of alterations in cancer cells, researchers have made impressive progress and are thus much closer to being able to design highly selective therapies based on the critical molecular defects in an individual tumor. But for most tumors, this type of approach is still hit or miss, because oncologists are severely hampered by an inadequate understanding of the fundamental processes that are altered in a particular tumor.
It can be inferred from Paragraph 5 that we can cure cancer by
选项
A、making the infectious cells unsteady in gene.
B、killing the cells in the patient’s body.
C、designing lethal medicine to change the gene of the body.
D、enhancing the DNA repair process.
答案
A
解析
推理判断题。根据题干提示可以定位至第五段。该段首句谈到“那些在基因方面不稳定的细胞会死去”,并且在下文谈到“如果我们能够弄清楚为什么某个肿瘤内的细胞的基因不稳定,我们将能够研制出能选择性地杀死肿瘤内的癌细胞”,因此可以推断出,可以通过“使癌变细胞在基因上不稳定”来杀死它们治疗癌症,故选[A]。
转载请注明原文地址:https://kaotiyun.com/show/2U74777K
0
考研英语一
相关试题推荐
IntheBritishIslesthetemperature______.FewpeopleintheUnitedStateslosttheirlivesbecause______.
Americanstodaybelievethatacceptablesocialbehaviorfollowseffortlesslyfrompersonalvirtue.The(1)_____betweenmoralsa
Whenwomendobecomemanagers,dotheybringadifferentstyleanddifferentskillstothejob?Aretheybetter,orworse,manag
Aspartofastudentsocialsurveyproject,youareleadingagrouptovisitanexhibitioninasmalltown.Writealetter;1)a
Asafreshmaninuniversity,youhavesomequestionsinjoiningactivitiesinschool.WritealettertothePresidentofStudent
Theclassicdifficultyfeltwithdemocracyarisesfromthefactthatdemocracycanneverexpressthewillofthewholepeoplebe
(46)Thejobofraisingchildrenisatoughone.Childrendon’tcomewithaninstructionmanual.Andeachchildisdifferent.So
Workhardandgetahead.That’swhateveryAmericanlearnsgrowingup,butformillionsofthem,it’sgettinghardertotellthe
Workhardandgetahead.That’swhateveryAmericanlearnsgrowingup,butformillionsofthem,it’sgettinghardertotellthe
随机试题
复位操作是指当报警事件处理完毕后,为使()恢复到正常监视状态而进行的操作。
(2018年第53题)医院通行推床的通道最小净宽度为()。
按我国《公司法》规定,发行股份获得的溢价收入,应当列为()。
会员制期货交易所会员大会有()以上会员参加方有效。
“变量与函数”是初中数学教学中的重要内容,请完成下列任务:给出y=4x+6以及4x+6=0,则指出哪个是函数,如果是函数中的变量是?常量是?
义务教育阶段教学计划的特征:强制性、普遍性、免费性。()
语言的意义可以分为两类,由词的语法关系产生的意义叫________________,人们对现实现象的反映以及由此带来的人们对现实现象的主观评价,叫作________________,简称________________。
弱势群体
与社会主义革命不同,新民主主义革命仍属于资产阶级革命的原因在于
WhatisTRUEaboutGeneralMladic?
最新回复
(
0
)