BIOLOGY 1033 EXAM TWO STUDY
GUIDE BRCC QUESTIONS AND
ANSWERS
Ityseparatesytheyinternalycontentsyofyaycellyfromyitsyexternalyenvironment.yItsystructureyi
sycomposedyofyayphospholipidybilayerythatyisyhydrophilicyonytheyoutsideyandyhydropho
bicyonytheyinside.yTheymembraneyalsoycontainsyproteinsyandycarbohydrates.y-
yanswer--
1.yWhatyisytheystructureyofyplasmaymembraneyandywhatyareyitsymajorylipidyandyproteiny
components?
Theymembraneyisyconsideredyaymosaicyofylipid,yprotein,yandycarbohydrateymolecules.y
Ityresemblesyayfluidymosaicybecauseylipidsyandyproteinsycanymoveyrelativeytoyeachyoth
erywithinytheymembrane.y-yanswer--
2.yExplainywhyytheymembraneyisycalledyfluidymosaic?
Theyphospholipidybilayeryandytransportyproteins???y-yanswer--
3.yWhichycomponentyisyimportantyforypassageyofylargeyandysmallychargedymoleculesya
crossytheymembrane?
Theyphospholipidybilayeryandytransportyproteinsy-yanswer--
3.yWhichycomponentyisyimportantyforypassageyofylargeyandysmallychargedymoleculesya
crossytheymembrane?
Small,ynonpolar,ylipidysolubleymoleculesy-yanswer--
4.yWhichytypeyofymoleculesypassythroughylipidybilayeryreadily?
foundyinymanyycellyplasmaymembranes.yPoweredybyyATP,ytheypumpymovesysodiumya
ndypotassiumyionsyinyoppositeydirections,yeachyagainstyitsyconcentrationygradient.yUsi
ngyactiveytransporty(ATPyforyenergy).yPotassiumyhasyayhighyconcentrationygradientyins
ideyandylowyoutside.ySodiumyhasyayhighyconcentrationygradientyoutsideyandyayloweryin
side.y-yanswer--5.yWhatyisysodium/potassiumypump?yHowyityworks?
-
Inyanyisotonicysolution,ywaterywillyenteryandyleaveytheycellyatyanyequalyrate,ysoytheycellsy
willymaintainytheirynormalyshape
-
Inyayhypotonicysolution,ytheycellywillygainywater,yswell,yandytheyinternalypressureyincrea
sesyandymayyeventuallyybursty(hemolysis)
, -
Inyayhypertonicysolution,ytheycellywillyloseywateryandyshrink,yandyitsyinternalypressureywi
llydecrease.y-yanswer--
6.yKnowywhatyhappensytoyanyanimalycellyplacedyinyisotonic,yhypotonicyandyhypertonicy
solution.
Exocytosisy-yanswer--
ayprocessyinywhichytheymaterialyinsideytheycellyisypackagedyintoyvesiclesyandythenyexcr
etedyintoytheyextracellularyenvironment.
Endocytosisy-yanswer--
theyplasmaymembraneyinvaginates,yoryfoldsyinward,ytoyformyayvesicleythatybringsysubst
ancesyintoytheycell.
receptor-mediatedyendocytosisy-yanswer--
aycommonytypeyofyendocytosisyinywhichyayreceptoryinytheyplasmaymembraneyisyspecifi
cyforyaygivenycargo.
Pinocytosisy-yanswer--
thatyinvolvesytheyformationyofymembraneyvesiclesyfromytheyplasmaymembraneyasyaywa
yyforycellsytoyinternalizeytheyextracellularyfluid.y*Thisyallowsycellsytoysampleytheyextracel
lularysolutes.yPinocytosisyisyparticularlyyimportantyinycellsythatyareyactivelyyinvolvedyinyn
utrientyabsorption,ysuchyasycellsythatylineytheyintestineyinyanimals.
Phagocytosisy-yanswer--(fromytheyGreek,ymeaningycell-
eating)yinvolvesytheyformationyofyanyenormousymembraneyvesicleycalledyayphagosom
e,yoryphagocyticyvacuole,ywhichyengulfsyaylargeyparticleysuchyasyaybacterium.y*Onlyyce
rtainykindsyofycellsycanycarryyoutyphagocytosis.
Exocytosis.y
•yCertainyhormones,ysuchyasyinsulin,yareycomposedyofypolypeptides.yToyexertyitsyeffect
,yinsulinyisysecretedyviayexocytosisyintoytheybloodstreamyfromybetaycellsyofytheypancrea
s.
•yDigestiveyenzymesythatyfunctionyinytheylumenyofytheysmallyintestineyareysecretedyviay
exocytosisyfromyexocrineycellsyofytheypancreas.y-yanswer--
8.yWhichyprocessyisyinvolvedyinyreleaseyofyhormoneyorydigestiveyenzymesyfromyglands
ysuchyasypancreas?
Mitochondriay-yanswer--
oftenycalledythey"powerhouses"yory"energyyfactories"yofyaycellybecauseytheyyareytheypri
maryysiteyofymetabolicyrespirationyinyeukaryotes.y*Dependingyonytheyspeciesyandytheyt
ypeyofymitochondriayfoundyinythoseycells,ytheyrespiratoryypathwaysymayybeyanaerobicy
oryaerobic.y*yInyeitherycase,ytheyresultyofytheseyrespiratoryyprocessesyisytheyproductiony
ofyATPyviayoxidativeyphosphorylation
Vacuoley-yanswer--
playsyaykeyyroleyinyregulatingytheycell'syconcentrationyofywateryinychangingyenvironmen
talyconditions.y*Theycentralyvacuoleyalsoysupportsytheyexpansionyofytheycell.yWhenythey
centralyvacuoleyholdsymoreywater,ytheycellygetsylargerywithoutyhavingytoyinvestyaylotyofy
energyyinysynthesizingynewycytoplasm.
GUIDE BRCC QUESTIONS AND
ANSWERS
Ityseparatesytheyinternalycontentsyofyaycellyfromyitsyexternalyenvironment.yItsystructureyi
sycomposedyofyayphospholipidybilayerythatyisyhydrophilicyonytheyoutsideyandyhydropho
bicyonytheyinside.yTheymembraneyalsoycontainsyproteinsyandycarbohydrates.y-
yanswer--
1.yWhatyisytheystructureyofyplasmaymembraneyandywhatyareyitsymajorylipidyandyproteiny
components?
Theymembraneyisyconsideredyaymosaicyofylipid,yprotein,yandycarbohydrateymolecules.y
Ityresemblesyayfluidymosaicybecauseylipidsyandyproteinsycanymoveyrelativeytoyeachyoth
erywithinytheymembrane.y-yanswer--
2.yExplainywhyytheymembraneyisycalledyfluidymosaic?
Theyphospholipidybilayeryandytransportyproteins???y-yanswer--
3.yWhichycomponentyisyimportantyforypassageyofylargeyandysmallychargedymoleculesya
crossytheymembrane?
Theyphospholipidybilayeryandytransportyproteinsy-yanswer--
3.yWhichycomponentyisyimportantyforypassageyofylargeyandysmallychargedymoleculesya
crossytheymembrane?
Small,ynonpolar,ylipidysolubleymoleculesy-yanswer--
4.yWhichytypeyofymoleculesypassythroughylipidybilayeryreadily?
foundyinymanyycellyplasmaymembranes.yPoweredybyyATP,ytheypumpymovesysodiumya
ndypotassiumyionsyinyoppositeydirections,yeachyagainstyitsyconcentrationygradient.yUsi
ngyactiveytransporty(ATPyforyenergy).yPotassiumyhasyayhighyconcentrationygradientyins
ideyandylowyoutside.ySodiumyhasyayhighyconcentrationygradientyoutsideyandyayloweryin
side.y-yanswer--5.yWhatyisysodium/potassiumypump?yHowyityworks?
-
Inyanyisotonicysolution,ywaterywillyenteryandyleaveytheycellyatyanyequalyrate,ysoytheycellsy
willymaintainytheirynormalyshape
-
Inyayhypotonicysolution,ytheycellywillygainywater,yswell,yandytheyinternalypressureyincrea
sesyandymayyeventuallyybursty(hemolysis)
, -
Inyayhypertonicysolution,ytheycellywillyloseywateryandyshrink,yandyitsyinternalypressureywi
llydecrease.y-yanswer--
6.yKnowywhatyhappensytoyanyanimalycellyplacedyinyisotonic,yhypotonicyandyhypertonicy
solution.
Exocytosisy-yanswer--
ayprocessyinywhichytheymaterialyinsideytheycellyisypackagedyintoyvesiclesyandythenyexcr
etedyintoytheyextracellularyenvironment.
Endocytosisy-yanswer--
theyplasmaymembraneyinvaginates,yoryfoldsyinward,ytoyformyayvesicleythatybringsysubst
ancesyintoytheycell.
receptor-mediatedyendocytosisy-yanswer--
aycommonytypeyofyendocytosisyinywhichyayreceptoryinytheyplasmaymembraneyisyspecifi
cyforyaygivenycargo.
Pinocytosisy-yanswer--
thatyinvolvesytheyformationyofymembraneyvesiclesyfromytheyplasmaymembraneyasyaywa
yyforycellsytoyinternalizeytheyextracellularyfluid.y*Thisyallowsycellsytoysampleytheyextracel
lularysolutes.yPinocytosisyisyparticularlyyimportantyinycellsythatyareyactivelyyinvolvedyinyn
utrientyabsorption,ysuchyasycellsythatylineytheyintestineyinyanimals.
Phagocytosisy-yanswer--(fromytheyGreek,ymeaningycell-
eating)yinvolvesytheyformationyofyanyenormousymembraneyvesicleycalledyayphagosom
e,yoryphagocyticyvacuole,ywhichyengulfsyaylargeyparticleysuchyasyaybacterium.y*Onlyyce
rtainykindsyofycellsycanycarryyoutyphagocytosis.
Exocytosis.y
•yCertainyhormones,ysuchyasyinsulin,yareycomposedyofypolypeptides.yToyexertyitsyeffect
,yinsulinyisysecretedyviayexocytosisyintoytheybloodstreamyfromybetaycellsyofytheypancrea
s.
•yDigestiveyenzymesythatyfunctionyinytheylumenyofytheysmallyintestineyareysecretedyviay
exocytosisyfromyexocrineycellsyofytheypancreas.y-yanswer--
8.yWhichyprocessyisyinvolvedyinyreleaseyofyhormoneyorydigestiveyenzymesyfromyglands
ysuchyasypancreas?
Mitochondriay-yanswer--
oftenycalledythey"powerhouses"yory"energyyfactories"yofyaycellybecauseytheyyareytheypri
maryysiteyofymetabolicyrespirationyinyeukaryotes.y*Dependingyonytheyspeciesyandytheyt
ypeyofymitochondriayfoundyinythoseycells,ytheyrespiratoryypathwaysymayybeyanaerobicy
oryaerobic.y*yInyeitherycase,ytheyresultyofytheseyrespiratoryyprocessesyisytheyproductiony
ofyATPyviayoxidativeyphosphorylation
Vacuoley-yanswer--
playsyaykeyyroleyinyregulatingytheycell'syconcentrationyofywateryinychangingyenvironmen
talyconditions.y*Theycentralyvacuoleyalsoysupportsytheyexpansionyofytheycell.yWhenythey
centralyvacuoleyholdsymoreywater,ytheycellygetsylargerywithoutyhavingytoyinvestyaylotyofy
energyyinysynthesizingynewycytoplasm.
