生物专业英语(蒋悟生第二版)课文翻译lessonthree

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1、LessonThree（2学时）CellularReproduction:MitosisandMeiosis教学H的：使学生掌握细胞的有丝分裂和无丝分裂的作用机理，有丝分裂和无丝分裂之间的区别和相同点。相关英语词汇以及主要用法。教学重点：有丝分裂和无丝分裂中相关的概念和功能，及相关英语词汇的掌握教学难点：专业英语词汇的记忆讲授方法：以学生翻译为主，老师讲解相失专业知识辅助学生理解授课时4月12日教学内容：TheNucleusandChromosomesThecellnucleusisthemainrepositoryofgeneticinformation.Withinthenu

2、cleusarcthechromosomestightlycoiledstrandsofDNAandclustersofassociatedproteins.LongstretchesofthecontinuousDNAmoleculewindaroundtheseclustersofproteins，orhistones,formingbeadlikecomplexesknownasnucleosomes.Morecoilingandsupercoilingproducesadensechromosomestructure.EachlongstrandofDNAcombines

3、withhistonesandnonhistoneproteinstomakeupthesubstancechromatin•细胞核足贮藏遗彷信息的主要场所。DNA盘绕成螺旋线以及相关的成簇蛋白质。DNA螺旋线缠绕成簇的组蛋白形成珠链状的核小体。这些螺旋和超螺旋形成致密的染色体组结构。每个长链DNA与组蛋內和非組蛋內一起构成染色质物质。Apictorialdisplayofanorganism’schromosomesinthecoiled,condensedstateisknownasakaryotype.Karyotyperevealthatinmostcellsallbut

4、sexchromosomesarepresentastwocopies，referredtoashomologouspairs.Non-sexchromosomesarccalledautosomes.Organismswhosecellscontaintwosetsofparentalchromosomesarecalleddiploid;thosewithcellscontainingasinglesetofparentalchromosomesarecalledhaploid.染色体致密的超螺旋状态我们称染色体组。除了性染色体外，人多数细胞的染色体组成对出现，称同源染色体对

5、。非性染色体称常染色体。生物细胞含冇两套父母木染色体的称：倍体；含冇单套染色体的称单倍体。TheCellCycleThecellcycleisaregularsequenceinwhichthecellgrows，preparesfordivision，anddividestoformtwodaughtercells，eachofwhichthenrepeatsthecycle.Suchcyclingineffectmakessingle-celledorganismsimmortal.Manycellsinmulticellularorganisms,includinganim

6、almuscleandnervecells,eitherslowthecycleorbreakoutofitaltogether•在细胞中•长过税屮，细胞循环遵循特定程序，分裂准备，分裂成2个子细胞，子细胞再循环。此循环使得单细胞永生。多细胞生物中的许多细胞，包括动物肌肉和神经细胞，要么降低循环速度，要么同吋分裂。Thenormalcellcycleconsistsoffourphases.ThefirstthreeincludeGl，theperiodofnormalmetabolism;Sphase，duringwhichnormalsynthesisofbiological

7、moleculescontinues,DNAisreplicated，andhistonesarcsynthesized;andG2，abriefperiodofmetabolismandadditionalgrowth.TogethertheGl，S，andG2phasesarecalledinterphase.ThefourthphaseofthecellcycleisMphase，theperiodofmitosis，duringwhichthereplicatedchro