Chương 1-Sinh Lý Tế Bào

Sinh ly thc vat Sinh ly te bao Trang 1

Chng 1: SINH LY TE BAO I. KHAI NIEM Nam 1665, Robert Hooke khi quan sat te bao mo vo cay di knh hien vi thay rang

mo vo cay co cau tao gom nhng khoang giong nh hnh to ong, ong goi ten la cell. T te bao hay cell c rut ra t tieng Latin cella, co ngha la phong.

Dan dan, vi s phat minh knh hien vi ngay cang toi tan, nhng hieu biet ve te bao ngay cang hoan thien hn.

Hoc thuyet te bao do nha thc vat hoc ngi c M. J. Schleiden va nha ong vat hoc T. Schawann nam 1938 a ra. Hai ong cho rang: Tat ca thc vat va ong vat eu c cau tao nen t nhieu nhom te bao, va te bao la n v can ban cua sinh vat.

That vay, te bao c xem nh la n v c ban va cau tao gom nhieu bo phan nho, vi nhng chc nang chuyen biet bieu hien cho s song.

V the, nghien cu sinh ly cay la phai nghien cu sinh ly te bao va cach thc nhng hoat ong hp tac gia cac te bao e phan anh sinh ly cua toan cay. Cung tng t nh the, cau truc va hnh dang cua cay la phan anh cua so lng, cach sap xep va kieu hnh cua nhieu te bao rieng le.

Muc ch cua chng nay la gii thieu nhng cau truc c ban cua te bao vi chc nang sinh ly cua chung va ch ra s ket hp cua te bao thanh mo va c quan cua cay nh the nao.

II. HNH THAI VA CAU TAO TE BAO Te bao co the co hnh luc giac, hnh tron, hnh bau duc, hnh si, hnh liem, hnh sao.

Kch thc te bao thay oi t m-cm. Tat ca te bao thc vat eu co to chc cau tao chung, bao gom: vach te bao, mang te bao va chat nguyen sinh. Te bao chat, nhan, cac bao quan, tat ca cung c bao boc bi mang, mang nay c xem nh la mang bao ve e phan biet cac khu vc chc nang trong te bao vi nhau va gia te bao vi moi trng xung quanh.

1. Mang te bao (Plasma membranes) - Mang sinh hoc (Biological membranes) Tat ca mang sinh hoc eu la lp oi cha lipid, protein va 1 lng nho carbohydrate.

Tuy theo nhiem vu ma thanh phan lipid, protein, carbohydrate thay oi t mang te bao nay sang mang te bao khac, giup cho mang co chc nang va nhiem vu rieng biet, mang co be day khoang 50-65A.

He thong mang sinh hoc bao gom: - Lipid - Protein mang va Ao khoac

a/ Lipid Hau het nhng thanh phan lipid trong mang te bao eu la phospholipid. Phospholipid

la phan t lng cc, co 1 au k nc cau tao bi chuoi hydrocarbon dai khong cc la 2 acid beo; va 1 au a nc cau tao bi nhom phosphate noi cong hoa tr vi nhng thanh phan hu cc co the thay oi nh serin, choline, glycerol hay inositol.

Trong moi trng nc th mang co cau tao gom 2 lp phospholipid nh vay se co au hng vao trong la au k nc va au hng ra ngoai la au a nc. Lp oi phospholipid cha 1 t le ln acid beo bat bao hoa. Chnh cau truc 2 lp nh vay khien cho mang co 3 ac tnh quan trong e giup mang co the thc hien nhieu nhiem vu khac nhau o la (i) giup cho mang trang thai linh ong, (ii) on nh ve mat cau truc va (iii) khong tham vi phan ln cac phan t sinh hoc va chat hu cc. Co mot ngoai le ang chu y la 3


chat H2O, CO2 va O2 lai tham rat nhanh. Tnh long cua lp oi lipid quan trong v chung cho phep nhng phan t lipid rieng le hoac nhng phan t k nc co the khuech tan nhanh, van toc co the la 1ms-1.

b/ Protein mang Protein chiem khoang 50% trong lng mang, trong trng hp mang trong ti the t le

nay cao hn nhieu. Protein gan mang gom co: protein noi tai va protein ngoai vi, tuy theo v tr cua

protein nam khoang trong lp oi cua mang hay nam au a nc cua mang. Protein noi tai co the la 1 protein rieng le hay la phc hp bi nhieu protein vi

thanh phan khong protein. Protein noi tai co the ch nam mot ben mang trong khi mot so khac (goi la transmembrane protein) nam trai qua 2 mang, v the chung co 1 phan tng tac vi pha ben ngoai cua te bao va 1 phan nam ben trong au k nc cua mang, va phan th ba nam tng tac vi te bao chat. Trong te bao, protein noi tai ong vai tro quan trong trong viec van chuyen cac chat t trong te bao ra ngoai va tham thau cac chat t ngoai vao trong.

Protein ngoai vi gan vi be mat cua mang (au phospholipid phan cc hay phan a nc cua protein noi tai) bang cau noi ion hay hydro. Protein ngoai vi gi mot so vai tro trong nhiem vu mang, th du nh no am nhiem nhng tng tac gia mang va nhng thanh phan cua bo xng nh vi si va vi ong.

Protein mang gi vai tro chc nang hn la vai tro cau truc. Protein mang co lien quan en tat ca hoat ong bien dng co lien quan en mang, th du vai protein co nhiem vu nh la enzyme, vai loai khac giup chon loc cac chat tham qua mang, cung co nhng protein ong vai tro nh la chat chuyen van ien t.


c/ Ao khoac La lp si mong va tha nam ngoai mang nguyen sinh, cau tao bi nhng lp oligo-

saccharid, glycolipid hay glycoprotein cua protein noi tai hay protein ngoai vi. Ao khoac ong vai tro quan trong trong viec duy tr tnh nguyen ven cua mang, neu ao khoac b hong, te bao se khong hoat ong bnh thng. Ao khoac giup te bao hoat ong bnh thng va giup s trao oi chat c de dang t ben ngoai vao ben trong te bao mot cach co chon loc, che ch mang nguyen sinh giup gia tang tnh tham cua mang.

2. Vach te bao (Cell wall) ay la mot cau tao ac biet ch co te bao thc vat, vach te bao giup gi hnh

dang te bao, bao ve lp te bao tran ben trong va duy tr tnh trang ran chac cua te bao. Vach te bao la mot mang tham nc.

Co 2 loai la vach te bao s cap va th cap. a/ Vach s cap (Primary wall) Hien dien te bao con non, hay ang tang trng.

Vach s cap la lp mong, co be day khoang vai m, la chuoi polymers cua glucose goi la cellulose, cellulose la si dai glucoses khong phan nhanh, noi vi nhau bi noi 1 - 4 glucan. Mot si cellulose co the cha hn 3.000 n v glucose. vach te bao s cap, phan t cellulose c xep thanh chuoi dai va song song, goi la vi si. Moi vi si co ng knh khoang 5-12nm va cha khoang 36 chuoi cellulose rieng biet noi nhau bi cau noi hydro gia nhom hydroxyl (-OH) vi n v glucose lan can. Cach sap xep nay giup cho vi si lien ket lai va giup tang sc manh cua vach, giup cho vach co the chu ng c lc cang ma khong b v (1 vi si cellulose chu lc tng ng vi 1 sp thep co cung kch thc).

vach s cap cac vi si co khuynh hng xep ngau nhien trong khi nhng te bao ang tang dai chung co khuynh hng xep song song vi chieu tang trng. Nhng vi si cellulose c nam trong 1 chat nen phan ln la hemicellulose va hp chat pectin. Hemicellulose la 1 phc hp nhieu ng khac nhau, hnh thanh nhng mang co nhieu nhanh. Hemicellulose co the trch c trong moi trng kiem (NaOH 7,5%).

Hp chat pectic chiem khoang 35% vach s cap, cung la nhom nhieu loai ng khac nhau, ac biet la acid galacturonic la dang acid cua ng galactose. Hp chat pectic cung la thanh phan chnh cua phien gia(middle lamella), la 1 hp chat ciment lien ket vach s cap te bao lan can vi nhau. S mem cua trai khi chn la do co s phan huy bi enzyme cac hp chat pectic cua phien gia, do o mo cua trai xanh thng cng va tr nen nhao mem khi trai trng thanh.


Trc ay, chat nen trong vach te bao c xem nh la dang gel ong nhat co hay khong co cau truc. Thi gian gan ay, nhieu nghien cu cho thay hemicellulose va pectin co the bao quanh vi si cellulose va t nhieu c nh hng song song vi chung.

Vach s cap cung co the cha 10% glycoprotein vi thanh phan aminoacid hydroxyprolin. Glycoprotein

giau hydroxyprolin la thanh phan co cau truc mang giup gia tang sc manh cua vach va co nh hnh dang vach te bao mot khi te bao ngng tang trng.

Nhng nghien cuu gan ay cung cho thay trong cau truc vach te bao cung co s xuat hien cua prolin, glycine hay threonin.

b/ Vach th cap (Secondary wall) c hnh thanh t trong vach s cap khi

te bao ngng tang rong va bat au trng thanh. Vach th cap day va cng hn vach s cap, cha khoang 45% cellulose, 30% hemicellulose va 22 28% lignin (trong vai trng hp co the len ti 35%). te bao cay than go co vach day, vach th cap gom 2 lp rieng biet tuy theo hng cua cac vi si, 2 lp vi si thng nam xoan quanh truc te bao; lp ngoai cung phan tiep giap vi vach s cap, vi si thng tao thanh goc canh vi truc te bao; lp vi si ben trong hau nh xep song song vi chieu dai truc.

Lignin ben va chac hn vi si cellulose, kho b phan huy neu khong dung hoa chat, do thanh phan cua ligin co 1 he thong cau noi phc tap gia nhieu thanh phan ru phenolic. Ben canh cellulose, lignin cung la thanh phan sinh hoc co cau truc quan trong. S phoi hp gia cellulose va lignin giup cho go ran chac.

c/ Cau lien bao (Plasmodesmata) Khi te bao ang phan chia lp

mang ngan cha hoan chnh, van con nhng vung ma te bao chat cua 2 te bao con van lien lac nhau, cellulose bat au xay dng vach gia tang be day nhng v tr lien lac nay tr thanh mot he thong kenh mang goi la cau lien bao co ng knh khoang 60nm, gom co vong noi chat va vi ong. Nam gia nhng cau lien bao la nhng ong lien bao hnh thanh do s keo dai cua vong noi chat. Ong lien bao giup s lien lac t te bao nay sang te bao khac va gia cac ong va cau lien bao vi nhau.


Theo Robard va Luca 1990, so lng cau lien bao chiem khoang 0,1 - 10m2 dien tch cua vach te bao hp thanh nhom nhng lo s cap. Cau lien bao nho va u e ngan chan cac bao quan van chuyen gia te bao, nhng rong u e giup cho s trao oi cac phan t nho hoa tan trong te bao chat. V the cau lien bao ong vai tro nh mang o lng lng chat tan va giup s lien lac gia cac te bao.

Khi vach th cap c hnh thanh, nhng lo th cap c thanh lap, nhng lo nay hnh thanh nhng cap lo vi vach oi dien. Nhng te bao co cau truc vach th cap khong con te bao chat se hnh thanh nhng mo moc, khi o cap vi lo la con ng cho dong nc va cac chat hoa tan i qua.

S lien lac cua nguyen sinh chat qua cau lien bao hnh thanh 1 mang li te bao chat lien tuc trong cay c goi la con ng symplast. Trong khi s lien tuc gia cac khoang gian bao, vach te bao va nhng vung mo dan khong song c xem nh con ng apoplast. Khai niem ve symplast va apoplast la quan trong e xem xet s van chuyen cua nc va chat tan trong cay.

3. Nguyen sinh chat (Protoplasm) va cac bao quan (Organelles)

a/ Nguyen sinh chat Nguyen sinh chat ben trong cua te bao c to chc thanh mot so khu gii han bi

mang c goi la bao quan. Phan dung dch long cua nguyen sinh chat c goi la te bao chat. Te bao chat cha 1 lng ln protein va nhng thanh phan hoa tan thng ong gop vao tnh chat vat ly cua 1 loai te bao.


b/ Nhan (Nucleus) Nhan la trung tam thong tin cua te bao cha vat chat di truyen DNA (deoxyribo-

nucleic acid) ma hoa cho viec tong hp RNA (ribonucleic acid). RNA c a ra ngoai te bao chat, o no trc tiep tong hp nhng protein chuyen biet. Trong te bao khong phan chia, DNA ket hp protein thanh si dai nam rai rac goi la nhiem sac chat chromatin. Tong chieu dai cac si chromatin trong te bao thc vat co the at t 1-10m nhng no co the xep va trong nhan vi ng knh khoang 10m. Nhng te bao khong phan chia nay cung cha nhng hach nhan la trung tam tong hp ribosome, nhng hach nhan se bien mat khi te bao phan chia. Trong qua trnh phan chia DNA xoan ngan lai day len hnh thanh nhiem sac the.

Nhan thng co ng knh khoang 5 - 30m va c bao boc bi 2 mang goi la lp bao nhan. Mang trong va mang ngoai noi nhau lo nhan; Lo nhan hnh thanh nhng kenh cho s van chuyen RNA t nhan vao te bao chat. Trong hau het te bao eucaryote, bao nhan se bien mat khi te bao phan chia va hnh thanh lai xung quanh DNA cua te bao con.

c/ Ti the (Mitochondrion) c tm thay tat ca te bao song, la bao quan giup chuyen hoa nang lng trong te

bao sinh vat noi chung, hay te bao thc vat noi rieng. te bao thc vat ti the hnh tron hay hnh ong, ng knh khoang 1m. Mang ngoai ti the thng phang, nhng mang trong co nhieu nep gap; mang trong co khoang 75% protein ong vai tro quan trong trong viec truyen nang lng. Ti the la ni xay ra cac hoat ong ho hap cua te bao. Trong qua trnh nay, ng c oxid hoa e giup s tong hp ATP t ADP va P vo c (Pi). ATP c chuyen qua nhng vung khac can nang lng cho cac hoat ong cua te bao.

d/ Lap (Plastids) Lap cung la nhng bao quan co cau truc mang kep, hnh thanh t mot tieu bao quan

goi la tien lap (proplastids). Tien lap co the t phan chia va cung co cha thong tin di truyen rieng cua no la DNA di dang vong kep.

Bot lap (Leucoplasts): khong co mau sac, la ni tch luy chat d tr. Lap d tr tinh bot con c goi la amyloplast, d tr dau goi la lipoplast, oleosome hay elaioplast va d tr protein th goi la aleuroplast. Bot lap va diep lap co the bien oi qua lai tuy theo trang thai sinh ly va ieu kien chieu sang.

Sac lap (Chromoplasts): cha nhieu carotenoids hn diep lap va la nguon cua mau vang, cam, o cua la hoa trai, nhat la la vang mua thu. Sac to trong sac lap thng rat am va hnh thanh dang tinh the.

Diep lap (Chloroplasts): cha sac to quang hp diep luc (Chlorophyll) va nhng protein lien quan en qua trnh quang hp, tao mau xanh cua la cay. Diep lap c hnh thanh t tien lap xuat hien giai oan phan chia te bao va s hnh thanh diep lap can s co mat cua anh sang.


Te bao mo phan sinh cha nhieu tien lap co t hoac khong co mang trong, khong co diep luc va thanh phan khong ay u cua enzymes thc hien qua trnh quang hp. Anh sang thuc ay s bien oi tien lap thanh diep lap. Di s chieu sang, nhng enzymes c hnh thanh t tien lap hay van chuyen t te bao chat, sac to hap thu anh sang c san xuat va mang se phan chia nhanh hnh thanh ban stroma va nhng n v grana.

Hat giong thung nay mam trong at ni khong co anh sang, va diep lap ch hnh thanh khi choi non c tiep xuc vi anh sang. Neu hat giong c nay mam trong toi, tien lap se phan hoa thanh diep hoang lap cha nhng mang ban tinh the dang ong. Thay v diep luc, diep hoang to co mau xanh vang goi la tien diep luc.

Ch vai ngay sau khi a ra anh sang, diep hoang lap se chu s bien oi tao thanh mang thylakoid va mang stroma, tien diep luc oi thanh diep luc.

S duy tr cau truc cua diep lap tuy thuoc vao s hien dien cua anh sang v diep lap trng thanh co the oi thanh diep hoang lap khi at trong toi.

e/ Vong noi chat (Endoplasmic reticulum - ER) va the golgi Vong noi chat va bo golgi hp thanh mot he thong mang giup cho s tong hp va

ieu tiet lipid, protein. Mang hien dien trong vong noi chat va bo golgi la loai mang cau tao bi lp oi phospholipid xen lan vi protein noi tai va ngoai vi. Nhng mang nay cung hnh thanh nhng tui hnh ong hay nhng tui dep goi la cisternae.

Nhieu nghien cu cho thay vong noi chat la thanh phan lp mang ngoai cua bao nhan keo dai co cha khoang lumen. Co 2 loai vong noi chat :

Vong noi chat go ghe (Rough ER): Hnh thanh t nhng vong noi chat thng

co dang phien va cha nhng the ribosomes gi nhiem vu sinh tong hp protein va protein mang, Protein c tong hp se xuyen qua mang vao khoang lumen van chuyen en vong noi chat lang la vung co hnh ong khong co cha nhng hat ribosomes. Khi con trong ER protein c bo sung them ng vao e hnh thanh glucoprotein. Glucoprotein c cha trong khoang lumen va sau o c van chuyen xuyen qua mang ER vao te bao chat hay khong bao.


Vong noi chat lang (Smooth ER) : Vong noi chat lang gi nhiem vu sinh tong hp lipid va thanh lap mang. Mot iem ang lu y la trong hat, lipid uc d tr di dang oleosome. Oleosome c boc trong mang n lipid, au co cc oi dien vi mat chat long cua te bao chat va uoi k nc bam vi lipid d tr. Lp mang n nguyen thuy co the c xem nh la dau vet cua s hnh thanh oleosome trong ER. Nhng nghien cu ve te bao hoc cho thay co s tong hp mi lipid c tch luy trong khoang gia cua 2 lp mang dan en viec 2 na cua lp oi tach ra e hnh thanh oleosome.

Phc hp golgi: la chuoi tui dep, 2 au phong len, c hnh thanh t vong noi chat va sau o tach ri khoi ER. Bo golgi c xem nh la ni tong hp va che bien chuoi carbohydrate cua glycoprotein c chuyen en no t ER thong qua tui van chuyen. Mang cua tui van chuyen ket hp vi mang cua bo golgi giai phong vat chat vao golgi cisternae cua phc hp golgi. ay ng c bien oi va dai ra nh them vao nhng goc ng mi. Glycoprotein a c bien oi se ri phc hp golgi qua nhng tui tiet va giai phong ra ben trong te bao hay nhng ni nh la ni d tr protein hay c thai ra khoi te bao qua mang sinh hoc. Mot nhiem vu quan trong na cua phc hp golgi la tong hp cac phc hp ng (e giup hnh thanh chat nen cua vach te bao) va giai phong chung vao ni co s hnh thanh vach trong giai oan phan chia va tang trng cua te bao.

f/ Ribosomes Ribosomes la ni tong hp protein. Ribosomes khong uc xem nh la bao quan v

no khong co gii han mang. Tuy nhien, v tnh cach tien hoa va s quan trong cua chung trong viec sinh tong hp protein nen ribosomes c thao luan ay nh la 1 bao quan.

Ribosomes la 1 chuoi phc tap cua RNA va protein, la nhng hat nho co ng knh 25m. Ribosomes hoan chnh c hnh thanh t te bao chat la phc hp gom tieu n v ln va nho c tong hp trong nhan. Ribosomes co the xuat hien t do trong te bao chat trong khi nhng hat khac th dnh vi mang cua vong noi chat. Mot te bao co the cha hang tram ngan ribosomes, tuy thuoc nhu cau protein cua c the thc vat.

g/ Vi the (Microbodies) Vi the la nhng bao quan co kch thc nho 1, c bao boc bi nhng mang n,

ong vai tro quan trong trong nhng phan ng bien dng chuyen biet va thng co nhng enzymes ac hieu hay nhom enzymes chuyen biet.

Peroxysome: La bao quan dang hnh cau cha 1 lng ln enzyms catalase (40% tong so protein trong perroxysomes) dung trong nhng phan ng oxid hoa e bien oi nhng san pham oc cho cay (H2O2). Cung vi ti the, peroxysomes la ni tieu thu oxy trong te bao. Peroxysomes cung phan huy chat beo thong qua qua trnh oxy hoa (nhng khac enzyme vi ti the) va tham gia vao hien tng quang ho hap - con ng bien dng quan trong cua qua trnh quang hp.

Glyoxysomes: Hien dien nhieu trong hat giong, ac biet la nhng hat co chat d tr la dau. Glyoxysome cha enzymes cua chu trnh glyoxylate c dung e bien oi acid beo thanh glucose qua qua trnh glucose giai (roi glucose c van chuyen en phoi nhu


ang tang trng va c s dung nh la 1 nguon carbon va nang lng cho hoat ong tang trng). Glyoxysomes va Peroxysomes ch khac nhau ve t le enzyme va chung co the chuyen oi qua lai lan nhau, giai oan cay con (nhat la giai oan hat nay mam) th glyoxysomes chiem a so va giai oan sau th peroxysomes chiem a so.

h/ Khong bao (Vacuole) La bao quan de nhan thay trong hau het te bao trng thanh cua thc vat bac cao.

te bao nay khong bao co the chiem 80-90% the tch te bao. Trong nhng te bao trng thanh nay nguyen sinh chat vi tat ca cac bao quan xuat hien nh 1 lp mang mong ep sat vao vach te bao. Nhng te bao non hay mo phan sinh khong co khong bao, khong bao hien dien di dang tien khong bao. Tien khong bao c hnh thanh t 1 mang li trans-golgi. Khi te bao trng thanh, tien khong bao hp lai thanh 1 khong bao ln.

Khong bao c bao quanh bi mang khong bao va dung dch ben trong goi la dch te bao. Khong bao cha ion vo c, acid hu c, ng va nhng hp chat th cap bao gom cac sac to. Nong o chat tan cao la cong cu e hap thu nc can cho s dan cua te bao.

Khong bao con cha nhieu enzymes thuy giai nh protease, ribonuclease, glycosidase. Nhng enzymes nay se c giai phong vao te bao chat tham gia vao s phan huy cua te bao trong qua trnh lao hoa; Nhng enzymes nay cung tham gia vao cac s bien oi cac thanh phan cau truc cua te bao suot i song cua cay. Nhng protein a c chuyen hoa trong khong bao c goi la protein bodies, co nhieu trong hat. giai oan nay, nhng protein c d tr se b thuy phan va chuyen ra te bao chat c dung cho s tong hp protein..

4. Bo xng (xytoskeleton) Bo xng ong vai tro quan trong trong viec quyet nh s to chc cua te bao chat,

hnh dang, s phan chia tang trng va phan hoa cua te bao. Bo xng cua te bao thc vat co thanh phan cau truc la nhng vi si, vi ong do

protein co dan actin va myosin tao ra, nam len loi vi protein noi tai hay di mang. * Vi ong (Microtubules): La

nhng ong dai ng knh khoang 24nm, ng knh vung loi khoang 12nm, c thanh lap t tieu n v cua protein hnh cau la tubulin co khoi lng phan t khoang 100.000 dalton, va c hp thanh bi 2 chuoi polypeptid ( va tubulin).

* Vi si (Microfilaments) : Cau tao bi 2 chuoi protein actin xoan nhau thanh hnh xoan oc, co ng knh khoang 6nm.

Vi si c hnh thanh t tieu vi si, tieu vi si c cau tao do nhng tieu n v tubulin lien ket nhau, tieu vi si se lien ket thanh vach cua vi ong.

Bo xng c nghien cu trong te bao ong vat t nhng nam 1960, nhng tren thc vat no khong chac chan v vach te bao nang cho te bao tran va quyet nh hnh dang cua te bao thc vat, nen s hieu biet ve bo xng thc vat con la van e cha ro. Khi vi si va vi ong c chng minh te bao khong phan chia, ngi ta co the quan sat chung di knh hien vi va kham pha bang cach tieu huy vach te bao va tach mang te bao


va nhng thanh phan te bao chat khac vi chat tay. Mi ay, thanh phan th ba la filament trung gian c kham pha va c at ten nh vay v no co ng knh khoang 10-15m, la trung gian gia ng knh cua vi si va vi ong.

Thuat ng bo xng la ten goi khong thch hp v no co ham y cau truc cng ran vi nhiem vu on nh, nhng ay ngi ta thay vai tro cua no rat nang ong. Vi ong c hnh thanh va tai tao khi te bao phan chia, tang rong va phan hoa. Vi ong hnh thanh thoi nhiem sac ong vai tro quan trong trong viec chuyen ong cua nhiem sac the trong suot qua trnh phan chia te bao. Vi ong cung nh hng va nh v vach te bao mi cua te bao con va hnh thanh vach cellulose cua te bao trng thanh.

Vi si kiem soat s nh hng va dong chay lien tuc cua te bao chat, nhng thanh phan nho va bao quan trong te bao chat xung quanh chu vi cua te bao. Vi si hnh thanh cum hay bo song song vi hng cua dong te bao chat. Vi si con ong vai tro quan trong trong s phat trien cua ong phan. Khi hat phan nay mam, vi si phat trien thanh nhng ong dai i xuong nuom nhuy e giai phong giao t c en noan. S tang trng cua ong phan ch pha au va nhng mach cha tien chat cua vach te bao c dan xuyen te bao chat en vung au ang tang trng bang mang li cua vi ong.

III. MOT SO TNH CHAT HOA LY CUA CHAT NGUYEN SINH 1. Chat nguyen sinh la mot he keo phc tap * He keo Cac he keo n gian eu do hai loai chat khong hon hp vi nhau tao nen, phan biet

la hai tng goi la tng phan tan (ran) va tng lien tuc (long). He keo c phan biet vi dung dch that cho kch thc cua tng phan tan la cac hat co ng knh nam trong khoang 1-100m (0,001 0,01mm), con dung dch that th ng knh hat nho hn 1m.

Neu tng lien tuc (dung moi) la nc th goi la hydrosol. Trong hydrosol, hat keo thng hap phu cac ion trong dung dch tao thanh mixen keo tch ien. Ngoai viec mang ien th ban than hat keo thng co cac goc a nc nh NH, -OH, -COOH, CHO nen co the hap thu nc mot cach rat chac che lam cho hat keo co mot mang nc bao boc xung quanh. Trng hp nc lien ket vi cac hat keo nh vay goi la s thuy hoa. Hien tng nay co c nh vao tnh lng cc cua nc.

Nh vay, trong hydrosol moi mot mixen keo eu co cac phan t nc bao boc xung quanh va s di chuyen cac hat keo rat kho khan, duy tr s on nh cua he keo.

* Nhng bien oi trong he thong keo - S ngng ket: moi phan t keo eu c tch ien. Neu cac phan t mang ien cung

dau th chung ay nhau, neu khac dau th chung hut nhau. Neu sc ay ln th he keo ben. Ngc lai, neu lc hut ln th cac phan t keo xch gan lai vi nhau, ln dan va lang xuong. o la hien tng ngng ket.

Trong hien tng ngng ket hnh thanh hai pha ro ret la pha dung moi hoa tan va pha chat hoa tan.


S ngng ket phu thuoc vao: S tang nong o cac chat ien phan lam triet tieu ien tch cac phan t keo; Tang nong o cac phan t keo do o tang lc hut cua cac phan t keo.

Hien tng chuyen gel-sol: Sol la trang thai long cua keo (co tnh nht), khi o hat keo hoan toan phan tan trong trng lien tuc con gel la trang thai ran hay na ran cua keo (co tnh an hoi), nhng hat keo co ket cau khong oi xng se hut lan nhau nhng bo phan nhat nh tao nen chat keo trang thai gel co ket cau hnh vong lap the.

ac iem cua keo la kha nang chuyen t trang thai sol-gel va ngc lai. S chuyen sol-gel trong he keo co the c tao ra do thay oi nhiet o, nong o ion hydro tc thay oi pH, tang them chat ien phan hay tac ong c hoc.

- Hien tng coaxecva: cac phan t keo thng co mot lp nc bao quanh nhng v mot ly do nao o ma lp nc nay mat i va cac hat keo lien ket lai vi nhau trong mot mang nc chung, tao thanh cau truc hat goi la coaxecva.

* Chat nguyen sinh la mot he keo phc tap co ay u tnh chat va dau hieu cua nhng ai phan t trong dung dch

Trong te bao th chat nguyen sinh cung xay ra cac hien tng a ke tren ung nh trong he keo noi chung, v the chat nguyen sinh c coi la mot he keo (Ma cac hat keo cua no la cac protein). Tuy nhien, chat nguyen sinh co o ben vng cao, do cac mixen keo c bao phu bi mot lp kep cac ion va co mang nc rat day bao boc, v vay muon lam cho chat nguyen sinh ngng ket rat kho. Thng dung axeton hay ru hoac cac loai muoi ac e hut nc mi lam keo nguyen sinh chat ngng ket.

trang thai sol keo hoat ong rat manh nen thuc ay cac qua trnh sinh trng cua te bao. Trong i song cay trong khi cay con non, cac giai oan sinh trng nhanh va ra hoa th keo nguyen sinh chat thng trang thai sol e cho cac qua trnh trao oi chat c tien hanh thuan li. Keo dang sol co li cho qua trnh trao oi chat nhng khong co li cho thc vat khi gap ieu kien bat li cua moi trng.

Nguyen sinh chat dang gel a nc khi mat nc nhieu th the tch co lai va khi gap nc th no hut nc rat manh, gel mat nc cang nhieu th hut nc cang manh, ap lc trng cang ln (ap lc nay cac hat giong kho co khi at ti tren 1000 atm). Keo nguyen sinh chat dang gel th tnh chong chu cao hn nhng mc o trao oi chat kem. Trong nguyen sinh chat th hien tng coaxecva co lien quan ti viec hnh thanh cac c quan t, v ay nh la s hnh thanh mot to chc song au tien. Operin cho rang cac hat coaxecva co kha nang hap thu cac enzym va anh hng en hoat ong cua enzyme.


2. ac tnh vat ly cua chat nguyen sinh Chat nguyen sinh c ac trng bi tnh long ong nhat khong tan trong nc, kha

nang thay oi thuan nghch thanh phan va o nht cua mnh, tnh an hoi. Cac tnh chat nay ch bieu hien khi chat nguyen sinh trong mot te bao nguyen ven.

* Tnh long cua chat nguyen sinh: Chat nguyen sinh co tnh na ac na long, tnh long the hien s van ong va sc cang be mat cua no. Nh o ma co s trao oi chat gia cac te bao va co s tang cng kha nang hap phu cac chat.

* Chat nguyen sinh co o nht cau truc: chat nguyen sinh co mot o nht ang ke v vay no c xem nh la mot chat na long (o nht la sc can cua cac phan t trt len nhau). Trong te bao cua cay au nga th o nht chat nguyen sinh ln gap 24 lan o nht nc nguyen chat va 13 lan ln hn o nht dch te bao cua chnh cay o.

Nhng iem ac biet ay la o nht chat nguyen sinh la o nht cau truc, ngha la cac phan t trt len nhau theo mot ng nhat nh. ieu nay the hien mot cau truc phc tap cua chat nguyen sinh lien quan en kha nang cua mixen keo hnh thanh nen nhng lien ket tam thi khong ben. Cac mixen keo ay chnh la cac cao phan t sinh hoc ( protein, axit nucleic, lipoit).

o nht thay oi tuy theo ieu kien moi trng: nhiet o cao th o nht giam, Ca++ lam tang o nht, K+ lam giam o nht. o nht cao th sc chong chu cua thc vat ln, o nht thap th sc chong chu thap nhng cac hoat ong trao oi chat tang. o nht thay oi tuy theo tuoi c the (thi ky cay con co o nht thap, sau o tang dan len nhng en thi ky cay ra hoa ra nu th o nht lai giam xuong mot cach ot ngot va lai tang len sau khi cay ket thuc thi ky ra hoa- chnh v vay ma cay giai oan ra hoa de b anh hng cua ieu kien ngoai canh).

* Tnh an hoi: Tnh an hoi la kha nang quay tr lai trang thai ban au sau khi b bien dang. Ngi ta thay rang tnh an hoi cang cao th kha nang chu kho cua chat nguyen sinh cang ln.

IV. S TRAO OI NC CUA TE BAO THC VAT 1. Hien tng khuech tan va tham thau Giong nh trang thai kh, trong dung dch cac phan t cua chat hoa tan cung luon

luon tranh thai chuyen ong khong ngng. S chuyen ong nay mac du cham chap hn s chuyen ong cua cac phan t kh nhng cung dan en ket qua la cac phan t chat hoa tan co khuynh hng phan phoi eu ra cac khoang khong gian co the choan c (Khoang ay chnh la the tch dung moi).

Neu tren ng khuech tan ma cac phan t chat tan ay gap mot mang th s khuech tan ay tr nen phc tap hn theo nhng mc o cao thap khac nhau tuy thuoc vao cac lo nho tren mang.

Chnh s khuech tan cua nc va chat tan qua mang ay goi la s tham thau. nhng nghien cu cho thay ngoai loai mang nh tren th con co nhng mang khac ch cho nc hay noi mot cach tong quat hn la ch cho dung moi i qua ma noi chung khong cho chat tan i qua. Nhng mang nh vay goi la nhng mang ban tham. S khuech tan qua mang ban tham goi la s khuech tan mot chieu cua nc hoac dung moi sang dung dch.

Lc gay ra s chuyen dch cua dung moi vao dung dch qua mang goi la ap suat tham thau.


Theo Vanhop, ap suat tham thau phu thuoc vao nong o phan t, nhiet o, s ien ly cua dung dch va co the tnh theo cong thc:

P = RCTi Vi R: hang so kh = 0,082 T: nhiet o tuyet oi C: nong o dung dch tnh theo M i= 1+(n-1) = Chat ien ly; n = so ion ma phan t phan ly oi vi nhng chat khong ien phan th i=1. Trong cay, dch te bao tao ra P va ai lng P mot ai lng bien oi. Nhng nhom

cay sinh thai khac nhau th co P khac nhau. Cay moc at kho can th co P ln. Td: Ap suat tham thau cua dch te bao mot so loai cay:

Rong uoi cho 3.13 atm Beo hoa dau 3.49 atm Cay au leo 10.23 atm Cay b ngo 9.63 atm Phi lao 19.86 atm Sn 24.08 atm

P con thay oi theo thi gian va co nhp ieu ngay nh sau: sang thap, tra cao va chieu lai thap xuong.

2. Cac qua trnh tham thau vao trong te bao thc vat Trong te bao thc vat, cac lp mang cua chat nguyen sinh la nhng lp mang gay ra

hien tng tham thau trong te bao. Toc o cua nc xam nhap vao te bao hay thoat ra khoi te bao phu thuoc vao tnh tham khac nhau cua mang te bao va mang chat nguyen sinh. S xam nhap cua nc vao te bao co the xay ra theo ba trng hp: ang trng; u trng va Nhc trng.

Khi ta ngam te bao vao nc hoac dung dch nhc trng (dung dch co ap suat tham thau thap hn ap suat tham thau dch te bao) th nc t trong dung dch ngoai i vao khong bao va lam tang the tch cua khong bao. Ap suat nay lam cho khong bao to ra va ep thanh te bao goi la ap suat trng nc, ap suat nay lam mang te bao cang ra, mang te bao se sinh ra mot lc chong lai va goi la sc cang trng nc. Khi hai ap suat nay bang nhau th s tham thau dng lai. Khi te bao trang thai bao hoa th the tch te bao la cc ai. Khi o chat nguyen sinh dnh chat vao mang te bao va sc cang trng nc at en gia tr cc ai.

Ngc lai, neu em te bao o ngam vao dung dch u trng (dung dch la u trng th dung dch co P > P dch te bao) th nc t te bao ra ngoai va the tch te bao nho i, mang te bao tr lai bnh thng, sc cang trng nc bang khong va the tch te bao mc toi thieu. Neu dung dch ngam te bao vao qua u trng th nc t khong bao tiep tuc i ra ngoai lam khong bao co lai keo theo nguyen sinh chat tach ri khoi mang te bao. Hien tng chat nguyen sinh tach khoi mang te bao goi la hien tng co nguyen sinh.

Co nhieu dang co nguyen sinh: luc au la co nguyen sinh goc, sau la co nguyen sinh lom va cuoi cung la co nguyen sinh loi. Hien tng nay lien quan ti o nht chat nguyen sinh: te bao nao co o nht chat nguyen sinh cao th co nguyen sinh lom, con te bao nao co o nht chat nguyen sinh thap th co nguyen sinh loi (V nguyen sinh chat de tach ra khoi vach te bao) => Co the dung

phng phap nay e xac nh te bao cua mot loai thc vat nao o co o nht chat nguyen sinh cao hay thap.


Neu nh em te bao ang co nguyen sinh nay at vao dung dch nhc trng th te bao lai dan dan tr ve trang thai bnh thng va xay ra hien tng phan co nguyen sinh.

Hien tng co nguyen sinh the hien s song cua te bao, bi v ch co te bao song mi co hien tng co nguyen sinh. Te bao chet th mang ban tham b pha huy.

C s cua hien tng co va phan co nguyen sinh la tnh chat tham thau cua te bao. 3. Khai niem ve sc hut nc cua te bao thc vat , luc nao cung co s thoat hi nc t la, do vay t khi co s bao hoa nc

trong te bao ma cay thng trang thai thieu nc. trng hp te bao bao hoa nc th ap suat trng nc (P) bang vi sc cang

trng nc (T). Nh vay, trang thai thu nc cua te bao th P > T va P - T = S. ay S la sc hut

nc . Nh sc hut nc ma nc co the i vao te bao lien tuc. S phu thuoc vao trang thai

bao hoa nc cua te bao. Khi te bao heo th S ln, khi te bao bao hoa nc th S = 0 v luc ay P =T P -T = 0. Nh vay chnh ap suat tham thau P a tao ra sc hut nc S. Nhng neu theo cong thc S = P T th S luon luon < P, ma trong thc te ta thay co trng hp S > P. Macximop a cho thay co trng hp te bao mat nc khong phai do tham thau ma la do bay hi trong moi trng khong kh kho, luc o te bao mat nc rat nhanh, the tch cua ca te bao giam i, do te bao nhan nheo lai. Nguyen sinh chat trong trng hp nay khong tach ra khoi mang te bao. Luc nay th sc trng nc mang gia tr am v the khi thay vao cong thc ta se co S = P + T .

Sau ay la s o Urprung bieu hien s lien he gia ba ai lng P, S, T.

Sc hut nc S bieu th tnh trang thieu nc trong te bao va do o co y ngha ln trong viec s dung ch tieu nay e xay dng che o ti nc cho cay.

4. Vai tro cua keo sinh chat trong viec hut nc Ta biet rang S xuat hien do co P trong khong bao. Nhng trong nhng te bao cha co

khong bao th van co S. S trong trng hp nay do ap lc phong cua keo gay nen khi cho cac mixen keo hap thu nc. Protein th cho ap lc phong cao hn tinh bot v vay ta thay hat au trng nc n ln hn hat lua. Nh vay S khong phai ch sinh ra do qua trnh tham thau thuan tuy ma con do tnh chat ly hoa cua he keo cua chat nguyen sinh.


V. S HUT CAC CHAT HOA TAN VAO TE BAO 1. Tnh tham cua te bao Kha nang cho cac chat hoa tan i vao hoac ra khoi mot mang ngan la tnh tham. Vay

tnh tham cua te bao la kha nang cua te bao hap thu nhng chat hoa tan vao te bao va cho nhng chat hoa tan ra khoi te bao.

oi vi te bao, tnh tham co ac iem rieng. o la kha nang ch tham nhng chat hoa tan ma khong tham vi cac chat khong tan, va no khong tham mot cach thu ong theo tnh chat vat ly va hoa hoc n thuan ma la tham co tnh chon loc.

2. Phan loai cac chat theo tnh chat vat ly va xac nh kha nang tham cua chung vao te bao

Cac chat khong phan cc: la nhng chat co ien t phan bo ong eu gia hai nguyen t. Th du nh cac chat CH4, chat co nhom CH3, C2H5, C4H9, C6H5 la nhng chat de hoa tan trong m va cac dung moi khac, cac chat nay de xam nhap vao te bao.

Cac chat phan cc: cac ien t lien ket gia hai nguyen t vi nhau qua nghien ve mot nguyen t nao o. V the chung nh la mot chat co tnh lng cc. Th du nh ru etylic, cac chat thng co nhom OH, COOH, NH2, CHO, SH, COONH2 va la nhng chat co noi oi, noi ba, cac chat nay kho xam nhap vao te bao.

Trong thc te co nhng chat va co nhom phan cc va co nhom khong phan cc. Luc o se tuy theo nhom nao chiem u the. Th du chat C2H5OH th nhom khong phan cc nhieu nen de tham, con etylenglycol HOCH2CH2OH phan cc nhieu nen kho tham.

oi vi cac muoi vo c: th tham vao te bao cham hn ca cac chat hu c phan cc va quy luat rat phc tap. Trong thc te san xuat ngi ta ap dung nhng hieu biet nay trong viec che tao cac loai thuoc tr sau, diet co.

3. Cac yeu to anh hng len s xam nhap cac chat vao te bao a/ Moi lien quan gia he so tham va he so phan tan Trong viec xac nh tnh tham ngi ta con tnh en he so phan tan: Hoa tan trong m He so phan tan = ------------------------------ Hoa tan trong nc oi vi cac chat khong phan cc th kha nang hoa tan trong m nhieu, tc la he so

phan tan ln. ngc lai oi vi cac chat phan cc th kha nang hoa tan trong nc ln nen he so phan tan nho.

Cac chat co he so phan tan cao thng de xam nhap vao te bao va khong phu thuoc vao kch thc cua chung.

b/ Tnh tham va kch thc, trong lng cac phan t Trong lng va kch thc cac phan t cang ln th cang kho xam nhap vao te bao.

Th du nh saccharose th de xam nhap vao te bao, nhng tinh bot, glucogen th khong xam nhap c vao te bao, acid amin th de xam nhap vao te bao nhng cac protein th xam nhap vao te bao rat kho.

Tuy vay, viec xam nhap cac chat vao trong te bao con phu thuoc vao ac tnh cau tao tng loai te bao, nhat la mang te bao, chat nguyen sinh.

c/ Anh hng cua cac chat ion hoa len s xam nhap cua chung vao trong te bao Noi chung cac chat ien phan th xam nhap vao trong te bao kho hn. Kha nang xam

nhap cua cac chat ien phan phu thuoc vao so phan t khong phan ly. Neu so phan t


khong phan ly nhieu th s xam nhap de dang hn, nhanh hn --> Viec tch ien a anh hng en s xam nhap vao te bao.

Nhng ion tch ien cao th s xam nhap cang kho. Na+, K+ xam nhap de hn Ca++, Mg++. Ion Fe+++ lai cang kho hn khi xam nhap vao te bao. oi vi amin cung vay.

Tuy nhien, oi vi cac ion cung hoa tr th th kha nang tham vao te bao cung khac nhau. Th du NH4+ xam nhap vao te bao nhanh hn K+ va K+ lai vao nhanh hn Na+.

V sao vay? Ngi ta giai thch bang mc o thuy hoa cac ion. Cac ion thng hut va gi cac phan t nc quanh mnh va chnh mang nc mot cho s xam nhap cua cac ion b can tr. Nh vay la mc o thuy hoa cac ion khong giong nhau va t o gay ra s xam nhap nhanh cham vao te bao.

Noi chung, oi vi cac ion khong tch ien th xam nhap vao te bao de dang. Con cac phan t tch ien th khi xam nhap se b cac ien tch trai dau cua mang gi lai. Ngi ta a o ien tch cua mang va thay no tch ien dng.

d/ Anh hng cua nhiet o len tnh tham Khi nhiet o tang a cung cap nang lng cho mot so phan t lam cho so phan t nay

co u kha nang vt qua chng ngai nao o tren mang te bao. He so nhiet cua tnh tham khoang 2-4 e/ Khi te bao b thng ton Th tnh tham cung tang len va co khi mat han tnh tham chon loc (hat chet). f/ Anh hng cua trang thai sinh ly en tnh tham Te bao hoat ong manh th oi hoi nhieu chat dinh dng. V the chung luon luon ton

tai mot gradien nong o tao ieu kien cho s khuech tan lien tuc cac chat vao te bao. Tuy nhien co trng hp cac chat xam nhap vao te bao ngc gradien nong o la

trng hp van chuyen tch cc qua mang. Tat nhien la khac vi trng hp khuech tan, trng hp nay phai co s cung cap nang lng.

Trong thc te thay co trng hp mot loai tao Nitela nong o K+ trong te bao cao gap 1.065 lan moi trng, nhng K+ van tiep tuc i vao te bao.

4. Cac thuyet giai thch tnh tham cua mang te bao Thuyet Oreton: Qua th nghiem thay hau het la cac chat tan trong m eu de tham

vao te bao, va a i en ket luan la mang te bao can ban phai c cau tao bang nhng chat m.

Thuyet mang ray cua Traube-Ruland: Mang te bao co cau tao lo hong. Thuyet Lepeskin: Mang te bao ngoai lipid con co cac protid. No co cau tao kham.

Theo thuyet nay th s bien oi tnh tham phu thuoc vao s bien oi t le gia lipid va protid. Khi mang cau tao nhieu lipid th cho cac chat tan trong m i qua, khi nhieu protid th cho cac chat tan trong nc i qua.

Quan niem hien nay: Thay c la ban chat tnh tham cua te bao rat la phc tap. Tnh tham la mot qua trnh sinh ly rat phc tap, no lien quan en toan bo hoat ong song cua te bao - nhat la ho hap va cac qua trnh trao oi chat khac.

VI. MO VA C QUAN (Tissues and Organs) 1. Mo nhng sinh vat a bao nh thc vat th nhng te bao to chc lai theo nhng nhom

co cung chc nang goi la mo. Mot so mo th n gian va ch gom mot kieu te bao giong nhau, mot so mo khac th phc tap hn va cau tao t mot so kieu te bao khac nhau. Mac du


rat a dang ve hnh dang va cau truc nhng noi chung th co the chia lam mot so mo chnh nh sau

a/ Mo phan sinh (Meristems) Mo phan sinh la ni te bao phan chia tao ra te bao mi, khac vi ong vat, mo phan

sinh thc vat luon sinh trng khong gii han. Co hai mo phan sinh chnh la mo phan sinh nh va mo phan sinh ben. Mo phan sinh

nh nam nh choi va nh re giup tang chieu cao choi va chieu dai re. Kieu sinh trng nay goi la sinh trng chnh va nhng te bao cung nh nhng mo tao ra t mo phan sinh nh se tao ra bo khung chnh cua cay. Phan ln cay cung se tang ng knh than va re nh vao viec tao ra them mo mach cho bo khung cay. S sinh trng ben nay c goi la sinh trng th cap va do mo phan sinh ben la tng tang libe go (vascular cambium) thc hien.

b/ Nhu mo (Parenchyma) La mo hien dien chu yeu cay, co ca than la re va mo mach. Te bao nhu mo

thong thng ch co vach s cap, vach th cap th t co. Te bao nhu mo la ni chu yeu dien ra qua trnh quang hp, d tr, va trong trng hp mo mach th giup van chuyen nc va chat hu c. Te bao nhu mo van con kha nang phan chia va gi vai tro quan trong trong viec tai sinh va han gan vet thng.

c/ Mo c gii (Supporting tissues) Mac du cau truc cay chu yeu da vao ap suat trng nc va s lignin hoa mo mach

nhng van can s tr giup cua mo day (collenchyma) va mo cng (sclerenchyma- cng mo).

Mo day la nhng te bao nhu mo tr giup ac biet cho cac mo con non. Mo day thng tm thay phan vo canh non, cuong la va doc gan la. Cau truc ac biet cua te bao mo day la co vach s cap day len.


Mo cng th ngc lai nam tha tht khap ca cay, trong ca hai mo s cap va th cap. Co hai kieu te bao mo cng la te bao a (sclereids) va te bao si (fibers). Te bao a hnh a giac trong khi te bao si mong va dai. Ca hai loai te bao nay eu co cach th cap hoa day va lignin hoa rat nhieu. Te bao a co nhieu vo hat, qua hach. Te bao si co nhieu vo cay va la cay.

d/ Mo mach (Vascular tissues) Mo mach c quan tam chu yeu vi chc nang dan truyen nc, dinh dng va san

pham quang hp. S tien hoa cua cay mach dan a giup no chiem lnh c nhieu vung sinh song tren can. Co hai kieu mo mach la mo go (xylem) va mo libe (phloem).

Mach go co cau truc va chc nang phc tap, la c quan chu yeu e dan nc, d tr va nang cay.

Mach libe cung co cau truc va chc nang phc tap, la c quan van chuyen san pham quang hp t Sources en Sink.

Mo mach cung co hai loai la mo s cap va mo th cap theo nguon goc hnh thanh cua no t mo phan sinh.

e/ Mo bieu b (Epidermis) Mo bieu b la lp te bao ngoai cung nhat che phu la, than non, re va qua. Te bao

bieu b thng co cung hnh dang va xep rat chat vi nhau. Mat ben ngoai te bao bao phu bi mot lp cutin e chong mat nc.

2. C quan Giong nh cac te bao hp vi nhau lai thanh mot nhom goi la mo vi nhng chc

nang rieng biet th nhieu mo se hp lai tao thanh mot c quan. Nhng c quan chnh cua cay la re, than, la va hoa.

a/ Re (Roots) Re phat trien t re mam hay re phoi thng c goi la re chnh (re coc), re moc ra

t re chnh goi la re ben. cay hai la mam th re chnh thng chiem u the nen moc sau va dai con cay mot la mam th re chnh thng chet sm va bo re phat trien mot he re chum.

Chc nang chnh cua re la giup cay ng vng, hap thu nc va dinh dng trong at. b/ Than (Stems) Than cay la truc keo dai t phoi mam thong qua s phan chia te bao vung mo phan

sinh nh choi. S phan chia te bao cung nay cung tao ra tien la va tien hoa. iem ra la va hoa goi la mat va khoang gia cac mat goi la long. Ngay di nh sinh trng th cac tien la nam rat gan nhau va kho phan biet c long, khi te bao sinh trng th cac ot se ri nhau ra va long dai ra. Khi long khong dai ra c th xuat hien cay dang hanh (bulbs) hay hoa th (rosette), luc o ta thay hnh nh tat ca cac la eu moc ra t mot iem. Trong phan ln trng hp th mot phan nho mo phan sinh van con nam goc la va no se hnh thanh choi ben (axillary buds), co the moc thanh nhanh mi hay hoa mi. Phan ln than cay moc tren mat at nhng cung co loai moc di mat at nh khoai tay chang han.

S sap xep mo trong than co the rat khac nhau tuy theo tuoi va cay hai la mam hay mot la mam.

Vai tro cua than la dan truyen, d tr va nang . c/ La (Leaves) La la nhng phien hay ban mong nh vao than cay bi cuong hay be la. Phan mat

ngoai la la bieu b tren va bieu b di va gia la cac te bao nhu mo quang hp. Phan ln


cay hai la mam co hai loai te bao nhu mo la nhu mo dau (palisade mesophyl) va nhu mo khuyet (spongy mesophyl).

Trong la cung co mot he thong mach dan noi lien vi he thong mach dan than thong qua cuong la. cay hai la mam th mach dan hnh thanh mot mang li nho e van chuyen nc va dinh dng ti tng te bao quang hp ong thi van chuyen nhanh san pham quang hp ra khoi ni san xuat. cay mot la mam th gan la tao thanh mot he thong gan nho nam song song nhau va cung gi nhiem vu nh cay hai la mam.

P = RCTi

Chương 1-Sinh Lý Tế Bào

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