Test bank For Essenal Cell Biology 3rd Edion Bruce Alberts Download Here
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!CHAPTE" !D#A "EP$CAT$%#& "EPA$"& A#D "EC%MB$#AT$%# D#A "e'licaon !() T*e 'rocess o+ D#A re'licaon re,uires t*at eac* o+ t*e 'arental D#A strands be used as a ------------------------------------ to 'roduce a du'licate o+ t*e o''osing strand./a strand./a00 catalyst/b0 co1'etor/c0 te1'late/d0 co'y !(2 D#A re'licaon is considered se1iconserae because ----------------------------./a0 a4er 1any rounds o+ D#A re'licaon& t*e original D#A double *eli5 is sll intact/b0 eac* daug*ter D#A 1olecule consists o+ two new strands co'ied +ro1 t*e 'arent D#A 1olecule/c0 eac* daug*ter D#A 1olecule consists o+ one strand +ro1 t*e 'arent D#A 1olecule and one new strand/d0 new D#A strands 1ust be co'ied +ro1 a D#A te1'late !(3 T*e classic e5'eri1ents conducted by Meselson and Sta*l de1onstrated t*at D#A re'licaon is acco1'lis*ed by e1'loying a ---------------- 1ec*anis1./a0 connuous/b0 se1iconserae/c0 dis'ersie/d0 conserae !(6 $+ t*e geno1e o+ t*e bacteriu1 E. coli re,uires about 27 1inutes to re'licate itsel+& *ow can t*e geno1e o+ t*e +ruit 8y Droso'*ila be re'licated in only 3 1inutes9/a0 T*e Droso'*ila geno1e is s1aller t*an t*e E. coli geno1e./b geno1e./b00 Eucaryoc D#A 'oly1erase synt*esi:es D#A at a 1uc* +aster rate t*an 'rocaryoc D#A 'oly1erase./c0 T*e nuclear 1e1brane kee's t*e Droso'*ila D#A concentrated concentrated in one 'lace in t*e cell& w*ic*
increases t*e rate o+ 'oly1eri:aon./d0 Droso'*ila D#A contains 1ore origins o+ re'licaon t*an E. coli D#A. !(; Meselson and Sta*l grew cells in 1edia t*at contained di D#A was se'arated +ro1 =*eay> D#A in t*e Meselson and Sta*l e5'eri1ents.B. Describe t*e t*ree e5isng 1odels +or D#A re'licaon w*en t*ese studies were begun& and e5'lain *ow one o+ t*e1 was ruled out de?niely by t*e e5'eri1ent you described +or 'art A.C. @*at e5'eri1ental result eli1inated t*e dis'ersie 1odel o+ D#A re'licaon9 !(! $ndicate w*et*er t*e +ollowing state1ents are true or +alse. $+ a state1ent is +alse& e5'lain w*y it is +alse.A. @*en D#A is being re'licated inside a cell& local *eang occurs& allowing t*e two strands to se'arate.B. D#A re'licaon orgins are ty'ically ric* in (C base 'airs.C. Meselson and Sta*l ruled out t*e dis'ersie 1odel +or D#A re'licaon.D. D#A re'licaon is a bidireconal 'rocess t*at is iniated at 1ul'le locaons along c*ro1oso1es in eucaryoc cells. !( Answer t*e +ollowing ,uesons about D#A re'licaon.A. %n a D#A strand t*at is being synt*esi:ed& synt*esi:ed& w*ic* end is growingt*e 3 end& t*e ; end& or bot* ends9 E5'lain your answer.B. %n a D#A strand t*at is being used as a te1'late& w*ere is t*e co'ying occurring relae to t*e re'licaon origin3 o+ t*e origin& ;& or bot*9 !( How does t*e total nu1ber o+ re'licaon origins in bacterial cells co1'are wit* t*e nu1ber o+ origins in *u1an cells9/a0 ) ersus )77/b0 ; ersus ;77/c0 )7 ersus )777/d0 ) ersus )7&777 !( T*e c*ro1an structure in eucaryoc cells is 1uc* 1ore co1'licated t*an t*at obsered in 'rocaryoc cells. T*is is t*oug*t to be t*e reason t*at D#A re'licaon occurs 1uc* +aster in 'rocaryotes. How 1uc* +aster is it9/a0 2G/b0 ;G/c0 )7G /d0 )77G !()7 D#A 'oly1erase cataly:es cataly:es t*e oining o+ a nucleode to a growing D#A strand. strand. @*at 'reents t*is en:y1e +ro1 cataly:ing t*e reerse reacon9/a0 *ydrolysis o+ PPi to Pi I Pi/b0 release o+ PPi +ro1 t*e nucleode/c0 *ybridi:aon o+ t*e new strand to t*e te1'late/d0 loss o+ ATP as an energy source !()) Figure J!()) s*ows a re'licaon bubble.
Figure J!()) A. %n t*e ?gure& indicate w*ere t*e origin o+ re'licaon was located /use %0.B. abel t*e leading(strand te1'late and t*e lagging(strand te1'late o+ t*e rig*t(*and +ork K"L as and N& res'ecely.C. $ndicate by arrows t*e direcon in w*ic* t*e newly 1ade D#A
strands /indicated by dark lines0 were synt*esi:ed.D. #u1ber t*e %ka:aki +rag1ents on eac* strand )& 2& and 3 in t*e order o rder in w*ic* t*ey were synt*esi:ed.E. synt*esi:ed.E. $ndicate w*ere t*e 1ost recent D#A synt*esis *as occurred /use S0.F. $ndicate t*e direcon o+ 1oe1ent o+ t*e re'licaon +orks wit* arrows. !()2 @*ic* o+ t*e +ollowing state1ents about t*e newly synt*esi:ed strand o+ a *u1an c*ro1oso1e is true9/a0 $t was synt*esi:ed +ro1 a single origin solely by connuous D#A synt*esis./b0 $t was synt*esi:ed +ro1 a single origin by a 1i5ture o+ connuous and disconnuous D#A synt*esis./c0 $t was synt*esi:ed +ro1 1ul'le origins solely by disconnuous D#A synt*esis./d0 $t was synt*esi:ed +ro1 1ul'le origins by a 1i5ture o+ connuous and disconnuous D#A synt*esis. !()3 Nou *ae discoered an =E5oO> 1utant +or1 o+ D#A 'oly1erase in w*ic* t*e 3(to( ; e5onuclease +uncon *as been destroyed but t*e ability to oin nucleodes toget*er is unc*anged. @*ic* o+ t*e +ollowing 'ro'eres do you e5'ect t*e 1utant 'oly1erase to *ae9/a0 $t will 'oly1eri:e in bot* t*e ;(to(3 direcon and t*e 3(to(; direcon./b0 $t will 'oly1eri:e 1ore slowly t*an t*e nor1al E5oI 'oly1erase./ 'oly1erase./c0 c0 $t will +all o< t*e te1'late 1ore +re,uently t*an t*e nor1al E5oI 'oly1erase./d0 $t will be 1ore likely to generate 1is1atc*ed base 'airs. !()6 A 1olecule o+ bacterial D#A introduced into a yeast cell is i1'orted into t*e nucleus but +ails to re'licate t*e yeast D#A. @*ere do you t*ink t*e block to re'licaon arises9 C*oose t*e 'rotein or 'rotein co1'le5 below t*at is 1ost 'robably res'onsible +or t*e +ailure to re'licate bacterial D#A. ie an e5'lanaon +or your answer./a0 'ri1ase/b0 *elicase/c0 D#A 'oly1erase/d0 iniator 'roteins !(); Most cells in t*e body o+ an adult *u1an lack t*e telo1erase en:y1e because its gene is turned o< and is t*ere+ore not e5'ressed. An i1'ortant ste' in t*e conersion o+ a nor1al cell into i nto a cancer cell& w*ic* circu1ents nor1al growt* control& is t*e resu1'on o+ telo1erase e5'ression. E5'lain w*y telo1erase 1ig*t be necessary +or t*e ability o+ cancer cells to diide oer and oer again. !()! @*ic* diagra1 accurately re'resents t*e direconality o+ D#A strands at one side o+ a re'licaon +ork9
!() $ndicate w*et*er t*e +ollowing state1ents are true or +alse. $+ a state1ent is +alse& e5'lain w*y it is +alse.A. Pri1ase is needed to iniate D#A re'licaon on bot* t*e leading strand and t*e lagging strand.B. T*e sliding cla1' is loaded once on eac* D#A strand& w*ere it re1ains associated unl re'licaon is co1'lete.C. Telo1erase is a D#A 'oly1erase t*at carries its own "#A 1olecule to use as a 'ri1er at t*e end o+ t*e lagging strand.D. Pri1ase re,uires a 'roo+reading +uncon t*at ensures t*ere are no errors in t*e "#A 'ri1ers used +or D#A re'licaon. !() Because all D#A 'oly1erases synt*esi:e D#A in t*e ;(to(3 direcon& and t*e 'arental strands are an'arallel& D#A re'licaon is acco1'lis*ed wit* t*e use o+ two 1ec*anis1s connuous and disconnuous re'licaon. $ndicate w*et*er t*e +ollowing ite1s relate to /)0 connuous re'licaon& re'licaon& /20 disconnuous re'licaon& or /30 bot* 1odes o+ re'licaon. ------ 'ri1ase------ single(strand binding 'rotein------ sliding cla1'------ "#A 'ri1ers------ leading strand------ lagging strand------ %ka:aki +rag1ents------ D#A *elicase------ D#A ligase !() T*e synt*esis o+ D#A in liing syste1s occurs in t*e ;(to(3 direcon. Howeer& sciensts synt*esi:e s*ort D#A se,uences needed +or t*eir e5'eri1ents on an instru1ent dedicated to t*is task.A. T*e c*e1ical synt*esis o+ D#A by t*is instru1ent 'roceeds +ro1 t*e 3(to(; direcon. Draw a diagra1 to s*ow *ow t*is is 'ossible and e5'lain t*e 'rocess.B. Alt*oug* 3(to(; synt*esis o+ D#A is c*e1ically 'ossible& it does not occur in liing syste1s. @*y not9 !(27 D#A 'oly1erases are 'rocessie& w*ic* 1eans t*at t*ey re1ain g*tly associated wit* t*e te1'late strand w*ile 1oing ra'idly and adding nucleodes to t*e growing daug*ter strand. @*ic* 'iece o+ t*e re'licaon 1ac*inery accounts +or t*is c*aracterisc9/a00 *elicase/b c*aracterisc9/a *elicase/b00 sliding cla1'/c0 single(strand binding 'rotein/d0 'ri1ase !(2) Qse t*e co1'onents in t*e list below to label t*e diagra1 o+ a re'licaon +ork in Figure J!(2).A. D#A 'oly1eraseB. single(strand binding 'roteinC. %ka:aki +rag1entD +rag1entD.. 'ri1aseE. sliding cla1'F. "#A 'ri1er. D#A *elicase
Figure J!(2) !(22 "esearc*ers "esearc*ers *ae isolated a 1utant strain o+ E. coli t*at carries a te1'eratur te1'erature( e( sensie ariant o+ t*e en:y1e D#A ligase. At t*e 'er1issie te1'erature& t*e 1utant cells grow ust as well as a s t*e wild(ty'e cells. At t*e non'er1issie te1'erature& all o+ t*e cells in t*e culture tube die wit*in 2 *ours. D#A +ro1 1utant cells grown at t*e non'er1issie te1'erature te1'erature +or 37 1inutes is co1'ared wit* t*e D#A isolated +ro1 cells grown at t*e 'er1issie te1'erature. T*e results are s*own in Figure J!(22& w*ere D#A 1olecules *ae been se'arated by si:e by 1eans o+ electro'*oresis /P& 'er1issieR #P& non'er1issie0. E5'lain t*e a''earance o+ a disnct band wit* a si:e o+ 277 base 'airs /b'0 in t*e sa1'le collected at t*e non'er1issie te1'erature. te1'erature.
Figure J!(22 !(23 Telo1eres sere as ca's at t*e ends o+ linear c*ro1oso1es. @*ic* o+ t*e +ollowing is not true regarding t*e re'licaon o+ telo1eric se,uences9/a0 se,uences9/a0 T*e lagging strand telo1eres are not co1'letely re'licated by D#A 'oly1erase./b0 Telo1eres are 1ade o+ re'eang se,uences./c0 Addional re'eated se,uences are added to t*e te1'late strand. /d0 T*e T*e leading strand doubles back on itsel+ to +or1 a 'ri1er +or t*e lagging strand. D#A "e'air !(26 Sickle(cell ane1ia is an e5a1'le o+ an in*erited disease. $ndiiduals wit* t*is disorder *ae 1iss*a'en /sickle(s*a'ed0 /sickle(s*a'ed0 red blood cells caused by a c*ange in t*e se,uence o+ t*e (globin gene. @*at is t*e nature o+ t*e c*ange9/a0 c*ro1oso1e loss/b0 base('air c*ange/c0 gene du'licaon/d0 base('air inseron !(2; Een t*oug* D#A 'oly1erase *as a 'roo+reading +uncon& it sll introduces errors in t*e newly synt*esi:ed strand at a rate o+ ) 'er )7 nucleodes. To w*at degree does t*e 1is1atc* re'air syste1 decrease t*e error rate arising +ro1 D#A re'licaon9/a0 2( +old/b0 ;(+old/c0 )7(+old/d0 )77(+old
!(2! @*ic* o+ t*e c*oices below re'resents t*e correct way to re'air t*e 1is1atc* s*own in Figure J!(2!9
Figure J!(2!
!(2 A 1is1atc*ed base 'air causes a distoron in t*e D#A backbone. $+ t*is were t*e only indicaon o+ an error in re'licaon& t*e oerall rate o+ 1utaon would be 1uc* *ig*er. E5'lain w*y. !(2 Beside t*e distoron in t*e D#A backbone caused by a 1is1atc*ed base 'air& w*at addional 1ark is t*ere on eucaryoc D#A to indicate i ndicate w*ic* strand needs to be re'aired9/a0 a nick in t*e te1'late strand/b0 a c*e1ical 1odi?caon o+ t*e new strand/c0 a nick in t*e new strand/d0 a se,uence ga' in t*e new strand !(2 A 'regnant 1ouse is e5'osed to *ig* leels o+ a c*e1ical. Many o+ t*e 1ice in *er lier are de+or1ed& but w*en t*ey are interbred wit* eac* ot*er& all t*eir o
'oly1eri:es t*e correct se,uence be*ind it as it 1oes along t*e te1'late. D#A ligase seals t*e nicks in t*e re'aired strand./c0 D#A da1age is recogni:ed& t*e newly synt*esi:ed synt*es i:ed strand is iden?ed by an e5isng nick in t*e backbone& a seg1ent o+ t*e new strand is re1oed by an e5onuclease& and t*e ga' is re'aired by D#A ligase./d0 A nick in t*e D#A is recogni:ed& D#A re'air 'roteins switc* out t*e wrong base and insert t*e correct base& and D#A ligase seals t*e nick. !(3) Nou are e5a1ining t*e D#A se,uences t*at code +or t*e en:y1e '*os'*o+ructokinase in skinks and Vo1odo dragons. Nou noce t*at t*e coding se,uence t*at actually directs t*e se,uence o+ a1ino acids in t*e en:y1e is ery si1ilar in t*e two organis1s but t*at t*e surround surrounding ing se,uences ary ,uite a bit. @*at is t*e 1ost likely e5'lanaon +or t*is9/a0 Coding se,uences are re'aired 1ore eWciently./b0 Coding se,uences are re'licated 1ore accurately./c0 accurately./c0 Coding se,uences are 'ackaged 1ore g*tly in t*e c*ro1oso1es to 'rotect t*e1 +ro1 D#A da1age./d0 Mutaons in coding se,uences are 1ore likely to be deleterious to t*e organis1 t*an 1utaons in noncoding se,uences. !(32 So1e1es c*e1ical da1age to D#A can occur ust be+ore D#A re'licaon begins& not giing t*e re'air syste1 enoug* 1e to correct t*e error be+ore t*e D#A is du'licated. T*is gies rise to 1utaon. $+ t*e cytosine in t*e se,uence TCAT is dea1inated and not re'aired& w*ic* o+ t*e +ollowing is t*e 'oint 1utaon you would obsere a4er t*is seg1ent *as undergone two rounds o+ D#A re'licaon9/a0 TTAT/b0 TQAT/c0 TAT/d0 TAAT !(33 During D#A re'licaon in a bacteriu1& a C is accidentally incor'orated instead o+ an A into one newly synt*esi:ed D#A strand. $1agine t*at t*is error was not corrected and t*at it *as no e
e5'lain w*y it is +alse.A. $oni:ing radiaon and o5idae da1age can cause D#A double( strand breaks.B. A4er da1aged D#A *as been re'aired& nicks in t*e '*os'*ate backbone are 1aintained as a way to iden+y t*e strand t*at was re'aired.C. De'urinaon o+ D#A is a rare eent t*at is caused by ultraiolet irradiaon.D. #on*o1ologous #on*o1ologous end oining is a 1ec*anis1 t*at ensures t*at D#A double(strand breaks are re'aired wit* a *ig* degree o+ ?delity to t*e original D#A se,uence. !(3 Seeral 1e1bers o+ t*e sa1e +a1ily were diagnosed wit* t*e sa1e kind o+ cancer w*en t*ey were unusually young. @*ic* one o+ t*e +ollowing is t*e 1ost likely e5'lanaon +or t*is '*eno1enon9 $t is 'ossible t*at t*e indiiduals wit* t*e cancer ca ncer *ae -----------------------./ ----------------------./a0 a0 in*erited a cancer(causing gene t*at su
