医学生物化学简答题考场必备文档格式.docx

医学生物化学简答题考场必备文档格式.docx

《医学生物化学简答题考场必备文档格式.docx》由会员分享，可在线阅读，更多相关《医学生物化学简答题考场必备文档格式.docx（11页珍藏版）》请在冰点文库上搜索。

-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