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Everylivingcellcontainsgenes.Theyaretoosmalltobeseeninamicroscopebuttheyareveryimportant.Eachsetofgenesinthebodycontainsalltheinstructionsneededtomakeahumanbeing.Somegenesdeterminehaircolor.Somedete
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更新时间:2024-04-20 20:59:09
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Everylivingcellcontainsgenes.Theyaretoosmalltobeseeninamicroscopebuttheyareveryimportant.Eachsetofgenesinthebodycontainsalltheinstructionsneededtomakeahumanbeing.Somegenesdeterminehaircolor.Somedeterminetheshapeofanose.Somegeneshelpdetermineyourheightandevenyourweight.

GenesaremadeofachemicalcalledDNA-thelettersstandfordeoxyribonucleicacid(脱氧核糖核酸).Intheearly1950'stwoscientistsFrancisCrickandJamesWatsonfiguredouthowthepartsofDNAfittogether.OncescientistsunderstoodthisstructureitbecamepossibletotakepiecesofDNAapartandputthemtogetherinnewways.Newkindsofgenescouldbemadeinthismanner.

Scientistshavestudiedthegenesofmanyplantsandanimals.Theyhaveworkedoutwhichgenesaffectthecolorofatomatoandthethicknessofitsskin.WorkingoutwhichgenesdeterminewhichfeaturesiscalledgeneticmappingscientistshavebeguntheHumanGenomeProjectanambitiousefforttomapallthegenesinthehumanbody.

Somegenesmaybedefective(有缺陷的).Forexamplesomethingmightbewrongwiththegenethatmakesbloodclot(凝聚).Ababybornwiththisdefectivegenecouldsufferserioushemorrhages(出血)orevenbleedtodeathbecausehisorherbloodfailstoclot.Ifscientistseverlearnhowtomapallthegenesinourbodiestheycandeterminewhetherornotanunbornchildhasanydefectivegenes.Theymightevendiscoverhowtotreatthesegenesbeforethechildisborn.

1.WhatwastheachievementofFrancisCrickandJamesWatson?

A.Theydiscoveredwhypeoplehavedifferenthaircolors.

B.Theylearnedthatsomepeoplebleedforlongperiodsoftime.

C.Theylookedathumancellsunderthemicroscope.

D.TheyworkedoutthestructureofDNA.

2.Whatisthemainideaofthispassage?

A.Defectivegenescanneverberepaired.

B.Genesaretoosmalltobeseenthroughamicroscope.

C.Geneshelpscientistsunderstandhowlivingthingsdeveloptheircharacteristics.

D.TheHumanGenomeProjectmayexplaintheroleofeverygeneinthebody.

潘且鲁回答:
  1.D2.C分析:每一个活的细胞都含有基因,它们虽然很小,但却非常重要。基因是带有遗传信息的DNA片段,DNA是脱氧核糖核酸的缩写。一些基因决定头发的颜色,一些决定鼻子的形状,一些决定一个人的身高...
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