Doyouknowwhypeoplelookthewaytheylook?Whatinsideourbodiesmakesusgrowinacertainway?TheanswerisDNA.ItwasfirstdiscoveredbyayoungSwissdoctorin1868.DNAislikeacomputerprogramforyourbody.Almosteverycell(细胞)i

　　Doyouknowwhypeoplelookthewaytheylook?Whatinsideourbodiesmakesusgrowinacertainway?TheanswerisDNA.ItwasfirstdiscoveredbyayoungSwissdoctorin1868.

　　DNAislikeacomputerprogramforyourbody.Almosteverycell(细胞)inyourbodyincludesDNA.ThewayDNAinthecelldecideswhyyouarethewayyouare.Forexampleyourfriendmighthavelargerearsthanyou.ThisisbecausetheirDNAisdifferentfromyours.

　　DNAlivesinthecellandisorderedinastructurecalleda“doublehelix(双螺旋)”.Ineachdoublehelixtherearelinkscalledaschromosomes(染色体).Thesechromosomesaremadefromfourbasesthatarrangethemselvesinmillionsofdifferentways.ThewaythesebaseschoosetolineupiswhatmakestheDNAcodeforthatcell.

　　DNAisalsocalleda“gene(基因)”.Thisisaveryinterestingthing.Genesarepasseddownfromyourparents.Thatiswhyyoumighthavethesamesmilelikeyourdad’sormom’s!

　　InFebruaryscientistsfoundtheskeleton(骨架)ofRichardIIIKingofEnglandfrom1483-1485underacarparkinEngland.Itseemsunlikelythatscientistscouldidentifya527-year-oldskeleton.Howevertheymatchedtheskeleton’sDNAtoasamplefromoneofhisdirectdescendants(后代).Howamazing!

　　1._______discoveredDNA.

　　A.ASwissscientist              B.ASwissdoctor

　　C.Ayoungstudent                D.ASwissworker

　　2.WhichofthefollowingisWrong?

　　A.DNAisapartofthecell.

　　B.DifferentpeoplehavedifferentDNA.

　　C.Thechromosomesaremadeupoffourbases.

　　D.Scientistscouldnotidentifya527-year-oldskeleton.

　　3.Whatisthemainfunctionof“genes”?

　　A.Theydecideyourchildren’sappearancesorcharacters.

　　B.Theymakeyourchildrenhavethesamesmileasyou.

　　C.Theymakeyourchildrenstayhealthy.

　　D.They’regoodforscientificresearches.

　　4.What’sthemainideaofthispassage?

　　A.WhatdecidesDNA.            B.HowDNAisarranged.

　　C.Whatgenesarelike.        D.HowDNAworksinourbody.