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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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submitted by wasabilateral(47)
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I nkhit ti sha nmogehsit to od with ynicelg eud( ot its lmsal eszi ti anc fti in nyma psleca rehew teroh omnai sdcai cna ont dan cnhee it ovrdisep trcasruul“t sscapo”etmcn to hte angle,loc i..e utp a nikk in eth aphal .elihx) fI necgily is miepadlsc yb motshenig eles, I tdno’ inhkt npllgoo-reac acn omfr its rccerot nrsyoedca tu.eurrcst

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jotajota94  !True aosl, iegylcn is /31 of ocnlaelg lafa hscain, so ti askem senes atht souitbtiunst twhi ealnina chh(iw is chum begi)rg lowud lade ot rsnoiidutp in het apalh xileh .ofiamnort +2
jotajota94  !Treu a,slo lcyengi is 31/ of gllacneo laaf ha,isnc os ti ksmea snsee htta uobnititssut tihw ninalae wh(ihc si uhcm )eibgrg doluw deal to itundpsiro ni het ahlap hxile ornmiafto. +
thepacksurvives  nyGclie si mllas adn nbdye, hchwi wllsao ti ot fomr hte friisbl orf the pelrti elxih +
brasel  loAs ni erlaegn (FA 0128 gp 05) IO is morf orpslemb fgiormn hte ilrpte lxehi iwchh is edrosncay rtuercu.st yoaltFr,tuen hyet vaeg us stemignho to esnoar wtih ni eht tnsiqoue G&tla(gylA-;) +3
amy  naC osneemo lhpe me stnuednrad wyh A si ctnir?ocer 002AF2 apge :05 liTrep elhix fo 3 laoegnlc a csihna is efmdro fomr pcernolgalo aiv nryeogdh dna flesiddui nb.do Is isht veyr irmials ot whta A si ic ni?ergA.bd rceedDaes egddnhbnyoro- ranmftioo tbeneew oalnlecg s.emulolce +
umpalumpa  Teh aoaxinlptne negvi yb lwaaritealbas oducl rwok fi het qnseotiu udwol asy -g-&Ayatll;G .nttuoima ovwer,He teh inqoeust tasets ahtt tereh is an ygl;G-ta&Al- atmn.utoi +


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submitted by cellgamesgojan(43)
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I df,eugri ilygn-cY-Xe si chtenyaclil ienrdedsco a rpri“mya oaimn aicd uurstterc of a piote”nr necis hte fntidieoin of a yPmairr eucursrtt fo a tiopenr si “a lairne hcian of noami .sda”ci If uoy smse whti teh mraiyrP ,ucteusrtr as ni teh nsteuioq smte, you aonnct morf eht ceoySandr rtuurctse of eht e,tponir cihwh is eienddtmre yb het gdhordebgyninno- hicwh ocrscu teeewnb teh epditpe nbkcaoeb, nndeedintep of eht R opurgs. I epho hsti dmea nse.es

morF kwiipadie: do“ancyeSr tesuurtrc is mlaroyfl deeindf by the eattrpn of egyohdnr sodnb enetweb the amoni eondhgry and borycaxl xnoeyg staom ni eht ipteedp ekonbcab”. pamhe(iss nmie)

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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)

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 +4  upvote downvote
submitted by usmle11a(102)
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ok gsyu dan i quteo rofm ipt.rw/et//ech1tistocs/./e4imeewsowpulralr2n:sds0tof-tgtcsemeopoiahb

"%09 evha na niibaietefdl ieegtnc mtniotua OLC A11 dna LCO A21
seausc mablrnoa celgnlao s-liosnirckng via a gnelyic ntbiustoitus ni the ploengraocl oelecmlu "

hwich emsna ttha IO sha a neylcgi tbsontstuiiu nad otfrreeh ist lnuaeb to rmfo a sraceyond ue.strcurut

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 +4  upvote downvote
submitted by hungrybox(1277)
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eDu to ns'icglye lsaml z,ise it atsecer is""nkk ni eht ioman diac euqse.cne sThee skkni rae eeendd ot tcolerrcy mrfo eth onecyadrs seutrt.cru

htOre sasrwn:e

  • awedneek" aiencrniott weebent olaenlcg nda anclro"egptyo - lnalgeoc + cyogenoptlar = llgaircte.a ehT otqsneiu emts metiosnn many desefct ni ONEb tepy( I ogacnll)e but on noenitm fo cdeftes ni aeTlOclagrW (pety II n)olagcle
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 +1  upvote downvote
submitted by basic_pathology(25)
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X-G-Yly is naobcekb for oencllga aaplh niahc. 3 aelnogcl palha nchasi slprai ot fomr tlerpi e.ixlh nycGlei hsa on R up,rog nwlglaoi rof fybxliitlie nad minrofato fo elptri hxl.ei oN lngcyei tesvpnre thsi uintcusoon gilrn,pisa vnetnripge het mfoainrto fo onclgela nsydeaorc rsertctu.u

aleRcl ttah lahse-halpeic nda -sbhattesee are eplmasex of reysdocan .ructteruss Tsih nac be thhuotg fo a tnamsinofeait of het laahp lx.eih

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 +0  upvote downvote
submitted by an_improved_me(91)
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tNrAoeh ywa to gte ta it si aiv enna:tliomii

.A degnohry bgnnodi uldotwn aylrel acheng ensic etrhine eianaln nor igyecln ear oapB.r l ylG t&;g lAa sholtun'd eghnca who elropin si fidoedim (I aemn it ,LCDUO fi treeh asw a rtseic caridnnhe ro gehsom,int tub otn a etrga wsrn.e)aD nghoitn ot ainitcde atht lngeaocl odtrndeegai si aertled in speenros ot na AA uotsiitu.bnst Al,so in eht ocntxte fo IO cwih(h is the enespntgir a)pm,olticn we yealrad knwo ttah eht mrbloep n'dotse hvae igatnynh to od ithw d,ioteerngda mroe hiwt het caegnh ni oErucinr.tntust/cufe ntolsyHe dt'no nwok.

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submitted by drdoom(1206)
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re’eHs eno wya ot e-soretascfiloenpim- deerd“scea bydongrdnho-e io:”arnftom m’I tno a gib afn of itsh eiln fo nri,ensgao tbu hatlnlceicy ainalne as a sedi gpuor sha omre orednys*gh rfo tnaeploti engrydoh nndgibo nhta nlgciey:

l:iaanen C3H—
ne:icygl —H

So, lchlae“nct”,iy ninalea wdulo eritmp mero hn-reydonbdgo afmnroo,it hciwh tgihm waoll uyo ot eitenimla atht .icheco

Ttha a,dis ti esems tsamlo msespilibo ot uerl out tih(towu yerv ciahlecnt elgkedwon or oems dvpreoid peremilatnxe )aatd tath eth iglyhlst aglerr anianel odes ton pmiiar hgonyder oibdgnn tbeenew agnoecll lumlesoce aiv strice as(ipta)l etire.cnnfere In prsleim ,esmrt ceins aaenlni is ,eaglrr uoy ldowu hknit htta it mstu msoeowh rifnerete hwit eth nb-oydndogegihrn atth corusc htwi hte ydiwp-tel lngicey.

---
lti*yctSr ne,iskpga ts’i not eht mebrnu fo gdhnyeors ubt aols teh etthsnrg of the loidep ttah alteitsafic eygorhnd obgni:dn a ynodrheg unodb to a gynrtols etlrcgenoieeatv ulecleom eilk lnroeufi lwil pe”p“ara oemr tispevoi ,dan htu,s bhreyongnddo- mroe orntsgyl with a rnaeby noxgye pacedom(r with a ngrhedyo cenndceto to bnoc,ra fro )lep.mxae

rFrthue aeg:indr

  1. .mtpndwu/.hmichlutuuei/p/.r/s.owehed:b/hwedstdpgqlchl
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hungrybox  pAiaeetpcr the reotff tbu hsit si raf oot lngo to be lu.seuf +30
drachenx  gyrxubonh si a inkgeafr ehrat +
drdoom  r@dxhacen hh,aa nah, ocnmig ackb to tsih i leaizer i saw obbrplay nreegv-gieok llo +1
blueberrymuffinbabey  stni' eht hyrngedo obgndin nntepdeed no the yyddhartoxel enprlio and ey?nsli os tath olt'wdnu larlye eb the usies here incse htose n'eart hte asa egbni r?aldeet +
drdoom  ybeer@blur idArnccgo ot rbeAlts’ MBoC ese( asTngetn at rhg,)it odhlxiyesrnyy and nioehrloypxdry tetborniuc rengyhdo bdnso ttha ormf twnbeee eht nihsac ntah”i,“cn(eri as pedosop to aarnh-ti;inc hte hnscai, fo r,uoecs aer estapera tedlipe;ppsyo ahtt is, septraae noclgela opersn;it nda riasticetnon nebewet eeatpras ncihas [aasteper ppielestpdyo] si htwa we alcl qrarnuyet“a ;stueurrtc” see ntgaTen boaev.) dAn in sthi c,esa sa uyo pntio ,otu hte tsem bsdericse a ;&Glya-ltAg iitn.osstbuut thTa esmse to eman owt :stnghi 1)( hte htere estaepra laglecon dpyeptsiople lwil nto “ckap ][as i”lthtyg ot frmo eht tplrie exilh y=utraerqan( cr)rtusteu ew lla wnko nda velo dan )(2 noeripl inrgs ilwl afli to early uetqi sa sng,lyu oisngcomimrp teh ihcllea notracoionmf tath ndiesfe an alahp nhcai nrsodcae(y= tr;erucuts hte shpeas tath fomr wihnit a iesnlg )lyieppd.tepo +
tadki38097  lsoa uyo 'antc H dobn hwti ca,nrbo 'its ont aprlo nuhoeg +
amy  AF0220 5P0 aes:tt irtnafomo fo wil(pglnroeaochhc is het epiltr xhiel ctutrur)se via yhdnerog dan elii.ddfus oS A is rrtinocce bc trehe rae on oalnegcl lsceuoelm eyt d(n2 tstruuecr nspehap ta lrecoogpanl )lvlee +
drdoom  @may lreitp hxeli si a tnryuearaq rtrsetcuu iensc( rietlp lxehi is a ephas atht mfsro WTENEEB etrsaeap or lad”t“u la-pnocllanl/rgceogoe petiedps). mrra,yiP rdoyensac adn iatyrrte rttucruses rae onrtipiecsds fo a nglies ypedi.tpoepl ecnO yuo aehv 2 ro oerm poeytpdpeils irtniengact ihtw aech toreh .e.(g, gomnebiHlo )lomeeulc oyu heav qtarauynre tcser.utur +

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)

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submitted by nmb29(0)
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I gmthi be itrnivheogkn it ,tub H nbdo nfatmoior of 'saa kmsae hte rynocasde uurettsrc of eht pontrei gacoll(ne in tshi sa.e)c ehT yGl to Ala sbtniuoutsti sdoe surtle in sesl H odnb tmi,orfaon btu of ldiuavdnii a'sa nto entebwe lcgonela eslmoclue ahtt( ihgmt eb oerm fro rreauanytq erustu)crt

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lpp06  I iktnh teh yek is in teh nsware ,hgpnairs eth eswanr iinnogmtne os-dHnb ssay su"tronipDi of snHbdo- etebwne gloclnae seo Aellguhhulmo"ct lalecogn esod duerong bgnHnd-io ot sptuopr the telrip lxei,h sthi si edno nthwii eht msae nleaclgo ie kmigon.ecLunll netfreidf glcelano ollseeumc sucroc aiv teh selyni - xseyloihrdnyy liksn edon in the MCE +1
kevin  this si het neo eotcmmn ttha nialyfl dhlpee em utnrddsnea why ttah was oiccr.enrt thnak yuo +


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submitted by j123(16)
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raiyrmP crttsruue = oaimn cdia qsaeecrcdueSnyen o eursttcur = rtutuesrc omrefd hiwt a linsge naomi dcai ecnsuqee abt(e epdltae sthe,e lphaa ,xhile raeT)treycit sutrtcreu = tlelmuip rdyoescan trecssturu gtiriancten egethotr uiml(ptel tbae eedtalp heetss atkcsed on pot fo hace oreth, u)yQrtern tacear etutrrcsu = penirot urestrtuc eormfd frmo glodnfi fo lla aeyrtirt rtuusetscr to mkea gidbnin ise,st ce.t

neicS teh ailanen swa tup ni pacel of eth eGnc,yil eth irpamyr ttcreusru swa nlaueb to rfom na phlaa hlxie eisnc alpah xehil tcurteruss need a lcptriuraa nuqeseec (lgy - -x y) in oerrd ot ormf ndryghoe nbsdo to keep hte lhxei etbl.sa

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 -1  upvote downvote
submitted by unknown001(9)
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wtah si ngaeclol ? a orecndasy ritenpo t.ruurcets

newh oyu eeomrv gnl,eyci eth most undatban oainm acid , mrof eth rurcsreop emeloclu ilwl oyu get a poprer yceodnars ctrtusreu ? NO

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unknown001  rgnoie sthi +
drdoom  nac oyu ?eoataberl t'haws orwng htiw oury m?mtcoen +


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 -4  upvote downvote
submitted by lilmonkey(63)
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lyG si aporl, alAienn si nopaonrl adn oi.chyphdobr eensssMi nnostineraveovc ntamou.ti eTesh AsA hvae nedefirtf lhmeicac prtrsepioe wihch lead to isdpudert ptniore ldngiof resocnd(ay tes)cutur.r iSalmri to lGu - alV iisustntbuto in lSiekc Clle ieeDsas.

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