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Retired NBME 21 Answers

nbme21/Block 3/Question#28 (reveal difficulty score)
A 1-year-old girl is admitted to the hospital ...
Disruption of the secondary structure of collagen molecules 🔍 / 📺 / 🌳 / 📖
tags: biochem

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 +16  upvote downvote
submitted by wasabilateral(47)
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I kinth it sah nhemsgtoi to do thiw gyeinlc due( ot sti sallm zise it acn itf ni nyma aseplc hewer eorht moina cadis cna not dan enech ti sedropvi tl“utrrcuas cp”eactmosns ot eth ocgl,lean e..i tup a nkki ni teh hpala ex.)hli If lcnyegi is cdaelmpis by imosngeht lse,e I otdn’ hnkti an-cleloorpg cna mrof tis roecctr socnadyer cr.tstureu

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jotajota94  ruT!e ,aosl lyencgi si 13/ fo gllcaneo aalf shacni, os ti keasm neses that unitbuosttis thiw nlaenai (iwchh si uhcm egbig)r udowl lade to ionsrpdtiu ni the hpala ilhex afom.notri +2
jotajota94  e!uTr oas,l nygclei si 13/ fo laoglecn fala snci,ah os ti kaesm ssnee that unoustbitits whit aneanil (chihw is hucm ibrgge) uwodl adle to intidsoupr in het alahp lhxei m.otnfroai +
thepacksurvives  lyeGnic is lsalm dna bdye,n iwchh wlosla it ot mrof the ifbislr orf hte tlierp ixhle +
brasel  lAso in laregne FA( 8201 pg 5)0 OI si ofrm oerbmslp fgnriom the eirltp ixlhe iwchh si ascdonyer u.urtcetrs tFolur,aetny heyt agev us mhtiegnso to rnesao iwth ni the tioueqsn ;Ga&)-ytlg(Al +3
amy  Can noesmeo pehl em tnusnarded ywh A si ?ccntoeirr F0A202 gaep :05 irlTpe lexhi of 3 aecoglln a nihcas si rdomef mrfo nrgalooclep iav rygndhoe nad lifsedudi dn.bo sI shti eyrv smliria ot hatw A is bdrg.ecAnii ? seaDreedc oghrdno-yebdn fnomoairt teebwen lcgoalne cl.oemsuel +
umpalumpa  heT tnaeoxlapni vengi yb telawaairlsab cdolu owkr if the uneostiq dluwo say llt;yAG--&ag .toamtiun evHrowe, eht ntoiseuq tsaste ttah terhe is na ;-G&lglyAta- ua.toimnt +



 +13  upvote downvote
submitted by cellgamesgojan(43)
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I gfiue,dr gyi-neXcl-Y is tyilnlhceca odecnerdis a pi“ymarr onami ciad trteusrcu fo a i”prteon esinc hte eftnodiini of a mPaiyrr uretutcrs fo a peinrot si a“ anilre anhci fo omian ”.dacis fI uyo essm iwth the arimPry r,stucetur sa ni hte eiuotnqs tm,se uoy canton omfr the orcSandey utrrectus of eth ntrpieo, wchhi si rtidneeemd by eht eognhdrng-ndboiy ihhcw usccro ewnetbe eth tideepp bacebkno, ndepeninted fo the R usrpgo. I pohe hsti aemd ee.ssn

oFmr ipikwdiea: droyanec“S cttrusuer is mfrlyalo inefded by eht antpter fo gdorhney sonbd wtbeene the amion rdygheno dna rbaclyxo ngeoxy stmao in eth edppeti nckbobae.” emishas(p )ienm

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From Molecular Biology of the Cell:

Biologists distinguish four levels of organization in the structure of a protein. The amino acid sequence is known as the primary structure of the protein. Stretches of polypeptide chain that form α helices and β sheets constitute the protein’s secondary structure. The full three-dimensional organization of a polypeptide chain is sometimes referred to as the protein’s tertiary structure, and if a particular protein molecule is formed as a complex of more than one polypeptide chain, the complete structure is designated as the quaternary structure.

https://www.ncbi.nlm.nih.gov/books/NBK26830/#A406

+5/- drdoom(1206)


 +4  upvote downvote
submitted by usmle11a(102)
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ko yusg dan i tueoq frmo ir1w/eifsph4s:eeocesp0lowmtontacs.-eshr/ti./co/aesg/utwl2pmoritbtdte

9"%0 aevh na bdainietefil ceetnig monttaiu CL O A11 and LCO 2A1
sauc se bmlnaoar llcgaoen snisgrikcnl-o aiv a nyiglec ntbtiuusisto ni eht ooarnlcegpl leoelmuc "

hwhic ensam atht OI sha a lgyeinc sittosuutbni dna hotrrefe ist bnleau to ormf a ordcanyse cu.ruetsurt

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 +4  upvote downvote
submitted by hungrybox(1277)
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Deu ot ycgli'sen almls ,szie it cstaree nik"k"s in eht namoi daci uenee.sqc eTseh iknks era neddee to rcytcorel fmor the ardcoyens ecuttrus.r

reOth wses:arn

  • andek"eew arciinteton eeentwb onllgaec dna taolpeycnor"g - alencolg + tnoglrpeyoca = laril.gceat The eitosuqn tmse onimestn mnay fdctees in bENO (tepy I gnloe)lca utb no ntenomi fo cstfeed in claOagTWerl (yept II llanegoc)
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 +1  upvote downvote
submitted by basic_pathology(25)
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-X-YylG si ecbkanbo rof nalceogl alaph c.hnia 3 glcnaeol aahlp achins pilsar to rmfo eltpir xil.eh elGycni has on R ougp,r alilognw ofr yblilxtfeii nda mofnatoir of ptelri eh.ilx No gynelci tepevsnr this suoonuinct raspiigl,n egtprienvn teh miofnrtoa fo ncgoalel rsdaocnye rttr.eucsu

Rcleal hatt echsplhl-aiea dna easestthb-e ear xlspeeam of yndrcosae crtuu.sstre hTis can eb ughohtt of a iisanmeoftant fo het lphaa le.hix

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 +0  upvote downvote
submitted by an_improved_me(91)
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hNotreA awy ot egt ta ti is avi :noaimetinil

A. erghdnoy ngdbnio oltwdun rllyae agchen scine iherten annelai onr neicylg ear aB.op lr lyG t&g; Aal 'tluhdnos naghec ohw poienrl si ideimdof (I neam it LCD,OU if ehert swa a etisrc nanercdhi or htomsiegn, tbu otn a retag we. r)Dsna ginhtno ot idneatic that lgceanol drenagedoti is adtreel in rseenosp ot an AA nttotiuubs.is Ao,sl in eht txonect of IO (hwhci si het tngesipenr p,cl)atimno we rlydeaa nokw ttah eth eolmrbp eotsnd' have atnighyn to od iwth tneo,daedgir mreo iwth the cgeahn in cicu.u eEutfr/otnrtsn elosynHt do'tn kno.w

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 +0  upvote downvote
submitted by drdoom(1206)
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’esrHe eon awy ot smreoticepe-s-onilfa “dcersdaee gbonrddhen-oy frt”oiaom:n ’mI ont a gib naf of sthi inle fo negrna,iso utb yeialtlchcn laennai sa a sdie rogpu sah rmeo ohsrg*dyne rfo olpientat edhyrong ongibnd thna engycil:

lanean:i HC3—
clyigne: —H

oS, nl,yahceic”“lt nlnaaei loudw pemtir erom gnodeh-bryond a,mofrtoni iwchh itgmh owall uoy ot aitmleien htat c.heioc

tTah ad,si ti meess tosmla pssibomile to leur tou ih(otwut eyrv nthiceacl deknewgol or eosm dovepdir leetnxrieamp )tdaa atht the yligsthl algrre lanneia seod nto irpima ondyeghr ngdbnoi ewtbene aenocllg osleelmcu iva itserc sata)i(lp n.neifcrertee nI lermpis serm,t esnic niaalne is earl,rg ouy duwol nhitk ttah ti mstu wshmeoo rinrfeeet twih hte yb-iognhnenogdrd atth uscocr hitw eth yplet-diw yieglnc.

---
citrylSt* piaks,egn sti’ ton the ebnrum fo enyorhsdg tbu also teh tgernths of eht eodilp htta iataictefls grdeynho bdinno:g a eydnghor nbduo ot a yrsontlg egnartoveectiel lcemleuo leki oierulnf wlil rep”aap“ rome pvoietis and, s,tuh rogndhoy-dbne ermo yrnglost hiwt a nreaby gneoyx (dacrpeom wiht a rodyegnh cnctoeedn to raocbn, rof xpmela.e)

Furhetr g:driena

  1. ecg.d/qbue.u.ttm/ulhrlmoesuhc.ntdhspdwp/w/hlewid/p:hi
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hungrybox  erceipApta teh ertfof btu isth si afr oto ogln to be efus.ul +30
drachenx  hrgnxouby is a efkairgn rteha +
drdoom  ehdca@rnx ha,ha nha, mcongi akbc ot tsih i rezaiel i asw orbylabp iovgk-gneree oll +1
blueberrymuffinbabey  tis'n eht ydhrngoe dinbong pedeendtn on teh retaxdyylhod liornep nda yil?nes so atht 'nwdltou eyallr eb eht siseu rehe iscen toseh 'ntera eht aas inegb l?dertea +
drdoom  @luyrbrebe cArdiongc to Alsrbet’ oBMC e(se sgTtnane at rgt),ih ynylieyxordsh and helndyoyxprrio rnteiuotbc nrgdhoye nsdbo htat morf neetwbe teh asnchi i(t”riachnn,e“ sa ppoosed to anic-thra;ni eht i,schna fo s,ucroe rea esteapar iedeyspptl;op ahtt si, rteaaspe cngloeal eps;ntoir and aincentrisot eeetbwn parastee aincsh pe[arseta ilepo]tesydpp is thaw ew clal qrtauny“are tsurr”etu;c ees aTntneg baeov.) Adn in htsi ca,es as you pnito uto, eht tmse iercbsdse a A;l-&yGaglt tsb.stntiiouu aTht esmes ot eamn tow nh:gtsi (1) eth reeth eseapatr nleocalg eppsoiyedlpt iwll tno pk“ac []sa gt”tlyhi ot fmro eth lpietr lehix teuyqn=a(rar s)rructtue ew lal nkow nad eolv dna )2( onerilp ngisr liwl lifa ot alery tueiq as nylg,us gmniprcmoios het ecihlla nooarmnftioc atth eifdens an hlaap incah yas(c=oernd su;urecttr teh sapesh atth mrfo inhtiw a gliens ptyo.id)lpeep +
tadki38097  also uyo na'tc H nobd whit ,bcnoar sit' ont lprao goeuhn +
amy  002A2F 50P st:eat natiorfmo of hlwccnhepiogoalr( is teh eilptr hxlei eutcsturr) via ydgnhero nad lisfd.iude oS A is crctonrie bc eethr rae no lgoalnec lcolumsee yet d(n2 rusrceutt nehsppa ta conearlgplo v)elle +
drdoom  aym@ ltrepi ehxli is a rnueyqatar utsucerrt se(icn pirtel xihle si a hpsea tath sofmr WNBEETE pseratae ro “lu”dat p/cen-glaolaeloglrnco ).itepspde ai,rmPry crynodsae nad ertirayt tsusrcteur are cesinrptiods of a ielngs iedpetlpyp.o cOne oyu evah 2 ro eorm poteelspidpy rieignnattc twhi cahe ehotr .e,g(. nmeiogbloH mleeluc)o yuo veha tyeanruqar ettus.rruc +

From Molecular Biology of the Cell:

Hydroxylysines and hydroxyprolines are infrequently found in other animal proteins, although hydroxyproline is abundant in some proteins in the plant cell wall. In collagen, the hydroxyl groups of these amino acids are thought to form interchain hydrogen bonds that help stabilize the triple-stranded helix. Conditions that prevent proline hydroxylation, such as a deficiency of ascorbic acid (vitamin C), have serious consequences. (Emphasis mine)

https://www.ncbi.nlm.nih.gov/books/NBK26810/#A3555

+1/- drdoom(1206)

From Molecular Biology of the Cell:

The primary feature of a typical collagen molecule is its long, stiff, triple-stranded helical structure, in which three collagen polypeptide chains, called α chains, are wound around one another in a ropelike superhelix (Figure 19-43). Collagens are extremely rich in proline and glycine, both of which are important in the formation of the triple-stranded helix. Proline, because of its ring structure, stabilizes the helical conformation in each α chain, while glycine is regularly spaced at every third residue throughout the central region of the α chain. Being the smallest amino acid (having only a hydrogen atom as a side chain), glycine allows the three helical α chains to pack tightly together to form the final collagen superhelix (see Figure 19-43).

https://www.ncbi.nlm.nih.gov/books/NBK26810/#_A3551_

+/- drdoom(1206)


 +0  upvote downvote
submitted by nmb29(0)
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I ihtmg be regvitinnohk it ,btu H obdn rftanioom of as'a amkes teh edyoacnsr eurttsrcu of teh ripteon a(glocnle in htis e.s)ca heT lyG ot Ala onuubsitstti odse strule in ssel H bnod t,anifromo ubt fo iidnvialud a'sa tno eewnteb onllgeac eueoclmls at(ht tighm eb more for rtquayeran ucrturet)s

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lpp06  I ktihn hte yek si in eht srwena rhaingp,s het esnwra omtneniign Hsn-dob yssa "Drsntuopii of -Hdbnos ebtwnee cogenlla "ltcmAgeehoouhsllu nlgoalce osde oduenrg H-ngdinob ot toppusr eth letrip iehl,x htsi si endo ihtwin hte same coleganl ecumglik Lonln.ie tfndieerf lonlagce secmloeul orsucc avi eth yilsne - sydeyhilnorxy skiln noed ni het EMC +1
kevin  hsti si the oen tomncem atth lnfylai pehedl me ternadsdun why hatt aws nertcocir. nthka uoy +



 +0  upvote downvote
submitted by j123(16)
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imPayrr uttseurrc = onami icda oeSnccy dasrqeeune usrettruc = uurtrcets dfroem tiwh a ilsgne iaomn acid sqeuncee tb(ae pdlatee sehet, aaphl el,hxi ryTeitacre )t erttucrus = lleitpum adeocnsry etucrursst tnatinregic ehogttre lt(mepliu etab atdelpe shsete estdcak on pot fo echa hoe,tr ruaye rrettacQ)n utseurrtc = eoiprnt surtteucr ofdrme fomr noldgfi fo lal ityertra etrrctussu ot akme ngindbi e,itss tce.

Sneic het eanalni aws put ni aelcp fo hte lyeGci,n eht rpmriya rscuuttre saw ebauln ot mrfo an lhapa hxlie ecins alhpa ihlxe ctrsureuts ened a cilarutpar uqseeecn y(gl - x- )y in redor ot mrfo ogrydenh dbnso to eekp the heilx bat.lse

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 -1  upvote downvote
submitted by unknown001(9)
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awth is ecangoll ? a ydasornce rnptioe csetutr.ur

wehn ouy vemoer ,ncglyei hte tsom bandtanu inoma iadc , mfor teh corrpeurs colemule lilw you gte a orpper rsadcoeny uttrercsu ? ON

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unknown001  egirno shit +
drdoom  acn oyu taeelra?ob hs'wat norgw iwht ruyo mnmeco?t +



 -4  upvote downvote
submitted by lilmonkey(63)
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ylG is por,al Aenailn si prnlonao dan rhopdcbo.hiy inssMsee tnsnvaeeoncivor .aotmuint ehseT AAs evah tfeefrnid hiecclma porrpeseit hhciw aled to depirsdtu roeiptn oifnldg (aoyredsnc c)settur.ur iSlarmi ot ulG - aVl tutniisobuts ni ilkSce lCle eeasisD.

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