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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 hnikt ti has hosemnitg ot od tihw nyiclge ued( to ist slmla izes ti acn fit in mnay epaslc ewhre rtohe maino ascdi can not dna hceen ti vpodrsie stuarcturl“ a”ectonmpssc ot hte lnlecg,oa .ie. utp a ikkn ni teh hpala ihexl.) fI egcinyl si pmicdlesa yb nhieomtgs lse,e I tnd’o kinht opalcogrl-ne acn fmro tis torcrec doeynarcs rtct.ureus

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jotajota94  eur!T ,saol nceligy is /13 fo lcalogen flaa sac,nih os it keams essen tath uttnosibistu thwi naleian ihc(hw is hucm ei)ggrb wodlu aled ot idtiospunr in the lphaa hxiel .nmioroatf +2
jotajota94  uTr!e ,aslo lygncie is 3/1 of lglocnea alaf ncis,ah so it esamk neses atth utbusitonist twih eanilna chw(hi si cuhm rigebg) dlouw eadl ot tipusniord ni eht lpaah heixl tfo.aonrmi +
thepacksurvives  Gcnleyi si sllma nda d,enby hiwch awlols ti to rfmo teh sibrfil fro teh perilt lxehi +
brasel  Aols in glerane (AF 2018 pg 50) IO si form esormlbp omigrnf eth iertlp lxhie wchih is yaoredcns csuretrut. uelaytroF,nt heyt gvae us mtignseoh to noaser itwh ni the sinetuoq lg;-)ya&l(AGt +3
amy  nCa omeosen ephl me drseatnudn hwy A is reiocntr?c F2A020 apeg :50 pilreT ihxle fo 3 ngllacoe a aicnhs is rmdoef frmo pollrangeoc vai yoegrndh nda ufesiidld d.bon sI hist vyer rmisial to wath A is n gAbdiecri.? Dcsaedeer ybnnohr-eddog moirfoatn eeebtnw legcanlo sceml.euol +
umpalumpa  hTe onentialapx gvein by lbrsetawaalia culdo kowr if eth qiteuson ouldw ays galGAl&-;ty- iottuanm. w,eHevor het tuqsonei setsta ahtt rehet si na Gl-A-ygtl&;a uoattnm.i +



 +13  upvote downvote
submitted by cellgamesgojan(43)
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I re,gidfu gXil-cenyY- is naciychltel renseicdod a ay“primr mnioa dica sttruucer fo a rtienp”o sinec teh iionneftid of a mPriyar ectrsutur fo a eiortnp si a“ aerinl cnahi fo inaom c”.said fI uoy mses hiwt eth yamPrri sertcu,rtu sa in eht sqiuonet mse,t oyu tcaonn morf eth eracoyndS reuuttsrc fo teh ,onetpir whhci is eeenitddmr yb hte nindenyorhg-obdg hwich souccr enbeewt het eedpitp nabkobce, ndpeeitdnen of teh R sgou.rp I phoe isth mdea sne.es

rFmo eiidpiwka: yaenSo“rcd cttueurrs si mrloflay dedeifn yb eth rtnptae fo hynoegrd nsbod beewent eth animo gyednhor nad cbrxoyal gxneoy mtsoa in eth dppeiet ocbbkean”. i(sspameh n)mie

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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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ok ugsy nad i uqeto fmor s/oetse:c/4tpierc-c1hpww.adletna/.sw0rrostugits2/th/eisiopbtfeommelo

%9"0 ahev an lnfiiatdeeib neiectg umatotin L CO 1A1 nad OLC A12
ucsesa oaablnrm ogllance gkscnsiilron- vai a ygnilec ottutsibunis ni teh rlpaolgonce ceelomlu "

iwhhc amnes htta OI ahs a ycenilg itntsbtiuous and tfrreoeh ist aeblnu ot frmo a yandrcseo usrteut.rcu

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 +4  upvote downvote
submitted by hungrybox(1277)
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uDe ot cselingy' lsalm ,szei ti aertcse inks"k" ni hte imona idac eu.neeqcs Teshe skikn rea ddneee to rryectlco fmor the csyaordne tce.urturs

thOer nwse:sra

  • eeeak"nwd tcaentoirin wetneeb enollacg dna apyrtnclogeo" - llngaeoc + grypenotaloc = elir.atclag hTe steunioq mste onntemsi myan cdtesfe ni bOEN pte(y I ocgnle)al btu no etnniom fo tcsdefe in lWgcraalOeT pet(y II lolceng)a
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 +1  upvote downvote
submitted by basic_pathology(25)
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--YGXly si ekabnboc orf lgenaolc haapl .achni 3 glclnaoe paalh shnaic slrpai to fmro rlpeit hielx. ilnecGy sah no R rop,ug oillnawg for fixybelliti and romtoinaf fo ptrlie xli.he oN ynlcgie nvpeestr hsit ouontucisn npi,alrisg pnreviengt hte aormtfoin of olcanegl dcrnayoes cttuu.rres

aeclRl htat hlhpai-ecelas nda s-athseetbe era pameslex fo dnaycoesr cutrsrut.se hTis anc eb tuthgho of a mtsafoeaiintn fo het alhpa el.hix

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 +0  upvote downvote
submitted by an_improved_me(91)
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ArtNeho awy ot egt at it si avi :ieoiitnmnla

.A ndegoyhr gnodnbi wdtolnu arlely ngaehc ecsin henetir ianenla ron cyenlgi era rlo.pBa Gly ;gt& Ala hdoluns't ecgnha ohw onprlei si ieofiddm (I mane ti DOCLU, fi heert wsa a cistre erhiadnnc or mg,hiensot ubt nto a agert )e .rwDnas tognnhi to dceiatin thta eognacll droteadeing si arletde ni rnpeeoss to na AA usson.titubit os,Al ni teh cnxetot fo OI ich(wh is teh srpeetingn ipco,la)tmn ew rlyeada kwon atht teh emlpbor 'odetsn veah iayntnhg ot od iwth naod,getiedr rmoe wiht eht ehncag in rcrsuofn cEtt.n/eiutu oteyHlns 'nodt nk.wo

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 +0  upvote downvote
submitted by drdoom(1206)
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rees’H neo ywa ot ten-lsofaepiorsmec-i ser“cdadee deoby-rhgnnod io”:tafromn m’I ton a gbi fna of iths inle of r,ainonesg tub elhlacyicnt anenial as a edsi oprug ahs erom n*dgyrheso rfo pntloatie yherdgno ngbiond hnat ynleicg:

eani:nal C3H—
nceyil:g H—

oS, laccni,t“eh”yl leainan odlwu tmepri roem onyhd-rbodgne fntim,roao ihhcw tmigh oawll you ot eimnetlai hatt ochi.ec

ahTt ,idas it essme mtoals psileoibsm to rule otu i(wuohtt eyrv nhelcciat oenwdkegl or moes pdrioevd ntplexereaim t)daa htta eth lyihltgs geralr nanilae esod ton mrpaii ehdynorg ngbidon weenteb oecnallg selmcleuo aiv tecisr pa)ialst( eeifrennre.tc In srpmiel ,mters nisec nenaila is ae,rrlg yuo uwdol khitn htta it tmsu oswehmo ernirefet whti het n-oenydbigornhgd ttah ocsruc with eth el-wipytd ylcengi.

---
Scrtity*l psgak,nie ’tis otn the bnermu of rgdynesoh tbu sloa eht enhgrstt fo the eipodl ttha laficttaeis hydonger ngd:obni a hogndery dnubo ot a sntoylrg ctraeeotlenevgi leolumec ikel liouenfr liwl ar“”ppea reom piotvise nda, ,usht hognoyrbn-ded remo stlygorn wiht a ynaebr gynexo m(ocdrape iwht a orgyhden coendntce ot nobc,ra ofr .)aempxel

Fturreh aeigndr:

  1. wetm/l/suerp/tuuqpdtmbis/whedhhoddcnw.c/.hlulh:gpie..
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hungrybox  Acpetepira the eftrof tub stih si far oto nlog ot eb .ueulsf +30
drachenx  nbghoyxru si a nfrgikae etrah +
drdoom  ne@xacdhr a,ahh nah, coingm kcba to shit i eaezlir i asw byopbalr vkinoeg-eegr lol +1
blueberrymuffinbabey  stni' het hnerdgyo nobnigd ddteneepn on teh traodylhxeyd pilnero dan l?sneyi so atth londt'wu yerall eb het eissu hree icesn those 'eatrn het asa ebgni letaedr? +
drdoom  yeelb@urrb cricAdngo ot sltrbAe’ MCoB (ese Ttnnages at gtih)r, yxryinhyoesdl nad porxeydnhlroiy ntitorcbeu edrnoghy sbond htat romf bewenet eth ihcasn h(ctr“na”i,nei sa epoodsp to -aaiht;nnirc het cihsan, fo c,ureso era saeeatrp eoiledytp;psp hatt i,s taapeers algoecln rtin;oeps and nsttcioenria etweben seratpea incash estarap[e yoeplpdipt]es is wath we alcl “yruanqetra r”;urtctues ese etnngTa voaeb). Adn in shti aesc, sa yuo otnip otu, eth emst iseedcbrs a ;laA->lyG .tossituunbti aTht sseem ot eanm two ih:sgtn 1)( hte terhe partaese nogllaec eydpppotiles will otn “apkc a[]s htyt”igl ot omfr eth rtplie ixlhe t(uen=qraary euturstr)c ew all nowk dna vole and )(2 nroplie gnisr wlil aifl ot leary ieuqt as ,usnlyg pmroisgcoimn hte caehlli ontiramncoof htat isfdeen na lpaah nahci y=oarnscd(e trutecusr; het psshea that mrfo htnwii a gnesli p.l)ydopeetpi +
tadki38097  losa uoy ac'nt H odnb ihwt anro,bc 'sit otn loapr uhgeno +
amy  0A220F 50P tse:at onfmraito of gceorhnwllhiopca( is het ilpret hxlei csurrtut)e vai nhdreogy nda .ufsliddie oS A is rencitcor bc there aer no gcollaen mcleuseol yte d(2n urtcrseut hpnepas ta rcoenglopla eellv) +
drdoom  ym@a pteril xihel si a qaratyuern ursutcter si(cne ertlip xeilh is a eaphs ttha rmsfo EETENWB aeetaprs or dluta“” oaepo-grllcelnnaloc/g )i.eesppdt imrPyar, oedrcnysa nad artitery trsstcrueu rea eotiisrdcsnp fo a egilns epedity.oplp ceOn uyo ehva 2 ro more yepdetilsppo rttgcininae hiwt echa rohte ge(.,. eHngolbomi ecumlelo) uyo aehv natraryueq sr.tcueurt +

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 hmtgi be thiknvgreoin ti bu,t H dobn otniomfra of aa's asemk teh ynsrcaedo trsuetruc fo het oprinte la(genolc in ihts e.cas) The lyG ot Aal tuinbiottsus dose srletu in ssel H ndbo otorianfm, btu of iaudldivin sa'a nto weenebt cogllnae meleocslu atth( hgimt be ermo rof etryaaqunr suru)tcetr

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lpp06  I tnihk eht yek si ni eth saenrw i,anshrgp the serwan eginnnoimt on-Hsbd ssay u"pontiiDsr of Hsb-odn etwenbe econgall e glAeuolutlhc"hsom allgnoec dsoe egdronu oHgid-bnn ot uprsopt eth pltrei e,ihxl stih is edon iwhnit the smea cngaoell ngelLelcmuko.iin intffrdee gnaleclo loscleume ocrusc aiv teh nyleis - enslydxryiohy lsikn oned in hte MEC +1
kevin  ihts si het eno emonmtc htat alfyinl ldhpee em raunddsnte yhw atht saw tecrrcoi.n kathn oyu +



 +0  upvote downvote
submitted by j123(16)
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iPmarry trrecutsu = naoim daci qSecs euncyodnerae esrutcutr = tcurtseru odferm ihwt a egnlsi ianom aidc eunecqes (beta peleatd ,etehs pahla h,xile erTtt e)icyra scturuetr = meptllui ecrnysoda tcrrutseus icgnttaneri etorhegt mlletiu(p etab etaplde teessh dkctsae on pot of ahce tehr,o ratr)euertQacyn rtsruetcu = nripoet errustutc omefrd mrof gfdlnio fo lla trytaeir ctrseuusrt to eamk igbnind ,tsise te.c

Sicne teh niealan swa utp ni acepl of the ,ineylcG het rriapym rrtuctseu was leanub ot form an aaphl ihelx cneis phlaa xielh tstrruecus dnee a iclapatrur eseuqcne (gyl - x- )y ni redro to rfom oehynrdg nbsdo ot peke eht lxieh lea.stb

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 -1  upvote downvote
submitted by unknown001(9)
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twha is enllcgao ? a oandyescr eitpnro utectrs.ur

enhw oyu eemrov nilcey,g eht mtos anuntdab namoi caid , rmof eht rcrerosup leeuocml iwll uyo get a rerppo dsyonacer ruscuetrt ? ON

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unknown001  groeni hist +
drdoom  acn you ereoal?tab 'shwat nogwr iwth uyro meotcn?m +



 -4  upvote downvote
submitted by lilmonkey(63)
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lyG is ,rpola aneAiln is nnparool nda iocyprb.hhod nMissees intonsvvaroenec .untimaot sheeT sAA haev dnrfeetif hacelicm ppotrisere iwhhc ldae ot eddiurpts entriop oildfng (ydonaresc rrtcuestu). lrmiSia to uGl - laV oiunutbssitt ni Sickle Clel eseiaD.s

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