生物学课上一部分讲座45 listening lecture2 script45听力脚本.pdfVIP

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Professor:Sothat’stheoverviewofthehumanimmunesystem.Butwehaveafewminutesleft.Any

questions?George?

George:Yes,youtalkedaboutTcells—naiveTcells.Canyougooverthatpartagain?Andalso,whydo

wecallthemthatanyway?

Professor:Alright,they’re,they’reknownasTcellsbecausetheydevelopinthethymus.

George:Thewhat?

Professor:Thymus.That’sT-H-Y-M-U-S.It’sasmallorganinthebody.Anyway,that’swhywecallthem

that.Theycomefromthethymus.AndTcellsareapartofthebody’simmunesystem.Theycan

recognizeandeliminatecellsfromoutsidethebodythatmightcausedisease.

Student:Butwhynaive?Imean,wemightcallpeoplenaiveiftheydon’thaveenoughexperienceto

knowaboutthedangersoftheworld,buthowcanyoucallacellnaive?

Professor:Well,whenthistypeofimmunecellencountersacellfromoutsidethebody,likemaybea

bacterium,itinteractswiththatbacteriumandlearnstorecognizeit.Sowhenevertheimmunecellruns

intothatkindofbacteriuminthefuture,itwillattackandkillit.Atthatpoint,wecallitamemoryTcell

becauseit’slearnedtorecognizeaproteinmarkerthatidentifiesthisparticularkindofbacterium.But

beforeit’slearnedtorecognizeanyparticularproteinfromoutsidethebody,wecallitnaive.Okay?

Student:Yeah,Igetit.

Professor:There’salotofbiochemistryinvolvedthatwe’llgetintothenextlecture.Butyourquestion

remindsmeofaboutastudythatsomeofmycolleaguesaredoing.Itrelatestocaloricrestriction.

Student:Caloric?Likecaloriesinthefoodweeat?

Professor:Exactly.We’retalkingaboutthesugars,carbohydrates,