CHNG XIV: T BIN NHIM SC TH

CHNG XIV:T BIN NHIM SC TH1T BIN NHIM SC TH Khi nim t bin NST:

B NSTn bi(n=9)2n=184n=366n=548n=7210n=90

t bin cu trc NST l nhng bin i trong cu trc hoc s lng NST, do cc tc nhn gy t bin tc ng trc tip ln cu trc ca NST hoc gy ri lon qu trnh phn bo. T BIN NST: La nhng bin i v cu truc va s lng nst3T BIN CU TRUC NSTT BIN S LNG NSTT BIN NST* Nguyn nhn:Cac tac nhn vt ly, hoa hoc cua mi trng, sai sot trong giam phn lam bin i cu truc va s lng NST* Gy hu qua nghim trong: Hiu qua tc thiGy ri loan hoat ng cua b gene va giam phnAnh hng sc sng, hu thu cua ca thT BIN CU TRC NHIM SC TH* Nguyn nhn pht sinh: t bin cu trc NST c th xut hin trong iu kin t nhin hoc do con ngi Nguyn nhn: Do cc tc nhn vt l v ha hc trong ngoi cnh ph v cu trc nhim sc th hoc gy ra s sp xp li cc on ca chng lm thay i thnh phn, s lng v trnh t cc gen trn NST5T BIN CU TRC NHIM SC THTnh cht ca t bin cu trc NST: t bin cu trc NST lm bin i cch sp xp bnh thng ca cc gen nn thng gy hi i khi t bin cu trc NST cng c li c ngha trong chn ging v tin ha6

7

8* inh nghia: Cc t bin cu trc NST hay cn gi l sai hnh NST (chromosome structure) hay cu trc li NST (chromosome rearrangement) c pht hin bng phng php t bo hc. Cc t bin loi ny thc cht l sp xp li cc gen hoc gim hay tng liu lng gen.

9T BIN CU TRUC NSTT BIN CU TRUC NSTCo 4 loai t bin cu truc NST:+ Mt oan:+ Lp oan: + ao oan+ Chuyn oan: Gia cac NST- Do s t gy v ni li bt thng ca cc on trn cng mt cp tng ng hoc thm ch gia cc cp khc nhau nh trong trng hp chuyn on

BN TRONG NSTt bin NST

12Cc dng t bin cu trc NST:CAEBDFHGCAEBDFHGCAEBDFHGCAEBDFHGCAEBDFHGCAEBDFHGCAEBDFHGEFAHCBGCBECABFHGCAFBDEHDCAEDBFHGEOMNDFHGCAQPRBQOMNPROMNQPRCAEBDFHGOMNQPRAECBDFHGS PHAT SINH T BIN CU TRUC NSTSai hnh NST lin quan n s t on ca NST. C khi 1 NST b t ra qu 2 on v sau c ni li nhng thng khng gi cu trc c. iu dn n nhiu kiu t bin cu trc NST khc nhau. Cc on vng trn khng tm ng thng b mt i trong phn bo.C th xy ra trng hp 2 on c tm ng ni nhau, khi phn bo s b ko cng ra 2 u thnh cu chromatid v sau b t ra khng u to ra mt ci mt on v ci kia tng on.

MT OANMt nhim sc th b khuyt mt i mt an c gi l t bin mt an (deletion) hay khuyt onMt on c th xy ra ti mt phn bn trong nhim sc th, gi l mt on gia hay mt an khe (interstitial deletion)an nhim sc th b t v khng ni li c, gi l mt on mt (terminal deletion). on t gy c cha tm ng th c on ny ln nhim sc th mt an thng s b dung gii trong qu trnh phn bo. C ch mt oan do trao i cheoMT OANS thiu mt on NST gm 2 loi: mt on (deletion) gia NST v mt nh (deficiency). on NST b mt nu nh c th mang 1 gen hoc mt phn gen. Trong trng hp ny hiu qu kiu hnh c th ging nh xut hin alen t bin locus . Cc mt on khng c t bin nghch, bi v on NST b mt kh ngu nhin c gn tr li do t bin. Nh mt on c th phn bit vi t bin gen.

HIN TNG GIA TRIS mt nh ca on NST mang gen tri A cho php alen ln a c biu hin kiu hnh.Khi mt sinh vt d hp t (Aa), s mt on c A th alen ln a trn NST kia c biu hin kiu hnh. Hin tng ny gi l "gi tri" (Pseudodominant), Locus tng ng trng thi bn d hp t (Hemizygote).

MT OANTip hp gim phn I khi c mt onS mt on c th d hp c th pht hin k trc ca gim phn I khi cc NST tng ng bt cp. Nu c mt on s thy xut hin mt vng trn do khng c on NST tng ng.HU QUA MT OANKhi trng thi d hp, cc gene gy cht c th gy ra s pht trin bt thng. Khi cc th mt an trng thi ng hp, chng thng b cht do khuyt hn cc gene thit yu. HI CHNG CRY-DU-CHATKhi mt vai ngn ca NST s 5, karyotype 46,XY,del(5p) dn n hi chng mo ku (Cri du chat). Tr s sinh b hi chng ny c ting khc nh mo ku. Bnh c gp vi tn s 1/50.000 tr, biu hin chm tr, u nh v him khi sng c ti lc trng thnh.

Hi chng mo ku:(mt on NST s 5)

HU QUA MT OANS mt mt phn vai di ca NST s 22 (c gi l NST Philadelphia, ly tn thnh ph ni pht hin ra u tin). N c tm thy t bo ty xng (cng vi cc t bo c NST bnh thng) ca 90% nhng ngi bnh bch huyt myelocyt kinh nin (mt dng ung th). Thng on b mt c chuyn n mt NST di hn (thng l NST s 9).

T BIN CU TRC NHIM SC TH

* t bin lp on: Khi nim: Mt on NST b lp li 1 ln hay nhiu ln lm tng s lng gen trn .27II. T BIN CU TRC NHIM SC TH

* t bin lp on: Hu qu:Lm tng hoc gim cng biu hin ca tnh trng.i khi lp oan co li cho tin hoa la tao vt liu di truyn miV d: Lp on rui gim gy hin tng mt li, mt dt.28LP OANLp on c th cnh nhau, xa nhau trn cung mt NST hay vo cc NST khc.Nh lp on c th nghin cu nh hng ca s lng v v tr khc mc bnh thng ca mt on NST hay gen.Kiu hnh ca lp on c khi tri, c khi ln hay trung gian hoc c tc ng tch ly.

HU QUA LP OANt bin tri mt thi Bar (B) nm trn NST X ca Drosophila.:Tng mt on, d hp t +/Bar th mt b hn bnh thng mt t, hp cnh nn c dng ko di. Rui ng hp BB c mt nh hn. Nu lp on i, tng hn bnh thng 2 on s l t bin Bar kp, c kiu hnh mt nh hn na nn gi l "thi kp".S on lp li c th n 7 on thnh "siu Bar" mt nh nht.Gen mt thi B c tc ng gia tng theo chiu gim kch thc mt, s on lp cng nhiu, mt cng b.S on cng tng th kiu hnh cng tr v bnh thng hn.T BIN CU TRC NHIM SC TH

* t bin o on: Khi nim:Mt on NST b t ra ri quay ngc 1800 lm thay i trnh t gen trn .

5/25/201332T BIN CU TRC NHIM SC TH

* t bin o on: Hu qu:C th nh hng hoc khng nh hng n sc sng.V d: rui gim thy c 12 dng o on lin quan n kh nng thch ng nhit khc nhau ca mi trng.33HU QUA AO OAN- Trt t cc gene trong on o ngc li vi trt t bnh thng. Ty theo s tng quan ca on o vi v tr tm ng, c th chia lm hai kiu o an: an o khng cha tm ng, gi l o on cn tm (paracentric inversion)on o bng qua c tm ng th gi l o on quanh tm (pericentric inversion).

Ngun gc ca o on

o onCAEBDFHGCAFBDEHDCAEBDFHGCAEDBFHGAO OAN MANG TM NG(Pericentric inversion)

Tm ng nm bn trong on b o. Trong gim nhim I cc NST tng ng khi tip hp s to vng trn kp. Nu trao i cho xy ra gia 2 si NST n trong vng o on th 2 chromatid ca mi NST thng c chiu di khng cn bng nhau. Trong trng hp ny, mt na sn phm ca gim phn va c lp on li c mt on nn mt sc sng. Na khc ca cc giao t (khng c trao i cho) c sc sng bnh thng gm 1/4 c on vi trnh t gen bnh thng v 1/4 c o on

TRAO I CHEO AO OANAO OAN KHNG MANG TM NG(Paracentric inversion)Tm ng nm ngoi on b o. Trao i cho xy ra bn trong on o to NST hng tm (c 2 tm ng - decentric chromosome) v trong k sau I s to nn cu ni, ni 2 cc t bo. Cu ni s b t bt k ch no to ra cc on khng cn bng cha lp on hoc mt on. V d trng hp xy ra trao i cho gia 4-5

TRAO I CHEO XAY RA OAN BI AOSan phm giam phn do kt qua trao i cheo n vong ao oan khng mang tm ng

T BIN CU TRC NHIM SC TH

* t bin chuyn on: Khi nim: - L s trao i on gia cc NST khng tng ng, mt s gen trong nhm lin kt ny chuyn sang nhm lin kt khc.- Trao i on c th xy ra trong i NST tng ng (thng khc chc nng) nh gia X v Y hoc gia cc NST khc i.

42T BIN CHUYN OANC hai kiu chuyn an: + Chuyn on gia (interstitial translocation) l s di chuyn mt on cho mt nhim sc th khc m khng nhn li, tc chuyn on khng thun nghch+ Chuyn on thun nghch (reciprocal translocation), tc c s trao i qua li hai chiu

43HU QUA CHUYN OANS chuyn on thun nghch (reciprocal) xy ra do s trao i cc on gia 2 NST khng tng ng.Cc dng c chuyn on thng na bt dc (50% giao t cht). Mt s gen ca mt nhm lin kt gen c th chuyn sang nhm lin kt gen khc, s thay i nhom gen lin ktChuyn on c th gy hiu qu v tr (position effect).VD: t vng ng nhim sc (euchromatin) chuyn sang vng d nhim sc (heterochromatin) t c hot tnh hn.

445/25/201345

Qua trinh giam phn xay ra th di hp chuyn oan

T BIN CU TRC NHIM SC TH

* t bin chuyn on: Hu qu:Chuyn on ln thng gy cht hoc mt kh nng sinh sn. i khi c s hp nht cc NST lm gim s lng NST ca loi, l c ch quan trng hnh thnh loi mi Chuyn on nh khng nh hng g.5/25/201346T BIN CU TRC NHIM SC TH

* t bin chuyn on: V d: ngi, t bin chuyn on khng cn gia NST 22 v 9 to nn NST 22 ngn hn bnh thng gy nn bnh ung th mu c tnh.

5/25/201347Chuyn onChuyn on trn cng mt NST:CAEBDFHGAECBDFHGChuyn ontrn cng mt NSTCAEBDFHGEOMNDFHGCAQPRBQOMNPRChuyn on tng hChuyn on khng tng hCAEBDFHGCAEBDFHGOMNQPRQOMNPR

NHIM SC TH U (ISOCHROMOSOME)Cc NST c hai vai di khng u nhau c th chuyn thnh NST u vi 2 vai bng nhau v chiu di v tng ng vi nhau v mt di truyn nh s phn chia tm ng khc thng vung gc vi s tch tm ng bnh thng.NST X tm mt ca Drosophila c th chuyn thnh dng "X dnh" do s phn chia tm ng theo chiu vung gc vi bnh thng. Do s phn chia khc thng , 2 chromatid thay v phn li v 2 cc li dnh nhau, c on b mt.

CHUYN OAN ROBERTSON(Robertsonian translocation)

Hnh thnh NST tm gia do s ni li ca 2 NST.Chuyn on thun nghch c thc hin gia 2 NST tm u A v B:+ Khi A b t pha di tm ng to vai di mt tm ng+ Cn B b t u mt ngn trn tm ng, 2 on ni nhau to NST tm u mang tm ng ca B.on c tm ng A vi vai ngn ni vi on ngn ca B hnh thnh NST con c tm ng A. NST con mi c nhiu cht d nhim sc khng quan trng nn thng mt i. Chuyn on Robertson c hu qu lm gim s lng NST.

MT OANLP OANAO OANXEN OANCHUYN OANT BIN S LNG NSTa bi th (polyploidy): hiu theo ngha rng l s thay i s lng NST. S thay i s lng NST c nhiu kiu: a bi nguyn (euploidy), a bi lai (alloploidy) v a bi lch (aneuploidy)

T BIN TH A BIinh nghia: trong th a bi. B NST cua t bao sinh dng la 1 bi s cua n nhng ln hn 2n+ 3n, 5n .. La th a bi le+ 4n, 6n.. La th a bi chnC IM TH A BIT bao a bi co lng AND tng gp bi nn qua trinh tng hp cht hu c din ra manh me. C th a bi co t bao to, c quan dinh dng ln, phat trin khoe va chng chiu tt.Th a bi le thng khng tao giao tTh a bi ph bin thc vt. ng vt it gp vi c ch xac inh gii tinh bi ri loanC CH PHAT SINH TH A BITh a bi le:Trong giam phn: toan b NST b hoc me khng phn li, tao giao t 2n. Giao t 2n kt hp vi giao t n tao hp t 3n (th tam bi)Cy 4n lai cy 2n tao cy 3nTh a bi chn: Trong nguyn phn: cac NST t nhn i nhng khng hinh thanh thi v sc tao t bao 4nTrong giam phn: toan b NST khng phn li tao giao t 2n. Giao t 2n kt hp vi giao t 2n tao hp t 4n (th t bi)A BI NGUYN S tng nguyn ln b NST n bi ca mt loi, c gi l a bi th nguyn hay a bi th thun. y l a bi hiu theo ngha hp, nu c c th 2n NST th dng 3n, 4n, 5n ... l cc dng a bi th.

TH N BIMt s sinh vt Eukaryote bc thp nh vi nm, vi to c nhn n bi. Cc c th n bi sinh vt bc cao thng t hn v c sc sng km hn dng lng bi bnh thng. Cc thc vt n bi c tm thy nhng thng bt thu. Mt s t ng vt tn ti dng on bi. Mt ngoi l ng lu l ong c v ong v v.

TH TAM BITam bi NST (3n) c th c to nn do s kt hp gia cc giao t n bi vi giao t lng bi.B NST n bi th ba ca th tam nhim thng phn b vo cc t bo sinh dc vi nhiu loi t hp khc nhau, to nn cc giao t mt cn bng di truyn. Cc th tam bi c bt th cao nn trong thin nhin, chng thng dng sinh sn v tnh nh cy chui.t bin a biDa hu tam biChui tam bi

TH T BIT bi NST (4n) c th xut hin trong cc t bo c th do s tng i s NST ca t bo soma. S tng i s NST c th xy ra nh tc ng ca alkaloid colchicine vo t bo hoc do s hp nht ca cc giao t 2n 2n=6 2n=6121212122n = 62n = 6T bo 2n n=3 n=3Giao tabHnh 24.5: S hnh thnh th t bi ( 4n ) do ri lon trong nguyn phn hoc gim phn 4n = 1212121212Hai ln nguyn phnHp t 2n = 62n = 62n = 6

4n=124n=124n = 12Giao t

H 24.1. T bo cy ru c b NST khc nhau

C ci t bi (b)ba24.4. Qu ca ging to lng bi (a) b2nc3nd4na3na.Cy tam bi (3n=36) b6nb.Cy lc bi (6n=72)

c9n c.Cy cu bi ( 9n=108 )H 24.2.Cc cy c c dc c b NST khc nhau

an(T bobnh thng)12ndd. Cy thp nh bi ( 12n= 144 )

H24.3:C ci lng bi (a)aT bi (b)b

Th lng bi (phia trai) va th t bi (phia phai) cua nho

A BI LAIa bi th lai c c khi c 2 b NST ca 2 loi khc nhau cng ng chung trong mt t bo (2nA + 2nB).

Th a bi lai tao thanh khi lai gia hai loai Raphanus vi BrassicaA BI LCH HAY A NHIMS thay i s lng NST ch lin quan n mt cp hoc mt s cp NST c gi l a bi th lch.Cc dng a bi th lch:+ Th n nhim hay th mt (2n - 1)+ Th tam nhim hay th ba (2n + 1)+ Th t nhim hay th bn (2n + 2)+ Th tam nhim kp (2n + 1 + 1)+ Th v nhim hay th khng (2n - 2)

C CH PHAT SINH TH DI BITrong qua trinh giam phn. 1 cp NST nao o khng phn li tao giao t n+1 NST va giao t n 1 NST. Cac giao t nay kt hp vi giao t binh thng n se tao ra th di biC ch hinh thanh cac giao t tha hoc thiu nhim sc th do s khng chia ly cua nhim sc th trong giam phn

GIAO T (n 1)GIAO T (n + 1)GIAO T (n + 2)GIAO T (n 2)GIAO T (n)GP bnh thngRi lon GPT BIN S LNG NSTTH DI BI NST GII TINH NGIXXX (HI CHNG SIU N): N, bung trng, da con khng phat trin, kho co conOX (HI CHNG TURNER): thiu 1 NST s 15. N, lun, c ngn, si n v sinh.XXY (HI CHNG KLINEFELTER): Nam, mu mau, tay chn dai, si n, v sinhOY : Khng thy ngi, co le hp t a cht ngay sau thu tinhHI CHNG TURNERHenry Turner m t u tin ngi n mt mt NST X (OX), c cng thc 2n - 1 = 45. Hi chng c nhiu biu hin c trng nh ln (chiu cao < 1,5 m), c quan sinh dc km pht trin (khng dy th), km thng minh ...

Hi chng Terner

B NST ca bnh nhn Turner

Bnh Turner ( OX )

B nhim sc th ca bnh nhn turnernh chp bnh nhn turner B nhim sc th ca n gii bnh thngHI CHNG KLINEFELTERHenry Klinefelter m t nhng ngi nam d 1 NST X (XXY), cng thc 2n + 1 = 47. Hi chng c nhng biu hin c trng nh bt th, ngn tay, chn di, pht trin ngc, c tnh n v suy gim tr tu

Hi chng KLINEFELTER

HI CHNG DOWNLangdon Down pht hin, thng l tam nhim cp NST s 21 ca ngi. T l xut hin khong 1/600 tr s sinh. Ngi bnh c mt s biu hin c trng nh: thoi ha tr tu, mt ging mt ngi Mng c. C mi lin h thun gia s tr sinh ra mc bnh Down v tui ca cc b m. T l l 1/500 cc b m 20 - 30 tui, 1/300 cc b m 40-45 tui v 1/60 cc b m ln hn 45 tui. Tui cha hu nh khng nh hng.

Ngun gc Hi chng DownBNH V TT DI TRUYN NGI

Nhim sc th bnh nhn aoNhim sc th ca ngi bnh thngABHi chng Down (th di bi NST thng)

BNH V TT DI TRUYN NGI

M PH , C RT , MING HI H ,MT HI SU .

3 NST s 18 (hi chng edward)

3 NST s 13 (hi chng Patau)Quan st hu qu ca t bin nhim sc th ngi

Hi chng Patau86Quan st hu qu ca t bin nhim sc th ngi

87T BIN GY TAO HAY CAM NG* Tac nhn gy t bin:+ Tc ng gy t bin ca bc x ion ha+ Cc tc nhn gy t bin ha cht

BC XA ION HOATia X, cc tia phng x , , , cc neutron v c tia t ngoi u l cc tc nhn gy t bin. Tr tia t ngoi c kh nng xuyn thu yu nn ch tc ng ln cc sinh vt n bo v giao t, cc tia khc u c tc dng gy t bin ln tt c cc dng sinh vt. * Tc dng gy t bin ca phng x c 2 c im:+ Khng c ngng tc dng, tc khng c liu v hi+ S lng t bin t l thun vi liu lng phng x, khng ph thuc cng v thi gian chiu x

nh sng nhn thy ch l mt phn rt nh ca ph sng in t. Sng c bc sng cng ngn th cha nng lng cng ln v kh nng xuyn thu cng mnh. So vi nh sng nhn thy (bc sng khong 10-4 m), cc tia X, tia , tia v tr c bc sng t 1 nm v ngn hn, c gi l bc x ion ha. Cc bc x ny c to ra nh cc my chiu tia X, proton, neutron v c pht ra t cc ngun phng x nh radium, cobalt 60, ... to cc tia anpha, beta v gamma

BC XA ION HOALIU LNG VA CNG BC XA- Cc th nghim sau nm 1927 vi bc x nng lng cao cho thy cc t bin gy to (t bin cm ng) ph thuc rt ln vo liu lng, liu cng ln tn s t bin cng cao. Khi liu lng qu cao, s ph thuc c phc tp hn, c th do nhiu t bo b cht.- Bc x ion ha c hiu qu gy t bin tt c cc sinh vt v khng c liu lng ngng, c ngha l d liu lng thp vn c kh nng gy t bin.

TAC NG TIA T NGOAITia t ngoi c bc sng di (10-5-10-6 cm) nn kh to ion, c l ch tc ng n nhng cht hp thu n trc tip. Trong t bo cc cht hu c mch vng ch yu nh purin v pyrimidin hp thu trc tip tia t ngoi. ADN hp thu tia t ngoi mnh nht bc sng 2537 Di tc dng ca tia t ngoi, cytosine gn thm phn t nc vo lin kt C=C ca mch vng v thymine b t lin kt C=C mch vng ni 2 phn t thnh dimer thymine.

TAC NHN HOA CHT* Cc tc nhn gy t bin ha hc c th chia thnh cc nhm sau:Nhm 1: Cc cht c ch tng hp baz nit trong cu trc ADN nh cofein, ethyl uretan ...Nhm 2: cc cht ng ng vi baz nit nh cofein, 5-bromuracil, cc cht ny gn ging vi baz nit nn ADN gn nhm khi tng hp.Nhm 3: Cc cht alkyl ha lm t mch ADN nh ethyl methanesulfonate (EMS), methyl methanesulfonate (MMS), ethylene imine (EI) ...Nhm 4: Cc cht khc nh cht oxy ha - kh nh HNO2, hydroxygenlamine (H2NOH).Nhm 5: Cc cht chm vo ADN gm proflavin, cht mu acridin.