BCH exam 2 Questions And Answers

BCH exam 2 Questions And Answers
-tCORRECTttANSWER-HYDROLYSIStOFtNUCLEICtACIDS
Modificationtoftnucleictacidstrequirestthetabilityttothydrolyzetthetphosphodiestertbondstthatth
oldtthemttogether

2tMethods:
1.tAcid/BasetHydrolysis
2.tEnzymatictHydrolysis
-tCarriedtouttbyt2tgeneralttypestoftnucleases
1-tExonucleases
2-tEndonucleases

2tSub-tTypes:
TypetA
Cleavet3'tend
*t(closerttotbAsetoftsugar)
TypetB
Clevet5"tend
*aBovetsugart(andtabovethast5tletters)

Cephalint-tCORRECTttANSWER-
Atglycerophospholipidtintwhichtthetaminotalcoholtistethanolaminetortserine

LiketLecithin,tittconsiststoftatcombinationtoftglyceroltesterifiedtwithttwotfattytacidstandtphosp
horictacid.tWhereastthetphosphatetgrouptistcombinedtwithtcholinetintLecithin,tittistcombinedt
withtthetethanolaminetintCephalin.

Coconuttoiltistparticularlythightint___________t__________t(bothtsaturated)tandtcontainstlit
tletunsaturatedtfattytacidt-tCORRECTttANSWER-laurictandtmyristictacids

ComparetandtcontrasttCa+tATPasetandtH+,tK+tATPaset-tCORRECTttANSWER-
Ca+tATPase:
Ca2+tactstastcellulartsignal
Muscletcontraction:tnervetimpulset→tSRt→treleasetoftstorestCa2+t→t[tCa2+t]tincreases
Muscletrelaxation:tCa2+thasttotbetpumpedtbacktintotSRtvesicles,tthististdonetbytCa2+tATPa
se
pumpst2tCa2+tionstINTOtSRtforteachtATPthydrolyzes

GastrictH+/K+tATPase

,couplestATPthydrolysisttotthetpumpingtoftH+tpittoftthetceltandtK+tintotthetcell
electricallytneutraltbecausetchargetist+1tintbothtdirections
thetK+tiontistpumpedtouttalongtwithtatCl-
tiontintanothertelectricallytneutraltprocesstusingtassociatedtmembranettransporttsystem

nettresulttistmaintenancetofthightHClt[t]tintstomach
bctpHtoftstomachtist0.8ttot1tandtcellstthattformtthetliningthavetatpreferencetoft7.4tsottheretistat
concentrationtgradienttacrosstthetmucosaltcells
thistconcentrationtdifferencetistessential,tBUTtbecausetoftpassivetforces,tthetgradienttwontt
betmaintained

structurallytverytsimilarttotNa+/K+tATPase

Definetatglycoproteint-tCORRECTttANSWER-
proteinstthattcontaintoligosaccharidetchainst(glycans)tcovalentlytattachedttottheirtpolypepti
detbackbone.

-tcantbetanytformt(mono,tdi,tpoly)torttheirtderivatives

DefinetthetDt&tLtstereochemistrytoftcarbohydratest&thowtittistdeterminedt-
tCORRECTttANSWER-basedtofftglyceraldehyde,tCH2OHtdowntintfishertprojectiont

-tlooktattsidetoft-OHtgroupt

-OHtontright:tD-tconfigurationt
-OHtontlefttL-tconfigurationt

***tOHtofthighesttnumbertCarbon

DemonstratetthetdifferencestbetweentRNAtandtDNA.
WhattaretthetmajortdifferencestbetweentRNAtandtDNA?tWhattrestrictionsdoestRNAtpresent
?t-tCORRECTttANSWER-
RNAthastOHtgrouptatt2'tposition,twhereas,tDNAthastonlytathydrogen
DoubletstrandedtRNAt→tcelltdealth
Restriction:tcanteasilytbetdestroyedtbytalkalinestbecausetoftthetOHtgrouptpresent
Doestnottfollowtchargaff'strule

DNAtcontainstThymine,tRNAthastUraciltinstead
SingletstrandedtDNAt→tcelltdealth

Describetactivettransportt-tCORRECTttANSWER-
movementtoftparticlestacrosstplasmatmembranetAGAINSTt[t=tgradient
energytcantbetprovidedtviatATP,tlighttenergy,tortEnergytstorestintiontgradient
UsetoftLighttenergy:tusedtbytcertaintproteinstsuchtastHalorhodopsintortBacteriorhodopsinttot
drivetcellulartprocesses
lighttEtsetstuptatprotontgradienttacrosstthetproteintthattdrivestconformationaltchangestintprot
einstthattfacilitatetprotontexporttfromtcell
requirestspecifictcarriertproteins

,ex:tabsorptiontoftglucosetandtaminotacidstbytcellstintthetsmalltintestine
Alltactivettransporttreactionstaret_PROCESSEStOFtCOUPLED_treactions.

Describetandtexplaintthet""mosaic":tparttoftthetfluidtmosaictmodelt-tCORRECTttANSWER-
Amphipathictmoleculestconstitutetliquidtcrystallinetaggregatestintwhichtthetpolartgroupstaret
directedttowardstthetoutertphasetandtthetnon-polartgroupstaretsituatedtinsidetthetbilayer
Transmembranetproteinstwhichtpasstthroughtthetlipidtbilayertpossessttheirtactivetsidettowar
dstoutertphasetandthydrophobictpartttowardstinteriortandtaretoftapprotientetsidettotfittintthetlip
idtbilayer
Thetdistributiontoftphospholipidstintthetoutertandtinnertsurfacetisthighlytasymmetrical
Thetoutertlayertconsiststmainlytoftlecithintandtsphingomyelintwhiletthetinnertlayertistcompos
edtmainlytoftphosphatidylethanolaminetandtphosphatidylserine
Glycolipidstaretmainlytpresenttintouterthalftoftthetbilayer
Thetmaintcomponenttoftthetplasmatmembranetistthetphospholipidtbilayertwiththydrophilictpo
lartheadstoftthetlipidstorientedtoutwardstandthydrophobicttailsttowardstinsidetformingtthetcor
etoftplasmatmembrane

Describetandtexplaintthet"fluid"tparttoftthetfluidtmosaictmodelt-tCORRECTttANSWER-
Fluidity:
Fluidt2Dtmodel
Thetmaintcomponenttoftthetplasmatmembranetistthetphospholipidtbilayertwiththydrophilictpo
lartheadstoftthetlipidstorientedtoutwardstandthydrophobicttailsttowardstinsidetformingtthetcor
etoftplasmatmembrane
phospholipidstaretfreettotmovetsideways
membranetproteinstmaytbetfluidtortanchored
anchoredtstrengthentmembrane
proteinstandtlipidstaretfreettotmovetlaterally,tbuttNOTtfacettotface
membranestaretintmotiontwithtfasttdriftingtlipidstandtslowertdriftingtproteins

describetbulktflowt&titstsubtypest-tCORRECTttANSWER-
ulktFlow:tVesiclestaretusedttottransporttlargetparticlestacrosstplasmatmembrane
requirestenergy

2tTypes:
Exocytosis
cytoplasmictvesiclestmergetwithtplasmatmembranetandtreleasetitstcontents
ex:tgolgitbodytvesiclestmergetwithtplasmatmembranetandtreleasettheirtcontents
ex:tnervetcellstreleasetNT

Endocytosis
PMtsinkstinward.tpinchestofft&tformstatvesicle
vesicletoftentmergestwithtgolgitfortprocessingt&tsortingtoftitstcontents

-->t3tKinds:
Phagocytosis
"cellteating"

, membranetsinkstintandtcapturestsolidtparticlestforttransporttintotcell
ex:tbacteria,tcelltdebris,tfod

Pinocytosis
cellt"drinking"
celltbringstintliquid

ReceptortMediated
membranetsinkstintandtformstatCOATEDtPIT
thetpittpinchestclosedttotformtatvesicletaroundtthetbondtsubstance
cytoskeletontaidstintpullingtintthetmembranetandtvesicletformation
ReceptortproteinstintPMtbindtspecifictsubstances
e.g.tvitamins,thormones

Describetchanneltproteinst-tCORRECTttANSWER-ChanneltProteins:
facilitatestactivetORtpassivettransport
providestcorridorstthattallowtspecifictmoleculestortionsttotcrosstthetmembrane

uniport,tsymport,tortantiport

Describetdifferenttfunctionstperformedtbytthetplasmatmembrane.t-tCORRECTttANSWER-
Thetmaintfunctiontoftplasmatmembranetisttotseparatetthetcytoplasmtintthetcelltfromtthetoutsi
de

Othertfunctionstcantbet
Exclusiontortremovaltofttoxictmoleculestandtions
Importtoftcelltnutrients
Energyttransductiont(fromtsurroundingtsystems)t
Celltlocomotiont
Reproductiont
Signalttransductiont
Cell-celltcommunication

Describetfacilitatedtdiffusiont-tCORRECTttANSWER-
small,tpolartmoleculestandtionstdiffusetthroughtpassivettransporttproteins
withtconcentrationtgradient

DescribethowtthetoligosaccharidetchaintoftglycoproteinstfunctionstintSelectinst&tMucinst-
tCORRECTttANSWER-

Mucintistfoundtintsecretiontoftgastrointestinal,trespiratory,tandtreproductivettractstandtmem
branest
-tlubricantt&timmunologictfunctionst
-texhibitsthightcontenttofto-glycantchainst
-trepeatingtAAtsequencetSet,tThr,t&tPro
-tprotectivetbarrier,tcell-celltinteractions,tmaytcontain/masktsurfacetantigenst