BIOLOGY FORM 4 Chapter 3 - Movement of Substances Across the Plasma Membrane

8/18/2019 BIOLOGY FORM 4 Chapter 3 - Movement of Substances Across the Plasma Membrane

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MOVEMENT OF SUBSTANCES

ACROSS THE PLASMA MEMBRANE


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3.1 THE MOVEMENT OF SUBSTANCESACROSS THE PLASMA MEMBRANE

• Living cells carry !" li#e $rcess%

& A'sr' (a"er ) n!"rien"

& E*cre"e (as"e $r+!c"

& E*c,ange res$ira"ry (as"e $r+!c"

• T,ese $rcesses are IMPORTANT 'eca!se M.O.S.E.

a- Main"ain $"ial $H val!e

'- O'"ain n!"rien" #r e"a'lis

c- Secre"e !se#!l s!'s"ances /e*% ,rnes-

+- Eliina"e "*ic (as"e $r+!c"


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PLASMA MEMBRANE

• 0s very s#" an+ ",in

• 0" is ",e !"ers" s"r!c"!re # a cell

• Cvers ",e (,le cell an+ se$ara"es i" #r

e*"ernal envirnen"• A very eec"ive 'arrier agains" #ree en"ry #

s!'s"ances in" cell

• Ma+e !$ # "( layers # $,s$,li$i+s /'ilayers-

• Has ,y+r$,ilic ,ea+ an+ ,y+r$,'ic "ail• C,les"erl s"a'ili2es an+ s"reng",en ",e

e'rane aing i" re 4e*i'le


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• Pore Protein

T,is $r"ein lec!le ,as a "iny $re r c,annel(,ic, allows ions and small molecules to pass

through.

• Carrier Protein

T,is $r"ein lec!le ac"s as a carrier (,ic,

carries cnsi+era'ly big molecules such asglucose amino acids and !itamin C.

T,e s"r!c"!re # ",e e'rane is +e$ic"e+ as a

d"namic #uid in (,ic, lec!les # $r"ein las i# ",ey are 4a"ing in ",e li$i+ sl!"in. T,elec!les # $r"ein an+ li$i+ are not static '!"can mo!e $reel".


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PERMEAB0L0T5 OF THE PLASMA

MEMBRANE

• Sei&$erea'le

& All(s certain s!'s"ance " ve#reely

• Mveen" # s!'s"ances acrss ",e$lasa e'rane cc!r ",r!g, ",elipid la"er6 tin" pores r 'eing"rans$r"e+ 'y carrier proteins inan acti!e r passi!e (ay.


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S0MPLE 70FFUS0ON

• Ran+ veen" # ins r lec!les #r aregin # high water cncen"ra"in " a regin# low water cncen"ra"in6 i.e. $ollowing ",econcentration gradient.

• Occ!rs !n"il a s"a"e # e8!ili'ri! is reac,e+.

•

E*% ",e a'sr$"ins # li$i+&sl!'le s!c, asvi"ain A7E9 in" ",e villi6 an+ ",e e*c,ange #gases s!c, as *ygen an+ car'n +i*i+e'e"(een alveli an+ 'l+ ca$illaries.


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OSMOS0S

• 7i!sin (,ic, invlves veen" # sol!ent /e.g. (a"er- #r a regin # high water cncen"ra"in " a regin # low water cncen"ra"in acrss ",e $lasa e'rane.

• Occ!rs cn"in!!sly !n"il '", si+es # $lasae'rane ,ave ",e sae cncen"ra"in.

• E*% (a"er en"ering $lan" cells #r r" ,air6 an+sreg!la"in in a8!a"ic rganiss s!c, asAe'a.


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FAC0L0TATE7 70FFUS0ON

• Mveen" # s!'s"ances acrss $lasa e'rane !singcarrier proteins $ollowing ",e concentration gradient

• E*a$le # s!'s"ances% N" li$i+&sl!'le6 c,arge+

$ar"icles an+ 'ig lec!les /gl!cse ) ain aci+s-

• Have acti!e site e8!i$$e+ (i", speci%c substances

• :,en ;#r an e*a$le ;gl!cse lec!les approach ",isac"ive si"e an+ bind " i"6 carrier protein changesshape an+ transports ",e gl!cse lec!le in" ",e cell.


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ACT0VE TRANSPORT

• Mveen" # s!'s"ances acrss $lasae'rane against the concentrationgradient. T,is $rcess nly cc!rs in

li!ing s"stems (,ic, ac"ively $r+!cesenerg" ",r!g, respiration.

• Nee+s energ" $rom ATP molecules (,ic,

is !se+ #r ving ",e carrier protein s",a" ",ey can transport substancesagainst the concentration gradient.


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• Substances (,ic, are re8!ire+ " 'e"rans$r"e+ bind " ",e carrier protein.Carrier $r"ein recei!e energ" $rom ATP

molecules an+ change shape an+ getacti!ated to transport the substancescncerne+ acrss ",e $lasa e'rane

against the concentration gradient.

• E*a$le% Inta&e # ineral sal"s an+ ins'y r" ,air # $lan"s6 ",e reabsorption

# gl!cse an+ ain aci+s #r ne$,rnsin" 'l+ ca$illaries in ",e i+ney an+transport # $"assi! ins in" ",e cellsan+ ",e elimination # s+i! ins !" #

",e cell.


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3.


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&:a"er ve !" # ",e cell an+ ca!secrena"in #r anial cell an+ 4acci+

#r $lan" cell.• '"potonic

&Sl!"in !"si+e ",e cell less

cncen"ra"e+ ",an cy"$las in cell&:a"er re cncen"ra"e+ !"si+e ",e

cell

&:a"er ve in" ",e cell n ca!se,aelysis in #r anial cells an+"!rgi+ #r $lan" cells.


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Eec"s # Hy$"nic6Hy$er"nic an+ 0s"nic sl!"in n '", anial )$lan" cells

& Anial cell/RBC-


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&Plan" cells


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3.3&0$ac" # ssis n ,!an'eings an+ ",er rganiss

• Preser!ation in (ood

- Na"!ral #+ $reserva"ives incl!+es!'s"ances s!c, as sal"6s!gar an+ vinegar.

- Sal" !se+ #r ea" $reserva"in. A++ingsal" can +e,y+ra"e icr'es ",r!g,ssis since ",e cn+i"in is ,y$"nic "", cells # 'ac"eria.

- Hence6i" in,i'i" ",e 'ac"eria n #+ can las"#r "( years


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&T,e en+&

BIOLOGY FORM 4 Chapter 3 - Movement of Substances Across the Plasma Membrane

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