中科院分子生物学试题库题库4

1GLOSSARYAbundanceofanmRNAistheaveragenumberofmoleculespercell.AbundantmRNAsconsistofasmallnumberofindividualspecies,eachpresentinalargenumberofcopiespercell.Acceptorsplicingsite—seerightsplicingjunction.Acentricfragmentofachromosome(generatedbybreakage)lacksacentromereandislostcelldivision.Acrocentricchromosomehasthecentromerelocatedneareroneendthantheother.Activesiteistherestrictedpartofaproteintowhichasubstratebinds.Alleleisoneofseveralalternativeformsofageneoccupyingagivenlocusonachromosome.Allelicexclusiondescribestheexpressioninanyparticularlymphocyteofonlyoneallelecodingfortheexpressedimmunoglobulin.Allostericcontrolreferstotheabilityofaninteractionatonesiteofaproteintoinfluencetheactivityofanothersite.Alufamilyisasetofdispersed,relatedsequences,each～300bplong,inthehumangenome.TheindividualmembershaveAlucleavagesitesateachend(hencethename).Alu-equivalentfamilyisthesetofsequencesinamammaliangenomethatisrelatedtothehumanAlufamily.α-AmanitinisabicyclicoctapeptidederivedfromthepoisonousmushroomAmanitaphalloides;itinhibhitstranscriptionbycertaineukaryoticRNApolymerases,especiallyRNApolymeraseII.AmbercodonisthenucleotidetripletUAG,oneofthreecodonsthatcauseterminationofproteinsynthesis.AmbermutaiondescribesanychangeinDNAthatcreatesanambercodonatasitepreviouslyoccupiedbyacodonrepresentinganaminoacidinaprotein.AmbersuppressorsaremutantgenesthatcodefortRNAswhoseanticodonshavebeenalteredsothattheycanrespondtoUAGcodonsaswellasorinsteadoftotheirpreviouscodons.Aminoacyl-tRNAistransferRNAcarryinganaminoacid;thecovalentlinkageisbetweentheNH2groupoftheaminoacidandeitherthe3’-or-2’-OHgroupoftheterminalbaseofthetRNA.Aminoacyl-tRNAsynthetasesareenzymesresponsibleforcovalentlylinkingaminoacidstothe2’or3’-OHpositionoftRNA.Amphipathicstructureshavetwosurfaces,onehydrophilicandonehydrophobic.Lipidsareamphipathic;andsomeproteinregionsmayformamphipathic;andsomeproteinregionsmayformamphipathichelices,withonechargedfaceandoneneutralface.Amplificationreferstotheproductionofadditionalcopiesofachromosomalsequence,2foundasintrachromosomalorextrachromoxomalDNA.Anchoragedependencedescribestheneedofnormaleukaryoticcellsforasurfacetoattachtoinordertogrowinculture.Aneuploidchromosomeconstitutiondifferesfromtheusaldiploidconstitutionbylossorduplicationofchromosomesorchromosomalsegments.AnnealingisthepairingofcomplementarysinglestrandsofDNAtoformadoublehelix.Antibodyisaprotein(immunoglobulin)producedbyBlymphocytecellsthatrecognizesaparticularforeign‘antigen,’andthuswtriggerstheimmuneresponse.AnticodingstrandofduplesDNAisusedasatemplatetodirectthesynthesisofRNAthatiscomplementarytoit.Antigenisanymoleculewhoseentryintoanorganismprovokessynthesisofanantibody(immunoglobulin).Antiparallelstrandsofthedoublehelixareorganizedinoppositeorientation,sothatthe5’endofonestrandisaligenedwiththe3’endoftheotherstrand.AntiterminationproteinsallowRNApolymerasetotranscribethroughcertainterminatorsites.ApendonucleasesmakeincisionsinDNAonthe5’sideofeitherapurinicorapyrimidincsites.ApoinducerisaproteinthatbindstoDNAtoswitchontranscriptionbyRNApolymerase.Archebacteriacompriseaminorlineofprokaryotes,andmayhaveintronsinthegenome.Ascusofafunguscontainsatetradoroctadofthe(haploid)spores,representhingtheproductsofasihnglemeiosis.attstiesarethelocionaphageandthebacterialchromosomeatwhichrecombinationintegratesthephageinto.orexcisesitfrom,thebacterialchromosome.Attenuationdescribestheregulationofterminationoftranscriptionthatisinvolvedincontrollingtheexpressionofsomebacterialoperons.Attenuatoristheterminatorsequenceatwhichattenuatiojoccurs.Autogenousconhtroldescribestheactionofageneproductthateitherinhibits(negativeautogenouscontrol)oractivates(positiveautogenouscontrol)expressionofthegenecodingforit.Autonomouscontrollingelementinmaizeisanactivetransposonwiththeabilitytotranspose(cfnonautonomouscontrollingelement).Autoradiographydetectsradioactivelylabeledmoleculesbytheireffectincreatinganimageonpholtographicfilm.Autosomesareallthechromosomesexceptthesexchromosomes;adiploidcellhastwocopiesofeachautosome.Blymphocytes(orBcells)arethecellsresponsibleforsynthesizingantibodies.3Backcrossisanother(earlier)termforatestcross.Backmutationreversestheeffectofamutationthathandinactivatedagene;thusitrestoreswildtype.Bacteriophagesarevirusesthatinfectbacteria;oftenabbreviatedasphages.Balbainiringisanextremelylargepuffatabandofapolytenechromosome.BandsofpolytenechromosomesarevisibleasdenseregionsthatcontainthemajorityofDNA;bandsofnormalchromosomesarerelativelymuchlargerandaregeneratedintheformofregionsthatretainastainoncertainchemicaltreatments.Basepair(bp)isapartnershipofAwithTorofCwithGinaDNAdoublehelix;otherpairscanbeformedinRNAundercertaincircumstances.Bidirectionalreplicationisaccomplishedwhentworeplicationforksmoveawayfromthesameoriginindifferentdirections.Bivalentisthestructurecontainingallfourchromatids(tworepresentingeachhomologue)atthestartofmeiosis.Blastodermisastageofinsectembryogenesisinwhichalayerofnucleiorcellsaroundtheembryosurroundaninternalmassofyolk.Blockedreading