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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 sah snioehtmg to od ihwt nyclegi (ued to sti slalm seiz ti cna ift in nmay lpceas hwere hoter miano cdias nca ton and enche it provdeis tuc“lartusr ocstcn”apems ot eth leol,ngac ie.. tup a kkin ni teh haalp ihel)x. fI legciny si lemspcadi yb gonsmhite ,sele I ntod’ thkin lor-pgeolanc acn morf tsi crteroc sayceondr e.stuutrcr

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jotajota94  T!ure slo,a ilyegnc is 1/3 fo aelgclon afla anshc,i os it kseam nsese atht tutiuositsbn hwti ennalai hcwih( si cmuh )rigebg ulwdo aedl ot riupdisont ni the hlaap exhil i.ftnoomra +2
jotajota94  rTe!u so,la ieglncy si /13 of naeoclgl fala ha,cins so it akmes enses ttah tuiubtstnois tiwh eiananl h(wchi is uhcm gbrgei) dowlu ldea ot strnudipoi ni hte laaph lhexi onfat.imro +
thepacksurvives  lGneyci is lmasl and beyd,n iwchh laswlo it to romf het ibrflis orf eht ltipre xhile +
brasel  loAs in nlraeeg AF( 8102 gp 05) OI is frmo rplbmeos nrfgoim hte eptirl ixelh hchwi si deoayscnr steucurtr. tlF,toaryeun ythe vage su hitmegosn ot aesrno whti ni teh qstouein )aA;(-lt&Gygl +3
amy  naC osenemo ehlp me nerdntadsu why A is ccrrie?nto F20A20 gpea :05 lTeipr elhix of 3 gocalnel a naishc si roemdf mrof lolpngoacer iav egrdohyn nda idduifles bnd.o Is tsih eryv liamirs to athw A is Ar?bdn e.igci aeesedrcD gdyoohn-rbnde iranoftom newteeb lecgonla llsuo.ceem +
umpalumpa  hTe xnanleatpio evngi yb lewabiaaatrls uoldc kowr fi teh uosnqiet dwulo yas g-t;lG&ylAa- miut.otan vwreH,oe hte iotsuenq estsat ttha eterh si an &Ga-A-tyllg; tauitn.mo +



 +13  upvote downvote
submitted by cellgamesgojan(43)
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I dur,gefi cYneiXly--g is elclthcniay rdscdeneoi a “rpiyram aiomn dcai rtrtusceu fo a t”poenir nisec het defiionint of a mirayPr ecutrusrt fo a eoitrpn si “a iearnl cinah fo amnoi i”cd.sa fI ouy sesm ithw eth raryPmi ,ucrttrsue as in hte utnsoieq ,tmes uoy tconna mofr het anSyocrde cruttsreu fo eth ,oterpin cihwh si etrdemedni by eht ghroobngnydinde- cwhih osrccu wtebeen eth peeitpd nkeaobbc, eneipendntd of the R pu.grso I hope shti eadm n.ssee

rmFo piiaedkwi: yoe“Sancdr tcuetrrus is llymoafr fedndei yb hte tarnpte fo rdognhey nbods neetebw teh omina eygrhndo nda rclayxob ogyenx mosta in het epietdp eacbnobk.” eha(ssmip n)mei

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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 uysg dna i oetqu orfm ia/n.hie/etowh0p/4lttsdtto/rc.aii2swoeslgwotfsu:msrbcepermpo/e1-cest

%"90 vaeh na tfelbeiadiin genitec nutmtaoi LCO 1A1 dna OLC 12A
ssa uec aaolmrbn elcolagn lkssgniic-ron vai a iylcgne intsbututois ni the eoarnpgollc omeullce "

hhicw manse htat OI ahs a yilcgne iontstutusbi and fereorth ist anuleb ot fmor a acsnyreod sruc.tueurt

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 +4  upvote downvote
submitted by hungrybox(1277)
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eDu to icey'snlg msall zi,se ti asrecet iknsk"" in teh ainmo cida ene.qescu sheeT nkksi ear ededen ot terocyrcl rmof het rycdaenos .tcurrtues

eOrht wnse:asr

  • aneked"ew ctiatirnone tebwene lcnoglea adn oot"rnycpgela - oelgncal + arlocntyepog = a.tallrgcei Teh uteinqso tsme etnonmis aynm cdefste in bNEO t(eyp I a)gllneoc utb no niomnte fo eceftds ni rTceWlOglaa ep(yt II eloglan)c
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 +1  upvote downvote
submitted by basic_pathology(25)
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-lXy-YG si bneabokc ofr eagnlolc pahla hi.nca 3 egolnalc hapal sanihc rspila to orfm tperil hel.ix ycelnGi sha no R p,ougr onalglwi orf bfytelixili adn foirmtano of rilpet heli.x No cyelgni rvenptse iths uuncotions lpinagrsi, tneipngrev het aftrooinm of lnaelogc acysedonr s.uurtcter

caelRl atth hphcaaseei-ll nad thebasse-te rae psmlxaee of daensyocr uttsucser.r ihTs acn be htguhot fo a tesoftannimai of eth alaph lei.xh

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 +0  upvote downvote
submitted by an_improved_me(91)
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ohtAeNr awy ot gte ta ti is via ieloinni:atm

.A hnogdrye dgnobin toulwdn lerayl nagehc seicn teihnre nalneai orn lencygi rea lao.Bpr yGl gt&; Aal ndluho'ts egcahn owh orlpnie si idodfemi I( eanm it ,LCUOD fi there aws a streci hcrdnaien or thmeno,isg utb not a ertga wneD) .asr nginoth ot cneaidti htta ecllnoga etddgaioenr is daeertl ni neerossp to na AA isunttbosut.i Also, ni the etcontx fo IO hi(wch si het preinnetgs ),lmatonipc ew adraely wnok ttha the omrbpel d'tenso aevh hatgiynn ot od twhi gitderaoen,d mroe htiw teh eanchg in iurottrsctf /n.uecEun stHlyeno 'otnd kon.w

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 +0  upvote downvote
submitted by drdoom(1206)
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eer’sH eno way to ati-enpom-ielseofscr ecsdaer“ed -ddboengyorhn i:f”anromot m’I ton a ibg nfa of hits ilne of ar,gosinen btu ctlayilcnhe ialenan sa a sdie grupo ahs eorm nds*yrgeoh rof oielpnatt nhyerdog gnindob naht ngeciyl:

n:anilae 3CH—
y:cnigle —H

,So ,c”letnayclhi“ neanlai wodul rimtep emor dnonbhey-rdog aomnofi,tr hhwci itmhg owall yuo ot linmiaeet atth iec.coh

That ,sdai ti emses amlsot bispsomlie ot eulr uot toihw(ut ervy hnltcaiec eldowgenk or omse ipvdreod iapexermtlen ta)ad htta the yitsghll rgelar eainaln odes not irapmi yoenghrd ndbgoin etnweeb clnlgeoa leleusomc vai sertic )aatisl(p ecenrfir.nete nI splmeri stmr,e cines nilneaa is argler, you woudl ntikh htat ti sutm hooewsm nrtfrieee htiw the ngodbnrhno-igdye tath rcsouc twih eth itlyp-edw ygencli.

---
lcStriyt* ,kaengpsi i’st otn teh urebmn fo edgnhryso tub losa the ntsgerth fo eth liedpo htta tcsiilaatef yrengdoh ig:ndobn a drhnygoe udnob ot a tryognsl trvniaeelgectoe loeulcem elki inuerlfo lilw pear”“ap remo esvipiot ,dan h,uts -hegndbondory oemr lsoytgnr htwi a bareny egyoxn m(redpcoa htiw a rdehgnoy ncetencdo ot b,aorcn rfo x)pemeal.

erurFth eig:darn

  1. ultt/prew.wshdhpbihcsmhp/eio.:dewdh.ln.t/uqgumu/edl/c
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hungrybox  aripeptAec hte teorff tub hsti si far oot goln ot eb u.elfus +30
drachenx  nbxhyorug si a efgrnkai rteha +
drdoom  c@hxedran ah,ah h,na gcnmio kcab ot tshi i iarleze i wsa pyolbabr kngieoeerg-v llo +1
blueberrymuffinbabey  ni'ts hte ghonydre donbign dentpeedn no eht xhdtyyerdola neirplo nda ysle?ni os ahtt 'dtwnolu ylrale eb het uessi here insce toehs enat'r het asa nibeg teradl?e +
drdoom  erbyuerl@b Ancrigocd ot estrb’Al oMCB es(e antengTs ta tg)hri, nosyxlhiyrdey and phnorlryidexyo iorcuntteb yorehngd nsbdo htat rfom teeenwb teh hisnac rnen”iac,h“i(t as edpoosp ot iin-nctaahr; het ishca,n of rco,use rea artsepae pop;pisdeylte taht si, sapraete onecagll ;etponris nda niottsreanic neebetw eatapesr nhcais sp[reaate ys]oppetedilp si waht we lalc a“rqtunayre rtcert”usu; ees Tngaetn bveoa.) ndA in htsi aesc, as you ptino ot,u eth tems sedceisbr a tGAal-g&yl; s.btunsiottui Ttah seems to mnea wot gshtin: 1() het teher etsaaepr clagnelo yedptplpeios wlil nto ackp“ ][sa ”thgytli ot frmo het iteplr hlexi art=nu(rqyae tureuc)trs ew lal owkn dan vloe adn 2() rpienol nrgis wlli lafi ot eyral utqie sa ns,ugly ncisigmmorop the iahclel mofntrnoocai ttah esdefni na hlpaa achni =(ecnoyarsd tetscuru;r eht saseph atth rfmo iinhwt a sngile pdt.)ypolieep +
tadki38097  sola oyu c'nta H dobn thiw ,craobn i'st nto lropa ounghe +
amy  A220F0 P05 s:etat afrintomo fo whcieagphrnl(colo is eht elitrp hlxie rstctur)eu via enhoyrdg nad d.iledifus So A si reicocntr cb ehetr ear no elancogl elulcosem tye (d2n reurutcst asnphpe at eolrogaclpn )ellve +
drdoom  @mya lerpti lhiex is a aqnaeyurrt ucutsrter en(isc iltper ilxeh is a hseap hatt rfmso TEEEWNB eeptasar or utda“”l oaplcelce-/lonlgarngo esipt)pd.e rry,maPi dsneoyrac dan treyriat cessrttuur rea etrinpssodci fo a nseilg .ledopppyeit nceO uoy heva 2 or mroe leoidtpspype innairgtetc hitw cahe eroht .g,e.( gnimlebHoo euec)llom you have qyreauanrt .cuustrter +

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 thmgi be nhiinotekrvg it bu,t H bnod faonmitro of s'aa aksme teh ecsyaodrn trecsrtuu of hte nitpeor e(gclolna ni sthi e.ac)s Teh lyG to alA iutntsiobsut odse seutlr ni elss H donb af,rtomnoi tub of nidviduail s'aa not eeewbtn llnogeca eluselocm tt(ah imght eb eomr ofr yarqaeutnr u)rcrtestu

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lpp06  I tihnk hte eyk si in eht reswan has,rnpig het awsren niietomnng dnbsHo- ssay usDrto"inpi fo -sdnHob bntweee lgolcane m ugAhtsohoeuellc"l ncleloga dseo dunoerg b-Hniognd to rotsppu the ipretl l,iehx hsit si deno hiwnit hte asem oanlcegl kon uig.cmeneLlli teiedffrn cnalleog uomcelsel csrcou via the ylisne - relxynhyysido lnksi ndoe in eht EMC +1
kevin  htis is teh noe mtmcoen ahtt illfnay ehdlep em usrnnaetdd wyh taht wsa itrrco.nec takhn uoy +



 +0  upvote downvote
submitted by j123(16)
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mrraPiy tsruectru = ioman dica noeyn Ssreeuceqdca utsrrecut = tcresuutr ofermd wtih a senlig inmoa aicd ueqeecns b(tae eptdlae htese, haalp ielhx, eerTiact ryt) utsetcurr = uplmelti csneyorda cstrutrues tnrieatnicg tehotgre (meltpuil baet tpealed eehsst esdatkc on opt fo hace ohre,t ear)trcru ayQnet rstrtcueu = tpernoi usttcruer froedm ormf gfolnid of lal ieyratrt uuscerttrs ot keam nbgdiin si,est etc.

ncSie hte naienla saw upt in eaclp fo teh Gelyi,cn eht apmiryr rtusurtce was enalbu to frmo an ahalp hxiel scnei plaha ehxil rtssruuect eden a urlrptaica ecenuesq l(gy - x- y) in dorre to from doegynrh nbdso ot kpee hte xehli s.tebla

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 -1  upvote downvote
submitted by unknown001(9)
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ahwt is claegoln ? a eyadocsnr poetrni eu.rsctrtu

hewn uyo eoermv lcyie,gn het osmt tbunnaad ianom cdai , omfr het souprecrr emlucole lilw uoy tge a porrpe oscnedyar etrsurtuc ? ON

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unknown001  neigor this +
drdoom  cna you el?taoaebr staw'h rwnog hiwt uoyr onmectm? +



 -4  upvote downvote
submitted by lilmonkey(63)
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lyG is ,orpal elnaAni si aropnlon nad rc.yhopdbioh seMissne vreoitcsnaneonv mtotu.ani hesTe sAA aveh ednitfefr ehimlcca ioeeprstrp ihchw elad ot tiedsrupd otenpir gfnloid dayoesrcn( )cutseut.rr iailSmr ot ulG - alV tinbtsiousut ni lScike lCel .Daeessi

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