phuong phap giai bai tap di truyen hoc quan the lop 12

8/6/2019 Phuong Phap Giai Bai Tap Di Truyen Hoc Quan the Lop 12

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Trng Ph Thng Dn Tc Ni Tr Bc GiangB mn Sinh Hc*************************

Tn ti:

PHNG PHP GII BI TP DI TRUYN HCQUN TH CHO HC SINH KHI LP 12TRNG PTDT NI TR BC GIANG

Ngi thc hin

H v tn: Trn Quc Lp

Bc Giang, thng 4 nm 2008


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MC LC

PHN I: NHNG VN CHUNG1. L DO CHN TI..............................................................................

2. MC CH NGHIN CU CA TI ..............................................

3. PHM VI NGHIN CU..........................................................................

4. KHCH TH NGHIN CU V I TNG NGHIN CU...........

5. PHNG PHP NGHIN CU..............................................................

PHN II: NI DUNG NGHIN CUCHNG I: C S L LUN CA TI

CHNG II: NI DUNG NGHIN CU

.....................................................

PHN III: KT LUN - XUT1.Kt lun

2. xut


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PHN I

NHNG VN CHUNG

1. L do chn ti :Mt trong nhng mi quan tm hin nay ca gio vin vcn b qun l gio dc l nng cao cht lng gio dc vo to. y l nhim v hng u trng THPT nhmgio dc nhn cch ton din cho hc sinh.Vic dy v hc mn sinh hc tr thnh mt trong nhngnhu cu cn thit. Thi gian qua, nhn chung vic ging dymn sinh hc c nhiu ci tin nhm p ng nhim vrn luyn cc k nng vn dng vo thc tin cho hc sinhTHPT.Tuy nhin vic ging dy mn sinh hc trng PTDTNTvn cha p ng hiu qu nhng yu cu trn do nhiunguyn nhn khch quan v ch quan. Trc ht l do hnch v thi gian, ni dung chng trnh nhiu i hi giovin phi m bo truyn t y trong tng tit dy do

vy gio vin khng c nhiu thi gian cho hc sinh rnluyn, c bit l k nng lm bi tp. Ti mong mun quasng kin ca mnh cc em s yu thch mn v hc tt mnsinh hc hn.

2. Mc ch ca ti- a ra cc dng bi tp di truyn hc qun th


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- Hc sinh vn dng c cc dng bi tp vo lm bi tptrong sch bi tp

- Hc sinh hng th hc tp mn sinh hc hn

3. Khch th v i tng nghin cu- Khch th nghin cu : hc sinh khi lp 12 Trng PTDTNi tr Bc Giang- i tng nghin cu : Phng php gii bi tp di truynhc qun th cho hc sinh qua cc dng c th

4. Gii hn nghin cu ca ti:Phng php gii bi tp di truyn hc qun th cho hcsinh trng ph thng dn tc ni tr Bc giang qua ccdng c th

7. Phng php nghin cu :- Phng php c sch

+ Tm hiu ti liu v phng php gii bi tp di

truyn hc qun th+ c kt qua thc tin ging dy v lm bi tp


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PHN II

NI DUNG NGHIN CUCHNG I : C S L LUN CA TI

I. Qun th giao phi :1. nh ngha

- Qun th l mt nhm c th cung loi, tri qua nhiu thh cng chung sng trong mt mt khong khng gian

xc nh, trong cc c th giao phi t do vi nhau vc cch li mc nht nh vi nhm c th ln cncng thuc loi .

2. c trng ca qun th giao phi- Qun th l n v c s- Qun th l n v sinh sn ca loi

II. S cn bng thnh phn kiu gen trong qun th giao

phi :

1.nh lut Hacdi- Vanbec.1.1.v d: chn mt trng hp n gian l mt gen gm 2alen A v a th trong qun th c 3 kiu gen: AA; Aa; aa Gis cc kiu gen ny th h xut pht l:0.25 AA: 0,5 Aa: 0,25 aaCc c th c kiu gen AA cho ra ton loi giao t mangalen A; cc c th c kiu gen aa cho ra ton loi giao tmang alen a; cc c th c kiu gen Aa cho ra mt na giaot mang alen A v mt na giao t mang alen atrong tng s giao t sinh ra t th h xut pht t l s giaot mang alen A l

p(A) = 0,25 +2

5,0

q(a)= 0,25 +2

5,0


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Tn s tng i ca alen A v a th h xut pht la

A =

5,0 5,0 c ngha l trong cc giao t c cng nh trong ccgiao t ci s giao t mang alen A chim 50 % s gio tmang alen a chim 50%S kt hp t do gia cc loi giao t s to ra th h tiptheo c thnh phn kiu gen nh sau

p A q a

p A (0,5)2AA 0,5x0,5Aa

q a 0,5x0,5Aa (0,5)2aa

Thnh phn kiu gen th h sau l0,25 AA: 0,5 Aa : 0,25 aaTrong cc th h tip theo tn s vn khng thay i

1.2Ni dung nh lut Hacdi- vanbecTrong nhng iu kin nht nh th trong lng mt qun thgiao phi th tn s tng i ca cc alen c khuynhhng duy tr khng i t th h ny sang th h khc.

2. ngha ca nh lut hacdi-vanbec.2.1 ngha l lut

- nh lut hcdi vanbec phn nh trng thi cn bng ditruyn trong qun th- n gii thch v sao trong t nhin c nhng qun th duytr n nh qua thi gian di

2.2 ngha thc tin


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- T t l kiu hnh c th suy ra t l kiu gen v tn stng i ca cc alen v t tn s tng i ca cc alen

c th suy ra t l kiu gen, kiu hnh.3. Hn ch ca nh lut hacdi-vanbec

- trong thc t cc c th ng hp hoc d hp c sc sngv gi tr thch nghi khc nhau qu trnh t bin v qu trnhchn lc khng ngng din ra tn s ca cc alen b bin i

4. iu kin nghim ng ca nh lut hacdi-vanbec- Qun th giao phi- Tc ng ca qu trnh t bin v chn lc t nhin lkhng ng k

CHNG II : PHNG PHP GII BI TP DI TRUYN

HC QUN THI .Dng 1: Cho t l kiu gen xc nh tn s tng i cacc alen

Bi ton: Qun th ban u c thnh phn kiu gend AA + h Aa + r aa

Xc nh tn s tng i ca cc alen?Phng php gii:

Gi p l tn s ca alen A : p= d +2h

Gi q l tn s ca ale a : q = r +2

h

V d:Trong mt qun th sc ngi ta thng k thu c s liu

sau: Sc lng nu ng hp t 1050 con; sc lng nu dhp t 150 con; sc lng trng 300 con. Bit tnh trng


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mu lng do mt gen quy nh gm 2 alen v tc ng cachn lc t nhin trong qun th sc l khng ng k

Tinhs tn s tng i ca mi alen trong qun thQun th trn t trng thi cn bng cha? nu giaophi tip tc din ra trong qun th th phi sau bao nhiuth h qun th t trng thi cn bng

Bi lm:

Do lng nu trng thi d hp nn nu l tri so vi trng

Quy c gen: A nua trng- Tng s sc trong thi im thng k l1050 + 150 + 300 = 1500 conVy

+ T l sc nu ng hp c kiu gen AA =1500

1050 = 0,7

+ T l sc nu d hp c kiu gen Aa =1500

150 = 0,1

+ T l sc trng c kiu gen aa = 1500300 = 0,2Cu trc di truyn ca qun th sc ti thi im thng k l

0,7 AA : 0,1 Aa : 0,2 aa

- Gi p l tn s ca alen A : p = 0,7 +2

1,0 = 0,75

- Gi q l tn s ca alen a : q = 0.2 +2

1,0 = 0,25.

II . Dang 2: Xc nh trng thi cn bng di truyn ca

qun thBi ton: Gi s qun th ban u c thnh phn kiu gen

d AA + h Aa + r aaKhi no qun th t trng thi cn bng?

Phng phpGi p l tn s ca alen: A


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Gi q l tn s ca ale : a- Nu

p2 AA = d AA2 pq Aa = h Aaq2 aa = r aa

Th qun th t trng thi cn bngnu

p2 AA d AA2 pq Aa h Aa

q2 aa r aa

Th qun th cha t trng thi cn bng .

Ch :

D qun th t trng thi cn bng hay cha th tn stng i ca cc alen khng thay i

Nu qun th cha t trng thi cn bng th ch cn quamt th h ngu phi th qun th t trng thi cn bng ditruyn.Cu trc di truyn ca trng thi cn bng c dng : p2 AA :2 pq Aa : q2aa

V d: C cc qun th sauQun th 1: 0,64 AA : 0,32 Aa : 0,04 aaQun th 2 : 0,5 AA : 0,3 Aa : 0,2 aaCc qun th trn t trng thi cn bng di truyn cha?nu cha th khi no t trng thi cn bng v cu trc ditruyn ca n nh th no?

Bi lm:Gi p l tn s tng i ca alen A

q l tn s tng i ca alen a1. Xt qun th 1:


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q a pq Aa q2aa

Thnh phn kiu gen ca qun th : p2 AA : 2 pq Aa : q2aa

V d: Trong mt qun th la alen A quy nh mu xanh,alen a quy nh mu trngbit tn s tng i ca cc alen A l 0,8; tn s tng ica alen a l 0,2Hy xc nh thnh phn kiu gen trong qun th la nitrn.

Bi lm- Quy c A : Xanh

a: trng-Qua giao phn thnh phn kiu gen th h sau

p A q a

p A (0,8)2AA 0,8x0,2Aa

q a 0,8x0,2Aa (0,2)2aa

TPKG: 0,64 AA : 0,32 Aa: 0,04 aa

Dng 4: T t l kiu hnh xc nh t l kiu gan v tn sca cc alen

- Mt gen gm 2 alen- Tn s kiu hnh ln c kiu gen aa = x%- V qun th t trng thi cn bng di truyn nn

nghim ngp2 AA : 2 pq Aa : q2aa = 1


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v p + q =1m q2 aa = x% q= %x p = 1- %x

V d : mt qun th b c 1000 con ngi ta thy c 160con lng vng

a. Tnh tn s tng i ca mi alen trong qun thb. c lng s b lng trng thi d hp trong

qun th bit qun th t trng thi cn bng ditruyn

Bi lm

a. Tnh tn s tng i ca cc alen- b lng vng c kiu gen aa- t l b lng vng aa = 16%- V qun th t trng thi cn bng di truyn nnq2 = 16% q = 16,0 =0,4

v qun th t trng thi cn bng di truyn nnp + q = 1 p = 1- 0,4 = 0,6b. S b lng trng thi d hp

- S b lng d hp 2pq Aa = 2x0,4x0,6=0,48- S b lng d hp trong n l : 0,48 x1000 =480 con


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phuong phap giai bai tap di truyen hoc quan the lop 12

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