医学生物化学简答题考场必备文档格式.docx
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医学生物化学简答题考场必备文档格式.docx
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-OHendoftheRNAprimer,DNApolymeraseIIIcatalyzesthesynthesisoffourdNTPwithsinglestrandedDNAastemplatetosynthesize5'
-3'
DNA.The
(4)undertheactionofDNApolymeraseI,theRNAprimerswereremovedbyhydrolysis,andtheDNAfragmentwasfurtherextendedbytheenzymetofillthegap.WewillconnectthetwoadjacentDNAfragmentsbyDNAligase,formedacompletechainofDNA.The
2.DiscussthebasiclawofDNAreplication.
A.semireservedreplication:
whenreplicating,thedoublestrandedDNAofthemotherchainisbrokenintotwostrands,eachactingasatemplatetoguidetheoffspringtosynthesizenewcomplementarystrands.TheDNAdoublestrandofthedaughtercell,inwhichasinglestrandreceivescompletelyfromtheparent,andtheotherstrandiscompletelyresynthesized.Becauseofthecomplementationofbases,theDNAdoublechainsofthetwodaughtercellsareconsistentwiththeparentDNAbasesequence.Thisreplicationiscalledsemireservedreplication.
B.doublecopy:
copy,DNAfromthestartingpointtothedirectionofthetwosolutionchain,formingtwoextendingintheoppositedirectionofthereplicationfork,calledbidirectionalreplicationinprokaryotesarethestartingpointofthesinglebidirectionalreplication,eukaryotesisbidirectionalcopyingmultiplestartingpoint.
C.semidiscontinuousreplication:
thetwostrandsofDNAdoublehelixareantiparallel,andthedirectionofDNAsynthesiscanonlybe5'
.DuringDNAreplication,thedirectionofthe1strandsynthesisandreplicationforkinthesamedirection,cancontinuousreplication,calledtheleadingchain;
andthedirectionofanotherchainsynthesisandreplicationforkonthecontrary,notonlycontinuousreplication,dividedintoseveralfragments(Okazakifragmentsynthesis),calledtheentouragechain.Thecontinuousreplicationoftheleadingchainandthesuccessivereplicationofthechainarethehalfdiscontinuityofthereplication.
3.Whatisreversetranscription?
Whatisitssignificanceinmedicine?
UsingRNAastemplateand4kindsofdNTPasrawmaterials,theprocessofDNAsynthesisundertheguidanceofRNAdirectedDNApolymeraseinaccordancewiththeprincipleofbasecomplementation.The
ReversetranscriptaseispresentinalloncogenicRNAviruses,anditsfunctionmayberelatedtothemalignanttransformationofthevirus.VirusbyreversetranscriptionofRNAtoformaDNA(thevirus),andthenintegrateintothehostcellchromosomeDNA,thegeneticinformationoftheviruswasexpressedinthehostcells,namelyhostcellproteinsynthesisinadditiontotheirown,someproteinsandcansynthesizevirusspecific,andthelatterhadcloserelationshipwithcancer.
4,thereplicationofDNADNAandwhataretheirfunctions."
DNAdirectedDNApolymeraseofEscherichiacoliDNApolymerase,includingDNApolymeraseI,II,III,ofwhichDNApolymeraseplaysamajorroleinrepairofdamagedDNA,DNApolymeraseIIIplaysamajorroleinDNAreplication.The
(II)unwinding,helicase,includingunwindingenzymes,topoisomerase,singlestrandedDNAbindingproteins,theircommonroleistounravelandrationalizetheDNAdoublestrand.MaintainDNAinasinglestrandedstate.The
(III)primersareessentiallyDNAdirectedRNApolymerases,whichcanbeusedastemplatestosynthesizeshortstrandsofRNAtoprovide3'
-OHendsasDNApolymerasestoextendDNAstrandsforDNApreparation.The
DNAligaseconnectsthe3'
-OHendofDNAchainandthe5'
-PendofanotherDNAchain,formingtwophosphateesterbond,thusconnectingtwoadjacentDNAchainsintoacompletechain.The
5.WhyisthereonlyonechainintheDNAcopyasthemotherchain?
InthebiosynthesisofDNA,theparentstrandDNAisreleasedintotwostrands,andeachtemplateisusedastemplatetosynthesizethecomplementarychainofthetemplateaccordingtothebasepairingrule.ProgenyDNA,asinglereceivedfromparentalcomplete,anotherstrandiscompletelyresynthesis,twosubcellDNAandparentalDNAsequences,thiscopyiscalledsemiconservativereplication.
TheelucidationofsemireservedreplicationisofgreatsignificanceforunderstandingthefunctionofDNAandthecontinuityofspecies.TheDNAdoublestrandedtwostrandedsinglestrandhasabasecomplementaryrelationship,andonestrandinthedoublestrandcandeterminethebasesequenceofthecorrespondingstrand.Inthewayofsemireservedreplication,theprogenyretainedallthegeneticinformationofparentalDNA,reflectingtheconsistencyofDNAbasesequencebetweengenerationandgeneration.
Eleventhchapters:
1.Brieflydescribethebasicprocessoftranscription
TheinitiationofRNApolymeraseholoenzymebindingtoDNApromoterrecognitionsite,firstbytherecognitionofsigmafactorDNApromoter,withcoreenzymebindingsitesinthepromoteroftheDNAdoublehelixlocalopen,exposedDNAtemplatechain,RNAsynthesizedNTPinaccordancewiththeprincipleofbasepaircomplementarypositioningtemplateintothechain,byRNApolymerase,3'
isformedbetweenthefirstandthesecondNTP,5'
-twophosphoricacidesterbond,whilethereleaseofapyrophosphate,whenthefirsttwophosphateesterbondformation,sigmafactorshedding,startend.The
Theextension,RNApolymerasecoreenzymealongtheDNAtemplatechain3'
to5'
sliding,eachmovingonenucleotidedistance,thereisatemplateandcomplementaryNTPintothereactionsystem,thecatalyticRNApolymerase,onebyonetoforma3'
5'
-twophosphateesterbond,sothatanewRNAmoleculethesynthesisofcontinuousextension.The
TheterminationoftheDNAmoleculewithsignalterminationoftranscription,thissitehasarichGCregion,andtheinvertedrepeatsequence,thetranscriptiongeneratedRNAformahairpinstructure,movingthishairpinstructurecanhinderRNApolymerase,therebyterminatingtranscription.InadditiontoaproteincalledRhofactor,itsterminationsignalishelpfulforRNApolymeraserecognition,soterminationfactor.The
2.DescribethecompositionofEscherichiacoliRNApolymeraseandtheirrespectivefunctions
EscherichiacoliRNApolymeraseholoenzymebyalpha2betasigma'
iscomposedoffiveparts,ofwhichthealphasubunitdetermineswhichgenesaretranscription,transcriptionandthewholeprocessofbeta,betasubunitbindsDNA'
templaterecognitionsitesigmasubunittoidentifytheinitiationsiteofDNApromoterDNAbindingtranscription.The
3,theprocessinvariousRNA.
Includingsplicing,mRNAprecursor,removalofintronsplicingofexon5;
'
endcapmshare7Gppp;
the3'
endofpolyAtail;
basemodification.
TheprocessingoftRNAprecursorincludessplicing,removingredundantnucleotides;
3'
endplusCCA-OH;
modificationofbasetoformalkenylbase.
TheprocessingofrRNAprecursorsmainlyinvolvessplicingandbasemodification.
Twelfthchapters:
1.BrieflydescribetheclassificationofRNA,thestructuralcharacteristicsofvarioustypesofRNAandtheirrolesinproteinbiosynthesis
MRNA,the5'
endcapwiththestructureofm7Gppp;
endofpolyA;
threenucleotidesareconnectedinsequencetoformapassword,atotalof64passwords,including61passwordonbehalfof20kindsofaminoacids,1startcodon,stopcodon3.MRNAactsasadirecttemplateinproteinsynthesis.The
TRNA,anditssecondarystructureisclovershaped.Thereareaminoacidarms;
DHUrings;
anticryptographicrings,T,Crings;
extrarings.TRNAcanselectivelytransporttheactivatedaminoacidstothenuclearproteinbodiesandparticipateinproteinbiosynthesis.The
(3)rRNA,rRNAandavarietyofproteinsconstitutenuclearproteins,whichconsistoflargesubunitsandsmallsubunits,whicharethesitesforproteinbiosynthesis.The
2.ThesynthesisofDNA,thesynthesisofRNAandthesynthesisofproteinarecomparedfromtheaspectsofrawmaterials,templates,syntheticdirectionsandthebasiccharacteristicsofsyntheticmethods
InthesynthesisofDNAinthesynthesisofRNAinproteinsynthesis
Therawmaterialsin20kindsofaminoacidsindNTPinNTP
InthetemplatestrandmRNAtemplateinDNAinDNA
Thedirectionofsynthesisin5'
to3'
x5'
inN,C
Thesynthesiswayinsemiconservativereplicationcycleintheasymmetrictranscriptioninnuclearprotein
3.Whatarethestepsofeachaminoacidextensioninproteinbiosynthesis?
Carryone,
Theamino-tRNAenterscorrespondingtothemRNAcodeoftheacceptorsite.The
Thepeptide;
peptideenzymetoribosomelargesubunittopeptidylon(methionyl)transferredtothebasebyaalpha13aminoaminoacyl-tRNAontheformationofpeptidebonds.The
Displacement:
unloadedtRNAfromthenuclearproteinbody,thenuclearbodymovesalongthemRNAto3'
endofacodondistance,peptidyl-tRNAthenmovedtothedonorsite,bitempty.Andthenextcycle,carry,turnpeptide,shift.The
Fifteenthchapters
1,cAMPishowtogenerate?
Whatistheroleofinformationinthetransfer?
Watersolublehormonessuchasepinephrine,glucagonbindingandmembranereceptorspecificcomplexformation,mediatedbyGsproteinactivationoncellmembraneadenylylcycl
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