pp di truyen hoc

8/14/2019 Pp Di Truyen Hoc

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2/39

Tn s alen qun thTc gi:Chippi91a ln lc: 09:24:50 Ngy 01-02-2008

Vi mt qun th bt k vi thnh phn kiu gen:

AA ; Aa ; aa.

Tng s c th ca qun th l n.

Khi , gi f(A), f(a) ln lt l tn s alen A,a; f(AA), f(Aa), f(aa) ln lt l tn s kgen AA, Aa, aa tnh theo cng thc:

Tn s kiu gen bng t l mt kiu gen trn tng s kiu gen c th c trong qun th

Ta c:

f(A) = = + = f(AA) + f(Aa) = p(A)

Tng t, f(a) = f(aa) + f(Aa) = q(a)

V d:1 qun th cho: 0.4AA; 0.2Aa; 0.4aa. C tn s A = 0.4+1/2 x 0.2 = 0.5. tng tvi tn s ca a.

* Khi bi cho mt qun th v hi qun th c cn bng khng, th vic ca bnkhng phi l xem p+q c bng 1 hay khng, m sau khi tnh c p(A) v q(a) th bn phi xemf(AA) c bng hay khng; f(Aa) c bng 2pq hay khng v f(aa) c bnghay khng. Nu bng th qun th cn bng v ngc li.

V d:cng qun th pha trn. R rng c rt nhiu qun th c cng tn s alenA=a=0.5. C th l qun th 0.3AA, 0.4Aa; 0.3aa cng tha mn. Tuy nhin trong thc tch c 1 qun th c gi l cn bng di truyn, y l khi qun th c thnh phn kgen AA=0.25; Aa=0.5; aa=0.25.

* Trng thi cn bng di truyn ca qun th:
http://onthi.net/thanh-vien/Chippi91http://onthi.net/thanh-vien/Chippi91


3/39

- Nu 1 qun th khng cn bng th sau mt th h giao phi ngu nhin, qun th sthnh phn kiu gen: (AA) + 2pq(Aa) + (aa) = qun th cn bng.

- Nu qun th tip tc giao phi ngu nhin th cc th h k tip khng nhng tn salen khng i m tn s cc kiu gen cng c duy tr n nh. c gi l trng

thi cn bng ca qun th.- Quy lut Hacdi-Vanberg cng p dng cho gen trn NST gii tnh. Tuy nhin khc vigen trn NST thng, trng thi cn bng di truyn ca qun th khng c thit lpngay sau mt th h. V NST Y khng mang gen, ta c:

f( Y) = p(A); f( Y) = q(a)

Tn s cc kiu gen phn cc c th ci:

(AA) + 2pq(Aa) + (aa)

Cc dng bi tp lin quan:

1. Cho thnh phn kiu gen ca qun th, xc nh tn s alen, xc nh qun th c c bng hay khng.

==> Tnh theo cng thc v cch tnh pha trn.

2. Cho thnh phn kiu gen ca qun th, gi nh qun th ngu phi/t th phn. Htn s alen v thnh phn kiu gen sau n th h.

==> Ngu phi th ngay sau th h , qun th s cn bng, v duy tr sau n-1 th h.Cn nu l giao phi th t l d hp gim i 1 na sau mi th h. T l ng hp cng thm.

3. Cho 1 qun th trng thi cn bng, t l c th mang kiu hnh ln. Xc nh tn salen v thnh phn kiu gen ca qun th.

==> V cn bng nn t l aa=p.p. Vy khai cn ra ta c t l a. T lm nt biton.

Cc cng thc sinh hcTc gi: thanhtam12a1a ln lc: 14:30:35 Ngy 14-01-2008

S lng NST n mi cung cp chonguyn phn.- Nguyn liu cung cp tng ng:

( 1)2n (1)k l s tnguyn phnlin tip ca mtt bo, 2n l b NST lng bi ca loi.

- Nguyn liu cung cp to nn cc NST n c nguyn liu mi hon ton:
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4/39

( 2)2n(2)

S lng thoi t v sc c hnh thnh (hoc b ph hu) to ra cct bo con sau k tnguyn phn:

1

(3)S lng NST n mi trng cung cp cho 2k t bosinh tinh hoc sinh trng qua gim phn to ra tinh trng hoc trng:

(4)S lng thoi t v sc hnh thnh (hoc ph hu) cho 2k t bo sinh dc thc hingim phn:

(5)S tinh trng hnh thnh khi kt thcgim phnca 2k t bo sinh tinh trng:

(6)S lng trng hnh thnh khi kt thcgim phnca 2k t bo sinh trng l:

(7)S loi trng (hoc s loi tinh trng) to ra khc nhau v ngun gc NST:

(n l s cp NST)(8)

S cch sp xp NST k gia I cagim phn:C 1 cp NST c 1 cch sp xpC 2 cp NST c 2 cch sp xpC 3 cp NST c 4 cch sp xp (9)

Vy nu c n cp NST s c cch sp xp NST k gia I.S loi giao t to ra khi c trao i on.- Trng hp 1:loic n cp NST m mi cp NST c cu trc khc nhau trong c k cp NST m mi cp c trao i on ti mt im vi iu kin n>k:

S loi giao t = (10)- Trng hp 2:Loic n cp NST, c Q cp NST m mi cp c 2 trao i on khngxy ra cng lc vi n > Q:

S loi giao t = (11)- Trng hp 3:loic n cp NST, c m cp NST m mi cp c 2 trao i on khngcng lc v 2 trao i on cng lc:

S loi giao t: (12)S loi giao t thc t c to ra t mtt bosinh tinh hoc mtt bosinh trng:- T mt t bosinh tinh trng:+ Khng c trao i on: 2 loi tinh trng trong tng s 2n loi (13)+ C trao i on 1 ch trn k cp NST caloi: c 4 loi tinh trng trong tng s

loi (14)+ C trao i on 2 ch khng cng lc trn Q cp NST caloi: c 4 loi tinh trngtrong tng s (15)
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5/39

+ C trao i on 2 ch cng lc v 2 ch khng cng lc: c 4 loi tinh trng trongtng s (16)- T mt t bosinh trng: Thc t ch to ra mt loi trng trong tng s loi trng hnh thnh trong mi trng hp:

, (16)S lngt bocon n bi c to ra saugim phn.- t bosinh tinh v sinh trng, mit bo sau khi kt thcgim phnto c 4t bon bi. Vy nu c t bobc vogim phnth ng vt s to ra:

x 4t bon bi (17)- thc vt mit bo sinh ht phn, khi kt thcgim phnto ra c 4t bo n bi, mit bony tip tcnguyn phn2 ln ch to nn 3t bon bi, hnh thnhnn ht phn chn. Vy s lngt bon bi to ra t 2k t bo thnh ht phn bng:

.12 (18)i vit bosinh non cu, mi t bosau khi kt thcgim phn to ra 4t bo n

bi trong c mtt bokch thc ln li tip tcnguyn phnlin tip 3 t va

to ra 8t bocon n bi, trong c 1t botrng chn. Vy nu c t bosinhnon khi kt thc qu trnh to giao t s to c mt s lng t bon bi bng:(19)

Nhng vn cn nh v ARNTc gi: david_tk a ln lc: 22:43:08 Ngy 16-02-2008

AXIT RIBNUCLIC( ARN)

1) CU TO V CHC NNG CHUNG CA CC LOI ARN:

a)Cu to chung ca ARN :Phn t ARN c cu to a phn gm nhiu n phn lcc ribnu .Mi ribnu c cu to bi 3 thnh phn chnh l :

-ng riboz

-Axit photphoric

-1 trong 4 loi baz nitric: A ,U ,G ,X ,ngoi ra cn gp 1 s baz gi him khc nhUridin gi , Ribtimindin , Inozin ,.... , t l baz him ARN nhiu hn ADN .

* CU TRC BC 1 : phn t ARN cu to bi 1 chui poliribonuclotit ni vi nhau bi lin kt photphoieste.Cc phn t ARN thng ch l 1 chui mch n chakhong t 50 -6000 ribnu, ngoi ra mt sloi virut c ARN mch kp .

* CU TRC BC 2:nhiu phn t ARN c th un cong v gp khc thnh nhngdng c bit to nn cu trc bc 2 ( tARN ) .Ngoi ra cn c cu trc bc 3.
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6/39

b) Phn loi ARN :

- ARN di truyn : l ARN mang thng tin di truyn gp a s virus thc vt v mt sthc khun th .Dng ARN c th dng mch n hay mch kp .

- ARN khng di truyn : c tng hp t ADN ,gm 3 loi :+ARN thng tin (mARN) :c cu trc mch n kch thc khng ng nht c

tng hp t cc gen cu trc hay gen iu ha v dng lm khun tng hp prtin ,gm khong t 75 -3000 ribnu. mARN chim t 5 -10% tng s ARN cat bo.

+ ARN vn chuyn(tARN) : l phn t nh ch c khong t 73 -90 ribnu c cutrc bc 3 c 3 chiu .Mi phn t tARN ch lin kt tm thi vi 1 loi axit amin nhtnh .C trn 60 loi tARN c pht hin .tARN c i sng tng i di ( c th qunhiu th ht bo).

+ ARN riboxom(rARN): chim ti 80% tng s ARN trong t bov l thnh phnch yu cu to thnh cc riboxom ngoi ra cn tm thy cc bo quan nh ti th , lpth ....c cu to t 160-13000 ribnu.

2) SINH TNG HP ARN (SAO M ) - IU KIN XY RA SINH TNG HPARN :

a) Sinh tng hp ARN bng c ch t nhn i :

-C ch ny thng gp virus ( tc l loi ARN di truyn )Phn t ARN mi c thp theo c ch t sao da trn mch khun l phn t ARN c vi s xc tc ca enzi

ARN- replicazb) Sinh tng hp ARN nh c ch sao m :

-C ch ny xy ra loi ARN khng di truyn v dng ADN lm khun.

-Din bin c k sch gio khoa lp 11

-Nm 1977 ngi ta pht hin ra sinh vt c nhn chun s m ha trn gen khng litc m b gin on bi nhng on khng b m ha .Trn gen c 2 loi

+Exons: l phn c sao chp sang mARN+Introns :l phn khn c sao chp sang mARN

-Chnh v vy s tng hp ARN c din ra rtheo 2 bc :

+Trnh t ADN c sao chp nguyn vn sang ARN to thnh phn t ARN cha cchc nng tng hp prtin.
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7/39

+Sau cc introns trong ARN c tch ri ra v cc exons ni lin vi nhau tothnh mARN hon chnh c chc nng tng hp prtin.

c)iu kin c tng hp ARN :

-Gen khi ng khng b c ch .-C s hin din ca mt s enzim c trng nh ARN -pholimeraza hot ng

-C s hin din ca cc cation ha tr 2 gip cho enzim hot ng

-Cn c nng lng ATP

Chuyn 3: Protein_ Gii m proteinTc gi:vananhdn92a ln lc: 14:06:16 Ngy 30-08-2008

II. Protein:- L thnh phn cu trc bt buc ca t bo, c cu to t cc nguyn t: C,H,O,NS - L i phn t cu to theo nguyn tc a phn gm nhiu n phn l cc Acid amC 20 loi acid amin khc nhau. T 20 loi ny c th cu to nn v s cc protein khnhau v thnh phn, s lng, v trnh t cc acid amin, m bo tnh a dng v c ca tng loi protein.- Cu to mi n phn gm c3 thnh phn chnh: Nhm COOH, nhm NH2 v gclin kt vi cacbon trung tm (C COOH v NH2 , c 1ngt H u lk vi C - C ny gi lC alpha). S khc nhau v thnh phn cu trc ca nhm R chia 20 loi aicd amin lm nhm: Acid, Bazo, Phn cc, Khng phn cc. Cu trc 4 bc ca phn t Protein:Bc 1:Cc n phn acid amin ca protein lin kt vi nhau bng lin kt peptit loi mnc, to thnh chui polipeptit mch thng.Bc 2:Cu trc bc 2 l cu trc vng xon l xo u n hoc gp np beta, cc np v vng xon c c nh bi cc lin kt hidro gia cc acid amin gn nhau.Bc 3:Chui xon cun xp to thnh cu trc c th trong khng gian 3 chiu, to ntnh c trng cho tng loi protein bng cc lin kt isunfua, lin kt ionvander_van tng tnh bn vng ca phn t proteinBc 4:2 hay nhiu chui cun xp bc 3 lin kt vi nhau to thnh phn phn t prothon chnh, c cu hnh khng gian c trng cho tng loi protein, gip n thc hic chc nng hon chnh. III. Vai tr ca ARN trong dch m:Cc loi ARN tham gia vo qu trnh dch m l: mARN, rARN, v tARN.

- mARN: l bn phin m t m gc ca gen cha ng thng tin gii m trnh ts lng, thnh phn ca cc acid amin trong phn t protein.
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- tARN: l ARN vn chuyn c 2 u, 1 u mang b 3 i m v u cn lmang cc acid amin tng ng lm chc nng vn chuyn cc acid amin nmARN tng hp protein.

- rARN: tham gia vo thnh phn ca Riboxom, ni tng hp nn chui polipeptit.

IV. Dch m:Dch m hay cn gi l gii m c thc hin ngoi t bo cht, gip t bo tng hnn cc loi protein khc nhau tham gia vo chc nng v cu trc t bo.L thuyt c bn cn nm:Gm 2 giai on:

Giai on 1:Tng hp ARN chuyn thng tin di truyn t gen sang sn phm prtin (xem phn tng hp ARN) Giai on 2:Tng hp prtin t bo cht gm 4 bc c bn: (Mt s sch chia l 2giai on: khi u, ko di v kt thc)+ Bc 1:Hot ho axit amin. Cc axit amin t do c trong bo cht c hot ho nh gn vi hp cht giu nng lng aenzintriphtphat (ATP) di tc dng ca mt s

loi enzim. Sau , nh mt loi enzim c hiu khc, axit amin c hot ho li lkt vi tARN tng ng to nn phc hp axit amin tARN (aa tARN).+ Bc 2:M u chui plipeptit c s tham gia ca ribxm , b ba m uAUG(GUG sinh vt nhn s), tARN axit amin m u tin vo ribxm i m ca nkhp vi m m u trn mARN theo NTBS. Kt thc giai on m u+ Bc 3:Ko di chui plipeptit, tARN vn chuyn axit amin th nht tin voribxm i m ca n khp vi m m u ca mARN theo nguyn tc b sung. aa1 tARN ti v tr bn cnh, i m ca n khp vi m ca axit amin th nht trn mARNtheo nguyn tc b sung. Enzim xc tc to thnh lin kt peptit gia axit amin m uv axit amin th nht. Ribxm dch chuyn i mt b ba trn mARN (s chuyn v) lcho tARN m u ri khi ribxm. Tip , aa2 tARN tin vo ribxm, i m can khp vi m ca axit amin th hai trn mARN theo nguyn tc b sung.

Lin kt peptit gia aa1 v aa2 c to thnh. S chuyn v li xy ra, v c tip tnh vy cho n khi ribxm tip xc vi b ba tip gip vi b ba kt thc phn tchui polipeptit lc ny c cu trc

aaM aa1 aa2 ... aan vn cn gn vi tARN axit amin th n.+ Bc 4:Kt thc chui plipeptit, Ribxm chuyn dch sang b ba kt thc lc nyngng qu trnh dch m 2 tiu phn ca ribxm tch nhau ra tARN, axit amin cui cnc tch khi chui polipeptit. Mt enzim khc loi b axit amin m u gii phngchui plipeptit. Cn lu trn mi mARN cng lc c th c nhiu ribxm trt qua vi khong cl 51 102. Ngha l trn mi mARN c th tng hp nhiu prtin cng loi.

S tng hp prtin gp phn m bo cho prtin thc hin chc nng biu hin tntrng v cung cp nguyn liu cu to nn cc bo quan va` m nhn nhiu chc nngkhc nhau. Nhng im cn lu :

- Dch m bt u khitARN c bit cho khi s gn vi n v nh caroboxom, phc hp s bm vo cc trnh t nhn bit c bit ca roboxom 5 ca mARN pha trc on m ho cho protein. Nh anticodon (b 3


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m) ca tARN-methionine kh s bt cp vi codon(b 3 m ho) xut pht AUtrn mARN, im P (P-site). Sau cc n v ln v nh gn vo nhau tothnh roboxom nguyn vn.

- bc kt thc, m kt thc khng c anticodon. Thay vo ccnhn tphng thch RFlm kt thc qu trnh. Mch polipeptit c NH2- v COOH

hon chnh s thot ra ngoi nh nhn t phng thch . Hnh nh qu trnh dch m:


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Qu trnh dch m.

sinh vt nhn thc, sau khi mARN c tng hp, hon thin, n s ri khi nhn, rngoi t bo cht, lm khun mu cho qu trnh dch m.

sinh vt nhn s, v khng c mng nhn, nn qu trnh phin m v dch m xy ragn nh ng thi.

Trong qu trnh dch m, mARN lin kt vi riboxom. Qu trnh dch m c thc hintheo 3 bc:

Hot ho a.a

Di tc dng ca enzim, v s dng nng lng, 1 phn t a.a s lin kt vi 1 phn ttARN ti v tr xc nh, to thnh phc h aa tARN.

Ta coi rng mi loi tARN ch lin kt vi 1 loi a.a; nhng mi loi a.a c th lin kvi nhiu hn 1 loi tARN (tnh cht tng t vi m b ba)

Dch m v hnh thnh chui polipeptit

Tiu phn b ca riboxom lin kt vi mARN, sau phn t tARN mang a.a m u(Met nhn thc, f-Met nhn s) n. B ba i m trn phn t tARN s lin kt thnguyn tc b sung vi b ba m ho trn phn t mARN. Sau , tiu phn ln cariboxom s lin kt, to thnh phc h mARN-riboxom, bt u qu trnh dch m.

Qu trnh ny cn c s tham gia ca cc yu t khc (If-I, If-II)


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tARN mang a.a th nht ti v tr A (tARN mang Met v tr P c sn), trong b bai m ca n lin kt b sung vi b ba m ho tip theo (sau v tr m u) trn mAR

Enzim xc tc hnh thnh lin kt peptit gia a.a m u v a.a th nht.

Tip , riboxom dch chuyn 1 nc trn mARN, khin cc tARN dch chuyn 1 v tr:+ tARN mang a.a m u -> v tr E. Lin kt gia tARN v a.a ca n b ph v, tARNri khi riboxom.

+ tARN mang a.a th nht -> v tr P.

+ 1 tARN khc, mang a.a th 2 vo lin kt vi b ba m ho k tip trn mARN.

C nh th, lin kt peptit c hnh thnh gia cc a.a theo th t nht nh.

Qu trnh tip tc cho ti khi gp b ba kt thc th dng li.Cc tiu phn riboxom tch nhau v ri khi mARN, gii phng chui polipeptit mic tng hp. Axit amin m u ri khi chui. Chui polipeptit tip tc c honthin v to thnh phn t protein hon chnh.

Poliriboxom:

Trn mi phn t mARN thng c 1 s riboxom cng hot ng, ti cc v tr khcnhau, ln lt tng hp nn cc chui polipeptit ging nhau. Nh , trong 1 khong thgian ngn, 1 lng ln protein c th c hnh thnh, p ng nhu cu ca t bo.

Cc riboxom, tARN c ti s dng nhiu ln, dng tng hp nn mi loi proteintrong c th. Cn cc mARN sau khi s dng thng s b phn hu. i sng ca 1mARN cng l 1 c ch iu ho hot ng gen.

I. M di truyn

1. Gii thiuTrnh t cc Nu trn gen, tng ng vi trnh t cc ribNu trn mARN quy nh trnh tcc a.a trong chui polipeptit theo 1 quy tc nht nh, c gi l m di truyn. Bng lthuyt v thc nghim, ngi ta chng minh c rng c 3 Nucleotit trn gen, tng l 3 riboNucleotit trn mARN quy nh 1 a.a; ta gi m di truyn l m b ba.


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2.c im ca m di truyn:

M di truyn l m b ba, ngha l c 3 Nu k tip m ho cho 1 a.a. M di truyn cc t 1 im xc nh v lin tc (khng chng gi ln nhau)

M di truyn c tnh c hiu, tc l 1 b ba ch m ho cho 1 a.aM di truyn c tnh thoi ho (d tha) ngha l c nhiu b ba khc nhau c th cngm ho cho 1 a.a.

M di truyn c tnh ph bin, tr 1 vi ngoi l, hu ht cc loi u dng chung 1 bm di truyn.

Trong 64 b ba, c 3 b ba khng m ho a.a: UAA, UAG, UGA - b ba kt thc. B bam u l AUG, quy nh axit amin metionin (Met) sinh vt nhn thc hoc foominmetionin (f-Met) sinh vt nhn s.

Chuyn 7: NST gii tnh - gen trn NST gii tnh -gen TB cht

Tc gi:Chippi91a ln lc: 17:42:00 Ngy 20-11-2008A. NST gii tnhTrong t bo, bn cnh cc NST thng tn ti thnh tng cp tng ng, ging nhauc 2 gii cn c 1 loi NST khc nhau 2 gii, c vai tr quan trng trong vic xc nh

gii tnh ca loi. Ngi ta gi y l NST gii tnh.B NST gii tnh cc loi khng ging nhau.

Nhm loi sinh vt Giici Gii c

Ngi, th, rui gim, cy gai, cy chua me XX XYChim, bm, b st, lng c, a s cc loi c,cy du ty XY XX

B xt, chu chu, rp XX XOB nhy XO XX

Thng thng ta xt NST gii tnh gm 2 chic X, Y. Gia 2 chic ny c vng NSTtng ng v khng tng ng. Vng tng ng gip chng tip hp vi nhau trongim phn.

Do vai tr quan trng ca mnh trong vic xc nh gii tnh, bi ton lin quan ti gentrn NST gii tnh l 1 dng bi ton hay gp nhiu k thi.

B. Gen trn NST gii tnh.
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1. Tng quan chung v gen trn NST gii tnh:

NST gii tnh cng cha gen nh cc NST khc, trong c nhng gen lin quan haykhng lin quan ti vic quy nh gii tnh.

Mt khc, gen c th nm trn vng tng ng gia 2 NST X v Y; nm trn vngkhng tng ng ca X hoc ca Y. Cc gen trn NST gii tnh vn tun theo quy lu phn ly, phn ly c lp, lin kt v hon v gen, tng tc gen... nh cc gen bnhthng.

V nguyn tc, xc nh 1 gen c nm trn NST gii tnh hay khng, ta s dng phplai thun nghch. Nu kt qu php lai thun v nghch nh nhau -> gen nm trn NSTthng; nu kt qu khc nhau -> c lin quan ti gii tnh.

2. Cch nhn dng 1 gen nm trn NST gii tnh:

Thng thng, khi bi ton cho s phn ly i con khc nhau 2 gii th ta c th ktlun gen nm trn NST gii tnh. Phn bit vi bi ton gen trong TB cht l kt qu con khc nhau ph thuc vo vai tr ca b m.

3. Cc bi ton c bn thng gp i vi tnh trng do 1

a. Gen nm trn vng khng tng ng ca NST Y.

c im: di truyn thng, tc l b XY truyn trc tip cho con trai XY. Mt vi tnhtrng ngi di truyn theo quy lut ny l dnh ngn tay th 2 v 3; mc lng vnhtai...

VD: B b bnh, sinh ra con trai tt c b bnh, con gi ko ai b bnh -> gen trn Y quynh.

b. Gen nm trn vng khng tng ng ca X

Chuyn 4: Bin d di truyn v c ch bin d: tbin gen

Tc gi:vananhdn92a ln lc: 17:40:23 Ngy 10-10-2008

Bin d v t bin (Thng tin b sung sch gio khoa) I. t bin gen: 1. Nhng kin thc cn nm:

a, nh ngha: t bin gen l nhng bin i nh trong cu trc ca gen thnglin quan ti mt hay mt s cp nucleotit. (t bn xy ra 1 cp nu gi chung l bin im).

b, Cc dng t bin gen:
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- Thay th mt cp nucleotit:Gen:ATGXATGX t bin ATGAATGXTAXGTAXG ------------------> TAXTTAXG

- Mt mt cp nucleotit:Gen:ATGXATGX t bin ATG _ ATGXTAXGTAXG ---------------- TAX _ TAXG - Thm mt cp nucleotit:Gen:ATGXATGX t bin ATGXAATGXTAXGTAXG ----------------- TAXGTTAXG

c, Nguyn nhn v c ch pht sinh t bin gen:- Nguyn nhn:

+ Do cc base dng him (dng h bin) kt cp sai trong nhn i DNA.+ Do DNA b tc ng bi cc tc nhn vt l, ho hc, sinh hc ca mt trnglm thay i cu trc ca n (nh cc loi tia phng x, tia t ngoi, cc ho cht gy bin hoc do mt s loi virut gy ri lon trong qu trnh nhn i DNA...)- C ch pht sinh t bin gen:Mi baz tn ti 2 dng cu trc c gi l tautomer. V d, adenin bnh thng manhm NH2 cung cp nguyn t hidro cho s bt cp b sung vi dng keto (C = O) catimin. Khi c bin i tautomer, adenin chuyn sang cu trc him l dng imino NH snt cp b sung vi xitozin. Timin c th chuyn sang dng enol (COH) ko cso trongDNA bnh thng v bt cp vi guanin. Kh nng bt cp sai ca baz vi tautomer kng c Watson v Crick nu ln khi xy dng m hnh chui xon kp.

S bt cp sai c th l cc t bin ng chuyn, trong purine thay bng purine khv pirimidine thay bng pirimidin khc.


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Mc d cc ADN polimerraza III vi hot tnh sa sai c kh nng nhn bit nhng ch bt cp sai v ct b, lm gim ng k cc sai hng nhng vn ko ht.

Cc sai hng trn c th dn n hai kiu bin i: ng chuyn hay o chuyn.

Cc bin i trn, ngoi vic thay th cc nucleotit trn mch ADN cn c th lm thmhay mt cc nucleotit gy n cc t bin nh hwowngr n kh nng tng hp protein.(Thng tin t Di Truyn Hc ca Phm Thnh H)

- nh hng ca t bin gen n sinh tng hp Protein:a, t bin lch khung:2 kiu t bin c hiu qu nng l thm base v mt base. Cc bin i n

thng lm enzym mt hot tnh. S thm hay mt mt cp base gy nn s dch m lkhung. T im bin i v sau, t b 3 b sai s ko di lin tc n cui mch polypeptit. S tng hp protein c th b kt thc sm nu s lch khung dn n codokt thc. b, t bin thay th:

Nu l t bin sai ngha th s thay th cp nu ny thnh cp nu khc s dn s thay th acid amin ny bng acid amin khc. Nu l t bin v ngha th s thay thcp nu khng nh hng n acid amin m codon m ho.


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Hnh nh v t bin sai ngha Ngoi cc sai hng trong qu trnh sao chp DNA, phn t DNA cn chu cc saihng ngu nhin c th dn n t bin. 2 kiu sai hng thng gp l mt puhoc mt amin. t bin cng c th xy ra bng nhng ho cht nhn to, chnc cu trc gn ging vi base nito, gy bt cp sai dn n t bin.http://baigiang.bachkim.vn/=> Cc bn vo link ny tm hiu thm mt s hnhnh

Chuyn 5: NST - t bin NSTTc gi:Chippi91a ln lc: 16:35:26 Ngy 12-11-2008

A. Nhim sc th - NST

I. Hnh thi v cu trc sinh vt nhn thc, tng phn t ADN c lin kt vi cc loi protein khc nha

(ch yu l histon) to nn cu trc c gi l NST (th bt mu vi thuc nhum ki

tnh) Cc protein khc tham gia hnh thnh cu trc NST c gi chung l protein phihiston. vi khun tht eubacteria (trong chng trnh ph thng c hiu l sinh vt nh

s n thun) ADN tuy khng lin kt vi protein histon (trn) nhng c lin kt vi c protein phi histon khc. Tuy nhin, i khi ngi ta cng coi vi khun vi ADN trndng vng l 1 NST ca vi khun.
http://baigiang.bachkim.vn/http://onthi.net/thanh-vien/Chippi91http://baigiang.bachkim.vn/http://onthi.net/thanh-vien/Chippi91


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vi khun c - archaea (cng l sinh vt nhn s, nhng c nhiu c im khc bi- c tnh ring l 1 lnh gii sgk 10) ADN vi loi c lin kt vi protein histon. phn ln cc loi, NST thng tn ti thnh tng cp tng ng, ging nhau v

hnh thi, kch thc v v tr tng ng ca gen (locut gen) nhng khng ging nhau vgen. Ring NST gii tnh c th tn ti ring l, tng ng hoc khng tng ng. M

loi c b NST c trng v s lng, hnh thi v cu trc. Tuy nhins lng NSTtrong b NST khng phn nh mc tin ha ca loi.1. Cu trc hin vi ca NST

Cu trc hin vi c hiu l cu trc quan st c di knh hin vi thng thngCu trc ny c nhn r nht khi lm tiu bn NST ca t bo trong k gia ca chu kt bo. Khi NST tn ti di dng si kp vi 2 cnh l 2cromatit.

Mi NST cha 3 trnh t nucleotit c bit:+ Tm ng:v tr lin kt vi thoi phn bo (v cng l v tr c nhn i sau cng)+ Trnh t u mt:trnh t lp li c bit gip bo v NST+ Trnh t khi u ti bn:trnh t m ti ADN c bt u nhn i NST thng c cc phn bt mu m (d nhim sc l vng ng xon cht, thng vng ny gen khng c phin m) v vng bt mu nht hn (nguyn nhim sc lvng c tho xon, thng xy ra s phin m gen tng ng)2. Cu trc siu hin vi ca NSTTrnh by mc cun xon t ADN -> NST vi s h tr ca nhiu loi protein.


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nh cc tia phng x, tcnhn ha hc v cc tcnhn sinh hc nh virus cth gy ra t bin dngny. Gm 4 dng: mt

on, lp on, o on vchuyn on.1. Mt on Mt on lmgim slng gentrn NST. Mton thng gy cht vgim sc sng hoc mt cctnh trng tng ng. Do ngi ta ng dng t binmt on loi khi NSTnhng gen khng mong

mun hoc xc nh v trca gen trn NST -> lp bn gen.2. Lp on Lp on lmgia tng s

lng gentrn NST. Lp on thng khng gy hu qu nghim trng nh mton, thng tng cng hoc gim mc biu hin ca tnh trng. Lp on c vaquan trng trong tin ha. Bng cch lp on km t bin c th lm xut hin gmi trong t bo,3. o on mt on film v tip hp ca NST o ono on, nhn chung,khng lm thay i s lng gentrn NST m ch lm thayi trnh t phn b gen, do mc iu ha c th thay i -> thay i mc biuhin ca tnh trng. C th d hp t mang t bin o on nu c trao i cho ra trong vng o on -> gim phn khng bnh thng, gy bn bt th. Tuy nhinc th ng hp v t bin ny vn sinh sn bnh thng. o on cng c vai tlm tng sai khc gia cc th, ni trong loi ->cch ly hnh thnh loi mi.(hnh nh NST o on tip hp -> cch nhn bit t bin o on)4. Chuyn on C th chuyn on t NST ny sang NST khc hoc chuyn on cng NST. Do c th lm thay i hoc gi nguyn s lng gen. Tuy nhin trong chng trnhthng ch xt chuyn on gia cc NST khng tng ng.Chuyn on tng hl 1 on ca NST ny chuyn dang 1 NST khc v ngcli.Chuyn on khng tng hl trng hp 1 on ca NST hoc c 1 NST nysp nhp vo NST khc (gi ring trng hp ny l t bin Robecson - gi thuytca qu trnh hnh thnh loi ngi t tinh tinh). Chuyn on thng gim kh nnsinh sn (bn bt th), sc sng c th gim, thay i nhm lin kt gen (c th ndng trong chn ging). Chuyn on c vai tr quan trng trong qu trnh hnh thnloi mi.(hnh nh 2 NST chuyn on v tip hp -> cch nhn bit t bin chuyn on)II. t bin s lng NST
http://tulieu.bachkim.vn/document/show/doc_id/55569http://tulieu.bachkim.vn/document/show/doc_id/55569


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L nhng t bin lm thay i v s lng NST trong t bo. Gm 2 loi: d bi(lch bi) v a bi1. D bi (lch bi)

L nhng bin i lmthay i s lng ca 1 hay 1 s cp NST. Thng gp:th khng (2n -2), th mt (2n-1), th ba (2n+1), th bn (2n+2)

t bin lch bi cung cp nguyn liu cho qu trnh tin ha. Trong chn ging, th s dng t bin lch bi a NST mong mun vo c th khc. Ngoi rangi ta cn s dung lch bi xc nh v tr ca gen trn NST.2. a bi L nhng bin i lm thay i s lng ton b b NST, lm tng 1 s nguyn ln(>2) b NST n bi ca loi. C 2 dng:a. T a bi (a bi cng ngun)Gm a bi chn v a bi l. b. D a biKhi c 2 b NST ca 2 loi khc nhau cng tn ti trong 1 t bo (lai xa)a bi thng gp thc vt. ng vt, a bi lm ri lon qu trnh xc nh g

tnh -> thng khng tn ti. a bi thc vt lm tng hm lng gen, t bo cac th a bi thng c kch thc ln, sinh trng mnh, chng chu tt. Th a bthng gp nhng vng lnh.a bi chn thng c kh nng sinh sn hu tnh, a bi l thng khng gim ph bnh thng, c th dn n bt th hon ton hoc khng hon ton.

Dng ton v c s vt cht v c ch di truyn (phn 2Tc gi:Sonic3k a ln lc: 23:47:06 Ngy 02-05-2008

PHN 2 : ARN v qu trnh tng hp ARN

A.) ARN ( AXIT RIBONUCLEIC ) :

I) Cu to chung : - Phn t ARN c cu to a phn gm nhiu n phn l ccRiboNucleotit .Mi Ribonucleotit cu to bi 3 thnh phn chnh l :

+ Axit Photphoric

+ ng Riboz

+ Baz Nitric , 4 loi : Adenin(A) ; Uroxin(U) ; Xitozin(X) ;Guanin(G)

- Cu trc bc 1 : Phn t ARN cu to bi 1 chui poliribonuclotit ni vi nhau blin kt photphoieste.

- Cu trc bc 2 : Khc nhau tu tng loi ARN :
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+ ARN thng tin ( mARN ) : Dng mch thng , tn ti lin kt ho tr. Thi gian tti ngn nht.

+ ARN vn chuyn ( tARN ) : Dng mch un khc, tn ti lin kt ho tr v lin kHidro. Thi gian tn ti tng i lu.

+ ARN riboxom ( rARN ) : Mch xon ni vi nghn n phn, tn ti lin kt ho tv lin kt Hidro. Thi gian tn ti lu nht.

II) Mt s dng ton thng gp :

Nhng kin thc cn nm v t bo hc (phn II)Tc gi: david_tk a ln lc: 12:51:33 Ngy 28-02-2008

NHNG KIN THC CN NM V T BO HC

(Phn II : Nhnt bo)

4)Ccbo quanc kch thc siu hin vi:

a)Li ni cht:

-L 1 h thng ng v khng bo cc nh xp theo hng ng tm t mng nguyn siti nhn.

-Thnh ng cu to bi 1 lp mng kp lipo- prtin.

-Chia lm 2 min:

+ Mng li khng ht gn mng nguyn sinh.

+ Mng li c ht gn nhn ,mt ngoi c nhiu ribsom dnh vo.

-Chc nng :dn cc cht dinh dng t ni ny n ni khc trongt bo,lm tng cc phn ng ho sinh trn b mt ,cch lit bocht thnh nhiu vng khc nhau.

b)Ribsom:

c tng hp t nhn con ri c phng thch rat bocht bm vo mt ngoi cali ni cht kt hp vi mARN to thnh cc chui polisom.

-Cu to : l nhng bo quanhnh tri l cc nh c ng knh t 150 -400 angstron.Gm 1 ht ln v 1 ht b bnh thng th tch ri nhau ,khi lm nhim v tng hp prtinth gn lin vi nhau .
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-Chc nng: l trung tm tng hp prtin cat bo.

5)Nhnt bo:

Mit bobnh thng c 1 nhn hnh cu ,hnh bu dc hay hnh nhiu thu c ng

knh t 7-8 micromet.a)Cu to

-Mng nhn : l h thng mng kp lipo- prtinc nhng l n thng vit bocht vli ni cht .

-Dch nhn : l cht lng c chit quang hnt bo cht cha NST v t 1-2 nhn con.

-Nhn con : l 1 hoc 2 th nh khng c mng ngn cch vi dch nhn , ln thay tu theo loit bo.

Nhn con cha nhiu rARN, prtin,men .Nhn con l ni tng hp rARN v ribsomcho t bo.

-Cht nhim sc : tn ti thnh tng si mnh c ht nh d bt mu vi thuc nhum bazic .NST c cu to bi cc n v l nuclsom.

b)Chc nng:

-Nhn rt quan trng trong i sng cat bo.

-Nhn iu ho ,iu tit mi hot ng sng ca t bongoi ra nhn cn mang ADNqui nh bn cht cc phn t prtintng hp c ribsom.

-Mi thnh phn ca nhn c 1 chc nng ring ,chng gn b cht ch vi nhau lmthnh 1 th thng nht trong nhn l trung tm iu khin mi hot ng sng cat bo.

6)Nhim sc th :

sinh vt c nhn chun c s vt cht ch yu ca tnh di truyn l NST .Miloi c 1 b NST c trng th hin cu trc ,hnh thi v s lng NST.

a)Cu to:

sinh vt c nhn chun ,ADN hp vi 1 loi prtinc bn to thnh phc hpnuclptin.

-Khi u ca cu trc xon ,khong 140 cp nu qun chung quanh mt octomer gm cp phn t histon khc nhau thnh 1 n v nuclsom .
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-Cu trc xon th 2 ,chui nuclsom xon li thnh n v solenoid ng knh300angstron.

-Cu trc bc 3 to thnh si c bn ng knh 3000 angstron.

-Sau si ny xon thnh si crmatit ng knh 7000 angstron-Cc crmatit c xon ln nht k gia ca qu trnh phn boto thnh 1 NST cng knh 14000 angstron

-Crmatit cn c cc loi prtin khc khng phi l histon nh cc loi ADN-Polymeraza ,cc prtiniu ho .

b)Hnh thi NST

-Cc NST c quan st r nht k gia ca qu trnh phn bov vo thi k ny cc

NST t nhn i ,c xon ti a ,hnh thi c trng .-Tu vo v tr ca tm ng ,ngi ta phn bit thnh 3 loi NST: NST cn tm ,NSTlch tm ,NST tm mt .

c)S lng NST :

-t bosinh dng vt bosinh dc s khai: NST tn to thnh tng cp tngng ,trong mi cp cc NST c hnh dng v kch thc ging nhau .

-t bosinh dc :do c ch gim nhim khi hnh thnh nn cct bo sinh dc ch cha

1 na s NST c trng ca lai gi l b NST n bi .d)Tnh khng c trng ca NST:

-Tn ti thnh tng cp tng ng cct bosinh dng vt bosinh dc s khai.

-Gm 2 loi l NST thng v NST gii tnh .

-Trong qu trnh phn ly v t hp chu s chi phi ca cc qui lut bin d nh nhau .

e)Tnh n nh ca NST :

Nh vo cc c ch sau :

-n nh qua cct bo sinh dng trong c th .

-n nh qua cc th h ca loi .

f)Tnh khng n nh ca NST :
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24/39

-Tnh n nh ca b NST ch tng i v l do cc tc nhn l ho ca mi trng ngohoc nhng bin i sinh l ho sinh trong ni bo gy t bin:

+t bin cu trc .

+t bin s lng .g)NST thng v NST gii tnh :

-C (n-1)cp hon ton ng dng ,ging nhau 2 gii c ci khng mang gen quynh gii tnh gi l nhng cp NST thng .

-Cn 1 cp ng dng gii ny nhng khng ng dng gii kia mang gen quy nhgii tnh ca sinh vt ngoi ra cn mang 1 s gen quy nh nhng tnh trng thng .

h)Chc nng ca NST :

-L ni tch lu bo qun thng tindi truyn cp t bo .

-C kh nng ti sinh.

-Phn ly v t hp n nh qua cc th h nh c ch :nguyn phn, gim phnv thtinh.

Gii ton vi nh lut Haci -VanbecTc gi: david_tk a ln lc: 20:35:29 Ngy 14-02-2008

*CCH TNH TN S TNG I CA CC ALEN:

1) Nu bi cho bit r t l kiu gen (lc ny ta khng cn ch lqun th ccn bng hay khng)

xAA : yAa : zaa

-Tn s tng i ca alen A = x+

- Tn s tng i ca alen a = z +

* V d :choqun thvi cc t l kiu gen nh sau 40% AA : 20% Aa : 40%aa

suy ra tn s tng i ca cc alen nh sau

-Tn s tng i ca alen A=0.4 + =0.5
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25/39

-Tn s tng i ca alen a=0.4 + =0.5

2) bi cho bit t l kiu hnh ln (lc nyqun thphi cn bng mi c th giic).

Qun thcn bng ta c t l kiu gen nh sau

AA : 2(pq)Aa : aa v p + q =1

-Bit t l kiu hnh ln suy ra q

- Suy ra p=1 - q

- Vy tn s tng i ca alen A = p

tn s tng i ca alen a = q* V d : qun thcn bng c tt c 400 cy trong cy qu chua l 100 cy .Bit

tnh trng qu chua l ln so vi tnh trng qu ngt hy tm tn s tng i ca mialen.

A : quy nh tnh trng qu ngt

a : chua

Cy qu chua c kiu gen ng hp ln aa chim 25% =0.25

Suy ra tn s tng i ca alen a=0.5

tn s tng i ca alen A=1-0.5=0.5

TM T L KIU GEN V T L KIU HNH CA QUN THT TH (QUA NHIU TH H T TH PHN)

i vi dng bi tp ny ta ch cn tm t l kiu gen sau s nhanh chng suy ra t lkiu hnh (da vo t l kiu gen) v vy chng ta ch tm hiu phng php tm t l kigen .

1) Nu bi ch yu cu kiu gen d hp (qun thban u ch c kiu gen dhp )-y l trng hp n gin nht.

Qun thban u c kiu gen Aa t th phn qua n th h ta c t l kiu gen d hp Aath h th n l
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26/39

T l ca AA =aa =

*V d:tm t l kiu gen Aa trongqun th qua 3 th h t th phn

Lc t l kiu gen Aa= =12.5%2)Nuqun thban u c kiu gen pht tp hn v bi yu cu tm t l ca cckiu gen sau n th h t th:

Qun thban u c t l nh sau xAA : yAa : zaa

Nu cho t th phn qua n th h ta s c t l nh sau

- T l ca Aa = y

- T l ca AA = x + (1- )

- T l ca aa = z + (1- )

*V d: trongqun thc t l cc kiu gen l 0.6 AA : 0.3 Aa : 0.1aa hy tm tl kiu gen qua 3 ln t th phn

-t l kiu gen Aa = 0.3 x =3.75%

-t l kiu gen aa = 0.1+ 0.15 x (1- )=23.125%

-t l kiu gen AA=0.6 + 0.15 x ( 1- ) =73.125%

Cc phng php lai gingTc gi:hoaculia ln lc: 18:45:21 Ngy 06-02-2008

Cc phng php lai ging

1. Lai cng dng( tthphn, giao phi cn huyt):a.Hin tng thai ha ging:

-Khi t th phn, giao phi cn huyt qua nhiu th h th sc sng i sau gim dnsinh trng, pht trin chm, bc l nhiu tnh trng xu.b.Nguyn nhn:

-Khi t th phn, giao phi cn huyt lin tc th t l d hp ngy cng gim, t l nhp ngy cng tng, cc gen ln c hi c c hi c biu hin.c.Vai tr ca lai cng dng:

- Duy tr v cng c cc c tnh tt ca ging.- To ra cc dng thun chng. Dng thun l c s cho cc php lai ging.
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27/39

- To nn cc dng ng hp t. Trong dng ng hp t, tnh trng tt hay xu u c biu hin. Nh , con ngi va kim tra c kiu hnh, va nh gi c thnh phkiu gen.2. To ging bng bin d t hp:- Cho giao phn gia hai ging khc nhau to ra bin d t hp. Sau , cho t th

phn / lai gn to dng thun chng. Dng thun chng mang c tnh ph hp sc chn lm ging.3. Lai khc dng - u th lai:a.u th lai:

- Khi lai hai dng thun chng c kiu gen khc nhau th cc con lai i F1 c sc sncao, sinh trng nhanh, pht trin tt, l u th lai.- u th lai cao nht F1, sau gim dn qua cc th h. ng ch y, u th lai biuhin r nht khi lai khc dng.b. Nguyn nhn: ( c s di truyn hc ca u th lai)

- Hin nay, tn ti 3 gi thuyt gii thch v hin tng ny:+ Gi thuyt v trng thi d hp:

P AABBDD x aabbddF1 AaBbDdtrong F1, cc gen ln c hi khng c biu hin v b gen tri ln t.

+ Gi thuyt cng gp ca cc gen tri c li:P AABBdd x aabbDDF1 AaBbDd

trong F1 c 3 gen tri c li, cn b hay m ch c 1 n 2 gen tri c li.+ Gi thuyt siu tri:

P AA x aaF1 Aa

AA < Aa > aa

trong F1 c s tng tc gia hai alen khc nhau ca cng mt l cut. Do c u thlai.4. Lai kinh t - lai ci tin :- Lai kinh t: l php lai gia hai ging thun chng khc nhau, con lai F1 c u th lai.Con lai F1 c dng lm thng phm, khng dng lm ging.- Lai ci tin: l php lai gia mt ging tt( thng l ging ngoi) lai lin tip nhiu vi con ni a phng nhm ci tin ging ni a phng.-Trong php lai ci tin, bc u to trng thi d hp nhm to u th lai. V sau, ttrng thi ng hp t nhm cng c c tnh tt ca ging.5.Lai khc th:- Khi lai hai th thun chng khc nhau, con ngi c th to ra u th lai, ng thi cth to nn ging mi.- Ch : Khi lai 2 th khc nhau c th to ra ging mi.

Lai 2 ging khc nhau ch to ra ging lai -> dng lm thng phm.6. Lai xa:- L php lai gia hai dng thuc ccloi( hoc chi, h) khc nhau.a.Nhng kh khn khi lai xa:

- thc vt, ht phn khng ny mm trn bu nhy ca hoa khc loi, hoc ny mm
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28/39

nhng kch thc ng phn khng ph hp dn n khng th th tinh.- ng vt, do cu to c quansinh snkhc nhau,tp tnh sinh snkhc nhau mchng khng giao phi vi nhau.- Kh khn ln nht l v mt di truyn nhiu mc :+ Hailoikhc nhau, c b NST khc nhau nn khng th kt hp c vi nhau trong

th tinh ,+ Hoc th tinh th hp t khng sng,+ Hoc sng th bt th.b.Bin php khc phc bt th do lai xa:

- Dng bin php a bi ha lm cho trongt bo c cha cc cp NST tng ng, tothun li cho qu trnhgim phn hnh thnh giao t nn th t bi hu th.- C th cha 2 b NST ca hailoi khc nhau c gi l th song nh bi.c.ng dng ca lai xa:

- Lai xa kt hp a bi ha to ra nhiu ging mi c gi tr: la m, khoai ty a bi chnng sut cao.7.Lait bosinh dng:

- Khi nuit boca 2loikhc nhau trong mt mi trng, ngi ta nhn thy c s kthp ngu nhin gia hai loit bo tot bolai.- Dng hoocmon sinh trng kch thcht bo lai c th pht trin thnh c th mi.- T bong vt cng c s kt hp ny nhng khng sng.- tng t l kt hp, ngi ta dng 1 trong 3 cch xc tc sau:+ Virus Xende+ Polietilen glicol+ Xung in

Dng ton v c s vt cht v c ch di truyn (Phn 1Tc gi:Sonic3k a ln lc: 22:56:47 Ngy 28-04-2008

PHN 1 : ADN V T NHN I ADN

A.) ADN :

I)Cu to chung:- Theo nguyn tc a phn gm nhiu phn t Nucleotit (Gi tt l Nu) .Mi Nucleotit gm c ng deoxyribz , Axit photphoric v mt Baz Nitric ( 1 trong loi l Adenin ; Timin ; Guanin ; Xitozin ; gi tt l A ; T ; G ; X ) . Mi mch n ADNgm 1 chui polinucletit ni vi nhau bi cc lin kt cng ha tr (hay lin kt photphoieste).

- Mi mt chui gm hai mch n .Gia 2 mch n, cc cp baz i din ni vi nhau bng cc lin kt hyro theo nguyn tt b sung : mt bazca mch ny lin kt vi mt baz ln ca mch i din. A lin kt vi T bng 2 likt hyro ,G lin kt vi X bng 3 lin kt hyr.

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29/39

1) Dng ton v s lng cc Nucleotit trong mi gen :

a) Cc cng thc cn nh :

- V trong phn t ADN ta lun c : Adenin ca mch ny lin kt vi Timin ca mch

kia, Guanin ca mch ny lin kt vi Xitozin ca mch kia , nn : ;( A;T;G;X l s lng 4 loi Nu trong phn t ADN).

- T ta c : v .

- Gi ln lt l s lng cc loi Nu trn mch th nht.

ln lt l s lng cc loi Nu trn mch th hai.

Ta c ; ; ;

=>

=>

- S lng Nucleotit trong phn t :

- S lng Nucleotit trn mi mch =

b) Cc bi tp v d:

Bi tp 1 : Mt phn t ADN c s lng Nucleotit loi Xitozin l 700 v gp i slng Nucleotit loi Timin. Tnh s cp Nucleotit trong phn t ADN ?

Tm tt bi : ;

Gii: - Tnh s Timin :

=>

- S cp Nucleotit =

Bi tp 2 : Cho phn t ADN c tt c 620 Nucleotit. S lng Adenin trn mchth nht gp 3 ln s Adenin trn mch th hai. S Xitozin trn mch th hai bng


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mt na s Xitozin trn mch th nht. Tnh s lng mi loi Nucleotit trn mimch n ca phn t ADN bit rng c 50 Guanin trn mch th nht.

Tm tt bi:

Gii: - T suy ngay ra

- M => =>

=>

- Mt khc =>

=> =>

=>

p s: ; ; ;

c) Bi tp t luyn :

Bi tp 3 : Mt gen c tt c 3400 Nucleotit. Trn mch th nht, s Adenin , Timin,Guanin ln lt l 305 ; 420 ; 700. Tnh s lng mi loi Nucleotit cn li trn mimch ca gen?

2) Dng ton v t l % cc Nucleotit :


- l t l % mi loi Nucleotit trong phn t ADN.

- l t l % ca mi loi Nucleotit trn mch th nht so vimch th nht.

- l t l % ca mi loi Nucleotit trn mch th hai so vimch th hai.


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- D thy : ; ;

- Lu : V l t l % ca Adenin trn mi mch nso vi s lng Nu

trn mi mch n ch khng phi l so vi s Nu ton phn t. Do :

;

(Nu bi h cho % Adenin ca mch th nht l 30% m khng ni r l so vi s Nmch th nht hay so vi ton phn t th bn c p dng cng thc nh trn v hiulun l so vi mch th nht i:D).

- Mt lu na : Ta lun c

b) Cc bi tp v d :

Bi tp 4 : Mt gen c 15% Adenin. Tnh t l % ca cc loi Nucleotit cn li tronggen ?

Tm tt bi: ;

Gii: - D thy

- Mt khc ta lun c : => =>

Bi tp 5 : Mt gen c tch s t l % gia 2 loi Nucleotit khng b sung l 4%. Bitrng s lng loi Adenin ln hn loi Guanin. Tm t l % tng loi Nucleotit cagen?

Tm tt bi: C th coi 2 loi khng b sung l Adenin v Guanin. =>

Gii: => ; Mt khc ta lun c

- Gii h :

- T => ;


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Bi tp 6 : Trn mch th nht ca gen c 10% Adenin v 30% Timin. Gen c540 Guanin. Tnh s Nucleotit ca gen ?

Tm tt bi: ; ; ;

Gii: - D dng suy ra lun :

=>

- M => . Kt hp vi G=540

=>

c) Bi tp t luyn :

Bi tp 7 : Trn mch th nht ca gen c cha A, T, G, X ln lt c t l l 20% :40% : 15% : 25%. Tm t l tng loi nucltit ca mch th hai v t l tng loiNucleotit ca gen ni trn ?

3) Dng ton lin quan n chiu di , khi lng , chu k xon ca gen :


- Mi cp Nucleotit c di => Chiu di gen l

- Mi Nucleotit c khi lng l 300(dv.C) => Khi lng ca gen l

- C 10 cp Nucleotit to thnh 1 vng xon => Chu k xon (s vng xon) ca gen :

b) Cc bi tp v d :

Bi tp 8 : Cho 1 gen c s Nucleotit l N. Lp biu thc lin h gia chiu di vkhi lng gen, gia khi lng v chu k xon v gia chiu di v chu k xon ca

gen.

Gii: - C => (1)

- => (2)


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- => (3)

T (1) (2) (3) => (4)

(5)

(6)

Bi tp 9 : Mt gen c 80 vng xon. Tnh chiu di v khi lng ca gen ?

Tm tt bi: ;

Gii: - p dng cng thc : =>

- Vy chiu di gen l :

- Khi lng gen :

Cch 2: Dng cng thc (5) v (6) bi tp 7 l c th ra lun. Tuy nhin nu trnh ca bn khng tt th cng khng nn nh my cng thc m ch cn tun t ginh trn l n ri :D

Bi tp 10 : Mch n th nht ca mt gen c chiu di . Hiu s gias Guanin trn gen vi 1 loi Nucleotit no bng 10% s Nucleotit ca gen. Tnhs lng tng loi Nucleotit ca gen ?

Tm tt bi: - (chiu di mch n th nhtthc cht l chiu di gen)

- Hiu s gia s Guanin vi 1 loi Nucleotit no : Ta c th hiul G-A, v hiu s gia G v X l 0 (v l) . Cn hiu s gia G v T th chnh l hiugia G v A. Vy :

Gii: - =>

=> => Gii h :


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c) Bi tp t luyn :

Bi tp 11 : Mt gen di c s Nucleotit loi Xitozin l 150.1) Tnh khi lng v s vng xon ca gen ?

2) Xc nh s lng v t l mi loi Nucleotit ?

3) Trn mch th nht ca gen c s Timin l 450 v s Guanin l 30. Tnh sNucleotit tng loi mi mch ?

4) Dng ton lin quan n cc loi lin kt ho hc trong gen :


- Lin kt ho tr l lin kt gia ng v Axit Photphoric, l lin kt ni gia cc Nucleotit vi nhau.

+ Trn 1 mch . S Nucleotit l => S lin kt ho tr trn 1 mch :

+ Tng s lin kt ho tr ni gia cc Nucleotit trong cng mt mch l :

+ Trong c phn t , tng s lin kt ho tr l :

- A lin kt vi T bng 2 lin kt hyro ,G lin kt vi X bng 3 lin kt hyr. Vy slin kt Hidro l :

b) Cc bi tp v d :

Bi tp 12 : Mt gen c 5998 lin kt ho tr v 4050 lin kt Hidro. Tnh s lngtng loi Nucleotit trn gen ?

Tm tt bi: s lin kt ho tr :

s lin kt Hidro : =>Gii: =>

- Gii h : =>

c) Bi tp t luyn :


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Bi tp 13 : S lin kt Hidro gia 2 mch n ca phn t ADN l . Phn t ADN ny c s cp Nucleotit G-X nhiu gp 2 ln s cp A-T.

1) Tnh s lng tng loi Nucleotit ca phn t ADN ?

2) Tnh khi lng , chiu di , s vng xon v s lin kt ho tr ca phn t ADN?

Bi tp 14 : Mch n th nht ca gen di v c t lAdenin:Timin:Guanin:Xitozin l 15%:30%:30%:25% .

1) Tnh t l A:T:G:X ca mch th hai ? T l tng loi Nucleotit trn gen ?

2) Tnh s lin kt Hidro v lin kt ho tr ca gen ?

-------------------------------------------------------------------------------------------------------------

B.) S T NHN I ADN ( T SAO , SAO CHP , TI BN ) :

I) L thuyt chung : - ADN c kh nng t nhn i to thnh 2 phn t ADN conging ht nhau v ging phn t m. ADN c sao chp theo nguyn tc b sung,nguyn tc bn bo ton v theo c ch na gin on (mt mch mi c tng hp tc cn mch kia c tng hp gin on.

- sinh vt nhn s E.Coli : Khi bt u sao chp, phn t ADN tch ra

to thnh hai mch n trong mt mch c u 3'-OH cn mch kia c u 5'-P.Enzim ADN polimeraza ch c th b sung Nucleotit vo nhm 3'_OH , do vy khi saochp, mt mch mi da vo mch khun c u 3'_OH th c hnh thnh lin tc.Mch th hai c hnh thnh tng on theo hng ngc li, sau cc on ny ni li vi nhau nh enzim ni. Cc on ny c gi l on Okazaki.

- sinh vt nhn chun : T bo ca sinh vt nhn chun c nhiu phnt ADN l chui xon kp gm 2 mch polinucleotit c sao chp ngc chiu nhau.S sao chp ca ADN bt u t mt im trn ADN. ADN tho xon hnh thnh ccvng sao chp. S sao chp ADN din ra nhiu vng sao chp v trn nhiu phn tADN.


1) S Nucleotit v tng loi Nucleotit c to thnh :


- Sau k t t nhn i ADN th s phn t ADN con l :


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- Tng s Nucleotit ca cc phn t ADN con :

- Tng s mi loi Nucleotit ca cc phn t ADN con : ; ;;

- S phn t ADN con m c hai mch u mi: (V trong s cc phn t ADN cotn ti 2 mch ban u).

- S lin kt Hidro hnh thnh :

- S lin kt ha tr c hnh thnh :

- Ni chung mi phn t ADN con c to ra t qu trnh t nhn i u ging phn ADN ban u , t thnh phn tng loi Nucleotit cho n khi lng , chiu di , s vxon , cc lin kt ho hc .....

b) Cc bi tp v d :

Bi tp 15 : Mt gen t sao lin tip to ra cc gen con c tng s mch n gp 16ln s mch n ban u ca gen. Hy xc nh s ln t nhn i ca gen ?

Gii: - Tng s mch n gp 16 ln s mch n ban u => Gen ny t nhn lin tip to ra 16 gen con.

- Theo cng thc : Sau k ln t nhn i th s gen con l :

=> => . Vy gen t nhn i 4 ln.

Bi tp 16 : Mt gen c 120 chu k xon v c 3100 lin kt Hidro. Gen ny t nhni to thnh 2 gen con. Tnh s lng tng loi Nucleotit sau khi gen ny t nhni.

Tm tt bi : ; ;

Gii : - S Nucleotit ca gen ban u l : =>

- Sau khi gen t nhn i , tng s Nucleotit v s lin kt Hidro c hnhthnh ln lt l : 4800 v 6200.

- Ta c h : => vi A' , T' , G' , X' lcc loi Nucleotit sau khi gen t nhn i.


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Cch 2 : Ta c th tnh s lng tng loi Nucleotit ca gen ban u trc ri t ra s lng tng loi Nucleotit sau khi gen t nhn i.

c) Bi tp t luyn :

Bi tp 17 : Mt gen di sau nhng ln t nhn i lin tip to ra mt sgen con. Trong s gen con m c hai mch n u mi l 6 . Tnh s lin kt hotr c hnh thnh ?

Bi tp 18 : Mt gen t nhn i to thnh 2 gen con hnh thnh c 3800 linkt Hidro. Trong s cc lin kt , lin kt Hidro ca cc cp G-X nhiu hn linkt ca cc cp A-T l 1000.

a) Tnh chiu di ca gen ban u ?

b) Gen ban u t nhn i lin tip 3 t. Tnh s lng tng loi Nucleotit sau ? 2) Dng ton v nguyn liu mi trng cn cung cp cho qu trnh t nhn i:


- S Nucleotit mi trng cn cung cp = S Nucleotit ca cc phn t ADN con - S Nucleotit ban u

Vy s Nucleotit mi trng ni bo cn cung cp l :

- Tng t s lng tng loi Nucleotit mi trng cn cung cp l :

- S lin kt Hidro b ph v trong qu trnh t nhn i :

b) Cc bi tp v d :

Bi tp 19 : Trn mt mch ca gen c 10% Timin v 30% adenin. Hy cho bit t ltng loi Nucleotit mi trng cung cp cho gen nhn i l bao nhiu?

Tm tt bi: ;

Gii: -Ta c :


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- M : =>

- Trong qu trnh t nhn i, t l tng loi Nucleotit mi trng cung cp bng t l tng loi Nucleotit ca gen ban u.

=> T l Adenin:Timin:Guanin:Xitozin mi trng cn cung cp :20%:20%:30%:30%

Bi tp 20 : Mt gen t nhn i 3 ln . Tng s lin kt Hidro trong cc gen con l

23712 . Gen c t l . Tnh s lng tng loi Nucleotit mi trng ni bocung cp ?

Tm tt bi: ; ; ;

Gii: - S lin kt Hidro trong gen ban u l : =>

- Ta c h : =>

=> S lng tng loi Nucleotit mi trng cung cp :

Bi tp 21 : Mt gen nhn i mt s ln s dng 5796 Nucleotit t do, trong c 1449 Guanin. Bit chiu di ca gen bng .

- Xc nh s ln t nhn i ca gen ?

- Tnh s lin kt Hidro ca gen ni trn ?

Tm tt bi: ; ; ;

Gii: - S Nucleotit ca gen : =>

- C : => =>

=> Vy gen t nhn i 2 ln.


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- T l ca Guanin cung cp so vi s Nucleotit mi trng cung cp chnh l tl ca Guanin trn gen.

=> . M

=> S guanin trong 1 gen : =>

- S lin kt Hidro :

c) Bi tp t luyn :

Bi tp 22 : Mt gen c s Nucleotit loi Adenin l 200 v chim 20% tng sNucleotit ca gen. Khi gen t sao 3 ln th s Nucleotit loi Guanin mi trng cncung cp l bao nhiu ?

Bi tp 23 : Mt gen c 15% Guanin nhn i 2 ln v nhn ca mi trng1260 Adenin.Khi lng ca gen ni trn bng bao nhiu ?

Bi tp 24 : Mt gen nhn i 3 ln v s dng ca mi trng 10500 Nucleotit,trong ring loi Adenin nhn ca mi trng 1575 . T l phn trm tng loiNucleotit ca gen l bao nhiu?

Bi tp 25 : Mt gen khi t nhn i thnh 2 gen con ly t mi trng 525Timin. Tng s Nucleotit ca 2 gen con l 3000.

a) Tm s Nucleotit mi loi cn dng cho qu trnh t nhn i ?

b) Nu tri qua 3 ln t sao th mi trng cn cung cp bao nhiu Nucleotit miloi ? Trong s gen con to thnh c bao nhiu gen con m c 2 mch u mi ?

c) S lin kt Hidro b ph v ? S lin kt ha tr hnh thnh ?

pp di truyen hoc

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