Công nghệ gen

NHA XUAT BAN KHOA HQC vA KYTHUAT

HA N(:n - 2006

CONG NGHE GEN •

GS.TSKH DAI DUY BAN

3

Diing te' belo go'e co 1111die'lf Trj cac bfnh hiim IIgheo vel xii 1I(;iIIJllf:

bflllt liei, dltr/flg, bfnh Parkinsoll, b¢nlt ling llil( mal( cac 10(li v.v...

rile:

D{ic hi¢T li¢lI pluip gen - la phuang pluip c"[(a IJ¢/llt b(illg gen vel Ilwoe

gen dang dl({/c thinh Mill", dd gop phdn die'li trf vel cltiia k/t6i f7l{jl st/ m(J1 so'

benh nan y nlur: X(/ nang, thieu mau hong call liem, b¢1I1t mall klt6 dong, ling

thu v.v ... N Jilt vcJy, 1'6rang cong Ilgltf gen dong vai tro clll; d90. Grill dciy vall

(Ie'stin xud: Ie' bao phoi goc (Ie.' bao mdm phoi} ell pliuc 111.1 ngliien ctru va

die'lI 11'1cling dang duac ban ali I'd pJul/ 11'ill1. dim r(J 1M coug nghf gen Cling

gop phdn qU{J/1 trong, vai fro Clta cuu Dolly vel ky tllll{it Ie' b(IO goc phoi da

ddy \'i¢c die'lf tri y 119Clell m(J1 tdm cao lion I1Ira.

Te' bao goc phoi t90 ur plio! nluin bdn vai Ie' bao sinh during Clta Jlgl((/i

bfllll c6 ('(Ie lai lillI/lilt:

+ Khoug hi hang /'''0 miln dich cdn Ira khi glu:p \'do COIhl

+ Co Ihinllitn nlw/111 vel bi~1 /10(1 1at ccl cac tii' bao va co qU(1Ildl thay

Di truyen hoc phdn tif nghien Clfll C(1'1I true cae gen \'(~SI_( "{III //(11111

('(Ie san phdm Clla cluing trong m91 rt bao. Ldnh r{te lUiy klu)l7g ngll'l1g dl(lC

pluit Irien III nlut ky rJlII~i( lien quan dell Sl/ tliao tdc ADN. ARN va protein

(hay doi mau If: \'0 manh me rna cac ky f/I/{(if do ngdy nay duac goi I" cong

ngh~ gen.

eollg Ilg/t¢ gen 1'(1 doi dd ddn toi nhiing (iell btl pili tliuang trong 111I/c

li/n y khoa vel trong /lOllg I1gllifp. Cong ngh¢ geu hi sai chi dd Clia Cong

Ilg/i¢ sinh hoc. N hel cong l1gh¢ gen llgui'ji ta dd wi dang I~W ra ('(Ie loai cay

trong, vtit nuoi bh?ll ddi gen nluim cling cdp luang thuc tliuc phci'm m(Jr cacli

d(Ji dao Fa da dang ..tao ra cdc loai 11111(/C. cac sinh phdm ({IIY gi(r dd1 lie'n dr!

chiia benh; sdn xudt fa cac b(J kit cliei'll dodn sam \'a chinh xac cdc benh ..1{10

ra clic vaccine (vacxin) pluin tir leli t61u;p depliong CelC b¢nh virus (virut) \'a

nhiem kill/ail.

tor GIOI THItu

4

C()l1g ng/i{1 gel/ Id gi? C(1c IlgU,will Iy ca ban Clia coug Ilgh¢ gen \'(II/;Ig

clullg c(}lIg I/gh~'ige/l trong Ulc liul, I'I/C kiuh Ie'(/II(/Cdan II/I/olle' tuio?

Trong J/ltirJlg nam quo, cluing toi dti C() 11I()f Sf)' cong trill" ughieu CII'II

('(II) /1() I'd ni'p Nha 111(/1(' \'(f chdn dodn sam ungthu ga/1, uug tlu: 1'{)J11 hong,

lI//g thu \'Ii I'd mot s(/ b~lI/i virus I'/{>/I ('() die'u kicJn fiell luutli cdc k,v Ihl/{If I'e'

c(mg Jlgh¢ gen. Do de)dl gop pluln him sang trJ nliiing vdn de' tren dong tltoi

df diip 1(lIg dirac nlut CCIII Clia (,(IC sill" vien dai hoc. ('(Ie hoc vien cao 1I<)c,

("(/('ngliifll cu« sinh 1'(/ nliu cdu tham klulo ctia ('(Ie can b(l gidug day, can btj

Ilgltihl ('11'11trong die Ilgdnh ('(>JIg/lgltf sinh hoc, y duoc, IIC)",!; ldm fllll," sdn;

cllllllg 16i bien SO<1I1 clI()i, sacl! "C611g Ilgltf 8(!11".

N (Ji dung cuon sdch g(5111J 6 clurong d/((1C s6p ~'el}tlieo ,llIr rlf logic Ilr

IIglfyhl Iy ('0 belli dell k)"':tluuit, flr ciC111gkin elell plll((, t{IP ciia Il1(J/llgclllll klioa

1t()C lti¢1I dai. Rieng pluin itng dung cit( ,N cdp I'iilngdll gr;n, vi Illii(/a bai bao

IIh;~'/( sarh kluic: lit?n q[(((11 d(1'1f <fa de' q/[J dell. Trang qu« trinh bihl .\'0<111

cI/(7c kft{)ng trtinh klu3i nhirllg thiel/ sot, Chung toi xiu cdm (1/1 .1'1/ d611g gop

C/((/ cdc h~11Idoc,

CII/iJig toi sin cdm an sl,rdollg grJP clia GS, L(I Dinl! LI(Ong, GS Nglly<?n

Dinh Huycn, TS Hr) HIf,YII" Thuy Duong, PGS Hoang Tit! Biell Ng~lc 1'£'1

nll"lll tac gid k/I(IC cW gil; trong phdn "lei; lieu tliam klulo' cia ClIl1g cc(p cho

CJ/flllg f(ii IIliiiu uu 'if /I be>'fell de" CW'j'1I scicli hOc/II chlnh 11(//1.

Chung f(Ji cilng cluin thtin]! cdm (/11 Nlui ,waf ban KIIO(/ hoc vel K)i

Iltl(~il wi Bien uip \'i£ill dd bien r(tp 1'(1C/IO xlllil bdn d/ C/l(;'11 such dirac slim

dell h~11/doc xa gun 1/'011g cd 111(/(.'.

5

1. Cong nghe gen.

2. Cong nghe nano hay con goi Ia c6ng nghe sieu nho,

3. Sinh hoc dien Ilr hay con goi lit Tin sinh hoc (bioinformarics).

4. Di~llttr quang hoc,

5. Xe hoi hydro.

6. Ky thuat mo phong sieu thuc,

7. Sieu dan nhict d\} cao,

8. Cong nghe tai sinh the gioi dong vat e6 dai,

9. May tinh thong minh,

10. Nhirng V~lt lieu moi.

Voi noi dung cua cucn sach nay. lac gia chi tap trung trinh bay v<!de

C{)NG NGH(t HU()NG Ten TUONG LA[

The ky XXI Iii the ky cua c6ng nghe cao, muoi cong nghe rnoi se dun

chung ra vao the ky nay. thea nhu VS.News, TS. Duong Huycn 16ng hop tu

biio chi.

Loai nguoi dang d~l chan vao Ihe' ky XXI c6 Ie luang lai con nhieu

dieu ky dieu rna tharn chi den cac nha tien trio cac nha lien doan lai unh nhal

cling kh6ng hlnh dung ra duoc. The ky XXI Iil ky nguyen cua cong ngh¢

gen, hi thudt vdt lieu sieu dan, bionics, sieu vi di¢n (It, cting ngh4 sieu

II/Ill ..• va con biet baa nhieu nhiing lien b¢ khac cua khoa hQC va cong nghc.

51! ket hop cua khoa hoc ky thuat voi cac y tuong cua nheng cai duu vi dai.

Kha nang vo han cua loai nguoi va cac nhu cau phat tri~n d5 d~y cuoc each

rnang khoa hoc cong nghe len den dinh cao moi.

M6i hom nay thoi n6 con Ia y luang cua mot ai do thl ngay mai no d5

co the la mot c6ng nghe duoc dua V~tO cuoc song. Muai cong nghc duoc coi

la co trien vong nhfll trong thap nicn sap toi cua the ky XXIIA:

., ,..' MODAU

6

khai niern, nhfing nguyen 19 co ban cua gen va coug ngh¢ gen mot trong

rmroi huang cua cong nghe cao:

Sinh hoc phan tir cua gen va cong nghe gen

Cac khai niern va nguyen 19 co ban cua cong nghe gen

Cong nghe gen trong nganh y va duoc hoc cung nlnr nganh nang

nghiep hien dai.

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PHAN A - KHAI NlitM vt GEN VA CONG NGH:E:GEN 11

. Chuang /. KHAI NI~M VB GEN vA CONG NGH~ GEN 12

Chuang 1/. SljSAO CHEP -SINH TONG HOP ADN 17

I. Sinh tong hop ADN a cac te bao sinh vat nhan so 17

I. Nguyen 19 cua SI! sao chep ADN 17

2. Cac enzym tham gia trong cac qua trlnh sao chep ADN 20

3. Cac giai doan sao chcp ADN 22

II. Sinh t(jng hop ADN (1 cac te bao sinh v~t nhan chuan 24

I. Giai doan GI 25

2. Giai doan S 25

3. Giai dean 02 28

4. Giai doan nguyen phan 28

III. SI! sua chua sai sot trong qua trinh sao chep sinh tong hop ADN 28

1. Cac tac nhan sinh, ly, hoa gay thuong ton ADN 29

2. Cac he thong sua chua thuong t60 va co che sua chira 30

Chuang III. SljPHIEN MA.- SINH TONG HOP ARN 33

I.Sinh long hop ARN a sinh vat nhan so 34

1. Mot s6 d~c di~m ve enzyrn ARN polymeraza 34

2. SI! mo' dau, keo dai va ket thuc SI!sao cac chuoi polyribonucleotid 38

Cong nghe gen

Uti gioi thieu 3

M&~u 5

MlJC LlJC

8

PHAN B - cAe PHUONG PHAp xAc DINH GEN

vA C()NG NGHt BIEU HItN GEN 93

CII/({lI1g VI. cAe ENZYM eAT, BIEN DOl vA NOI ADN 94

II. Sinh tcing hop ARN 0 sinh vat nhan'-chuan 40

1. MQt s6 d~c diem can phan biet 40

2. Ole giai doan rna dau, keo dai va ket thuc 51.! phien rna 42

3. Cac chat !IC che' SI! tong hop ARN 43

4_ SI.!hoan thien ARN ribosom 44

5. SI! hoan thien ARN thong tin 45

Chuang tv MAT MA D1TRUYEN, SljDlCH MA￾SINH TONG HOP PROTEIN 48

I. Mat rna di truyen 48

1. Cac phan Itt bao quan va van chuyen thong tin di truyen 48

2. Cach bao quan va van chuyen thong tin di truyen trong ADN va

mARN, cac bang chirng ve rna bo ba 48

3. Giai ma di truyen 51

4. Cac dac diem ella rna di truyen 52

II. SI! dich rna- sinh tcing hop protein 55

I, Cac chat tharn gia tong hop protein 55

2. Vai tro cua mot 56 yeu t6 quan trong tham gia qua trlnh sinh t6ng

hop protein 57

3. Cac giai doan cua qua trlnh sinh tong hop protein 64

CJll((/IZgV. DIEU HOA HOAT DONG BIEU HI.eN GEN 6R

I. Mo hlnh dieu hoa hoar dong bieu hien gen l:J te bao nhan so 69

II. Mo hinh dieu hoa hoat dong bieu hien gen 0 te bao nhan chuan 72

III. Mo hlnh dieu hoa hoat dong bieu hien gen 00 co the da bao bac

cao 80

IV. Mo hlnh dieu hoa hoat dong bieu hien gen thong qua mang te bao

trong SI! phan chia t6' bao 86

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1. Cac enzyrn han ch€ 95

II. Nhiing enzym khac lien quan den cac thao tac tren ADN 98

Chuang VIl. PHUONG PHAp TAcH CHIET AXIT NUCLEIC 109

I.SI! chuan bi ADN cua toan bo te bao 110

II. SI! chu11nbi ADN cira plasmid 112

Ill. SI.!chuan bi ADN cua thirc khuan th~ 114

IV. Cac phuong phap tach chiet axil nucleic CI,I th~ 116

Chuang vut. PHUONG PHAp LAl PHAN TVY A. PHUOl\:G PHAp

OANH DAU PHAN TV 124

I. Phuong phap 1ai axit nucleic 124

II. Phuong phap danh dau axit nucleic 126

CIII (CfIIg IX CAc LOAl YAT CH1) THU NHAN YA cAc LOAI

VECTO CHON DONG 129

I.Cac loai \'~t chu thu nhan 129

1. V~t ehu ia Ecoli va cac vi khuan khac 129

2. Vat chu la nam men va narn moe 129

3. V~( chu la tlurc vat bac cao 130

4. V~t chu lu de te bao dong vat co vu 131

II. Cac vecto chon dong 131

Chuang X. cAc LOAI VECTO TRONG TAO DONG 141

I. Nhirng van de chung 141

II. Ok loai vecto 143

Clll((II7~ Xl. S1}TAO DONG GEN vA PHAT BieN DONG CAN rIM 149

I. Cac buck cua tao phuong phap dong 149

Il. SI! phat hien dong gen can 11m 151

CIII((JIlgxn. PHUONG PHAp PCR DUNG TRONG TAO DONG

INVlTRO 153

I. Phan ung chuoi polymeraza 153

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PHAN C - UNG Dl)NG CVA C{)NG NGHt GEN 183

Chuang XVI. KHAr QUAT VE UNG DlJNG CUA CONG NGH~

GEN 184

L Khai quat ve irng dung cua cong nghe gen 184

II. Dieu rri gen 185

III. Chan doan gen 195

II. Cac chi tieu anh huong den phan irng PCR 160

III. Cac ung dung chu yeu cua phirong phap PCR 161

CIII((JlIg XJll. KY THU~ T BIEN NAP v). KY THUAT LAy NHIEM 163

I. Ky thuat bien nap-dua cac ADN cua plasmid vao te bao vi khuan 164

II. SI! chon 1LJad6i voi cac te bao tai t6 hop 165

III. Ky thuat lay nhiern-dira cac ADN cua phage vao cac te bao vi

khufrn 166

IV. Ky thuat bien n~\pvao cac t6 bao khong phai cua vi khuan 168

CJII((Jtlg XlV. cAc PHudNG PHAp xAc D!NH TRINH TVCUA

AXIT NUCLEIC 171

I. Phuong phap Maxam va Gilbert 171

II. Phuong phap Sanger 173

Chuang XV. CONG NGH~ BIEU HII;:N GEN 176

I. Nhirng van de chung cua cong nghe 176

IT. Cong nghe bi6u hicn gen trong E.coli 178

III. Cong nghe bieu hien gen trong narn men 181

11

PHANA

KHAI NIEM VE GEN VA

CONG NGHE. GEN

12

CO' so' sinh hoc phan ttl'dia gen chinb Tilacid nucleic (axir nucleic).

1\0 g6m eo acid deoxyribonucleic (ADN) va acid ribonucleic (ARN). Acid

nucleic dong vai tro quan trong trong vice bao ton noi gi6ng \,~l truyen thong

lin di truyen eho the h9 sau. Trong te bao, acid nucleic co th6 kel hop vdi

protein thanh nucleoprotein. Tnroc kia ngirci ta cho rang, acid nucleic chi co

trong nhan Ie bao nhung bay gia cluing pho bien (1cit ngoai nhan.

Oi ADN va ARN deu I~t nhirng phan nr polyme dai gem nhieu

monorne noi voi nhau. Trong ADN, monome do eo len If! deoxy￾ribonucleotld, con 0 ARN, rnonomc do co tell la ribouucleotid. M6i

nucleotid eo mot bazo nita (elfin xuat purin hay pyrimidin) mot dtrong

PCll(OZH vi't m(>t nh6m photphat.

13',mdoc co the tim thay cong ilurc cua de nuclcotid V~t cau true ADN,

A R 1\ <1h'(\'( ky mot cuon sach hoa sinh hoc hoac Sikh eli truycn hoc cling nlur

de sach sinh hoc phan tli nao do nen (1 day clning loi thiet nghi khong can

phiii nhac lai. Dung ve plurong dien phan Itt rna xct thl de acid nucleic n6i

tren dap trng day du de ticu chuan cua v~t chat di truyen.

I. VI no chua dung thong tin CJ dang ben vung, c6 th~ sao chep mot

each chinh xac d~ di truyen cho cac the he sau.

2. Chung c6 the 1<.10 thimh nhfmg phan tic khac mot each co co so d6

din cho C[lUtnic vi hoar dong ella te bao,

3. Dong thai cac acid nucleic cfing c6 kha n[mg bien d6i- mi'l di truyen

vit bien d6i I~l hai mat cua eli truyen hoc hicn dai.

~gi\y nay, nguoi ta cluing minh diroc rtl11g ADN lil v~t chnt di truyen

ClW hau hel sinh v~t, con ARN V~lv~ltchal di truycn cua met so virus (virut).

Ciic v~t chat di truycn ella tc bao Bam trong cac nhicm s.k the. co th~

KHAI NI~l\1 VE GEN vA CONG NGHe GEN

CHudNG 1

13

phan bier duoc ba loai nhiem sac the duai day:

I. VOi cdc phage, nhicrn sae the ella cluing HI nhirng ADN tran, chuoi

kep (soi kcp), mach vong khong co protein (d6 1ftphage).

2. V6i vi khudn. nhiem s5c the ciing ia nhiing phan (Ii ADN {riin chuoi

kep. mach vong sieu xoan va t~p (rung (j mot vung goi ia vung nhan khong

c6 rnang bao boc, Ben canh d6 vi khuan con c6 mot loai ADN khac dang

vong kep nho. do la cac plasmid - rna cluing ta se duoc doc nhieu a phan noi

v0 cue vccrc plasmid a cong nghe gen.

3. V6i cac sinh v{itnhtin chutin (eukaryote) nhu narn men. co th~ da

baa thi nhicm sac th~ la nhtrng phan eu ADN sci kep nam trong nhan eo

mung bao boc h~1Ilhoi. Ngoai ADN trong nhan. nhimg loai sinh V~lt nhan

chuan khac nhau co kieu nhan khtic nhuu ca. ve so lirong va hinh dang vii t<)P

hap thanh b(l nhiern stlC lh~. a dong vat, ngoai nhicm s,k (h~ ihuong con eo

nhiern sAc lh~ giai tinh dire va giai tinh cai (Y va X).

Tfit d. nhicm sac the do bo chat giiia ADN va ndm protein ltiston ciic

loai cling nhtr gfin 100 protei II khong histon l~IO fa the nhan (nucieosom).

Luong histon gan bang hrong ADN {rung nhiern s.le tb~. Protein histon hien

nay giG vai tro quan trong trong su dieu hoa heat d(>ng gen V~I biet hoa tc

bao. Con protein khong phiii histon thi gem cac cnzyrn can cho qu.i trinh sao

chcp. phicn ma, dich mii, cac polymeraza ADN. ARN ncn Juan luon bien

dong trong suer chu trlnh cua te bao va rut khac nhau (j cac te bao dITduoc

bier ho.i. Cac nhiern sfle thi! thuong (j de sinh v~t cung loai thi gi6ng nhau.

o ngjroi, narn girri co 44 nhiern silc th~ thuong va hui nhicm s~c tht gioi tfnh

HI X, Y va cr nii gioi cling co 44 nhiern sac th~ thtrong va hai nhiem sac th6

gi6'i tfnh Iax, X.

Trong te bao ella sinb v~lt nh£1I1 chufin, ngoai ADN nhitm stic the nhfln

nglfoi ta con thiiy co mot so ADN (1 t)' Ih~ va 1~IPthe {1 d(~ng ADN tran, m~ch

kep viI dong vong mlm a ngoai nhan. Hi~n nay nguoi ta ding cbu y kiwi thac

cae AON nay nhftt lu ella ty lhci trong phan bi¢t chung lo~i giun san, trong

phiin bi~t hai c6t, rno ma va ell trong ch5n doan ung tim.

Chlrng ta biet rtUlg. trong nucleosorn va ADN trong nhi~rn s~c the dui

hOIl nhicll so vai nhiem s~c the 110 da c1uqcthu g~}[1It nhat gitn 100.IGn va

gan v(1i his ton t<.IOnhi6m sac the c6 klch tlmac lOO nm vii 300 nm (1 pha nghI

hay 16'n han niiu a pha gifra.

6 pha nghI, khi nhuQm nguai la (huy chat nhiem s£c chia thanh hai

loai r6 ret: mot loai duoc nhuorn mau rat nhat goi la eM(r nguyen nliiem sdc,

con loai kia duoc nhuorn mau ral darn goi hi ch(ir di /lhiem .'Ide. Chat nguyen

nhiern S~IC la chat chua ADN 0 trang tluu hO~JId(jllg - pltir!1I nul. Chat di

nhiern sac ia chat chua ADN 0 trang thai klu}lZg phien nid duoc va n6 se sao

chep muon trong chu ky sinh san cua te' baa.

Can phan biet {] day nhiern sac th~ vi khudn chi rnang mot trlnh tl,(

ADN duy nhat, trong khi d6 nhiern sae th~ (J co th~ da baa (nhan chuan) lai

co nhieu dO<.H1 lap lai. Cac sinh vat khac nhau e6 so ADN I~p lai khac nhau.

C6 doan tir vai cap den vai tram cap bazo lap lai h~U1gtrieu Ijll trong gen va

rhuong narn grin tam dong hcac 6 hai dau cua nhiern sac the, cluing duoc sao

chep muon va kh6ng duoc phien rna. Con de dean lap lai hang chuc den vai

ngan Ian thl diroc phien rna va cfing thuong 1~1ARN ribosorn, ARN van

chuyen va histon.

Mot diem niia la i:J co th~ sinh vat nhan chuan, da bao e6 cac doan

kh6ng rnii hoa acid arnin duoc goi ia intron va dean duoc rna hoii goi Iii

exon. Cil hai doan deu phien ma ra phan tii tien chat cua mARN, nlnrng sau

do ticn chat mARN cua intron bi cat di con lai tien ehUt mARN cua exon

duoc noi lai voi nhau thanh phan tii mARN de di vao ribosom dich rna thanh

protein.

Hien nay. nguai ta x.ic dinh duoc illtroll co m¢f vai fro trong qlla triuh

biet 110(1 cua sinh vat eta bao, clnr khong phai nhlrng dean ADN du thira nhu

da nghi sai v~ n6 nhu nhirng narn truce day.

Tren nhiern stic the cua cac sinh vat nhan sa (prokaryote) cilng nlur

sinh vat nhan chuan ngircl ta con thay mot hien urong nhir sau: ngoai cac

gcn chiern vi trf co dinh tren nhiern sac the thl con co nlurng gen hru dong tir

vi trf n;IY den vj trf khae eua be) gen, nglloi ta g9i do la nhfi'ng "yell r{/ di

,r/ly(;'/l I'~ill d(jng" hay u'm g(Ji lei "!Jen Ilhdy". D6 iii nhCi'ng doc~n ADN co

khii nang xen vao m(>tso vj trf trong b(>gen va eGog e6 th~ tach raj khoi be;>

gen. Khi chung xcn VaG b(> gen thl lam bien ddi eli truyen con khi tach khoi

b(>gcn thl nhfrng bien dOi kh6ng con nCi'a.

Ngay nay, nguai ta xac nh~n nbCi'ng gen nhiiy do ton t~i me;>teach phei

n a tat d m9i sinh v~ltlam thay doi eflu true ella h~ gen, do do anh hLIong

n hoc.lt d¢ng gen.

Dong thong tin eli truyen ehay theo m(>t chi~u nhu so do 111nh1.1

15

Qua trlnh phicn rna (transcription) va dich rna (translation) va sao chep

DN (replication) iuan theo guy luat nay. a mot .wj' virus loai ARN th] co

ua trlnh phien rna nguoc (revertranscription) ".10 ra ban sao ADN IU ARN

¢ gen etta cluing.

Gen IiI dan vi co sa cua thong tin di truyen, rna cu the la mot doan

DN cua thong tin di truyen duoc phien rna sang phan IIIrnARN, roi sau d6

ich rna thanh mot protein nhat dinh. Cac gen narn tren cac nhiern sac th6 va

en nao dinh vi (1 dau thl d6 goi Ia locut cua gen d6. 0 cac sinh V~\t luong

oi, cac nhiern solc th6 sap xep thanh cac c~p tuong dong. Tren nhiern sde th~

rong dong. tai cac v! trf tuong irng ton tai cac dang khac nhau cua cung mot

en goi la ulen.

N6i den diu true cua mot gen. nrc HI n6i den don vi phien rna 1<)0 fa

ARN nam gifra di~rn kh6'i dau va diem kct thiic phien rna. Ben trong dan

i phien rna I~ml ot doan trinh W rna hoa con hui dfiu cua don vi phicn rna

on co vung dieu hoa nguoc hoac dieu hoa xuoi chua yeu t6 tang CUC1J1g

enhance) hoac diem chi huy cung voi promote phat dong va diem bam cua

nzyrn polyrneraza ARN.

Cau tnic gen cua sinh v~t nhan so nhu vi khuan, cac gen thuong sap

ep thanh nhom trong operon. Trong cac operon co ba loai nhom gen: cac

cn cau true (S), gcn phat dong (P) va gen chi huy (O) di lien nhau.

Nam ngoai operon con e6 gen ue che rna hoii protein uc che d~ tac

ong len gcn chi huy. Ki6m soat am tinh d6i voi operon, qua ngan chan

hong cho enzyrn polyrnereza ARN bam vao.

Trang cac gen cau true ella vi khu~n thuong b6 trf thea nh6m nen san

phJm phien rna mARN thuong mang thong tin dung cho nhieu protein, d6

goi la da cistron. Cac phan tv duoc t6ng hop cung lTI(:lt luc phu hop voi nhu

Hinh 1.1. Sa daly thuyet ttung tam cua Crick va v~n chuy~n thong tin di truyan. (1)

NhiJng mui ten dl1c;1Crick be; sung them vao nam 1970.

__ PROTEIN

D!CH MA I