2020考研每周时政热点考点练习题（第4周）

【导语】无忧考网发布国内国际时政参考100题如下：（2016年7月-2017年10月）【国内时政】1．庆祝中国共产党成立95周年大会2016年7月1日上午在北京人民大会堂隆重举行。中共中央

相关推荐：>>>2017年考研现场确认时间及地点汇总>>>全国各地2017年考研报考点汇总>>>2017年考研时间、研究生考试时间安排&g

相关推荐：>>>2017年考研现场确认时间及地点汇总>>>全国各地2017年考研报考点汇总>>>2017年考研时间、研究生考试时间安排&g

相关推荐：>>>2017年考研现场确认时间及地点汇总>>>全国各地2017年考研报考点汇总>>>2017年考研时间、研究生考试时间安排&g

相关推荐：>>>2017年考研现场确认时间及地点汇总>>>全国各地2017年考研报考点汇总>>>2017年考研时间、研究生考试时间安排&g

相关推荐：>>>2017年考研现场确认时间及地点汇总>>>全国各地2017年考研报考点汇总>>>2017年考研时间、研究生考试时间安排>>>2017年考研大纲下载及解析汇总>>>2017年全国硕士研究生招生简章专题新东方网校推荐：2017年考研政治、英语、数学课程！！点击进入免费试听>>Scientistshaveknownformorethantwodecadesthatcancerisadiseaseofthegenes.SomethingscramblestheDnainsideanucleus，andsuddenly，insteadofdividinginameasuredfashion，acellbeginstocopyitselffuriously.Unlikeanordinarycell，itneverstops.Butdescribingtheprocessisn'tthesameasfiguringitout.Cancercellsaresoradicallydifferentfromnormalonesthatit'salmostimpossibletountanglethesequenceofeventsthatmadethemthatway.Soforyearsresearchershavebeenattackingtheproblembytakingnormalcellsandtryingtodeterminewhatchangeswillturnthemcancerous——alwayswithoutsuccess.Untilnow.AccordingtoareportinthecurrentissueofNature，ateamofscientistsbasedatM.I.T.'sWhiteheadInstituteforBiomedicalResearchhasfinallymanagedtomakehumancellsmalignant——afeattheyaccomplishedwithtwodifferentcelltypesbyinsertingjustthreealteredgenesintotheirDNA.Whilethesemanipulationsweredoneonlyinlabdishesandwon'tleadtoanyimmediatetreatment，theyappeartobeacrucialstepinunderstandingthedisease.Thisisa“landmarkpaper，”wroteJonathanWeitzmanandMosheYanivofthePasteurInstituteinParis，inanaccompanyingcommentary.Thedramaticnewresulttracesbacktoabreakthroughin1983，whentheWhitehead'sRobertWeinbergandcolleaguesshowedthatmousecellswouldbecomecancerouswhenspikedwithtwoalteredgenes.Butwhentheytriedsuchalterationsonhumancells，theydidn'twork.Sincethen，scientistshavelearnedthatmousecellsdifferfromhumancellsinanimportantrespect：theyhavehigherlevelsofanenzymecalledtelomerase.Thatenzymekeepscaplikestructurescalledtelomeresontheendsofchromosomesfromgettingshorterwitheachroundofcelldivision.Suchshorteningispartofacell'sagingprocess，andsincecancercellskeepdividingforever，theWhiteheadgroupreasonedthatmakinghumancellsmoremouselikemightalsomakethemcancerous.Thestrategyworked.Thescientiststookconnective-tissueandkidneycellsandintrocedthreemutatedgenes——onethatmakescellsdividerapidly;anotherthatdisablestwosubstancesmeanttoreininexcessivedivision;andathirdthatpromotestheproctionoftelomerase，whichmadethecellsessentiallyimmortal.They'dcreatedatumorinatesttube.“Somepeoplebelievedthattelomerasewasn'tthatimportant，”saystheWhitehead'sWilliamHahn，thestudy'sleadauthor.“Thisallowsustosaywithsomecertaintythatitis.”Understandingcancercellsinthelabisn'tthesameasunderstandinghowitbehavesinalivingbody，ofcourse.Butbyteasingoutthekeydifferencesbetweennormalandmalignantcells，doctorsmaysomedaybeabletodesignteststopickupcancerinitsearlieststages.Thefindingcouldalsoleadtodrugstailoredtoattackspecifictypesofcancer，therebylesseningourdependenceontissue-destroyingchemotherapyandradiation.Beyondthat，theWhiteheadresearchsuggeststhatthisstubbornlycomplexdiseasemayhaveasimpleorigin，andtheidentificationofthatoriginmayturnouttobethemostimportantstepofall.注(1)：本文选自Time;08/09/99，p60，3/5p，2c注(2)：本文习题命题模仿对象2002年真题text41.Fromthefirstparagraph，welearnthat________________.[A]scientistshadunderstoodwhathappenedtonormalcellsthatmadethembehavestrangely[B]whenacellbeginstocopyitselfwithoutstopping，itbecomescancerous[C]normalcellsdonocopythemselves[D]theDNAinsideanucleusdividesregularly2.Whichofthefollowingstatementsistrueaccordingtothetext?[A]ThescientiststracedthesourceofcancersbyfiguringouttheirDNAorder.[B]Atreatmenttocancerswillbeavailablewithinayearortwo.[C]Thefindingpaveswayfortacklingcancer.[D]Thescientistssuccessfullyturnedcancerouscellsintohealthycells.3.Accordingtotheauthor，oneoftheproblemsinpreviouscancerresearchis________.[A]enzymekepttelomeresfromgettingshorter[B]scientistsdidn‘tknowthereexisteddifferentlevelsoftelomerasebetweenmousecellsandhumancells[C]scientistsfailedtounderstandtheconnectionbetweenacell‘sagingprocessandcelldivision.[D]humancellsaremouselike4.Whichofthefollowingbestdefinestheword“tailored”(Line4，Paragraph5)?[A]madespecifically[B]usedmainly[C]targeted[D]aimed5.TheWhiteheadresearchwillprobablyresultin___________.[A]athoroughunderstandingofthedisease[B]beatingoutcancers[C]solvingthecancermystery[D]drugsthatleavepatientslesspainful答案：BCBAD

相关推荐：>>>2017年考研现场确认时间及地点汇总>>>全国各地2017年考研报考点汇总>>>2017年考研时间、研究生考试时间安排>&g

相关推荐：>>>2017年考研现场确认时间及地点汇总>>>全国各地2017年考研报考点汇总>>>2017年考研时间、研究生考试时间安排&g

相关推荐：>>>2017年考研现场确认时间及地点汇总>>>全国各地2017年考研报考点汇总>>>2017年考研时间、研究生考试时间安排&g