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TRNG I HC NNG NGHIP H NI KHOA: TH Y

SINH VIN: LNG QUC HNG Email: [email protected] 1 -

CNG N TP MN DI TRUYN NG VTCHNG 1:CU 1: Trnh by khi nim v h gen, bng trn nhim sc th, locus v alen. Phn bit cc khi nim: gen, locus, alen1, Cc khi nim :- H gen: (genome) l mt b nhim sc th y trong 1 t bo, nhim sc th c sp xp thnh cp c gi l lng bi,mi cp nhim sc th gm 2 nhim sc th ging nhau hnh thnh ln cp nhim sc th tng ng.- Bng trn nhim sc th: l tng phn ca nhim sc th, c hin ln, hoc m hn hoc sng hn so vi cc phn k bn, do tcdng ca cc loi thuc nhum c trng khc nhau to ra cc gii hn phn bit c th sai khc gia cc nhim sc th.- Locus: V tr ring bit ca 1 gen trn nhim sc th.- Alen: Cc trng thi khc nhau ca 1 on ADN ti mt v tr ring bit trn nhim sc th.2, Phn bit cc khi nim:- Gen: c s dng 1 cch chung chung vi 2 ngha hoc l locus hoc l alen.- Locus: V tr ring bit ca 1 gen trn nhim sc th.- Alen: Cc trng thi khc nhau ca 1 on ADN ti mt v tr ring bit trn nhim sc th.CU 2: Phn loi nhim sc th theo v tr tm ng, trnh by khi nim bng trn nhim sc th, ngha ca phng php hinbng trong nghin cu kiu nhn cho mi loi.*)Phn loi nhim sc th theo v tr tm ng:- Nhim sc th tm mt(acrocentric): tm ng u mt- Nhim sc th tm lch(sub-metacentric): hai v khng u nhau- Nhim sc th tm gia(metacentric): tm ng chnh gia.*) Bng trn nhim sc th: l tng phn ca nhim sc th, c hin ln, hoc m hn hoc sng hn so vi cc phn k bn, dotc dng ca cc loi thuc nhum c trng khc nhau to ra cc gii hn phn bit c th sai khc gia cc nhim sc th.*) ngha ca phng php hin bng trong nghin cu kiu nhn cho mi loi.- Trng hp c cc nhim sc th khc nhau, nhng ging nhau v kch thc v hnh dng th ch sau nhi nhum phn ha (KT hinbng) th phn bit c chng qua s lng, thnh phn v v tr cc bng c hin ln.- So snh cc kiu bng trong cc V c v c ngha nghin cu v di truyn ging, v chng loi pht sinh. Mi quan h ditruyn gia cc qun th V, vt nui, c th c xc nh qua so snh c th ca cc bng hin trn nhim sc th. V d: CpNST th 2 ngi l do s ni li ca 2 NST khc vn ngi.- Ngin cu su hnh thi NST v hnh thi kiu nhn ca cc loi V, cc ging vt nui.CU 3: Trnh by cu trc phn t ca si nhim sc, ngha ca hnh thc cu trc ny.*) Cu trc phn t ca si nhim sc:- Mt ha hc: NST bao gm phn ln l axit deoxyribonucleic (DNA), v mt lng nh protein(histon). Histon c chc nng cutrc v lin kt, ADN hnh thnh nn thng tin di truyn, thng tin ny truyn t b m n con ci, t th h ny n th h khcthng qua qu trnh phn bo: gim phn v th tinh- Mi NST cha 1 phn t ADN xon kp, rt di kt hp vi nhng protein kim l histon (c t 100-200 aa) to thnh nhng n vc s l nucleosom.- Nucleosom gm 8 phn t histon ( H2A, H2B, H3 v H4) m cu trc chung ca cc protein kim l: (H2A)2; (H2B)2; (H3)2; (H4)2phn ny c coi nh li histon ca nucleosom.- Mt phn t ADN gm khong 200 cp base, trong 142 cp base qun quanh li histon. Phn cn li l ADN lin kt gia ccnucleosom.- Histon khng phi l thnh phn ca li nucleosom nhng n tham gia vo s kt hp gia cc nucleosom vi nhau.*) ngha ca hnh thc cu trc ny:- S nn cht ny gip h gen ca t bo c cha trong th tch ca nhn t bo khong 800-1000 m3.- m bo cc c tnh v chc nng ca NST nh vic truyn t thng tin di truyn,- Gip cc gen trn NST c th bc l trong cc qu trnh sao m v dch m ca t bo,..CU 4: Thnh phn ha hc, cu trc khng gian ca phn t ADN?*) Thnh phn ha hc ADN:- ADN l 1 polyme ln c trng hp t cc phn t n v l cc nucleotide.- Mi nucleotide c cu to t 3 thnh phn:+ Axit phosphoric: H3PO4+ ng pentose+ Cc base nit: A, T, G, C- Trong Axit phosphoric v ng pentose l ging nhau tt c cc nucleotide, ch ring thnh phn base nit l khc nhau giacc nucleotide. Do to ra 4 loi nucleotide ph thuc vo loi base cu to nn: A, T, G, C. Trong A v G thuc nhm purin ccu trc vng kp; T v C thuc nhm pyrimidin c cu trc vng n.- Trong 1 nucleotide th phn t ng pentose lm trung tm, cc base nit lin kt vi C1 ca ng, cn axit phosphoric lin kt C5ca phn t ng.- Cc nucleotide lin kt to nn phn t ADN polymer. Cc nucleotide lin kt vi nhau qua nhm phosphat, trong nhmphosphat 5 ca nucleotide tip sau s phn ng vi nhm OH v tr 3 ca nucleotide trc n to lin kt phosphodiester. Cnh vy mch ADN c ko di ra theo hng 5-3 to nn u 5-phosphat v 3-OH*) Cu trc khng gian ca phn t ADN+) Nm 1953 c James Waston v Fransis Cric m t nh sau:



- Phn t ADN gm 2 mch poly nucleotide lin kt vi nhau v qun quanh mt trc chung ( trc o). Khung deoxyribose-photphat pha ngoi.- Cc base hng vo pha trong ca chui xon kp, mt phng ca cc base song song vi nhau v thng gc vi trc o ca chuixon. Mi base ca mch ny c ni vi base ca mch kia bng nhng kin kt hydro v cc base lun bt cp theo nguyn tc bsung: A vi T,G vi C, trong A lin kt vi T bng 2 lin kt hidro cn C lin kt vi G bng 3 lin kt hidro.- Theo nguyn tc b sung ny m trong 1 chui ADN bao gi tng lng base loi A cng bng tng lng base loi T, v G bao gicng bng C. iu ny c Chargaff v cng s pht hin 1950 c: A+G = C+T- ng knh ca chui xon kp l 2,0 nm. Mt phng ca cc base lin k nhau th cch nhau 0,34 nm. Mt vng xon c 10 cpbase v c chiu di l 3,4 nm.CU 5: V sao ADN c t nhin la chn lm vt cht mang thng tin di truyn?ADN p ng c c nhng i hi tt yu ca vt cht di truyn- Vt cht di truyn phi tng tr tt c cc thng tin cn thit iu khin nhng cu trc c trng v hot ng trao ica t bo. Nhng chc nng ring bit ca c th sng lin quan ti s a dng ca protein m mi protein c quy nh bi 1on ADN. on ADN ny c trng bi kch thc v trnh t cc nucleotide c sp xp trong . Vi 4 loi nucleotide t hp tdo vi nhau v vi kch thc on ADN ty th c th to ra v s cc gen. V vy ADN tng tr tt c cc thng tin di truyn.- Vt cht di truyn phi c ti bn mt cch chnh xc truyn t thng tin cho th h sau. Nguyn tc b xung( A-T, G-C) theo sut chiu di ca 2 mch poly nucleotide trong chui xon kp ni ln kh nng nhn i chnh xc ca n. Cc base lin ktvi nhau bng lin kt hydro l 1 lin kt yu. Lin kt hydro rt d c thit lp cng nh rt d b loi b. y l 1 c im rtthun li cho vic tho xon, tch ADN thnh 2 mch n lm khun ri tng hp mch mi theo nguyn tc b sung v kt qulag hnh thnh 2 chui xon mi ging ht chui ban u.- Vt cht di truyn c kh nng sy ra v ghi nhn nhng bin i thng tin, khi cc thng tin bin i phi c n nhv di truyn c. C nhiu tc ng c th xy ra lm thay i thnh phn base v tr no trn chui ADN. T m di truynthay i dn ti thay i chc nng ca gen. Nhng trng thi khc nhau ca 1 gen l nguyn nhn ca tnh a dng di truyn sinhvt.CU 6: Anh hy trnh by hin tng bin np, ngha ca hin tng.*) Hin tng bin np:- Bin np l hnh thc lai c bit vi khun, khi ADN ca vi khun cho gn vo t bo vi khun nhn. Hin tng ny cn xy ra cc loi vi khun khc.- Th nghim ca Griffith lm trn ph cu khun nm 1928. Ph cu khun c 2 dng: S v R.+ Dng S c khun lc nhn, bn ngoi c bao bc bi 1 lp gip m c bn cht l polysaccharit, y l c quan sn sinh c t.+ Dng R khun lc sn si, khng c gip m do vy khng sn sinh c t. Trong iu kin bnh thng c 2 dng S v R c ctnh di truyn n nh.+ Tin hnh th nghim:

- Dng dng S tim cho chut th chut cht do vim phi vy dng S c c t v c kh nng gy bnh.- Dng dng R tim cho chut th chut bnh thng, khng mc bnh nh vy dng R khng c, khng gy bnh.- em dng S x l nhit trn vi dng R cn sng sau tim cho chut th kt qu l chut b mc bnh v cht, trn c th

chut ngi ta tm thy dng S c mng polysaccharit.- 1944, Avery v cng s lm sng t. Hin tng t bin ch sy ra 1 chiu t S sang R vi tn s rt thp, v vy c ch t bint R sang S khng c chp nhn.+ Th nghim ca ng:

- Dng dng R cho vo nc chit t dng S b s l bi nhit th xut hin s bin i t R thnh S. Ch phm tinh khitt nc chit l cc on ADN t do(ca dng S) xm nhp vo dng R.

- Kt qu dng R c nhng biu hin di truyn ca dng S: to thnh mng polysaccharit, c kh nng gy c, khun lcnhn.

- Nh vy nhn t gy bin np l ADN, chng b phn gii bi enzyme deoxyribonase.*) ngha ca hin tng:- Chng minh ADN mang thng tin di truyn v truyn t thng tin di truyn .- Vt cht thng tin c quy inh bi ADN m khng bi 1 phn no khc trong t bo.CU 7: Anh hy trnh by hin tng ti np, ngha ca hin tng.Tr li:*) Hin tng ti np: l s truyn cc thng tin di truyn (ADN) t vi khun cho sang vi khun nhn nh mt thc khun th. Thckhun th lm nhim v chuyn nhng gen khc nhau ca vi khun ny sang vi khun khc, thng thng l 1-2 gen, i khi l 3 genlin kt cht ch.- Hin tng ny c nghin cu k 1 s vi khun nh: salmonella Typhimurium, Escherrichia Coli, Shigella Staphylococcus.- Ngi ta phn lp cc dng vi khun Salmonella Typhimurium t chut b bnh st.- Dng 2A v dng 22A. Dng 22A mang t bin mt kh nng tng hp Tryptophan v vy khi mun nui cy phi cho vo mitrng c cht Tryptophan. Dng 2A khng b t bin nn vn c kh nng t tng hp Tryptophan v pht trin bnh thng trongmi trng khng c Tryptophan.- Dng 1 bnh ch U, y c ngn bi 1 mng lc vi khun ngn ko cho vi khun i qua nhng vn cho thc khun i qua c.em cy dng 22A vo 1 nhnh, cy 2A vo nhnh th 2.



- Mt thi gian sau thy pha bn cha dng 22A xut hin 1 s vi khun tng hp c Tryptophan, tuy nhin s lng ko nhiu,nhnh bn kia vn pht trin bnh thng. Tn s xut hin l 105. y ko phi l tn s t bin nghch t Tr- sang Tr+, v dng 22Ac tnh nh di truyn cao. ng thi ko tm thy nhn t bin np trong mi trng(ADN t do)- y, s chuyn dch cht liu di truyn t vi khun ny (2A) sang vi khun khc (22A) l do thc khun th m nhim. Thckhun th ngoi cht liu di truyn ca mnh cn c thm 1 mu cht liu di truyn ca vi khun 2A do ly c trong qu trnh xmnhim. Thc khun th t bn nhnh cha vi khun 2A, qua mng lc vi khun cm nhim vo 1 s t bo dng 22A v truyn chochng 1 mu thng tin ca dng 2A m chng ly c trong cha thng tin tng hp Tryptophan. on NST ngoi lai ny trthnh 1 b phn gn lin vi NST ca tb vi khun lm thay i kiu gen ca vi khun nhn.*) ngha ca hin tng:- Chng minh vai tr ca ADN trong di truyn.CU 8: Anh hy trnh by cu trc v hot ng di truyn ca virus v thc khun th, ngha?- Virus c kh nng gy nhim tb ng vt, t bo thc vt v cc tb vi khun, ring loi virus gy nhim tb vi khun gi l thckhun th(bacterriophage). Virus xm nhp vo tb vi khun v hy hoi vi khun.- Thc khun th cha c cu to tb v vy chng ch c kh nng sng v pht trin c trong tb vi khun.- Virus l thc khun th k sinh mc di truyn, chng s dng b my sinh tng hp ca tb k ch sn xut gen v protein camnh hnh thnh cc virus v cc thc khun th mi.*) Cu trc:- Thc khun th T2 gy nhim vi khun trc trng E.Coli c nghin cu y nht.+ C 2 phn: u v ui. Cu trc rt n gin, bao gm 1 phn t ADN chim 40% v 1 v bc protein chim 60%. u hnh lcgic cha vt liu di truyn l ADN, ui ko di c th co gin, tn cng l 1 phng mang nhiu si nh.*) Hot ng di truyn:- Thc khun ph hy tb vi khun theo c ch sau:+ Phn ui T2 gn vo tb vi khun, tit enzyme tiu hy vch tb. S dng ui nh kiu ci bm y ADN ca n vo tb vi khun.Trong tb vi khun, ADN ny ti bn nhiu ln, to 1 lng ln ADN virus sau s dng b my t bo vi khun tng hp protein to v v ui ca virus. Cui cng cc thc khun th T2 hon chnh c hnh thnh. Trong khong 15-45 pht sau khi xm nhp tbvi khun, t 1 thc khun th c th sinh ra thnh 100 n 300 thc khun th mi.- Thc cht ch c ADN ca thc khun th i vo tb vi khun cn lp v li bn ngoi v tiu bin i.*) ngha:- ADN quyt nh tnh di truyn, trao i cht v sinh sn.CU 9: Bng chng no khng nh ADN c ti bn theo c ch bn bo ton. Trnh by c ch chung v cc yu t tham gia qutrnh sao chp.*) Bng chng khng nh ADN c ti bn theo c ch bn bo ton l th nghim ca M.Meselson v F.Stahl.- Nm 1957 J.Stent v M.Delbruck a ra ba kiu sao chp ADN c th l:+ Kiu bo ton: chui ADN xon kp ban u c gi nguyn trong khi chui xon kp mi hnh thnh hon ton t nguyn liu mi.+ Kiu bn bo ton: chui ADN xon kp mi hnh thnh gm 1 si c ca cha m v 1 si c tng hp hon ton t nguyn liumi.+ Kiu phn tn: trong qu trnh ti bn, cc si ADN c t ra thnh cc on nh lm khun tng hp thnh 1 on nh mi, sau cc on nh ni li vi nhau. Do vy sau khi tng hp, mi si mi u cha c cc on ADN c v mi.- M. Meselson v F. Stahl chng minh ch c kiu na bo ton l ng:- Th nghim c tin hnh:+ Vk E.Coli c nui nhiu th h trn mi trng ch c duy nht l 15NH4Cl do vy sau qu trnh nui ton b ADN ca E.Coli chcha 15N nng, khc vi ADN bnh thng cha 14N nh. Hai loi ADN ny c th phn bit bng cch ly tm trong gradien nng ca Cesi Clorua(CsCl) n s cho 2 vch nng v nh.+ Sau a E.Coli c ADN nng vo nui mt ch cha 14NH4Cl (nh) 1 s th h v sau mi th h u tch ADN v cho ly tm.+ Sau th h th nht nu si kp ADN hnh thnh theo c ch kiu bn bo ton hoc phn tn th khi ly tm ta s ch c 1 vch trungbnh gia chui nng v chui nh. Thc t th nghm cho thy ng nh vy. Loi b gi thit v kh nng ADN c tng hp theokiu bo ton.+ Sau th h th hai, nui trn mi trng cha 14N nh, cc tc gi nhn c 2 vch nh v trung bnh trong ng nghim, chng t qutrnh tng hp ADN din ra theo kiu bn bo ton v nu theo kiu phn tn th ch c th c 1 vch ging vi vch trung bnh.*) C ch chung qu trnh sao chp:- Qu trnh sao chp l 1 qu trnh phc tp, c 1 s im khc bit gia tb Eukaryota v Prokaryote song nhn chung n vn tun theo1 c ch chung l:+ Cc lk hydro n nh cu trc xon v gn 2 mch vi nhau phi b ph v v tch ri 2 mch.+ Phi c on mi ADN hay ARN mch n ngn bt cp vi mch n khun.+ 4 loi deoxy nucleotide triphosphat ( dATP, dGTP, dCTP, dTTP) bt cp b sung vi cc nucleotide mch khun.+ Mch mi tng hp theo hng 5- P n 3- OH+ Cc nucleotide mi c ni vi nhau bng lk cng ha tr to mch mi.*) Cc yu t tham gia qu trnh sao chp:- Enzyme ADN helicase: tch 2 mch n trong chui xon kp ADN bng cch ct cc lk hydro nh s dng nng lng t cc ATP- Protein SSB (protein bm vo cc chui ADN n) cc protein bm vo cc chui ADN n sau khi c tch ra t chui xon kpdo enzyme helicase, ngn cn 2 chui n ko gn li vi nhau v ng thi ngn chn 1 chui n gp khc li to thnh 1 vng vko to ra vng t b sung.



- Cc primer: l cc on ARN mi (10-60 nucleotide) c tng hp nh xc tc ca ARN primase v c trnh t cc nucleotide bsung vi on ADN khun.- ADN polymerase: ngy nay ngi ta tm thy 3 loi ADN polymerase, mi loi ADN polymerase c 1 chc nng:+ ADN polymerase I: thay th cc ARN primer bng trnh t nucleotide ca ADN.+ ADN polymerase II: cha hiu ht chc nng ca n nhng chc nng chnh l sa cha ADN b tng hp sai.+ ADN polymerase III: c vai tr quan trng trong vic ko di chui ADN mi bng cch bm vo si khun v lp cc nucleotideb sung vo v tr tng ng v ni di ADN t primer.- ADN ligase: hn gn cc on Okazaki lm lin mch ADN mi c tng hp trn chui mun. Enzyme ADN ligase ko th ni 2phn t ca chui n ADN m chui ADN c ni phi l 1 phn ca phn t xon kp ADN.CU 10: mc phn t, qu trnh no m bo thng tin di truyn c truyn t chnh xc t th h ny sang th h khc? Trnhby c th qu trnh ?- mc phn t, qu trnh m bo thng tin di truyn c truyn t chnh xc t th h ny sang th h khc l qu trnh sao chpADN.*) Qu trnh din ra nh sau:- Di td ca enzyme ADN helicase cc lk hydro b ct t, chui xon kp m xon, khi 2 nhnh ca chui ADN tch nhau ra,cc protein SSB bm vo mi si n ngn ko cho chng cp i tr li vi nhau v cc si ADN n ko gp khc.- Qu trnh tng hp trn 2 si khun mu ny l khc nhau do nguyn tc si mi ch c tng hp theo chiu 5-3.- i vi chui sm ( 3-5) khi hai si ADN n tch ra th enzyme ARN primase bm vo v tng hp mt on ARN mi(doADN polymerase III ko c kh nng gn 2 nucleotide t do vi nhau m n ch c kh nng xc tc tng hp ko di phn t ADNtip tc t primer). Sau enzyme ADN polymerase III bm vo v tip tc ko di chui ADN bng cch gn cc nucleotide trongt bo c hot ha c kh nng cp i vi cc gc base tng ng ca mch gc (khun), hnh thnh nn chui b sung mi.- Do enzyme ADN polymerase ch c th thm nucleotide u 3 ca nhnh ADN mi ang di ra, s sao chp ch sy ra theohng 5-3.- Trn nhnh khun c chiu 5-3 th qu trnh tng hp mch mi theo chiu 5-3 ko th thc hin cng chiu vi chiu m cachc sao chp m n phi tng hp theo chiu ngc li vi chiu m ca chc sao chp v c tng hp khi ADN m c khong1000-2000 nucleotide.- Qu trnh tng hp sy ra trn chui mun(5-3): khi chc sao chp c m ra th trn chui mun cc protein SSB bm vo si nlm khun. Cc protein ny bm vo khong 1000 nucleotide lin tc sau enzyme primase mi tng hp on ARN mi, sau ADN polymerase III tip tc ko di chui ADN mi theo chiu ngc li vi chc sao chp ang c m to nn nhng on ADNmi c gi l cc on Okazaki. Khi on Okazaki mi c hon chnh, on ARN mi c loi b v thay th l cc nucleotide caADN nh td ca enzyme ADN polymerase I.+ Cui cng nhng mnh Okazaki c ni li vi nhau bi 1 enzyme khc l ADN ligase.CU 11: Trnh by cu trc ca gen?- on ADN c th m ha cho 1 phn t polypeptide c th, chui polypeptide c to ra qua qu trnh dch m t phn t mARN.- Gen cu trc: on ADN bao gm tt c cc nucleotide c phin m vo mARN.- Nhnh ADN m t mARN c to ra l nhnh c ngha(nhnh khun mu) cn nhnh cn li l nhnh i ngha.- Gen cu trc bao gm:+ Chui dn ng: vng khng phin dch pha trc b ba khi u, ch cho riboxom bm vo+ Gen cu trc: T nucleotide m ti thc s s phin m bt u (vng khi u phin m) n on cui l vng kt thc phinm.+ Chui ko theo: vng khng phin dch sau b ba kt thc cn thit cho qu trnh s l mARN.- Vng ngay st vng pha trc vng bt u phin m l c bit quan trng v l vng m ARN polymerase bm vo trc khibt u phin m. Vng ny l gen khi ng (promoter), im khi u phin m trn ADN. Promoter bao gm chui cc gc basec th , chui ny c kh nng bo th cao, chui base tng t tn ti hu ht cc gen.+ Chui base u tin ca promoter ca gen ng vt bc cao l TATAAA (gi l hp TATA), nm v tr bao gm 25 gc basengc ln, tc khong v tr -25.+ Chui GGCCAATCT( hp GAAT) v tr khong -75+ Chui GGGCGG( hp GC) v tr khong -90+ Nhng hp ny l v tr cho s nhn dng v l ch bm vo ca protein iu ha (nhn t iu ha), cc nhn t ny gip cho ARNpolymerase tm c v tr chnh xc cho s bt u qu trnh phin m. Chng iu khin qu trnh phin m.+ prokaryota, chng cng c chui base bo th tng t promoter ca chng l TATAAT v TTGACA- S kt thc phin m thc s ko di qua phn vng kt thc. Sau enzyme cha bit r ngun gc ct qu trnh phin m vngkt thc. Khng c chui base ph hp cho vng ny, nhng c vng bo th cao vi chui base AATAAA( AAUAAA mARN), ckhong 10-30 gc base ng vng kt thc, vng ny nh vng nhn dng cho nhn t iu khin qu trnh ct phin m.CU 12: Th no l hin tng gen phn ct, trnh by qu trnh trng thnh ca mARN.*) Hin tng gen phn ct:- V c nhn chun phn ln gen cu trc l di hn, cha cc phn m chng ko c mt mARN vo thi gian tri qua qu trnhphin dch l intron, cc vng c mt mARN trng thnh l exon.- Gen cha intron c gi l gen phn ct, mARN u tin cha trng thnh l bn sao u tin ca ton b gen cu trc, bao gmc exon v intron.- Trc khi mARN di chuyn t nhn ra t bo cht, intron c loi ra v cc exon c ni li vi nhau trong qu trnh ni ARN. Do vyARN trng thnh ch bao gm cc exon.



- S nhn dng v s loi intron hot ng c l do mi intron c hai gc base u tin u 5 v hai gc base cui cng u 3l bo th cao, chng ging nhau hu ht tt c cc intron (GU v AG). Do th t gc base c th hin dy m ha ca ADN, chonn quy tc ny gi l GU-AG.- Gen cu trc gm khong 1000 gc base(1 kb) n hn 2 triu gc base(2000 kb), vi trung bnh khong 100kb. Trong khi , slng axit amin trong 1 polypeptide khong 200 n 5000, trung bnh khong 330 a.a. mARN ch bao gm khong 600 gc base chon 15kb vi trung bnh khong 1kb. Nn exon chim 1 t l nh trong gen cu trc, phn ln ADN ca gen cu trc l cha intron,cc exon l 1 n v hot ng, c lp ghp theo nhng s phi hp khc nhau to ra cc polypeptide.*) Qu trnh trng thnh ca mARN- Ngoi vic ct b intron, s sao m mARN ban u cng c thay i theo 2 cch:+ u 5 c bo v bng m 5 bao gm cc nucleotide G c methyl ha.+ u kia, ui poly A c thm vo, ui poly A ny bao gm 1 s lng khc nhau (trung bnh 100-200) ca A+ V m 5 v ui poly A c vai tr quan trng i vi mARN trng thnh, cc vng khi u v kt thc s phin m ca gen ikhi c gi l vng m v vng poly A.+ Chui nucleotide AAUAAA v tr gc base t th 10 n 30 pha trc vng poly A c gi l du hiu poly Adenine ha. PolyAdenine ha l qu trnh b sung chui poly A vo u 3- OH ca mARN.- C nhng on ADN m chc nng duy nht ca n l to ra hoc tARN hoc rARN gi l gen. Gen l 1 on ca phn t ADNto ra phn t ARN c chc nng.CU 13: Trnh by s iu ha hot ng ca gen.- Qu trnh m hay ng gen b chi phi bi protein iu ha.- Protein iu ha l sn phm ca gen iu ha iu ha hot ng ca cc gen khc, protein ny bm vo hoc tch khi onchui base chuyn bit trn ADN, chui base ny c tnh bo th cao: hp TATA, hp GAAT, hp GC.- Chui base c chc nng tng t nhng n ko ng bn trong gen khi ng l gen tng cng. Gen tng cng nm pha trc,pha sau, i khi bn trong gen cu trc (trong intron), 1 s ng cc vng ln cn ca gen cu trc, 1 s nm rt xa, c th cch20kb.- Protein iu ha bo m tin hnh cc hot ng kim sot qu trnh phin m bng cch bm vo gen tng cng hay gen khing. Protein iu ha c chung 1 hoc nhiu chui a.a, chng c gi l cu hnh a.a di cc tn khc nhau.+ VD: ngn tay km( Zinger finger) l cu trc c to ra bi s nhc i nhc li ca cp phn t Cysteine, cp Cysteine c phn ct rabi 2 hoc 3 a.a khc, tip theo l 10 hoc s lng a.a tng t lp i lp li bi cp phn t histidine, chng cng b phn chia ct 2hoc ct 3 a.a khc nhau. Khi phi hp vi phn t Zn, 2 Cysteine lk vi 2 histidine v cc a.a gia hnh thnh ln ci vng nhnhng ngn tay, c kh nng bm vo ADN.+ Kha leucine, n bao gm leucine c nhc i nhc li theo chu k c 7 a.a 1 ln, to ra 1 chui xon kp vi leucine c sp xp theo1 mt. Hai phn t ni vi nhau theo kiu kha kp to ra 1 khi, mt u ni vi ADN.+ VD: S pht trin sm ca bo thai c kim sot bi 1 b cc gen phn on, cc gen ny chia phi thai cha bit ha thnh tngphn, sau bng b gen chuyn ha cng ngun, mi gen ny quyt nh s phn pht trin ca tng phn. VD, phn pht trinthnh no sau, phn pht trin thnh ty sng. Protein c m ha bi gen phn on hay gen chuyn ha cng ngun c cha cc dngc kh nng bm vo ADN nh l ngn tay km hay kha leucine. Nhiu gen trong s cc gen ny c cha cc vng khong 180 bp,c tnh bo th cao VBC, c gi l hp cng ngun, chng m ha cho 1 cu hnh c kh nng bm vo ADN c gi l vng cngngun. Vng ny c tnh bo th cao vbc. Do vy cc gen ny iu khin s pht trin sm ca bo thai, m ha protein iu ha,v protein iu ha theo cch m tay hay ng gen theo cch m t trn.- VD v s iu ha gen trong qu trnh sng l c ch kim sot, h qu trnh phin m ca gen quy nh lng trng g. Phn thormon i vo tb, sau ni vi 1 protein c gi l oestrogen receptor. T hp hormon v c quan cm th sau ni vi 1 vng baogm khong 250 gc base pha trc hp TATA ca gen m ha lng trng trng, v lm cho gen ny c m. Lng trng trng ctng hp.+ Mt nhm cc gen u c iu ha bng 1 cch thc, chng cng c cc vng chung ging nhau trong gen khi ng ca chng.- VD tt c cc gen cn c hot ha bi glucocorticoid, chng u c nhn t p ng vi glucocorticoid, c quan cm th bm vonhn t ny, v tip theo l chng c hot ha bi glucocorticoid, chui base lin ng ca n l: TGGTACAAATGTTCT.- Cc chui base cc vng ln cn ca gen c tm quan trng ko km bn thn cc gen. Thc t khi t gen c s dng, n thngko theo c gen khi ng, gen tng cng v cc vng nm gia chng.CU 14: Trnh by cc loi ADN.- Mc d gen c nhng vai tr cc k quan trng nhng ko phi tt c ADN u cha gen. Thc t, ch c 1 t l rt nh h gen caV cha gen, c th t hn 10% hoc rt nh ch 1%. S phn loi ph bin ca ADN nh sau+ Chui base n: y l loai ADN ph bin nht, chim khong 60-70 % h gen ca V. Chui base n nm di rc trong ton bgenome v chng to nn phn ln cc gen n c hiu ng ln.+ Gia nh a gen: Mi 1 gia nh gm c nhng gen ging nhau hoc rt ging nhau. Cc thnh vin trong gia nh a gen ny nmri rc trong genome hoc 1 s trng hp , chng nm thnh tng cm gm 1 s gen nm gn nhau. Cc gen trong gia nh a genny thng l cc gen m sn phm ca chng c yu cu vi s lng ln: histon, keratin, collagene, rARN, tARN.+ ADN lp: bao gm cc phin bn ca cc chui base ring bit c gi l n v lp. Kch thc ca n v lp l t 1 base cho nvi nghn base. N gi vai tr cha kha i vi 1 s bnh di truyn cung cp cng c quan trng cho vic ng dng thc t ca sinhhc phn t i vi ci tin vt nui v chm sc sc khe vt nui. Kch thc 1-1000 nu+ Nhn t di truyn c kh nng dch chuyn: (gen nhy) C c tnh qu bu l chui nucleotide 1 u l s nhc li o ngcca chui nucleotide u kia. VD: b c TGE vi 611 base. S nhc li l ng hp, do vy c kh nng cp i tip hp vi nhautrong qu trnh phn bo gim phn 1. Trong trng hp TGE, s cp i ca cc phn t nhc li to cho TGE chnh n thnh 1 ci



vng. Ton b TGE t ct khi vng m n hnh thnh v di chuyn ti vng khc trn cng NST hay NST khc, ri n gn vovng bng qu trnh o ngc.i khi TGE c ti bn v bn sao ca n di chuyn n 1 ch no , li bn gc ti v tr cca n. N lin quan ti qu trnh lan truyn rt nhanh sc khng vi cc loi khng sinh khc nhau vi khun. TGE c mt khpmi ni, s lng ln n hng trm ngn genome ca v c v, chim t 1-5% ADN tng s. TGE cn c kh nng t di chuyn lc bit quan trng, t TGE c th a vo gen cu trc v lm gen khng hot ng. V vy TGE l 1 ngun cc k quan trngca t bin, c t bin loi ny l b chn, TGE nguyn nhn ca ung th.CU 15: Bng chng no khng nh ARN l vt cht mang thng tin di truyn.- Phn t ARN gm 4000-6000 nucleotide, trng lng phn t khong 1,5 n 2 triu, c mt trong nhn t bo v bo tng. ARNc cu trc 1 si, 1 s c cu trc 2 si(ARN lm nhim v vn chuyn hoc ARN ca 1 s virus c bit)- ARN tn ti cc dng khc nhau trong t nhin, mi dng c chc nng ring bit, ARN mang gen, cc ARN khc u lin quanchc nng thc hin ha thng tin di truyn( mARN, tARN, rARN).- Vai tr ARN l vt cht mang thng tin di truyn c minh ha trn virus gy bnh m thuc l. Virus m thuc l c th coi nh 1phn t rt ln, khi lng phn t 39.000.000. M hnh ging nh bp ng gm 2.200 ht. Tt c cc ht ging nhau to thnh lpv protein, mi ht l 1 tiu n v protein gm 155 a.a, tt c c xc nh v trt t sp xp ht sc chnh xc. Di lp v proteinl ARN c cu trc 1 si gm 6.500 nucleotide.- Virus khm thuc l khi xm nhp vo t bo cy thuc l, lm dip lc b ph hy gy thnh m khm vng xanh trn l. Ccdng virus khc nhau c c trng gy bnh khc nhau.- Bng phng php ha hc, ngi ta tch thnh phn axit nucleic v protein ca ht virus, sau kt hp chng tr li thu c htvirus nguyn lnh. Ngi ta tng rng kh nng gy bnh s b th tiu do cch phn hy trn , nhng thc cht ch cn ring ARNcng gy bnh, phn protein ko c tc dng gy bnh- Th nghim:+ Tch ARN v protein ca 2 dng virus thu c: ARN1 v protein1; ARN2 v protein2+ Sau khi tch, kt hp li theo t hp mi: ARN1 v protein2, ARN2 v protein1+ Hai loi virus lai ny ti to v pht trin. Cho c hai dng c v 2 dng l gy nhim ln thuc l, bnh pht trin theo kiu dngvirus cung cp ARN.+ Cc dng lai, sau khi vo t bo sn sinh ra nhng th virus mi. iu ng ch l v mi hnh thnh ging nh v ca dngkhi u m t ARN c tch ra, ngha l ARN ca n ch sn xut loi protein ca n.+ Nh vy virus th ARN l vt cht mang thng tin di truyn.CHNG II:CU 16: Trnh by kin thc di truyn v enzyme hn ch?- Cc thc khun(Phage) xm nhim vo tb vi khun v sinh si nh b my sinh tng hp ca vi khun. Khi s lng phage tng ln,chng ph v t bo vi khun tip tc qu trnh xm nhim mi. Nhng trong 1 s trng hp, t bo vi khun vn nguyn vn mphage ko sinh si na. Hin tng ny do 2 nguyn nhn:+ ADN ca phage gn xen vo ADN ca tb vi khun di dng ko hot ng trong 1 thi gian di hay ngn.+ ADN ca phage b mt h thng bo v ca vi khun tiu dit khi va mi xm nhp.- Nm 1970, pht hin vi khun t sn sinh ra enzyme c kh nng phn ct ADN l i vo t bo vi khun(cc enzyme ny ch tmthy t bo prokaryota). Nh c ch ny m vi khun t bo v trc s tn cng ca virus. Loi enzyme ny l enzyme hn ch.- Hin tng t bo v ca vi khun l 1 h thng gm 2 loi enzyme:+ Cc RE ct ADN ca thc khun nhng v tr chuyn bit lun to thnh nhng trnh t c kch thc xc nh+ Enzyme Methylase gn nhm Methyl vo base A hoc base C v tr ct cc RE nn RE ko cn nhn bit c v tr ct nn ADN cavi khun ko b ct.- Tn gi ca cc RE+ Ch u tin, vit hoa l tn ca loi vi khun+ Hai ch tip theo, ko vit hoa l tn ca ging vi khun+ Cc ch sau ch ra tn ca dng vi khun+ Cui cng l ch s la m ch th t enzyme hn ch c pht hin ra (trng hp pht hin nhiu enzyme hn ch trn cng 1 dngvi khun)+ VD: enzyme Bam HI l enzyme hn ch nhn c t vi khun Bacillus amyloliquefacius, vi H l ch dng vi khun, I ch th t yl enzyme u tin pht hin trn vi khun ny.- Mt c tnh ca enzyme hn ch l c kh nng nhn din chui base c th(chui nhn dng) trn ADN xc nh v tr ct.Mi enzyme c hiu vi 1 trnh t c th. Trnh t nhn dng c c im l c ngc xui u c: trnh t cc base ca mch nny c theo hng 5-3 cng l trnh t cc base ca mch n kia c theo hng 3-5.- Cn c vo c im nhn dng v v tr ct ca RE ngi ta chia thnh 3 nhm:+ Nhm I: cc RE nhn bit c trnh t c th sau n s di chuyn trn phn t ADN n cch khong 1000-5000 nu v giiphng vi chc nu.+ Nhm II: cc RE nhn bit trnh t c th v ct ngay ti v tr + Nhm III: cc RE nhn bit c trnh t c th sau s ct phn t ADN v tr cch khong 20 nu.- Enzyme c 3 kiu ct:+ Ct nhnh ca chui xon kp ti cng 1 v tr li hai u bng+ Ct ADN theo hnh ch Z : u th l u 5; u th l u 3. Gi l u dnh c kt.- Enzyme hn ch v enzyme ni gip chng ta c th ct-ghp-ni- chuyn to ra cc phn t ADN ti t hp cng ngun v cngc th khc ngun thm ch khc loi.



CU 17: C ch no gip vi khun chng li s tn cng ca virus.-Trong 1 s trng hp, t bo vi khun vn nguyn vn khi b thc khun th xm nhp m phage ko sinh si na.Hin tng ny do2 nguyn nhn:+ ADN ca phage gn xen vo ADN ca tb vi khun di dng ko hot ng trong 1 thi gian di hay ngn.+ ADN ca phage b mt h thng bo v ca vi khun tiu dit khi va mi xm nhp.- Nm 1970, pht hin vi khun t sn sinh ra c enzyme c kh nng phn ct ADN l i vo t bo vi khun (cc enzyme ny chtm thy t bo prokaryota). Nh c ch ny m vi khun t bo v trc s tn cng ca virus. Loi enzyme ny l enzyme hnch.- Hin tng t bo v ca vi khun l 1 h thng gm 2 loi enzyme:+ Cc RE ct ADN ca thc khun nhng v tr chuyn bit lun to thnh nhng trnh t c kch thc xc nh+ Enzyme Methylase gn nhm Methyl vo base A hoc base C v tr ct cc RE nn RE ko cn nhn bit c v tr ct nn ADN cavi khun ko b ct.CU 18: i tng nghin cu ca di truyn phn t l g? K tn cc phng php thu nhn i tng , trnh by chi tit 1 trongcc phng php .*) i tng nghin cu ca di truyn phn t l cc axit nucleic (ADN hoc ARN) v cc cng c chnh ca k thut l cc enzymem quan trng nht l 2 enzyme: enzyme hn ch dng ct ADN ti nhng v tr c trnh t c th v enzyme ni (ADN ligase)dng ni cc on ADN li vi nhau. i tng phi c trc tin l axit nucleic.*) Cc phng php thu nhn gen:- Tch cc on ADN t b gen:+ Tch ADN ra khi cc thnh phn ca t bo bng cc phng php vt l v ha hc nh cc phng php: nghin lc, ly tm, sdng cc enzyme, cc ha cht tri qua nhiu quy trnh th ADN tinh khit c tch ra. Sau ADN c ct bi cc enzyme c hiu vni vi cc vector mang gen to plasmid ti t hp.+ Phng php ny mang tnh cht m mm v nguyn b gen tc l ton b ADN ca cc sinh vt khc nhau cha rt nhiu gen. Tuynhin hin nay ang c s dng trong vic lp ngn hng gen (th vin gen) ca cc sinh vt, c gi l ngn hng ca ADN bgen(th vin ca ADN b gen).- Tng hp gen bng phng php ha hc:+ 1969, nhm ca Khorana thc hin vic tng hp nhn to gen ln u tin. l gen m ha vic tng hp tARNala vnchuyn a.a alanine nm men, m lc cu trc c bit r. Gen ny di 77 cp nu, ko c cc trnh t iu ha v th ko chot tnh. V sau tng hp gen c hot tnh, l gen m ha cho cht c ch tARN vn chuyn tyrosin E.Coli c chiu dikhong 200 cp nu.+ Mun tng hp gen bng phng php ha hc th trc tin phi bit trnh t cc nu ca gen. S hon thin cc phng phpnghin cu cu trc bc 1 ca protein v cc sn phm khc ca gen, cng cc phng php xc nh trnh t cc nu thc ynhanh ng k vic tng hp nhn to cc gen.+ 1977, K.Ita kura v Boyer thnh cng trong vic tng hp nhn to gen m ha cho vic tng hp hormone Somatostatin cang vt c v biu hin trn tb E.Coli. Gen Somatostatin nhn c nh bit cu trc peptide ca hormone ch gm 14 aminoacide.+ To ra ni vi khun sn sinh ra isulin, hormone quan trng cha bnh tiu ng. Gen Isulin c tng hp t hn 40 onoligonucleotide, mi on cn bn c 6 nucleotide. T bo cha Plasmide mang gen Isulin tng hp ta proisulin, sau c l ha hc bin thnh isulin c hot tnh cu to t hai mch polypeptide A c 21a.a v polypeptide B c 30 a.a. Hai mch ni vi nhau nhcu disulfit.- Sinh tng hp gen t mARN tng ng+ Theo l thuyt trung tm ca di truyn hc th thng tin xy ra theo chiu: ADN mARN protein. T ADN qua phin m to ramARN sau t mARN dch m to ra phn t Protein+ Ngoi ra cn c 1 lp virus c vt cht mang thng tin di truyn l ARN nn mun truyn thng tin cho th h sau (phin m raARN tng hp protein th cn c AND). Lp virus ny c kh nng sao m ngc t ARN thnh ADN, sau t ADN li sy racc qu trnh di truyn bnh thng.+ Lp virus Ritrovirus v enzyme phin m ngc l Reveres trascriptase. Enzyme c kh nng tng hp nn mt mch ADN gi lc-ADN b sung vi ARN lm khun( hoc t 1 oligonucleotide theo hng 5-3) khi c mt mi. Cc mch n c-ADN c binthnh mch kp nh ADN polymerase v c gi l cADN kp. on c-ADN kp c gn vi Plasmide ri bin np vo vi khun todng c-ADN.+ Qu trnh phin m ngc gm 2 giai on:++ Giai on 1: mi oligonucleotide c gn vo ui poly A ca ARN cung cp nhm 3-OH cho enzyme phin m ngc bt usao chp to ra 1 mch n ADN gn b xung vi chui ARN++ Giai on 2: mARN s c loi b bng cch thy phn kim to ra 1 phn t c-ADN n c hnh kp tc. Chnh hnh kp tcny to nn on vng v sau chnh 2 on ca c-ADN bt cp b xung cho nhau v to ra 1 mi, to tin cho vic tng hptip mch ADN b xung cho mch c-ADN n ny.+ Nh vy ADN kp c hnh thnh, cui cng ch cn vic ct vng cung ha thin ADN thnh 1 ADN bnh thng. Vic ct nythc hin bi enzyme S1 nuclease.CU 19: Th no l ADN ti t hp? Trnh by nguyn l qu trnh tch dng( nhn dng)*) ADN ti t hp:- ADN ti t hp to ra do qu trnh trao i cho gia hai nhim sc t khc ngun ca cp NST tng ng trong gim phn 1. Khi ADN ti t hp c biu hin l s xp xp li cc gen trn NST trong t bo.



- ADN ti t hp c th l 1 t hp ca nhiu on ADN c ngun gc t nhiu loi, c th c 1 on ADN t virus, c 1 on ADNt vi khun.*) Nhim v ca SHPT l vic sn xut ra 1 s lng ko hn ch cc bn sao ca cc on ADN ring bit lm vt liu cho ccphn tch tip theo nh: xc nh trnh t cc gc base trn ADN v cc k thut phn t khc. Thc hin bng hai cch:- Tch dng gen( gene cloning) hay s nhn dng ADN- Phn ng chui trng hp PCR*) Nguyn l qu trnh tch dng( nhn dng)- a on ADN (m on ny s c nhn) c gi l ADN l hay ADN chm ghp vo 1 vector ADN (vt trung gian), vector ny ckh nng nhn ln trong vt ch.+ Yu cu:++ on ADN l v vector phi c cng u tng thch (chng c ct bi cng 1 enzyme hn ch)- Khi ADN vector v ADN l c hn hp vi nhau cng enzyme ADN ligase, mi u ca ADN l ni vi mi u ca ADN vector,qu trnh ny c gi l qu trnh ni. Phn t ADN mi to thnh l mt v d ca ADN ti t hp- Sau khi to c plasmide ti t hp, ngi ta a plasmide ny vo trong t bo vi khun cho chng nhn ln, cui cng chn lctrnh t cn quan tm.CU 20: V sao cn c vector chuyn gen? Ti sao Plasmide c chn lm vector chuyn gen?*) V sao cn c vector chuyn gen- chuyn gen t sinh vt ny sang sinh vt khc c th thc hin bng:+ Bin np+ Ti np+ Vi tim- Nhng cn c rt nhiu han ch khi thc hin nhng bin php trn:+ Nu ADN thm nhp vo tb th phn ln b phn hy, ch c 1 s cc t phn t ADN do ti t hp gn vo b gen tb vt ch mic th cng tn ti n nh. ADN ko c ti t hp v ko t sao chp ra nhiu bn s b mt trong phn bo.+ Cc gen thng c 1 bn duy nht trong tb n bi, li chim 1 on rt nh chm ln trong phn t ADN khng l, nn kh chuygen theo mun ch quan.- Vector chuyngen l phn t ADN c kh nng t ti sinh, tn ti c lp trong t bo v mang c gen cn chuyn.- Vector chuyn gen c cc c im :+ L nhng phn t ADN nh m bo cho vic phn tch bo qun d dng.+ C dim khi u sao chp cho ADN ca n c nhn ln v do vt dc duy tr trong qun th tb khi sinh vt ch sinh trng vphn chia.+ C t nht 1 trnh t nhn bit, ni m cc RE nhn bit ct h lm ch lp ghp cho on gen cn chuyn ni vo. Cc trnh tny nm xa im xut pht sao chp trnh ct nhm+ C cc trnh t iu ha to thun li cho s phin m ca gen c chuyn+ C cc gen nh du to iu kin cho vector d dng c pht hin.- Cc vector tha mn c cc k trn v thc t s dng l cc plasmide v cc phage.*) Ti sao Plasmide c chn lm vector chuyn gen- Plasmide l 1 phn t ADN si kp dng vng, di thng l 1-3 kb.- Tn ti t bo vt ch( vi khun, 1 s nm men) mt cch c lp vi NST ca vi khun- Chng truyn cc tnh trng ( tnh bn vng vi khng sinh) cho sinh vt ch gip cho vic la chn d dng trong nhng iu kinxc nh- Cc gen bn vng vi khng sinh do ADN plasmide m ha thng c s dng trong vic thit k cc vector dng cho k thut ditruyn v chng cung cp 1 phng tin thun li la chn cc tb c mang plasmide.CU 21: Trnh by v cc loi ADN ligase thng dng trong to plasmide ti t hp v trnh by v cc phng php ni.*) Cc loi ADN ligase thng dng trong to plasmide ti t hp- ADN ligase l mt enzyme ni quan trng trong t bo v chc nng ca n l sa cha cc mi lin kt phtphodiester b t gymt cc ngu nhin hoc do hu qu ca vic sao chp hoc ti t hp ADN .- Trong k thut di truyn n c s dng hn gn nhng ch gin on trong chui ng photphat, nhng gin on nythng din ra khi ADN ti t hp c hnh thnh bng cch ni cc phn t ADN t cc ngun khc nhau. Chc nng ny l htsc quan trng i vi s thnh cng ca nhiu th nghim, v v vy ADN ligase l enzyme ni ch cht trong k thut di truyn.- C hai loi enzyme ADN ligase c s dng ph bin nht trong k thut di truyn l ADN ligase ca E.Coli v ADN ligase caphage T4.+ E. Coli ADN ligase c tch chit t E.Coli v c tc dng xc tc phn ng ni hai trnh t c u so le.+ T4 ADN ligase enzyme ny c ngun t phage T4 xm nhim E.Coli ny c cng chc nng vi ADN ligase tch chit t E.Colinhng c bit n cn kh nng ni hai trnh t ADN u bng, do T4 ADN ligase c chung nht trong k thut to dng.*) Cc phng php ni:- Ni u bng:+ Ni nh Enzyme ADN ligase ca phage T4+ Cc on u bng c th c xut hin do vic s dng enzyme S1 nuclease trong qu trnh tch dng c-ADN hoc chng c th csinh ra do lp y cc u so le di tc dng ca ADN polymerase.+ ADN ligase ni cc u t vi nhau bng cch xc tc to ra cc lin kt photphodiester gia nhm OH u 3 on ADN nyvi nhm photphat u 5 ca on ADN kia



+ Nhc im:++ Hiu sut ko cao v c s phi hp c bit gia cc phn t gi li cc chui ADN li vi nhau.++ C th ko to ra cc trnh t nhn bit cho enzyme gii hn ti v tr tch dng gy tr ngi cho vic ct cc on cn tch dngkhi th ti t hp.- Ni dng u dnh c kt:+ Vecto chuyn gen l cc ADN dng vng c ct bi 1 loi enzyme gii hn chuyn thnh dng mch h c hai u c kt.+ Cc pt ADN cn tch dng ca b gen khc c ct bi cng loi enzyme .+ Do to ra nhiu on ADN thng vi cc u dnh c kt c trnh t b sung vi trnh t u dnh c kt ca ADN vecto.+ Trn ln ADN ca vecto vi ADN mang gen mun nhn dng cc u dnh c kt ca 2 loi ADN s bt cp b sung vi nhau,enzyme ADN ligase hn dnh cc on ADN vi nhau to plasmide ti t hp.- Ni dng cc on ni:+ Cc on oligonucleotide( ADN ngn c t 10-20 nucleotide) c th c tng hp ha hc nhn to. chnh gia c trnh t nhnbit c bit i vi mt enzyme gii hn no lm cc on ni.+ ADN ligase ca phage T4 c c tnh ni cc on ADN li vi nhau, nh vy m on ADN l c gn vi cc onoligonucleotide tng hp vi trnh t cn thit.+ Cc on ni s gn vo hai u ca on ADN l v khi ct bng enzyme hn ch nh enzyme ct ADN ca vecto th n s gnc vi vecto. Vi on ni ta chuyn c ADN l t ch ko c u dnh c kt thnh ADN l c u dnh c kt ph hp vicc u dnh ca vecto.+ S dng gn cc C-ADN v cc on ADN c u bng vo plasmide.Cu 22: a ADN ti t hp vo t bo ngi ta c th s dng nhng phng php no? Trnh by c th cc phng php ?Sau khi to c ADN ti t hp( plasmide), vic tip theo l bin np a n vo t bo. Cng vic ny c thc hin bng nhiucch.a. Ha bin np:- ADN ti t hp c vi s lng ln t bo vi khun, i vi t bo vi khun c th x l CaCl2 lnh km sc nhit(420C trong 2pht) th ADN ti t hp xm nhp vo t bo nhiu hn.- Hiu qu to cc th bin np(transformants) cao( 105- 106 transformant/1 mg ca ADN siu xon).- Nhng ci tin tip theo lm tng hiu qu bin np ln gp 100-1000 ln so vi ban u.- T nm 1970 tr i vn a plasmide ti t hp tr li vo t bo vi khun d dng hn.b. in bin np:- S dng dng in cao th cc b theo xung c th lm t bo hp th ADN nn c gi l in bin np.- Lc u phng php c s dng cho t bo ng vt c v, v sau n c s dng cho c t bo thc vt.- Hiu qu bin np cao, c th t ti 109 1010 transformant/1 mg ADN, cao gp 10 n 20 ln so vi x l ha cht.- Tuy nhin c t l t bo cht ng k, hiu qu cao t l cht 50-70%. Kh khn khc l phi ch dng c chuyn bit to dngin c hiu in th cao cho mt khi lng x l nh(20-40 microliter).c. Vi tim:- i vi cc t bo ng vt c v(thng l hp t) c th tim thng ADN ti t hp vo t bo.- T bo c gi trn u mt ng thy tinh, cn chic kim nhn c dng m xuyn qua mng t bo lm ng dn aADN vo trong t bo.- K thut ny i hi phi c mt my vi thao tc c hc vi 1 knh hin vi v c bit phi c k nng thc hnh tinh vi.d. Bn ADN ti t hp vo t bo:- i vi tb thc vt, mun thc hin bin np phi to t bo trn mt vch t bo( mng xenlulose) th ADN mi ngm c votrong.- Vic to t bo trn ko n gin, tn cng sc v thng t bo c sc sng km, kh phn chia t ti sinh- khi phi lm nhng cng vic k trn, phng php bn ADN ti t hp trc tip vo t bo thc vt c s dng.- Cc ht kim loi hoc vng( ng knh trung bnh 4micrometer) mang ADN hoc ARN c bn vo vi tc nhanh xuynthng vch t bo a vo trong.- Phng php ny c nhiu u th v c dng nhiu trong to cc thc vt nhim gen.Cu 23: Trnh by nguyn tc phn ng PCR?- K thut PCR s dng cc c im ca qu trnh sao chp ADN. Cc ADN polymerase dng cc on ADN mch n lm khun tng hp nn si mi b sung vi n. Cc si ADN mch n c th c to ra theo cch n gin l un nng dung dch ADNmch kp ti gn nhit si.- ADN polymerase cng i hi c mt on ngn ADN mch n( on mi-primer) khi u qu trnh sao chp. Cc primer nythng c tng hp nhn to vi di t 6-30 nucleotide. on ny gn kt vi khun ti im khi u sao chp. c im quantrng u tin ca phn ng PCR v ADN polymerase c iu khin tng hp mt on ADN c th.- Trong k thut PCR, cc on mi c chn chn hai u ca on ADN cn nhn ln( mi xui v mi ngc), sao cho cc siADN tng hp mi c bt u ti mi on mi v ko di v pha on mi nm trn si kia v vy m qu trnh tng hp t u3 ca mi mch ko di lin tc do ko xut hin nhng on Okazaki v vy ko cn s c mt ca cc enzyme ADN ligase.- Gm 3 giai on chnh:+ Giai on tch hai mch: nng nhit ln 90-95 0C hai mch ADN si kp tch nhau ra thnh hai mch n lm khun cho qutrnh tng hp.+ Giai on bt cp mi: nhit c h xung 30-65 0C nhit ny thch hp cho vic gn cc mi hai u ca on mchADN cn nhn ln.



+ Giai on sinh tng hp: Nhit c nng ln 720 C y l nhit thch hp cho enzyme ADN polymerase hot ng tip tclp ghp cc nucleotide b xung vi mch khun ko di si ADN mi.- Lc u khi phn ng mi c ng dng ngi ta cha pht hin ra loi enzyme Taq ADN polymerase th c sau mi chu k ngita li b sung ADN polymerase nh vy lm hiu qu phn ng ko cao v tn rt nhiu enzyme.- Khi ngi ta pht hin ra loi vi khun c kh nng chu nhit cao sng thch nghi sui nc nng l Thermophilus aquaticus thvic thc hin phn ng thun tin hn nhiu, ngi ta ch vic b sung enzyme Taq ADN polymerase mt ln vi cc nguyn liukhc nn tng hiu sut phn ng.- Sau n phn ng s to ra 2n bn sao cc phn t ADN mch kp nm gia 2 on mi.Cu 24: V sao khi thc hin phn ng PCR ngi ta phi dng t nht l hai mi( primer) xui v ngc.Khi c 1 mi tham gia phn ng:

- Kt thc ko c ADN hon chnh- Hiu sut phn ng thp- Sau n chu k thu c 2n phn t.

Cu 25: Thnh phn ca phn ng PCR, cc u nhc im ca phn ng PCR?a. Thnh phn ca phn ng PCR:Trong ng eppendor gm c cc thnh phn sau:- ADN khun mu, tc l on ADN cn c khuch i c tch trit t h gen ca ng vt hoc bng cc phng php khc.- Cc primer gm c mi xui v mi ngc- Enzyme Taq ADN polymerase- Bn loi nucleotide c hot ha : dNTP- Dung dch m(buffer), c bit l ion Mg2+ c vai tr xc tc c bit trong vic tng hp ko di si ADN mi( n to phc hatan vi cc nucleotide c hot ha lm nguyn liu cho qu trnh tng hp si ADN)b. u, nhc im:- u im:+ Thi gian thc hin phn ng cc nhanh, ch cn mt khong 3 gi khuch i mt trnh t ADN quan tm so vi phng phpto dng ca k thut ADN ti t hp phi mt mt tun hoc lu hn.+ Thc hin n gin hn, t tn km hn, n c thc hin n gin, t tn km n c thc hin trong ng nghim plastic nhgm cc phn ti thiu c s dng. Trong khi , phn ng to dng i hi cc vt dng t tin, cc nucleotide triphotphat phimang phng x u dng v cc thao tc phi c thc hin kho lo c bit.+ tinh sch ca mu ko cn cao, phn ng PCR c th c thc hin vi cc mu axit nucleic th. V d nh mu mu hay ccdu vt trong phn tch php y. iu ny ngc vi ti t hp ADN trong to dng l cc on gen v vecto u cn tng i tinhkhit.Phn ng PCR hp dn cc nh nghin cu ngay t lc ra i trong vic khuch i cc trnh t axit nucleic c hiu v chunon phn t.- Nhc im:+ Kch thc ca trnh t cn c khuch i l gii hn u tin, tr mt s ngoi l, phn ng PCR ko hot ng c vi nhngon ADN ln hn 3kb. Vi cc di ln hn iu kin ti u cho phn ng phi c xc nh qua thc nghim.+ S ngoi nhim l vn ln t ra cho phn ng PCR, vn ny c bit quan trng i vi cc ng dng v chun on, dphng v hu qu rt nghim trng. Ngun ngoi nhim ln nht thng l cc sn phm khuch i ca cc phn ng ln trc.Ngi ta chng minh c rng vic m np cc th nghim s khin cho cc phn t c khuch i trong mt khong khnggian kn nh phng th nghim s khin cho cc phn t c khuch i thot ra khi ng nghim bay lo lng trong khng kh vbm vo tng la, ca, cc thit b, dng c, sau li nhim vo cc phn ng PCR ln sau.Cu 26: Cc lnh vc ng dng ca phn ng PCR, cho mt v d c th ng dng trong chn nui- th y.Phn ng chui trng hp( PCR) c rt nhiu ng dng trong nhiu lnh vc khc nhau:- Trong nghin cu khoa hc PCR gip hu ch cho vic xc nh trnh t cc nucleotide cn c nhn ln, s dng PCR tchdng nhng on ADN c hiu, gip cho vic pht hin kp thi cc t bin, cho php phn tch lin kt gen t nhng t bo ringl; gip nghin cu qu trnh tin ha mc phn t. Thm ch gip phc hi nhng gen tn ti cch y hng chc triu nm.- Trong chn ging vt nui, c bit i vi ng vt v thc vt bc cao, vn trc y vic la chn cp cha m lm ging l rtkh khn v chng ta la chn ch cn c vo nhng gi tr kiu hnh v vy cn rt nhiu nm chn lc nhng ngy nay k thut PCRcho php thc hin ch trong vi ngy thm ch vi gi chng ta c th c bn cht di truyn ca con vt t m c th raphng hng x l thch hp.- i vi Y hc PCR c th chun on chnh xc cc bnh nhim trng t virus n vi khun v cc bnh do nm, k c HIV-AIDSchun on sm v theo iu tr ung th.- Trong t vn di truyn y hc, PCR cho php chun on nhanh, chnh xc cc bnh di truyn k c chun on trc sinh v giitnh v cc d tt bm sinh khc c th t khi thai c 8 tun tui v iu quan trng l ko cn chc i m ch cn ly mt git mungoi vi ca m lm mu th nghim.- Trong khoa hc hnh s, PCR c th gip chun on nhanh chnh xc th phm t mt vt mu kh, mt si tc hoc mt sinhphm no m th phm li ti hin trng. Ngoi ra PCR cn gip xc nh chnh xc cc quan h huyt thng nh cha-con,ng- chu.Cu 27: Trnh by phng php xc nh trnh t cc nucleotide ca Maxam- Gilbert( phng php ha hc)?- Cc chui nucleotide ging nhau( trnh t v di) c nh du ng v phng x P32 u 5. Cc on c mang ng vphng x ny c chia lm 4 nhm, mi nhm chu x l ha hc lm t chui nucleotide ti v tr nucleotide c base c th l:



+ X l methyl ha( dimethyl sunfate) th mch t G.+ X l pH=2 lm t base A hoc G+ X l bng hydrazine lm t C v T+ X l bng hydrazine nng mui cao lm t C.- Bn nhm c a ln bn bn thch acrylamide v c t ring pha cc m ca mi bn thch. Cc on nucleotide c kchthc ngn hn s di chuyn v pha cc dng nhanh hn.- Da vo kt qu in di c th xp cc on ADN theo th t t ngn n di c im mc chun l u 5 mang du phng x P32c pht hin nh phng php phng x t ghi biu hin vt en vo giy in nh.- Tng hp kt qu c 4 nhm trn 4 bn in di phn nh y trnh t ca chui nucleotide ban u mun xc nh trnh t.*) i tng: kch thc on ADN khong t 250 nucleotideCh khi thc hin th nghim:- cc bn thch va l gi v nh ci sng lc cc phn t ADN c kch thc khc nhau.- Thch agarose dng phn tch cc phn t ADN c s sai khc ln gia cc phn t v kch thc.- Thch acrylamide c kh nng phn bit cc phn t ADN sai khc 1 nucleotide.- ADN l phn t mang in tch m nn khi in phn s di chuyn v cc dng v cc on c kch thc khc nhau s di chuynkhc nhau vi vn tc t l nghch vi kch thc.Cu 28: Trnh by phng php xc nh trnh t cc nucleotide ca Sanger ( phng php dideoxy)?- Trnh t ADN cn xc nh phi c to dng trong mt vecto mch n(phage M13). Sau s dng ADN polymerase tnghp chui mi b sung vi chui cn xc nh trnh t. S tng hp mch mi bt u t mt mi c bt cp vi trnh t chuynbit trn phage M13, vi nguyn liu trng hp l cc nucleotide c hot ha dNTP, trong 1 loi nucleotide c nh dubng ng v phng x.- Phn ng c tin hnh trong 4 phn on ring.- Mi phn on cho vo mt trong 4 loi dideoxynucleotide vi hm lng rt nh (dideoxynucleotide l cc nucleotide c x lthay nhm OH u 3 bng H nn lm mt kh nng to lin kt photphodiester nn phn ng trng hp dng ngay) do khi c stng hp cn nucleotide trn mch th dNTP c s dng v ngay lp tc phn ng tng hp dng li ti .VD: trnh t cn xc nh l ATGCACTC nu trong mi trng c dideoxynucleotide loi C(ddC) th s c s tng hp ccoligonucleotide nh sau:ATGCATGCACATGCACTC- Sau bn phn ng ca 4 phn on s c em phn tch trn thch acrylamide v kt qu c c trn bn phng x t ghitng t nh phng php Maxam- Gilbert.*) i tng: kch thc on ADN khong t 250-300 nucleotideCHNG III:Cu 29: Trnh by c s sinh hc ca gii tnh?- Gii tnh c di truyn theo quy lut ca Menden, c quyt nh bi s c mt hay khng c mt ca NST Y.- Nm 1990 ADNrew Sinclair v ng nghip pht hin ra hiu qu quyt nh hnh thnh con c ca NST Y l do gen SRY vngquyt nh gii tnh ca NST Y.- SRY nm trn cnh tay ngn ca NST Y, gn vng NST gi. Vai tr:+ Gen SRY l du hiu u tin m sinh dc cha bit ha phi thai pht trin thnh dch hon hn l pht trin thnh bungtrng.+ Bn cht thc s ca du hiu ny cha c tm ra nhng sn phm polypeptide ca gen SRY l 1 protein c kh nng bm voADN, protein nh l 1 nhn t iu ha c kh nng khi pht 1 lot cc bc pht trin to ra s hnh thnh dch hon.- Nu m sinh dc cha phn ha, khng nhn c bt c tn hiu no t gen SRY th m pht trin thnh bung trng. Hormonebung trng sau to ra cc c tnh sinh dc th cp. Nu gen SRY gi tn hiu ca n n m sinh dc th cp.- Nu gen SRY tn hiu ca n n m sinh dc cha bit ha th m pht trin thnh tinh hon, t hormon sinh dc c to ra vc tnh sinh dc th cp c hnh thnh.Cu 30: Trnh by cc kiu xc nh gii tnh ng vt?1. Hin tng con c XX v con ci XY- Kiu hnh con c c kiu gen XX.- Kiu hnh con ci c kiu gen XY.- Nghin cu mc phn t ngi ta thy mt NST X ca con c XX c mt on thm rt nh t NST Y, on thm ny chagen SRY.- Con ci XY c th c gii thch nh:+ NST Y b mt 1 on c cha gen SRY.+ Gen SRY b t bin, thiu polypeptide c m ha bi gen SRY.+ Khi vng mt cc thng tin di truyn n t gen SRY, cc c th ny c bung trng pht trin. Cc c tnh sinh dc th cp chnh thnh. Mt s cc con ci XY, c cha gen SRY bnh thng nhng thiu receptor tng thch vi hormone c c to ra tdch hon, do vy hormon c ko c kh nng th hin, ch c 1 lng nh hormone ci pht huy tc dng. Do vy, c im sinh dcth cp l pht trin theo chiu hng ci.- Cc khuyt tt ny c gi l hin tng n ha dch hon. Gen m ha cho receptor ADNrogen nm trn NST X, hin tng nha dch hon l khuyt tt lin kt vi NST X. Hin tng ny xy ra b, cu, nga, ngi.



2. Cc dng gii tnh trung gian.- Hin tng gii tnh trung gian l cc c th c s hn hp ca c hai loi gii tnh c v ci.+ Gii tnh trung gian NST: C s pht trin ko bnh thng v gii tnh, nguyn nhn l c s bt bnh thng v NST gii tnh.+ Gii tnh trung gian c quan sinh dc: C th c kiu nhn ca con c hoc con ci bnh thng, song b phn sinh dc phttrin ko ph hp vi NST gii tnh. C th XX c dch hon hoc c th XY vi bung trng hoc Freemartin vi a s t bo chaXX.+ Trng hp c th c hai kiu gen XX v XY song c quan sinh dc ko pht trin, trng hp ny gi l suy gim c quan sinhdc.+ Gii tnh trung gian biu hin trn kiu hnh: C th NST gii tnh v c quan sinh dc bnh thng, nhng bt bnh thng xy ra ng sinh dc v cc c tnh sinh dc khc. VD: s n ha bung trng.+ Con th bt u cuc sng l mt con c, sinh sn ra trn 250 con ci. Sau n mt kh nng hng th giao phi vi cc con ci,thay vo n t c cha, ri sinh ra mt ba con c v bn con ci v n c th t nui con bng chnh sa ca n. Chng ta cth kt lun rng bt c ci g cng c th sy ra vi lnh vc gii tnh.3. Gii tnh c xc nh bi mi trng.- y l c ch rt him hoi ca loi giun bin Bonellia virides; cc u trng xut hin sau khi th tinh n sng t do trong mt thigian sau n chui vo vi con ci ri vo t cung ca con ci th li n thnh con c v c kh nng th tinh. Con ci, con c cchung kiu gen.Cu 31: Trnh by hin tng Freemartin?- Freemartin c s dng m t cc con ci v sinh khi c sinh i cng con c bt c ging no. Tp trung ch yu b.- Qu trnh hnh thnh nh sau: t nht c 2 trng cng rng mt lc, c s th tinh ca t nht mt trong hai trng vi tinh trng mangNST X, v t nht mt tinh trng mang NST Y, to ra t nht mt con c v mt con ci.+ C s pha trn mng m ca hai phi thai v c s ni mng chung ca h thng mch mu, to ra vng tun hon chung gia haiphi thai. C s trao i tb mu v c th mt s cht khc na gia hai phi thai.- Thng c s trao i cc tb bch cu v chng duy tr hot ng trong i sng ca tng phi thai. Kt qu, mi mt thnh vinca cp sinh i cha hai loi hng cu, hai loi bch cu: mt loi l ca bn thn n, mt ca c th sinh i vi n. Mi thnh vinth hin nhm mu ca ring n v nhm mu ca anh ch em sinh i vi n.- Ta c th phn bit c hai loi bch cu theo hai gii tnh:+ Bch cu c ngun gc t con c c kiu gen XY.+ Bch cu c ngun gc t con ci c kiu gen XX.C hai loi t bo ny cng tn ti trong mi c th sinh i khc gii tnh gi l th khm XX/XY.- Hin tng sinh i khc gii tnh, hu qu rt nghim trng vi c quan sinh dc v ng sinh dc ca con ci:+ Phi thai ci c 60 ngy tui, c quan sinh dc pht trin bnh thng, sau c xu hng pht trin theo hng c ha. Mt strng hp m sinh dc pht trin bnh thng thnh bung trng, mt s m sinh dc pht trin thnh m bung trng v dch honln ln, c nhiu bt thng vi ng sinh dc.- S chung mch mu gia cc c th sinh i khc gii t nh hng n c quan sinh dc c, v cu trc th bnh thng, tuy nhinnh hng kh nng sinh sn.V d:- b hin tng chng ng tun hon l khong 90% do vy khong 90% con ci l v sinh v l cc con Freemartin.- hu, d, ln, cu cng xut hin nhng t l c thp hn so vi b. Cu khong 1%. nga s trao i mu l rt ph binnhng ko dn ti v sinh.- Cch xc nh b con sinh ra c phi l Freemartin: l kim tra th khm bch cu XX/XY vi s lng gi l 200, khi bch cuXY ln th nht c pht hin th c th dng kim tra v a ra kt lun.- Cc k thut chun on Freemartin:+ Phng php Southern: s dng cc on ADN t NST Y c nhn pht hin cc t bo cha XY.+ Phng php PCR t cc on ADN ca NST Y c nhn pht hin cc t bo cha XY.- Nguyn nhn ca hin tng ny c th do l hormone c truyn t con c sinh i sang con cis, hoc s c mt ca tb mangNST Y. nhng cha r rng v cha gii thch c tt c cc con ci chung ng tun hon vi con c u b Freemartin.Cu 32: Trnh by hin tng di truyn b hn ch bi gii tnh.- Th nht n cho rng ko phi tt c cc t bin u gy nn tnh trng mt hot tnh mt s t bin lm cho gen trong t bo trnn hot ng m bnh thng n ko hot ng.- Th hai n cung cp cc minh chng khc nhau cho cc quan im pha trc.- i vi hot tnh ca enzyme aromatase ADN g, hot ng ca gen l ng tri ngha l i vi d hp t hot tnh ca enzymenm gia hai ng hp t. Tuy nhin trong trng hp ny hiu qu hot ng da g ca ng hp t l bng khng. i vi lngg mi, t bin l tri bi v d hp t sn sinh enzyme ADN, v v vy s lng oestrogen gy hin tng lng g mi.- Th ba, khi t bin sinh ra kiu hnh ch c nhn thy con c, s th hin bnh thng ca gen ch c quan st thy gmi. Nh vy hai alen locus to ra hai dng di truyn hn ch bi gii tnh.VD:- Kiu lng g in hnh l mt trong nhng c im sinh dc th cp c quyt nh bi s hot ng ca hormone oestrogen, mts lng ln oestrogen c to ra t ADNrogen bung trng bi enzyme aromatase.- mt vi loi dng g thuc hai ging Sebringt Bantam v Golden Campien, con trng c mu lng ging nh lng g mi. Hintng ny hnh thnh do c t bin gen quy nh s hnh thnh enzyme aromatase, lm cho gen ny c th hin c hai loi giitnh. con c, t bin ny lm cho mc oestrogen cao khc thng, n lt n enzyme tc ng hnh thnh nn lng g mi.



- Gen aromatase nm trn NST thng, nhng kiu di truyn lng g mi ko ging nh cc t bin nm trn NST quy nh, bi vkiu hnh mang t bin ch c th hin con c. y l v d ri lon hn ch bi gii tnh.CHNG IV:Cu 33: Khi nim v p ng min dch, cc loi p ng min dch trong c th do t bo bch cu Lympho m nhim?- p ng min dch l c th t ng p ng li s tn cng ca mt cht l i vo c th V thm ch ch tip xc qua da bngcch hy dit hoc lm mt hot tnh ca cht l.- Cc loi p ng min dch th:+ p ng min dch dch th:T bo B trng thnh i vo bo tng to ra mt s lng ln khng th( hnh thnh do s tc ng ca khng nguyn). Khi c thb tn cng bi khng nguyn ngay lp tc n to ra mt s lng khng th bm ngay vo khng nguyn to nn phc hp khngth- khng nguyn. Kt qu l to ra mt m tb mt hot tnh, c s kt ta hoc l t bo b cht.+ p ng min dch qua trung gian t bo:T bo T sau khi b kch thch bi khng nguyn, chng pht trin thnh cc dng khc nhau:- T bo T c: tiu dit cc tb l hoc cc tb ch b ly nhim bi virus.- T bo h tr T v t bo trn p T: cc tb ny hoc gip hoc cn tr cc hot ng ca cc tb T khc v cc tb B.Tb T sn sinhra lymphokine l nhn t ha tan, c vai tr tng cng tc dng hy dit ca cc t bo bch cu khc nh nh i thc bo, t bosao.Cu 34: Trnh by kin thc di truyn ca anh v khng th?- Khng th l cc phn t protein thuc vo lp protein c gi l protein khng th. Phn t protein khng th c bn bao gm bnchui axit amin: hai chui nh ging nhau( L) v hai chui nng ging nhau(H), cc chui ny ni vi nhau bi cu disulphide.- Mi mt chui bao gm 2 vng l vng thay i(V) v vng c nh(C): vng thay i l vng c s khc nhau cc khng thkhc nhau, vng c nh thng l ging nhau phn ln cc khng th khc nhau.- C bn cht l mt polypeptide do vy khng th l sn phm ca gen. Thc t nghin cu cho thy chui nh v chui nng cto ra t cc cm gen khc nhau. i vi chui nng c mt cm gen quy nh, i vi chui nh c hai cm gen( k v , ch mttrong hai cm gen ny c hot ha mt t bo c th no ). Tt c ba cm gen l rt ging nhau nhng chng cc nhim scth khc nhau. Tuy nhin, chng c th thay i do c s nhn on hay chuyn on.- Ngay sau khi c th c thm quyn min dch, tc l c kh nng to ra khng th, trc khi phi i u vi bt c khng nguynno, n sn xut ra nhiu hn mt t khng th khc nhau. Mi mt khng th khc nhau c to ra bng cc dng lymphocyte Bkhc nhau. C ngha l mt dng ring bit ch to ra mt loi khng th ring bit.Cu 35: Trnh by v khng nguyn t bo hng cu, bnh hy hoi hng cu ng vt s sinh?*) Khng nguyn t bo hng cu- Khng nguyn tb hng cu nm trn b mt tb hng cu.- Phn ln cc khng nguyn c bn cht l glycoprotein, khc nhau bi chui phn t ng bm vo chui polypeptide.- Khng nguyn tb hng cu c di truyn nh l sn phm ca gen.- Tt c cc khng nguyn pht sinh t cc alen ca 1 locus trong h thng nhm mu.- C nhiu h thng nhm mu khc nhau, mi 1 h thng nhm mu ph hp vi 1 locus khc nhau, c mt s lng ln cc alenc xc nh cc h thng nhm mu khc nhau.V d: ngi c nhm mu: A, B, O ngoi ra cn c nhm mu ph Rh.- ng vt bnh thng ko mang khng th tng ng vi khng nguyn tb hng cu nn c th truyn mu V c th tin hnhhon ton an ton vi bt k loi mu no m ko cn phn loi trc khi truyn mu.- Vic ny gy nn hin tng mn cm cho c th nhn v cho cc tb hng cu ca th h tip theo.- Nn trc khi truyn mu th cn phi phn loi chnh xc cc nhm mu phi ph hp v m tnh i vi khng nguyn tb hng cuc th nhn.- Nhng khng nguyn quan trng nht v mt lm sng l A ch; B mo; Aa v Qa nga; A,F v 1 s khng nguyn B b.- Nu c th cho cn c phn loi nhm mu ta s dng php th cho n gin: dng 1 git huyt thanh ca c th nhn trn vimt git dung dch cha hng cu ca c th cho, nu c s ngng kt th ko nn truyn mu gia hai c th. Nu nh ko xy rangng kt th vn phi cn thn trong qu trnh truyn mu v ko c phn ng ngng kt cng cha m bo rng vic truynmu s ko xy ra phn ng g.*) Bnh hy hoi hng cu:- Hin tng nga con sinh ra c biu hin ht sc hon ho lc mi sinh nhng sau tr nn yu t v chm chp ch trong vng24h sau khi sinh, xut hin hin tng thiu mu c tnh, vng da, hng cu b hy hoi, nhp tim v tun hon cao. Nga con thngcht trong vi ngy sau .+ S thng mu gia nga v bo thai sy ra trong qu trnh mang thai hoc ti thi im khi sinh n, c s gii phng tb mu t phithai sang h thng tun hon ca c th nga m.+ Ta nghin cu khng nguyn Aa ca h thng nhm mu . Phi thai k tha gen Aa t cha nn b v phi thai u dng tnh vikhng nguyn Aa(Aa+).+ Trng hp nga m ko mang khng nguyn Aa, nga m m tnh vi khng nguyn Aa(Aa-). Do khi tb ca phi thai i sang cth m, c th m nhn ra khng nguyn Aa l khng nguyn l nn c th m sn sinh ra khng th khng li khng nguyn Aa tronghuyt tng. Cc khng th khng khng nguyn Aa c di chuyn cng vi tt c cc khng th khc vo sa non( sa u) canga m, nga s sinh s nhn c khng th khi b sa u.+ Nguyn nhn ca hi chng NI: trong nhng gi u tin khi mi sinh, khng th khng khng nguyn Aa t sa non c hp thnguyn dng qua ni tng ca nga s sinh ri i vo h thng tun hon ca nga non, y chng nhanh chng hy dit tt c cctb mang khng nguyn Aa trn b mt dn n hy hoi cc tb hng cu.



- Hin tng ny ch xy ra vi nhm mu A v Q nga, nhm mu A xy ra nghim trng hn. Ngi ta cng pht hin loi lacng mang khng nguyn hng cu m ko c nga. Tt c cc phi thai to ra do giao phi gia la v nga sinh ra con la c himha NI. NI li rt him xy ra ln u tin vi con nga ci u tin v p ng min dch ln u thng l rt chm nn nga mcn cha b mn cm.*) Bin php:- Loi b huyt tng trong mu ca m s dng truyn cho con bng dung dch nc mui tit trng.- Ko cho nga non tip nhn sa t m trong vng 24 n 36h u sau khi sinh.- Phn loi mu cc con ci sau kim tra cc con nga ci c cha m tnh i vi khng nguyn Aa giai on 4 tun trc khisinh v khng nguyn ny l nguyn nhn trn 80% tt c cc trng hp NI nga.- lm lch pha vacxin nga trn c s nhm mu.CU 36: Trnh by v phc h ph hp t chc ch yu MHC?- Vic cy m, ghp c quan v cy da thng loi thi, nhng kh nng trn b gim khi hai c th l h hng thn thit.- Loi thi l kt qu phn ng min dch c quyt nh bi khng nguyn c mt trn b mt tb.- Mt nhm locus lin kt cht ch vi nhau c vai tr quan trng trong hin tng loi thi m ghp, cc locus ny l phc h phhp t chc ch yu( MHC).- Tt c cc loi V u c MHC ring ca chng.- V c h thng MHC bao gm xp x 3500kb gm rt nhiu gen.- MHC phn lm 3 vng:+ Vng I: cha mt vi gen, mi gen m ha cho 1 polypeptide, phn t polypeptide ny phi hp vi 1 phn t polypeptide khc l- microglobulin( m ha bi 1 locus khc trn NST khc) to nn phn t histoglobuline nhm I. Xem xt 3 gen A, B, C.+ Vng II: Hai chui v phi hp vi nhau to nn phn t histoglobuline nhm II, phn b cc tb lymphocyte B, i thc bov cc tb ui gai. Cha cc gen c sn phm polypeptide s l cc khng nguyn l nh TAP. DPA, DQA, DRA,(DN) m ha cho ;DPB, DQB, DRB,(DO) m ha cho ; vng DM m ha cho chui v .+ Vng III: cha hn hp cc gen c nhiu chc nng ch c mt s trong chng l lin quan n p ng min dch. Cc gen C2,C4A, C4B m ha cho polypeptide l thnh phn ca mt lot cc nhn t( mt b cc phn t hnh thnh nn mt t hp khuch icc hot ng ca enzyme, t hnh thnh nn cc v tr nt trn tb v cc tb cht).- Ta c cc trng hp:+ Hai c th c b MHC ging ht nhau cy ghp thnh cng l 100%+ Ch c mt kiu n bi ging nhau t l thnh cng 50%+ Ko c kiu n bi no ging nhau th t l thnh cng l 0%.- MHC c vai tr chnh trong tng hp m.- MHC cn p ng min dch vi mm bnh v k sinh trng. Bng cch to kh nng tb T nhn dng cc cht l. Histoglobulintrnh din cho tb T mt mu nh peptide ca mm bnh hay k sinh trng. Mnh ny c gi trong mt ci khe l vng bm peptide.Tb T nhn ra c peptide l ch khi peptide c trnh din bi histoglobulin. Hin tng hn ch MHC. Khi chng nhn ra peptidel cht l tb T s hot ha 1 trong hai h thng min dch : h thng p ng min dch trung gian t bo, h thng p ng min dchth.CHNG VI :Cu 37: Khi nim qun th, cc dng qun th ? Khi nim v tn s gen v tn s kiu gen ? Cho v d minh ha ?- Qun th l mt tp hp cc c th ca mt loi nht nh, tn ti trong mt thi gian tng i di( c nhiu th h), sng trn 1lnh th nht nh trong thc s din ra giao phi t do, v tch ring vi cc qun th ln cn mc cch li t nhiu.- Cc dng qun th : theo phng thc sinh sn ta c :+ Qun th giao phi ngu nhin : cc c th t do giao phi vi nhau, thng gp V.+ Qun th t phi : sinh vt lng tnh, khi giao t c v giao t ci ca cng 1 c th phi hp vi nhau hnh thnh hp t.TV gp thc vt t th phn, V gp l giao phi cn huyt.+ Qun th v phi : cc c th sinh sn theo phng thc sinh sn v tnh.- Tn s gen : T l ca mi mt alen trong ton b tng s cc alen ti 1 locus ca qun th.- Tn s kiu gen : t l ca cc c th mang kiu gen trong tng s cc c th mang cc kiu gen khc nhau ca qun th.V d : ly mu mu t mt n cu gm 175 con sau in di xc nh kiu hemoglobine cho mi con cu th c kt qu : 91 cth c kiu gen AA, 28 AB, 56 BB.Tn s kiu gen:AA= 91/175 = 0,52 ; AB= 28/175 = 0,16 ; BB= 56/175 = 0,32 ; tn s kiu gen = 0,52+ 0,16+ 0,32= 1.Ta thy qun th 175 con cu ly mu mu c tng s 2 alen ti locus cha gen quy nh cu trc protein ca hemoglobuline l alenA v alen B. Cc alen kiu gen AA l A v alen kiu gen AB l A t ta tnh c.Gen A= 0,52+ 1/2(0,16) = 0,6 ; Gen B= 0,32+1/2(0,16) = 0,4 ; tn s gen = 0,6+ 0,4 = 1.Cu 38: Khi nim v tn s gen, tn s kiu gen v mi quan h gia chng ? Cho v d minh ha ?- Tn s gen : T l ca mi mt alen trong ton b tng s cc alen ti 1 locus ca qun th.- Tn s kiu gen : t l ca cc c th mang kiu gen trong tng s cc c th mang cc kiu gen khc nhau ca qun th.- Mi quan h gia chng : Tn s gen ca mt alen chnh bng tng s gia tn s kiu gen ng hp t v alen cng vi 1/2 tns kiu gen d hp t c cha alen .- V d :+ ta xt locus cha gen quy nh mu lng b Shorthorn, do 2 alen quy nh l R v r. Ta c 3 kiu gen tng ng vi ba kiu hnhm ta phn bit c : RR c mu lng , Rr c mu lng lang trng , rr c mu lng trng.



+ Trong qun th ngi ta m c s c th c kiu gen RR l N1, s c th c kiu gen Rr l N2, s c th c kiu gen rr l N3.Tng s c th l T= N1+N2+N3

Kiu gen RR Rr RrTn s kiu gen N1/T N2/T N3/T

+ Mi c th b ti locus quy nh mu lng u mang hai alen nn tng s alen ca qun th l : 2T.Kiu gen RR rr

S lng alen 2N1+ 2 N2/2 2N3+ 2 N2/2+ gi p l tn s gen R ca qun th ta c : p= ( 2N1+ 2 N2/2)/ 2T = N1/T + N2/ 2T+ gi q l tn s gen r ca qun th ta c : q= ( 2N3 + 2 N2/2)/ 2T = N3/T + N2/ 2TCu 39 : Pht biu v chng minh nh lut Hardy- Weinberg ?- nh lut : Trong qun th giao phi ngu nhin c kch thc ln, ko c chn lc, t bin, di nhp c v cc qu trnh di truynt ng th tn s gen v tn s kiu gen ko thay i qua cc th h.- Chng minh nh lut :Xem xt 1 qun th ti mt locus c hai alen A v B, vi tn s gen tng ng l : p v q. Gi tn s kiu gen ca AA : P ; AB : H ;BB : Q. 0



O OO r2 231 0,462AB AB 2pq 17 0,034Tng cng 500 1,000

- tn s gen O l : r r 2 = 462,0 = 0,6797- tn s nhm mu B v O l: q2 + 2pq + r2 = ( q + r)2 = 0,106 + 0,462 = 0,568 nn q+r = 568,0 =0,7537 nn q= 0,7537- 0,6797 =0,074- Tn s nhm mu A v O ta tnh c p= 0,2477Cui cng:

Alen A: p= 0,2477Alen B: q= 0,0740Alen O: r= 0,6797Tng: = 1.0014

- Trong qun th c s lng alen ln hn 2 th tn s gen, tn s kiu gen vn tun theo ng nh lut Hardy- Weinberg .Cu 42: Trnh by nh hng ca chn lc lm gim tn s gen tri trong qun th, tc ng ca hnh thnh qun th mi ti tn sgen trong qun th?- Chn lc tc ng ln kiu hnh, chn lc la chn nhng kiu hnh c li v loi b nhng kiu hnh bt li, do s c kiu hnhny ng gp nhiu i con cho th h sau chng lm thay i tn s gen v tn s kiu gen trong qun th.- Chn lc c th tc ng bt c giai on no trong vng i ca mt qun th: t lc th thai, pht trin phi cho n khi th hsau c kh nng phi ging. Chn lc tc ng vo kh nng sng hoc sinh sn gi chung l kh nng thch ng.- V d: Xem xt qun th ch Labrador ti locus cha gen quy nh mu lng. Locus ny c 2 alen: alen E quy nh mu en tri sovi alen e mu vng. Qun th c 64% c th ng hp t vi alen ln(ee) quy nh mu lng vng, tng ng c tn s gen l 0,8,vi gi s l c t l Hardy- Weinberg trong qun th th E c tn s l 0,2.- Ngi lm cng tc ging quyt nh ch c ch c v ci c mu lng vng c gi li lm ging. Quyt nh ny dn ti ch sc chn lc hon ton loi mu lng en ra khi qun th. Mu lng en do gen tri E quy nh, tt c cc kiu gen c cha alen Es b loi b, loi ton b gen tri v tng ng vi vic chn u tin cho gen ln.- Do chn lc nn ngi ta ch ghp i giao phi gia cc c th c mu lng vng vi nhau( ee X ee) v cc th h tip sau ch clng mu vng(ee). Nh vy, tn s gen E thay i t 0,2 thnh 0, v tn s gen ln t 0,8 thnh 1.- Chn lc loi b kiu gen EE v Ee vi mt t l l s. Trc khi chn lc, tn s ca 3 kiu gen( EE, Ee, ee) trong qun th l:p2,2pq,q2 th sau khi chn lc, cc kiu gen EE v Ee s b gim i vi tn s tng ng l: p2s,2pqs. Tn s kiu gen ee vn c ginguyn q2 .- Tn s kiu gen EE v Ee sau khi chn lc s c tn s tng ng l: p2 p2s, 2pq 2pqs tng ng l: p2(1-s), 2pq(1-s)- Khi tng tn s ca ba kiu gen ny l: p2 p2 s + 2pq 2pqs + q2 = 1- ps(p+2q)= 1- ps(p+2(1-p))= 1-ps(p+2-2p)= 1-ps(2-p)- Tn s sau khi chn lc l: 1-ps(2-p), c gi tr nh hn 1. Tn s kiu gen sau khi chn lc l:+ p tn s gen E sau khi chn lc: p= tn s ca kiu gen EE + 1/2 tn s ca kiu gen Ee.+ S thay i v tn s gen l: p= -sp( 1- p2)/(1-sp(2-p)) du (-) c ngha l s thay i v tn s gen E l b gim i, ko phi l tngln.- Nu s chn lc hon ton i vi gen tri E, trong trng hp ny s=1 v p = -p v p = 0, gen E b loi b khi qun th ch saumt th h chn lc.*) Hnh thnh qun th mi ti tn s gen trong qun th:- Lm cho tn s gen trong qun th b thay iCu 43: Trnh by nh hng ca chn lc lm gim tn s gen ln trong qun th?- Chn lc hon ton loi b gen ln ko hiu qu ngay nh chn lc gen tri.- cc gen ln ngay lp tc ko th b loi ra khi qun th. V chn lc ko th pht hin ton b tt c cc gen ln do n cn tn titrong th d hp.- mt locus c 2 alen, E tri so vi e. Tn s E l p, e l q. Tng ng vi cc kiu gen EE, Ee, ee ta c tn s kiu gen l p2,2pq,q2.Nu chn lc lm gim tn s gen ln vi t l s, lm cho tn s kiu gen ee b gim i 1 t l l s. Sau khi chn lc tn s kiu gen ees gim i 1 t l l q2s, cn li vn gi nguyn. Tn s sau khi chn lc l: p2, 2pq, q2- q2s- Khi tng tn s ca 3 kiu gen ny l: p2+ 2pq+ q2- q2s = 1- q2s- tn s gen ln sau khi chn lc l q c c tnh: q=(q2- q2s )/(1- q2s) + 1/2 ( 2pq/ 1- q2s)- S thay i v tn s gen do chn lc: q = q- q = - sq2 ( 1-q)/ (1- q2s). Du l gim v tn s vi gen ln. Do s,q nh nn (1-sq2) xp x 1. nn q = - sq2 ( 1-q). Chn lc loi b hon ton gen ln th s=1. V 1- q2 = (1-q)(1+q) v q=q/(1+q) v q = - q2 (1+q).- Biu din tn s gen sau t th h chn lc( qt) so vi tn s gen gc q0 t phng trinh q=q/(1+q) ta c: 1/ qt = 1/ q0 +t- Chn lc loi b gen ln xy ra t t v hiu qu thp- Tn s gen ln gim th t l gen ln c du trong kiu gen d hp t tng ln do y hiu qu cai khi pht hin c ht kiugen d hpCu 44: Phn bit tnh trng Cht lng v tnh trng S lng ?

so snh Tnh trng cht lng Tnh trng s lngCp gen Do mt cp gen quy nh (di truyn n Do nhiu cp gen ti cc locus khc nhau quy



gen). nh (di truyn a gen), nhiu gen cngtng tc vi nhau hnh thnh nn mtkiu hnh.

Kiu hnh C th phn tch bit c (phn lp c)mt cch r rng. C tnh gin on.

Khng th tch bit c (khng phn lpc). C tnh bin d lin tc.

Tn s kiu gen Phn b gin on To thnh th hnh chung- th phn bchun.

Mi trng t chu nh hng ca mi trng. Lin quann cht lng khng o lng c, l tnhtrng cht lng

Chu tc ng ln t mi trng. Lin quann nng sut vt nui v c th o lngc, l tnh trng s lng.

Quy lut di truyn chi phi Quy lut di truyn c bn Quy lut di truyn c bn, quy lut tng tin,di truyn trung gian

Mc nghin cu C th Qun thCu 45: Nguyn nhn no dn ti tnh trng S lng c c trng bin d lin tc v phn phi ca n l phn phi chun? Minh habng v d c th?- Do nhiu cp gen ti cc locus khc nhau quy nh (di truyn a gen), nhiu gen cng tng tc vi nhau hnh thnh nn mt kiuhnh- Chu tc ng ln t mi trng.- Hot ng a gen lm cho tnh trng s lng c tnh bin d lin tc.V d minh ha:- Tnh trng sn lng sa b Holstein Friesian. Trong qun th ny, sn lng sa trung bnh l 3.180l/con/chu k v phng sai l315.352 lt2.- c im ca phn phi chun: ng cong c tnh i xng qua ng thng ct nh ng cong, ng thng i qua nh ngcong chia ng cong thnh hai phn bng nhau v ct trc honh ti im c gi tr trung bnh ca qun th, ng vi tn s c thln nht.- Trng hp 1: Ti 1 locus c hai alen khc nhau:+ Alen A c tc dng lm tng sn lng sa ln 1 lt.+ Alen a ko lm tng sn lng sa.Gi s ko c hin tng tri nn c 3 kiu hnh vi 3 kiu gen tng ng:+ Kiu gen AA lm tng 2 lt sa.+ Kiu gen Aa lm tng 1 lt sa.+ Kiu gen aa lm tng 0 lt sa.Nu tn s ca mi alen trong n b l 0,5 th phn b tn s ca sn lng sa to ra t s sai khc locus ny i xng v baogm 3 lp kiu hnh.- Trng hp 2: Tnh trng sn lng sa b quy nh bi 2 locus. Vi locus th hai c 3 kiu gen l: BB, Bb, bb chng cng nggp vo sn lng sa l 2, 1, 0 lt.+ Vi nh hng ca 2 locus ny ta c phn b kiu hnh tng ln: gm 5 lpAABB: 4 lt; AABb: 3 lt; AaBB: 3 lt; AaBb: 2 lt; AAbb: 2 lt; aaBB: 2 lt; Aabb: 1 lt; aaBb: 1 lt; aabb: 0 lt*) Qua y s lng locus nh hng ti tnh trng, c tng ln th s lp kiu gen, kiu hnh cng tng ln v khong cch gia ccphn lp nh li ti khi n thnh bin lin tc. Ngoi ra c s tc ng ca mi trng nh hng ti s biu hin ca tnh trngchng lm gim s sai khc gia cc lp kiu hnh.- Tnh trng s lng c quyt nh bng hot ng phi hp ca nhiu alen cc locus khc nhau.Cu 46: T l phn ly kiu hnh ca tnh trng s lng nh th no? Minh ha bng v d c th?- V hnh thc, t l phn ly kiu hnh ca tnh trng s lng ko tun theo quy lut Mendel.- Khi lai cc c th vi nhau, s biu hin ca tnh trng s lng ko biu hin theo quy lut nh tnh trng cht lng, cc lp kiuhnh ko c phn ly thnh cc t l r rt nh 3:1; 9:3:3:1.- F1 c gi tr kiu hnh tng i ng nht v l gi tr trung gian gia hai gi tr trung bnh ca qun th cha v m, F2 c kiu hnhko ng nht , trung bnh ca F2 thng trng vi gi tr trung bnh ca qun th F1 nhng t l phn ko r, mc bin d F2 lnhn so F1 v th hin s phn ly tng tin.- Tnh trng dy m lng ca ln do 2 cp gen B-b v F-f quy nh. Alen B v F, mi alen ng gp 0,4 inch cho dy m lng.Alen b v f mi alen ch ng gp 0,2 inch. Gi s ko c cc hiu ng ca tng tc gen cng nh ko c tc ng ca mi trng.Th h xut pht P: BBFF X bbff

(0,8+0,8) (0,8)Th h F1: BbFf dy m lng: (0,4 X 2) + (0,2 X 2) = 1,2 inch.- Ko tnh n tng tc gen v ngoi cnh nhng thc t lun xy ra.Th h F2:

Kiu gen Tn s kiu gen dy m lngBBFF 1 1,6BbFF 2 1,4BBFf 2 1,4



BbFf 4 1,2bbFF 1 1,2BBff 1 1,2bbFf 2 1,0Bbff 2 1,0bbff 1 0,8

Mc biu hin dy m lng: 1,6 1,4 1,2 1,0 0,8Tn s c th: 1 4 6 4 1Tng s gen tri( B hoc F): 4 3 2 1 0- Nhn xt:+ Gi tr trung bnh ca F1=F2 v bng 1,2 inch+ Mc bin d F2 l ln hn F1+ T l phn li kiu hnh 1:4:6:4:1 l t l khai trin nh thc Newton (a+b)n, vi n=2; nh vy s lng lp kiu hnh tng ln theo slng cc cp alen c nh hng n tnh trng, tun theo h s tam gic Pascal.- S cp alen tng ln th s lng lp kiu hnh tng ln- Tnh trng s lng c quyt nh bi s phi hp ca cc alen nhiu locus khc nhau, hiu qu cc gen c cng gp li.- Khi s lng cc cp alen tng ln th phn b tin n phn b chun.Cu 47: Th no l s phn ly tng tin? v d?- Trong s di truyn tnh trng s lng, khi lai 2 nhm c th khc nhau v 1 tnh trng s lng no th h F2, F3,.. xut hinmt s c th c gi tr vt qua cc gi tr bin ca cc qun th b m.V d:- Nghin cu mc en trng ca mu lng th Hymalaya, mc en trng ca mu lng th c bin thin rng phn thnh 19 lpkiu hnh khc nhau: t en tuyn, loang trng en n trng tuyn. Lp 1: en tuyn, lp 2: lng en pha lng trng, lp 3: lng engim lng trng tng ln, lp 19 lng trng tuyn.- Mc en trng v mu lng quy nh bi 4 cp alen: A1a1; A2a2; A3a3; A4a4. Cc gen tri c hiu ng nh nhau n biu hin mulng en. Gen ln quy nh mu trng.- Hot ng ca cc gen th hin nh sau:P: A1A2A3A4a1a2a3a4 X a1a1a2a2a3a3 A4A4Th thuc lp 4 v lp 5 Th thuc lp 15 v 16Phn lng mu en ch yu Phn lng mu trng ch yuF1: A1a1A2a2A3a3A4a4Th thuc lp 10 mu en v trng t l bng nhauF2: A1A1A2A2A3A3A4A4 a1a1a2a2a3a3a4a4Th c mu en tuyn Th c mu trng tuyn- F2 xut hin tt c cc loi kiu hnh t phn lp 1 n phn lp 19, trong cc c th lp 1,2,3 v cc lp 17,18,19 l cc c th cs phn ly vt ngch. S phn ly F2 trong trng hp 4 cp alen theo h s tam gic Pascal.- Cc c th mang 7 hoc 8 gen tri hoc ln l cc c th phn ly vt ngch v c kiu hnh en, trng hn b m. L c trng cadi truyn tnh trng s lng v rt c ngha thc tin cng tc chn ging.- D: t giao F1 to ra F2 sau t giao to F3 t gi li cc c th c kiu gen ng hp t mong mun F2 ,F3 lm ging to racc dng, ging mi c nng sut cao hn.Cu 48: Thc o no dng nh gi s sai khc gia cc c th trong qun th? Khi nim h s di truyn? Cng thc biu th?- Thng s dng xc nh mc sai khc gia cc c th trong qun th l phng sai( Cng thc:

)1/(2)1(2 nXxxS ). Phng sai kiu hnh( VP) l bin s dng o mc sai khc ca gi tr kiu hnh ca cc convt so vi gi tr trung bnh qun th.- Nu gi tr kiu hnh c th hin bng gi tr ca s sai lch so vi gi tr trung bnh qun th th ta c:VP = VA + VD + VI + VETrong : VP: phng sai kiu hnh

VA: phng sai gi tr cy gingVD: phng sai do tnh tri gy nnVI : phng sai do tng tc gen gia cc alenVE: phng sai do s sai lch nhng nhn t ko di truyn gy nn.

- Phng sai di truyn tng s( kiu gen) do mc sai khc ca cc c th c kiu gen khc nhau, o mc cc c th sai khcnhau do cc nhn t n nh vo lc th tinh. VE o mc sai khc t khi th tinh n thi im nh nghin cu kiu hnh. Ta c:VG= VA + VD + VI- Ta cng c phng trnh sau: 1= VA/VP + VD /VP + VI/VP + VE/VP. S ng gp bt k thnh phn no cho VP l t l c n trong VP- H s di truyn: l i lng biu th phn ng gp do sai khc v di truyn trong bin d kiu hnh chung ca tnh trng s lng qun th.- Cng thc biu th:+ Theo ngha hp: h2 = VA/VP



+ Theo ngha rng: H2 = VG/VP = ( VA + VD + VI )/ VPCu 49: Khi nim v h s di truyn? Cng thc biu th? ngha v yu t nh hng ti h s di truyn?- H s di truyn: l i lng biu th phn ng gp do sai khc v di truyn trong bin d kiu hnh chung ca tnh trng s lng qun th.- Cng thc biu th:+ Theo ngha hp: h2 = VA/VP+ Theo ngha rng: H2 = VG/VP = ( VA + VD + VI )/ VP*) ngha v yu t nh hng ti h s di truyn.- ngha:+ HSDT c biu hin bng s thp phn t 0-1 hoc di dng s phn trm t 0 -100 %.+ HSDT cng ln th kh nng di truyn ca tnh trng cng cao v ngc li.+ HSDT tng i n nh i vi mt ging trong vng 5-10 th h.- Cc yu t nh hng:+ Bn cht ca cc tnh trng: C 3 loi theo cu trc di truyn:++ Tnh trng do hiu qu cng gp ca gen quy nh, l tnh trng cht lng sn phm: t l m sa, t l tht x.. h2 0,4++ Tnh trng ngoi hiu qu cng gp(A) cn c tc ng D v I nh tnh trng s lng sn phm: sn lng sa, tc tng trng,tiu tn thc n. h2 t 0,2- 0,4.++ Tnh trng hiu qu tc ng A nh m D v I l ch yu l tnh trng lin quan n kh nng sinh sn: t l p n, sc sng icon. h2 < 0,2+ Cu trc di truyn qun th:++ Qun th c cng chn lc cao, cu trc di truyn ng nht. VA/VP nh, h2 gim xung++ Qun th ko chn lc, giao phi ngu nhin, hoang d, cu trc di truyn ko ng nht. VA ln, h2 tng ln.+ Ngoi cnh:++ Ngoi cnh tng i ng nht: VE gim, h2 tng ln.++ Ngoi cnh ko ng nht: VE tng, h2 gim xung.

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