Cẩm nang tự ôn và luyện thi sinh học phần 2

DQt bien gen a Dot bien gen la nhffng bien doi trong cau true cua gen thffdng lien quan den mot cSp nucleotit dot bien diem nhiT: ma't, them, thay the 1 cap nuclcotil.. Neu la dot bien

ChiTcfng 2

C O C H f e B l f e N D I

I T O M T A T N O I D U N G

Ve mat di truyen ngiTdi ta chia bien di thanh hai loai la bien di khong di

truyen (thiTdng bien) va bien di di truyen (bien di to hdp, dot bien)

1 Thifcfng bie'n

a) Trong qua trinh kieu gen hinh thanh kieu hinh con chiu anh hurdng cua

moi tru'dng Hien tu'dng mot kieu gen co the phan iJng thanh nhi?ng kieu gen

khac nhau trong nhiyng moi tru'dng khac nhau duTdc goi la su" mem deo kieu hinh

(thi/dng bien) Do mem deo cua mot kieu gen di/dc xac dinh bang so' kieu hinh

CO the C O cua kieu gen d6 Sir mem deo c6 diTdc la do c6 su" tuT dieu chinh cua cd

the de thich nghi vdi su" thay doi cua moi triTdng

b) M o i kieu gen chi c6 the dieu chinh kieu hinh cua minh trong pham vi nhat

dinh goi la mufc phan iJng cua kieu gen MiJc phan iJng do kieu gen quy djnh

kieu hinh la ket qua tu"dng tac gii?a kieu gen ydi moi triTdng, moi triTdng quy dinh

kieu hinh cu the cua kieu gen trong miJc phan iJng

c) Thirdng bien khong di truyen, nhu^ng nhd no cd the c6 kha nang thich i^ng

vdi nhifng bien doi cua moi tru'dng trong mot gidi han nhat dinh Trong san xuat

ngufdi ta da van dung siT mem deo kieu hinh de tang nang suat vat nuoi, cay

trong b^ng ki thuat san xuat hdp li ThiTdng bien con c6 vai tro gian tiep cung

cap nguyen lieu cho qua trinh tie'n hoa

2 Big'n dj to h(;p ^

a) Bien di to hdp la sir to hdp lai vat cha't di truyen cua bo me qua qua trinh

sinh san hiJu tinh Chung phat sinh do cd che phan l i doc lap, to hdp tu" do cua

cdc cap NST tirdng dong (xay ra trong giam phan va thu tinh) v^ do cd che hoan

vi gen (xay ra trong qua trinh trao doi doan)

b) Dot bic'n gen la nguyen lieu sd cap, qua giao pho'i da tao ra v6 so bien di

to hdp la nguon nguyen lieu thi? cap cua qua trinh tien hoa va chon giong

3 Dot bien

Dot bien la nhffng bien doi trong vat chat di truyen (gen NST) The dot bien

la ca the mang dot bien da bieu hien tren kieu hinh cua cd the

3.1 DQt bien gen

a) Dot bien gen la nhffng bien doi trong cau true cua gen thffdng lien quan

den mot cSp nucleotit (dot bien diem) nhiT: ma't, them, thay the 1 cap nuclcotil

tao ra cdc alen mdi, lam thay doi tan so alen va thanh phan kieu gen cua quan

the Nhffng tan so dot bien doi vdi moi gen rat tha'p (tff 10"^ - lO"*) ncn toe do

thay doi raft cham

Vai tro chu yeu cua dot bien gen la tao ra nguon nguyen lieu sd cap chu yev

cho qua trinh tie'n hoa va chon giong

Pf|^ Cty TNHH MTV DWH Khang Vigt

b) Dot bie'n gen phat sinh luc A D N nhan doi va dffdc tai ban qua cd che' tff

^hSn doi cua A D N : Cac tac nhan gay dot bie'n d trong hoac ngoai cd the (tac nhSn l i , hoa, bazd dang hiem, virut,, ) hoac cac roi loan sinh l i , sinh hoa trong te

j5^o da lam bie'n doi cau true cua gen dan de'n sai lech khung doc ma di truyen,

hoac lam roi loan qua trinh tff nhan doi cua A D N dan tdi cap doi nham ( V i du:

5 B U - A), lien ket sai ( V i du: 2 Timin trong cung mot mach A D N lien ket vdi

nhau), tao ra cac dang tien dot bie'n Cac dang t i l n dot bie'n nay c6 the dffdc cac enzim sffa chffa hoac tiep tuc nhan doi theo mau lap sai, lam phat sinh dot bie'n gen Ngoai ra, tac nhan gay dot bie'n c6 the lam cd che phien ma bi nham Ian dS'n sai sot trong ban phien

c) Dot bie'n lam thay doi cau true cua gen d i n den thay doi cau true cua protein, lam thay doi chffc nang cua no Hau qua phu thuoc vao loai dot bie'n, vao vi tri xay ra dot bie'n, vao sff thay doi chffc nang cua protein, vao sff to hdp gen va dieu kien moi trffdng (gia tri thich nghi cua mot dot bie'n c6 the thay doi t&y to hdp gen va dieu kien moi trffdng) ;• d) Bieu hien cua dot bie'n gen:

+ Dot bie'n giao tuT qua thu tinh di vao mot hdp tff Neu la dot bien troi se dffdc bieu hien ngay, neu la dot bien Ian thi khong bieu hien ngay (vi bi gen troi tffdng ffng la'n at) qua giao phoi dot bie'n Ian dffdc Ian rong trong quan the Khi gap to hdp dong hdp thi no mdi bieu hien thanh kieu hinh

+ Dot bien tien phoi dffdc bieu hien ngay tren kieu hinh cua cd the mang dot bie'n do

+ Dot bie'n xoma, neu la dot bie'n troi se bieu hien d mot phan cd the tao nen

+ Trong qua trinh kieu gen dot bie'n hinh thanh kieu hinh con chiu sff tffdng tdc gen va chiu anh hffdng cua moi trffdng

3.2 DQt bien cau triic NST

a) Dot bie'n cau true NST la nhffng bien doi trong cau true cua NST, thffdng lien quan den mot doan NST nao do bi mat, dao, lap, hoac chuyen vi tri dan den letm hong cac gen, lam mat can bkng gen va tai cau true lai cac gen tren NST nen thffdng c6 hai cho t h i dot bie'n Tuy vay, chung cung gop phan tao nen nguyen lieu cho qua trinh tie'n hoa va dffdc ffng dung de loai bo gen xau, chuyen gen (tff NST nay sang NST khac hodc loai nay sang loai khac), xac dinh vi tri cfia gen tren NST, lam tang cffcfng hodc bat boat gen,

b) Dot bien cau true NST phat sinh luc NST nhan doi, do cac tac nhan gay 30t bie'n lam cho NST bi dfft, gay (doan bi dfft c6 the mat, dao, chuyen) hoac lam cho NST trao doi doan khong can (dan den lap doan)

C^m nang ti; an va luygn thi Sinh hoc - Phung Duy DS'ng

3.3 Bgt bien so'lMng NST (lech bgi, da boi)

* Dot bien lech boi (dl hoi)

a) Dot bien lech boi la bien doi so lU'Ong xay ra d mot hay mot so cap NST

srctng dong O sinh vat \\idng boi c6 cac dang chinh nhiT:" the khong (2n - 2), thg

.ot (2n - 1), the mot kep (2n - 1 - 1), the ba (2n + 1), the ba kep (2n + 1+ 1),

ihe boo (2n + 2), the bon kep (2n + 2 + 2)

Hj b) Dot bien lech boi phat sinh liic NST phan li, do tac nhan dot bien lam cho

mot hoac mot so NST khong phan h:

+ Trong giam phan: Tao ra giao tu* thiTa hoSc thieu mot vai NST roi qua thu

tinh tao thanh cac the lech boi:

Vidu: ( n + I ) x n - > 2 n + 1 (theba)

(n + 1) X (n + 1) -> 2n + 2 (the bon) hoac 2n + 1 + 1 (the ba kep)

+ Trong nguyen phan: tao thanh te bao lech boi, hinh thanh the kham

c) Dot bien lech boi lam mat can b3ng cua toan bo he gen nen cac the lech

boi khong song dU'cfc, hoac giam siJc song, giam kha nang sinh san tiiy loai Tuy

vay, dot bien lech boi cQng gop phan cung cap nguyen heu cho qua trinh tien

hoa va dtfcfc iJng dung de xac dinh vi tri cua cac gen tren NST

* Dot bien da hoi (tvC da boi, df da boi)

a) Dot bien da boi la bien doi lam tang mot so Ian bo NST ddn boi (n) cua

loai va Idn hdn 2n Te bao da boi c6 so liTcfng ADN tang gap boi, nen qua trinh

sinh tong hdp cac chat hffu cd xay ra manh me Vi vay cd the da boi c6 te'bao to,

cd quan sinh diTdng Idn, sinh tru'dng va phat trien khoe, chohg chiu to't

Cac the da boi le hau nhiT khong c6 kha nang sinh giao tuT binh thiTdng, tao

ra qui khong hat Dot bien da boi c6 vai tr6 rat quan trong trong tien hoa, gdp

phan hinh thanh loai mdi, chu ycu la cac loai thiTc vat cd hoa va ciing cd vai tro

quan trong trong viec tao ra cac giong mdi

b) Dot bien da boi phat sinh luc NST phan li, do cac tac nhan dot bien gay roi

loan qua trinh phan li cua NST lam cho NST da nhan doi, nhifng khong phan li

nen so lifdng NST tang gap doi:

+ Trong nguyen phan cua te b^o sinh diTdng se hinh thanh the kham tif da

boi chfn, trong nguyen phan cua hdp tuf d nhffng Ian dau tien, trong khoang 2 - 8

te' bao se tao thanh the tif da boi chan

+ Trong giam phan cua te bao sinh due se tao thanh cac giao tu' khong giam

nhiem 2n, 3n, 4n roi qua thu tinh tao thanh cac the da boi chan hoac le

Vi du: 2n X n -> 3n (the tam boi)

2n X 2n-> 4n (the tu" boi) :

3n X 2n 5n (the ngij boi)

Neu cdc giao tur thuoc ciing mot loai se tao thanh the tiJ boi, neu cac giao tijT

thuoc 2 loai khac nhau se tao thanh the di da boi

.•'•St • • • •

Cty TNHH MTV DWH Khang Vi^t

VI du: Giao tuT 2n va n cua loai chuoi rilTng ket hdp vdi nhau trong thu tinh tao

thanh chuoi nha tam boi (3n) Ui da boi

Giao tur ni cua loai cai cu ket hdp vdi giao tuT n2 cua loai cai bap tao thanh cd

the lai (ni + nj) bat thu Gay dot bien tuT boi tao thanh the song nhi boi (2ni + 2n2)

a the di da boi hi?u thu , f,

I CAU HOI Ti; LUAN |

Cfiu 1: NhSng dot bien gen khong anh hufdng tdi cau true ciaa gen j •

Hiidngddn

Cic dot bien khong anh hU'dng tdi cafu true cua gen la:

- Dot bien thay the mot cap nucleotit lam xua't hien bp ba ma hoa mot axit

rain vdi bo ba ban dau

- Dot bie'n diTdc enzim sufa chffa ngay d dang tien dot bien, chiTa kip nhan

oi theo mau lap sai (thong thu'dng dot bien d bp ba md dau va bo ba ket thuc

ifdc suTa chffa ngay)

fiu 2: Nhffng dot bie'n gen lam anh hifdng nghiem trpng de'n the dot bien?

Hitdng dan

- Dot bie'n mat, hoac them mot nucleotit d sat bp ba md dau

- Dot bie'n thay the lam xua't hien bp ba ket thuc ngay khi bat dau dich ma Cfiu 3: Nhiyng dot bien gen nhuT the nao chi lam anh hifdng den mpt axit amin?

HUdng dan

- Thay the' mpt cap nucleotit lam xua't hien bp ba ma hoa axit amin khac vdi

bp ba md dau

- Mat, them mpt nucleptit d bp ba sat ngay bp ba ket thuc

Cfiu 4: Dot bie'n gen nhif the nao dan den hau qua lam chudi polipeptit mat mpt

axit amin va xua't hien 2 axit amin mdi

fV a* Hiiclngdan

Mat 3 nucleotit d ba bp ba lien tie'p nhau

Cfiu 5: Hau qua cua dot bie'n gen phu thuoc vao nhffng yeu to nao?

Hiidng ddn

1 Doi vdi cau true cua protein hau qua cua dot bie'n gen phu thuoc vao vi tr dot bie'n va loai dot bie'n

Vidu:

- Neu dot bien mat hoac them mpt cSp nucleotit xay ra d cuoi gen thi se ga)

hau qua it nhat, ngifdc lai xay ra dot bie'n cang d phia dau cua gen thi se gay n

hau qua cang nhieu

' - Neu mpt cap nucleotit bj thay the thi c6 the khong gay hau qua gi hoac ch gay bie'n doi mpt axit amin hoSc lam chuoi polipeptit bj ngan lai Ne'u mat hoac them I cap nucleotit thi tat ca cac bp ba tie'p sau do deu bi thay doi

2 Doi vdi the dot bie'n, hau qua cua dot bie'n gen phu thuoc vao si/ thay do

chiJc nang cua protein, vao to hdp gen va vao dieu kien moi tru'dng

Cim nang tu 6n va luygn thi Sinh hpc - Phung Duy B6ng

C&u 6: Tai sao n h i l u dot bien nhir dot bien thay the mot cap nucleotit lai hau

nhU' v6 hai doi vdi the dot bien

Hiidngddn

- Xet d mitc do phan tiJT, nhieu dot bien diem la trung tinh

- Dot bien thay the mot cap nucleotit thiTdng chi anh hudng den mot axit

amin hoac khong anh hU'dng den cau true cua protein

- D o t bien d i e m xay ra d bo ba m d dau hay bp ba ke't thuc deu diTcfc

enzim sufa chffa

- Dang tien dot bien c6 the dtfcJc enzim suTa chffa nen khong gay tac hai gi

" ' - M o t so dot bien geri c6 the lam thay ddi chffc naijg cua protein theo hufdng

CO Idi cho the dot bien * "

' - TiJy to hdp gen va tiiy moi triTdng dot bien c6 hai c6 the trd thanh c6 Idi

Cfiu 7: Sifphat sinh dot bien gen phu thuoc vao yeu to nao?

Hitdng ddn

- A D N CO nhan doi hay khong

- Tac nhan gay dot bien (loai tac nhan, lieu lufdng, ci/dng do) c6 thich hdp khong

C&u 8: Tan so' dot bien gen phu thuoc vao yeu to nao?

HUdng ddn

Tan so dot bien gen phu thuoc:

- Tac nhan gay dot bie'n (loai tac nhan, lieu Iffdng, cffdng do)

- Dac diem cau true cua gen (ben vffng hoSc it ben vffng)

Cfiu 9: Loai dot bien nao c6 the xuat hien ngay trong ddi ca the?

Hudng ddn

Dot bien xoma va dot bie'n tien phoi

CSu 10: Tai sao dot bie'n gen c6 tan so dot bie'n thap nhffng lai thffdng xuyen

xuat hien trong quan the giao phoi =(>,«,(

' Hitdng ddn

Yi so liTdng gen trong te bao rat Idn va so liTdng ca the trong quan the rat nhieu

Cfiu 11: Trong hai loai dot bie'n trpi va iSn Loai nao cd vai tro quan trong hdn

doi vdi tien hoa? V i sao? • ' '

HUdngdhi

Dot bie'n iSn c6 vai trd quan trong hdn doi vdi tie'n hda v i dot bie'n iSn it

nghiem trpng hdn va lan tran trong qu^n the nhd qud trinh giao phoi

Cfiu 12: V i sao dot bie'n gen cd vai tro chu ye'u cho vi$c cung cap nguyen lieu

cho qua trinh tieu hda?

Yi dot bie'n gen thffdng d trang thai lan, hau qua khong nghiem trpng nhff dot

bie'n cau true NST va dot bien gen xuat hien phd bien hdn so v d i dot bien NST

84

Cty TNHH MTV D W H Khang Vi$t

CSu 13: Dot bien genco nhffng diem nao gidng vdi bien di to hdp?

Dot bien gen lam thay ddi cau true cua gen, con bie'n di to hdp thi khong

Nguyen nhan gay ra dot bie'n gen la do cac tac nhan gay dot bie'n trong mdi trffdng, con nguyen nhan gay ra bie'n di to hdp la do sff to hdp lai vat chat di truyen von cd d bo' me

- Dd^i vdi sff tien hda cua loai thi dot bie'n gen cd vai trd quan trpng hdn

- Dot bien gen xuat hien dot ngpt gian doan con bie'n di td hdp cd the dmh hffdng trffdc b - •

Cfiu 15: N d i rang, dang mat hoac them mot cap nucleotit, lam thay ddi nhieu

nhat ve cau true protein cd hoan toan|chinh xac chffa? ,

Hudng ddn

Chffa, VI con tiiy thuoc vao v i tri ciia dot bie'n V i du: M a t hoac them mot cap nucleotit d Bp ba sat bp ba ke't thtic chi lam mat mot axit amin, con thay the mot cap nucleotit lam xuat hien ma ke't thuc d doan dau cua gen thi chudi polipeplit

cd the mat hau he't cac axit amin

C§u 16: SGK Sinh hpc 12 (trang 19) c6 ghi: "Dot bien thay the mot cap nucleotit

cd the lam thay ddi trinh tff axit amin trong protein" SGK Sinh hpc 12 - Nang cao (trang 35) lai ghi: "Nguyen nhan cua dot bie'n da bpi la do lai xa giffa hai loai khac nhau" Theo em, cd dung khong? V i M i •:>•:>(!;

Hudng ddn

Dot bie'n thay the mot cap nucleotit khong lam dich khung dpc ma di truyen nen khong the lam thay ddi trinh tff cac axit amin trong protein L a i xa giffa hai loai khong phai la nguyen nhan gay dot bien da bpi, v i bp NST cua cd the lai chi

la 2n, ne'u khong gay dot bien da bpi the -viV!

Cfiu 17: Trong miic cd che'phat sinh dot bie'n gen Cd sach cho rang:

1) Dot bie'n gen khong chi phu thuoc vao loai tac nhan, lieu Iffdng, cffdng

dp cua loai tac nhan gay dot bien ma con phu tlyipc vao dac d i e m , cau true

ciaa gen, • ''^-^ w hiw:/' • i-n;-, •

2) Ngffdi ta con gap cac dot bie'n nhff trong trffdng hdp xff l i A D N bang cha't acridin cd the lam mat hoSc xen them mot cSp nucleotit tren A D N

Hay phan tich cac y tren khi ndi ve cd che dot bien

Hudng ddn t?

Y thff 1 chi ndi ve tan so dot bie'n gen phu thuoc vao yeu t d nao C6n y thff 2 thi chi ndi den chat acridin la mot tac nhan gay dot bien mat hoac them mot cSp nucleotit, khong he ndi gi ve cd che gay dot bie'n -

C^m nang tij On luygn thi Sinh hpc - Phung Duy Dfi'ng

1 - D o t b i e n g e n k h o n g c h i p h u thuoc vao l o a i tac nhan, l i e u lifdng, cifdng dp cua

loai tac n h a n gay dot b i e n m a con p h u thupc vao dac d i e m , cau true cua gen

2 - T h o n g t h i f d n g sif t h a y d o i m o t n u c l e o t i t trUdc t i e n x a y r a diidi d a n g t i e n

d o t b i e n C a c t i e n d o t bie'n n a y t i e p tuc du'dc n h a n d o i t h e o m a u n u c l e o t i t l a p sai,

cac n u c l e o t i t l a p sai n a y se l i e n k e t v d i n u c l e o t i t b d sung v d i n h a u v a l a m p h a t

sinh d o t bie'n

3 - C h a t a c r i d i n c 6 the l a m m a t hoac t h e m m o t cap n u c l e o t i t t r e n A D N

H a y p h a n t i c h v e nhiJng y k i e n t r e n v a du'a ra y k i e n cua m i n h

HiCdng dan

+ V i r u t k h o n g p h a i l a s i n h v a t ( S G K S i n h hoc I d p 10) v i v a y c h o r a n g tac

n h a n s i n h hpc l a v i r u t t h i chufa c h i n h xac

+ B a z d d a n g h i e m k e t cap k h o n g d u n g t h i c 6 sach c h o r a n g , d o l a c d che'

T h i f c r a b a z d d a n g h i e m l a m o t tac n h a n hoa hpc g a y d o t bie'n C d che' g a y dot

bie'n cua b a z d d a n g h i e m la d o c h i i n g c 6 nhiyng v i t r i Hen k e t h i d r o b i t h a y d o i

l a m c h o c h u n g ke't cSp k h o n g d u n g ( d a n g t i e n d o t bie'n) Sif n h a n d o i cua A D N

t h e o m a u l a p sai n a y m d i l a m p h a t sinh dot bie'n g e n

+ T r i n h b a y v e c d c h e d o t bie'n g e n theo thiJ tiT nhu" 3 y d t r e n l a q u a thufa v i

y thu" 1 n o i v e t a n so d o t bie'n g e n p h u thupc v a o ye'u t o nao Y thu" 3 n o i v e

a c r i d i n l a m o t tac n h a n gay d o t b i e n Nhu'ng v a n k h o n g d a y d u

!, Co the dua ra nhu sau:

C a c tac n h a n g a y d o t b i e n d t r o n g hoac n g o a i c d the (tac n h a n l i , h o a , b a z d

d a n g h i e m , v i rut, ) hoSc r o i l o a n sinh H, sinh hoa t r o n g t e ' b a o d a l a m bie'n d o i

cau true cua g e n d a n de'n sai l e c h k h u n g d o c m a t r u y e n h o a c l a m r o i l o a n qua

t r i n h n h a n d o i cua A D N d a n de'n ke't cap b d sung k h o n g d u n g , h e n ke't k h o n g

d u n g ( v i d u tia tuf n g o a i c 6 t h e l a m cho 2 l o a i b a z d T i m i n t r e n c d n g m o t m a c h

A D N l i e n k e t v d i n h a u ) tao ra cac d a n g t i e n dot bie'n C a c t i e n d o t bie'n t i e p tuc

duTdc n h a n d o i t h e o m a u l a p sai l a m p h a t sinh d o t bie'n , t

C f i u 19: V i sao d o t bie'n c a u true N S T thiTdng gay h a i c h o the d o t bie'n

Hudng dan

D o t bie'n ca'u triic thtfcfng l a m h o n g g e n , l a m m a t c a n b a n g g e n , t a i c a u true

l a i cac g e n t r e n N S T n e n t h u t f n g g a y h a i c h o the d o t b i e n s jjaaftt i i i :

Cty TNHH MTV D W H Khang Vi$t

C S u 2 0 : V i sao d o t bie'n ca'u true N S T thtfdng g a y h a i nhu'ng l a i c 6 v a i t r o nha't

^ i n h d d i v d i t i e n hoa v a c h p n gid'ng?

Hitdng ddn - ^'

D o t b i e n ca'u triic N S T CO v a i tro nha't d i n h dd^i v d i tie'n hoa la v i :

- L a p d o a n N S T d a n de'n lap g e n , tao d i e u k i e n c h o d o t bie'n g e n , tao n e n

>c4c a l e n md i t r o n g q u a t r i n h t i e n hoa

- C a c d a n g d o t bie'n ca'u true N S T d e u gop p h a n tao n e n n g u d n n g u y e n l i e u

cho q u a t r i n h t i e n h o a

- D o t bie^n d a o d o a n , c h u y e n d o a n c 6 v a i t r o q u a n t r o n g t r o n g q u a t r i n h h i n h

thanh l o a i mdi V i d u : N h i e u l o a i m u o i , qua t r i n h dao d o a n du'dc lap d i lap l a i

t r d n c^c N S T da gop p h a n tao n e n l o a i m d i ^ l i f t /'sStW' I I A W J B 'J-i.'i^-'

D o t b i e n ca'u true N S T c u n g c 6 vai tro nha't d i n h t r o n g c h p n g i d n g v i :

- C h u n g c u n g ca p n g u y e n Heu c h o c h p n g i d n g

- Ngu'di t a CO t h e g a y d o t bie'n m a t d o a n n h o d e l o a i k h o i N S T nhu'ng g e n

k h o n g m o n g muo'n

- N g i r d i t a CO the g a y d o t bie'n lap d o a n , d e l a m t a n g s d l i f d n g g e n , t a n g so

lutJng san p h a m c u a g e n ( f ' ' ; - ^ ' / ' A , f > y : r ! : r [.iV\ '-"\

- Ngu'di ta CO t h e g a y d o t b i e n d a o d o a n , l a m t h a y d d i v i t r i cua g e n t r e n

N S T , l a m t a n g g i a m miJc d p b o a t d p n g cua gen

- Ngu'di ta CO t h e g a y d o t b i e n c h u y e n d o a n d e c h u y e n g e n lit N S T n a y sang

N S T k h a c , tijf l o a i n a y sang l o a i k h a c

C S u 2 1 : V i t r i diJt g a y k h a c n h a u t r e n N S T c 6 g a y r a nhiJng h a u qua k h a c n h a u cho the d o t bie'n k h o n g ?

" • ^ Hitdng ddn • ' '

D o a n N S T b i dt?t gay c d the x a y ra d d a u m u t giffa c i i n h h o a c m a n g t a m d p n g ,

l y r a nhiJng h a u q u a k h a c n h a u c h o the d o t bie'n:

+ D o a n d u t g a y d d a u m u t , c 6 the b i t i e u bie'n l a m m a t m o t lu'dng v a t cha't d i

iiyen, t u y v a y luTdng v a t chat d i t r u y e n b i m a t i t , k h o n g g a y ra h a u qua n g h i e m

' t r o n g N h U ^ g m a t d o a n d a u m u t l a m a t c a c t r i n h tiT n u c l e o t i t dijc h i e u , m a t khii i;nang b a o v e v a c 6 t h e l a m cho N S T d i n h n h a u k h i boat d p n g g a y tac h a i c h o the Jot bie^n

+ D o a n b i d u t g a y d giffa c a n h hoac c 6 m a n g t a m d p n g thu'dng g a y r a d o t

I b i e n dao d o a n l a m thay d d i v i t r i g e n t r e n N S T , n e n boat d p n g cua g e n c 6 the b i Ithay d d i , h o a c k h o n g boat d p n g hoSc t a n g , g i a m m u t b o a t d p n g , c 6 the g a y h a i

n h i e u h a y i t c h o t h e d o t bie'n

+ D o a n b i d u t g a y c 6 the g a y r a d o t bie'n c h u y e n d o a n l a m t h a y d d i n h o m

?en l i e n k e t l a m c h o the d o t bie'n thu'dng g i a m k h a n a n g s i n h san

87

Ca'm nang ti^ On va luyQn thi Sinh hpc - Phung Duy D6'ng

C a u 22: T h e da boi diTdc nhan bie't bang phu'dng phap nao?

Hudngddn

- D e m s d l i r d n g N S T l r o n g t c b a o d i r d i k i n h h i e n v i

- N h i n c d the da boi bSng mat thiTdng; C d quan sinh du"9ng Idn, sinh trirdng

phat trien manh,

C a u 23: NgiTdi ta c6 the tao ra the tiJ boi bang each nao?

HUffng ddn

Bang each:

a) Tac dpng vao luc N S T phan h trong nguyen phan tao ra te'bao sinh duTOng

4n phat trien thanh the kham 4n l y da boi

b) Tac dong vao luc N S T phan l i trong giam phan tao ra giao tuT 2n Cho cac

giao tu^ 2n cijng loai ket hdp v d i nhau qua thu tinh tao ra the tiT da boi 4n

c) Tac dong vao luc N S T cua hdp tu" phan l i trong nhiJng Ian nguyen phan

dau tien tao ra dot bien t i c n phoi, phat trien thanh cd the tu" da boi 4n

d) Cho lai khac l o a i tao ra cd the lai xa r o i gay dot bien 4 n tao thanh c d the

song nhi boi (the dj da boi 4n)

e) Cho l a i giffa cd the 6n v d i 2n, , •

g) Cho the t i J b o i sinh san hffu tinh hay sinh san sinh du'3ng

C a u 24: C6 the tao ra the tam boi b^ng each nao?

HUdng ddn

Bang each:

a) Cho ca the 3n sinh san sinh du'dng

b) Tac dong vao luc N S T phan l i trong giam phan tao thanh giao tuT 2n Cho

giao tijT 2n thu tinh v d i giao tu" binh thu'dng tao thanh the tiT da boi 3n

c) Cho lai hifu tinh giffa cd the tu" boi v d i cd the lu'Sng b o i

Cfiu 25: Cap bo me sinh mot diJa con dau long mac hoi chuTng dao (cSp NST thu" 21

CO 3 chiec) 6 Ian sinh ihd hai con cua ho c6 xuat hien hoi chilhg nay khong? V i sao?

HUdng ddn

Cd the xuaft hien nhutig v d i xac suat rat thap, v i tan so dot bien rat b6

C a u 26: Hay trinh bay k h a i quat ve cd c h e p h a t sinh dot bien

HUdngddn

Cac tac nhan gay dot bien tac dong va luc A D N nhan d o i , luc N S T nhan doi,

trao d o i doan, phan l i , gay r o i loan cac qua trinh do, hoSc l a m bien doi cau true

cua A D N cua N S T TiT do phat sinh dot bien

C a u 27: Hay trinh bay chi tiet ve s\i bieu hien k i c u hinh cua gen

2 Sir bieu hien k i e u hinh cua gen phu thuoc vao nhieu yeu to':

a) Chtfc nang cua gen: Trong te bao chi c6 mot so gen ma hoa cac axit amin, con dai da so gen dong vai tro khac, khong quy dinh t i n h trang nen khong bieu hien thanh k i e u hinh

b) Trang thai cua gen: Trong te bao ciing c6 nhieu gen bat boat, khong boat d6ng nen khong b i e u hien thanh k i e u hinh

c) V i t r i cua gen: Cac gen tren ciing mot N S T bieu hien k i e u hinh theo nhom li6n ket, cac gen nam tren N S T khac nhau, bieu hien k i e u hinh doc lap, gen nSm tren N S T thiTdng bieu hien khac gen nam trong N S T g i d i tinh Gen nam trong nhan bieu hien khac gen nam trong te bao chat,

d) Qua trinh sinh trifdng va phat trien cua c d the: T i i y tiTng g i a i doan sinh tru'dng va phat trien c6 su" bieu hien khac nhau V i du nhieu gen quy dinh cac tinh trang sinh due phu den tudi day thi thi m d i bieu hien k i e u hinh lu ! \

e) Su" tu'dng tac gen: Su" bieu hien kieu hinh chiu anh hiTdng cua tiTdng \ic gen

+ Tu'dng tac giffa cac gen alen:

- Tu'dng tac troi, Ian hoan toan

- Tu'dng tac trpi, Ian khong hoan toan <

- Tu'dng tac dong trpi

+ Tu'dng tac gii?a cac gen khong alen:

- Tu'dng tac b d sung • ,

- Tu'dng tac at che

h) B i e u hien cua dot bien gen:

- D o t bien xoma: Neu la dot bien trpi se bieu hien thanh the k h a m , neu la dot bien Ian thi khong bieu hien •

- D o t bien tien phoi: Du-dc bieu hien ngay trong ddi ca the

- D o t bien giao Xxi: Qua thu tinh d i vao mot hdp tuf la dot b i e n trpi se diTdc

bieu h i e n ngay, con dot bien khong bieu hien ngay va Ian tran trong quan the (nhd giao phoi) k h i gap to hdp dong hdp t h i m d i bieu hien k i e u hinh

J k i i ) Gen b i n h thirdng hoac gen b i dot bien diTdc d i truyen qua cac the he va

dirpc b i e u hien theo cac quy luat d i truyen

• 89

Ca'm nang tij On va luygn thi Sinh hpc - Phiing Duy Ddng

Cau 28: So sanh thiTdng bien va dot bien

a) Gio'ng nhau: » ^ (<,

- Qua trinh phat sinh deu c6 hen quan vdi moi triTctng ' •' '

- Deu CO bien doi kieu hinh

- Dot bien cung c6 the c6 Idi va cung c6 the xuat hien trong qua trinh phat

trien ca the

- Thu-dng bien cung c6 vai tro U-ong tien hoa (giup sinh vat thich nghi vdi sir

bien doi cua moi trifdng va gian tiep trong viec cung cap nguyen lieu cho qua

b) Khac nhau:

- Sir phat sinh thU'dng bien la do dieu kien moi tnrdng thay doi khong lien quan

den sir bien doi sinh li, sinh hoa trong te bao SiTphat sinh dot bien do cac tac nhan

gay dot bien U-ong moi trUdng hoac do roi loan sinh li, sinh hoa U-ong te bao

- Thu-dng bien chi xuat hien trong qua trinh phat trien ca the, xay ra dong

loat, theo hudng xac dinh, khong lam bien doi kieu gen nen khong di truyen

Con dot bien hau he't xuat hien d the he sau, xay ra dot ngot, gian doan, ngau

nhien, vo hudng lam bien doi kieu gen va di truyen cho the'he sau

- Dot bien la nguyen lieu chu yeu cua qua trinh tien hoa con thu-dng bien

chi CO vai tro gian tiep

Cau 29: So sanh thu-dng bien va bien di to hdp

, , : HUdngddn

a) Giong nhau:

- Deu CO sir bien doi kieu hinh ;

- Deu khong lam bien doi cau true cua gen

- Deu CO y nghia doi vdi thiTc tien san xuat va deu co vai tro nhat djnh doi

vdi tien hoa

, b) Khac nhau: M • S

Thu-dng bien khong lam thay doi vat chat di truyen, con bien dj to hdp c6

su- to hdp lai vat chat di truyen

- Nguyen nhan gay ra thu-dng bien la dieu kien moi trtfcfng thay doi con

nguyen nhan gay ra bien di to hdp la do sir to hdp lai vat chat di truyen cua bo

me qua sinh san hiJu tinh '

- Cd che phat sinh thudng bien la do phan u-ng cua cung mot kieu gen vdi

dieu kien moi trufdng khac nhau Con cd che gay ra bien di to hdp la do sir phan

li doc lap, hoan vi va to hdp cua cac gen

90

Cty TNHH MTV DWH Khang Vi$t

Thu-dng bien phat sinh trong qua trinh phat trien ca the, xay ra dong loat, tlieo mot hiTdng xac dinh va khong di truyen diTdc Bien di to hdp xua't hien qua sinh san hffu tinh xay ra rieng le, theo nhieu hUdng khac nhau va di truyen diTdc

Thu-dng bien khong phai la nguyen lieu cua chon giong, con bien di to hdp

la nguyen lieu quan trong cua chon giong

Cfiu 30: So sanh dot bien vdi bien di to hdp

Hiidngddn , ,, , \^

a) Giong nhau: ,

- Deu CO bien doi kieu gen

- Deu CO the xuat hien qua sinh san hifu tinh ;, :

- Deu lam bien doi kieu hinh

- Deu xua't hien rieng le, va di truyen du-dc

- Deu la nguyen lieu ctia tien hoa va chon gio'ng

!: - Dot bien xua't hien dot ngot, gian doan, ngau nhien v6 hu-dng, con bien di

t6 hdp xua't hien rieng le c6 the dinh hiTdng dirdc

- Dot bien la nguyen lieu sd cap, bien di to hdp la nguyen lieu thu" cap cua qua trinh tien hoa ,

III CAU HOI TRAC NGHIEM CSu 1: Dot bien gen la gi?

i A) La bien ddi vat chat di truyen xay ra trong cau true phan tu: ADN

i B) La bien doi trong cau true cua gen

I C) La bien ddi xay ra tai 1 diem nao do tren phan tuf ADN hoac ARN

f; D) Ca A, B, C deu dung

CSu 2: Dot bie'n gen xay ra vao thdi diem nao?

A) Khi ADN nhan doi B) Khi NST dong xoan

C) Khi ADN dang phan li D) Khi te bao bi benh

CSu 3: Nguyen nhan nao dot bie'n gen xua't hien?

A) Do NST bi chan dong cd hoc ">

Ca'm nang tij On va luygn thi Sinh hpc - Phpng Duy B6ng

C ) D o cac tac nhan gay dot bien trong va ngoai cd the hoac do r o i loan sinh

l i , sinh hoa trong te' bao

A) L a nhiyng bien ddi dot ngot ve cau true cua A D N

B ) La nhvtng bien doi vat cha't di truyen xay ra d cap do phan tuf va cap do te bao

C ) L a nhiyng bien ddi dot ngot ve cau true cua NST

D) L a nhi?ng bien ddi dot ngot, gian doan cua mot tinh trang

C S u 5: T h e dot bien la gi?

A) L a nhiTng ca the mang dot bien da bieu hien tren k i e u hinh cua c d the

B ) La nhi^ng bieu hien ra k i e u hinh cua te'bao b i dot bien

C ) L a ca the b i dot bien

D) L a trang thai c d the cua ca the bi dot bien

CSu 6: T a n so dot bien la gi?

A) La tan so xuat hien cac ca the b i dot bien trong quan the giao phdi

B ) L a t i le giao tuT mang dot bien tinh tren tdng so giao tuT diTdc sinh ra

C ) L a t i le gii?a the dot bien v d i tdng so ca the

D) L a t i le giffa ca the mang dot bien v d i tdng so ca the

C f i u 7: D o t bien xoma la loai dot bien:

A) X a y ra d te bao sinh diTdng

B ) X a y ra tai c d quan sinh dxidng

C ) DiTdc nhan l e n nhd nguyen phan r d i bieu hien d mpt phan cd the

D) Ca A , B va C deu dung

C S u 8: D o t bien giao tu^ la loai dot bien:

A) X a y ra tai te bao sinh due B ) X a y ra trong qua trinh g i a m phan

C ) B i e u hien d giao tur D) Ca A , B va C deu dung

C a u 9: D o t bien tien phoi la gi?

A) D o t bien xuaft hien vao giai doan dau cua sU phat trien p h o i

B ) D o t bien xuat hien d giai doan phoi phan hoa te' bao

C ) D o t b i e n xua't hien trong nhi?ng Ian nguyen phan dau tien cua hdp tur

D) D o t bien xua't hien trong qua trinh phat t h e n cua p h o i

C&u 10: N p i dung nao sau day sai?

A) D o t bien gen k h i phat sinh diTdc k i e u hinh ngay ra k i e u hinh

B ) Dot bien gen c6 vai tro cung cap nguyen heu chu ye'u cho qua trinh tien hoa

C ) D o t bien gen c6 the c6 I d i , c6 hai hay trung tinh

D) D o t bie'n gen la loai dot bien xay ra d cap do phan tuT

Cty TNHH MTV DVVH Khang Vi^t

fgu 11: Sd^gen trong te bao v i sao khong bang sd^tinh trang cua cd the:

A) V i chi c6 gen cau true m d i tdng hdp protein ., ,

B ) V i CO gen cau true bi bat boat • "" '

C ) V i CO rat nhieu gen dam nhiem cac chu'c nang khac '' ' >

D) V i ca A , B va C

cau 12: V i sao dot bien gen thifdng c6 hai, it c6 I d i , tan so thap nhiTng l a i la

nguon nguyen l i e u chu ye'u cua qua trinh tien hoa?

A) V i dot bie'n gen thiTdng iSn, dUdc Ian tran trong quan the, tao thanh ngudn

( gen dot bie'n dif triJ rat Idn va qua giao phd^i da tao ra v6 so' bie'n d i t d hdp

B ) V i dot bie'n gen hau qua khong nghiem trong va xua't hien phd bie'n hdn so

v d i dot bie'n N S T

C ) D o t bie'n gen c6 hai c6 the trd thanh c6 Idi tuy t d hdp gen va tiay dieu k i e n

f l m o i t r i ^ n g

D) V i ca 3 l i do tren f CSu 13: M o t gen k h i bj bie'n ddi ca'u true diTdc goi la: " "

A) M o t gen troi dot bie'n

B ) M o t alen cua gen bi dot bien, tao thanh alen m d i

C ) M o t gen troi va lan dot bie'n ,

is

D) M o t gen lan dot bien

Cfiu 14: N o i dung nao sau day chiTa chinh xac k h i de cap den hau qua cua dang

dpt bie'n thay the'mot cap nucleotit? j ,, ,

A) Co the khong l a m thay ddi axit amin nao trong ca'u trdc cua protein

B ) Co the chi l a m thay ddi mot axit amin trong chuoi polipeptit ,,

C) L u o n l a m thay doi mot axit amin trong chuoi polipeptit

D) Co the l a m cho chuoi polipeptit ngan l a i CSu 15: D o t bie'n nao sau day lam thay ddi ca'u true protein nhieu nha't? ^ A) Ma't 3 cap nucleotit , • -i ,

B ) Ma't 2 cap nucleotit ,\;':, a-i .n-'od'* ^

• C ) M a t 1 cap nucleotit d v i t r i dau gen i ; ; ; ; ' )

D) Ma't 1 cap nucleotit ci v i tri cudi gen

Cau 16: K h i n o i ve dot bie'n NST dieu nao sau day la sai?

A) L a nhu*ng b i e n ddi ve ca'u true N S T , ve so lufdng cua m o t cap N S T hoac tat

c a c a c c S p N S T ^'^

B y D o t bie'n N S T la nhffng bie'n ddi ve c d scl vat chat d i truyen d cap te'bao

C ) D o t bie'n N S T la nhffng bie'n ddi gay ra cic dang: Ma't doan, dao doan, ISp

I doan, lech b o i , da boi

C a u 17: K h i noi ve nguyen nhan gay ra dot bien NST dicu nao sau day la chua

chinh xac? , ; ^sj^

A ) Nguyen nhan gay ra dot bien NST la cac tac nhan l i , hoa trong ngoai canh

B ) Nguyen nhan gay ra dot bien NST la cac roi loan sinh li- sinh hoa trong te bao

C) Nguyen nhan gay ra dot bien NST la cac bazcf dang hiem, cac chat hoa

hoc nhif 5 B U , acridin tac dong vao luc A D N nhan doi

D ) Cau C chtfa chinh xac

C a u 18: K h i noi ve cd che gay dot bien NST cau nao sau day khong dung?

A ) Ccf che'gay dot bien NST la cac tac nhan gay dot bien lam diJt gay NST

B ) Ccf che' gay dot bie'n NST la cac tac nhan gay dot bien lam r o i loan qua

trinh tu" nhan doi cua NST

C) Cd che gay dot bien NST la cac tac nhan gay dot bien l a m r o i loan qua

trinh phan l i cua NST trong phan bao

D ) Khong CO cau nao sai

C a u 19: K h i noi den dot bien mat doan, dieu nao sau day khong dung?

A ) Doan bi mat c6 the d dau mut, giffa canh hoSc mang tam dong

B ) Xay ra trong qua trinh NST nhan doi

C) X a y ra trong qua trinh nguyen phan hoac giam phan

D ) Doan bi mat, ne'u khong chiJa tam dong se bi thoai hoa

CSu 20 : Phat bieu nao sau day sai?

A) Dot bien lap doan lam tang them vat chat di truyen, lam bien doi hinh thai NST

B ) Lap doan l a m tang hay giam cu'dng do bieu hien cua tinh trang

C) Hau qua cua lap doan lam thay doi nhom gen lien ke't

D ) C d che' phat sinh lap doan la do trao doi doan khong can gii?a 2 cromatit

trong cap NST ttfdng dong kep

CSu 21 : Cau nao sau day khong dung?

A ) Trong cac dang dot bie'n cau true NST, dao doan la dang dtfdc gap pho

bien hdn ca

B ) Trong cdc the lech boi, dang 2n + 1 va 2n - 1 gap pho bie'n hdn ca

C) PhiTdng phap pho bie'n nhat hien nay di/dc uTng dung de gay dot bie'n da

boi the la dung consixin vdi nong dp 0,1 - 0,2%

D ) Tat ca A, B va C deu diing

Cflu 2 2 : K h i de cap den dot bie'n chuyen doan NST dieu nao sau day dung?

A ) L i e n quan de'n nhieu NST khac nhau ciing dut doan, sau do trao doi doan

, dut v d i nhau ;r

B ) Cac doan trao doi c6 the xay ra trong mot cap NST tifdng dong nhUhg phai

khac chiJc nang, nhu-giQ-a NST X va NST Y

C) NST duflt mot doan, chuyen den vi tri mdi trong cung mot NST hoSc NST khac

D ) Tat ca A, B va C deu dung

C t y T N H H M T V D V V H K h a n g V i g t

C a u 2 3 : K h i di cap de'n nguyen nhan ve dot bie'n so Itfdng NST, cau nao sau

dSy khong dung? • ; v ^ ' •

A ) D o thoi vo sac khong hmh thanh hoac b i pha huy

B ) Do r o i loan cd che phan U cua NST d k i sau trong phan bao

C) D o NST khong phan l i trong qua trinh phan bao

D ) Khong cau nao sai ca

C a u 2 4 : Hau qua ciia dot bie'n mat doan doi v d i cau true NST la:

A ) L a m cho cac gen tren NST gan nhau hdn '

B ) L a m thay doi hinh dang, kich thu'dc cua NST ' ' •

C) L a m thay doi nhom gen Hen ke't cua NST '

CSu 2 5 : Hau qua cua dot bien lap doan doi vdi ca'u true NST la: , > i

A ) L a m cho cac gen tren NST xa nhau hdn ; <>

B ) L a m thay doi hinh dang kich thiTdc NST i., ^

C) Khong lam thay doi nhom lien ke't gen tren NST

D ) Tat ca A, B va C

CSu 2 6 : Hau qua cua dot bie'n dao doan doi vdi cau true N S T la: l \

A ) L a m cho cac gen tren NST xa nhau hdn i I

B ) L a m cho cac gen tren NST gan nhau hdn '

C) Khong lam thay doi nhom lien ke't gen tren NST •

-D ) Tat ca A, B va C

CSu 2 7 : Hau qua cua dot bie'n chuyen doan doi vdi cau true NST la: 1

A ) L a m cho cac gen tren NST xa nhau hdn, gan nhau hdn ; i ;

B ) L a m thay doi hinh dang, kich thifdc NST

C) L a m thay doi nhom lien ke't gen tren NST

D ) Tat ca A, B va C

C 5 u 2 8 : N o i dung nao sau day sai? ' ' ' •

A ) Dao doan xay ra k h i mot doan ben trong NST bi dut, doan nay quay ngiTdc

180"r6i dUWc noi lai i - n r : , ;

B ) Doan NST bj dao phai n l m d dau hay giiJa canh cua NST va khong mang

f tam dong

C) Dao doan i t anh hu'dng de'n siJc song cua sinh vat do khong lam ma't vat chat d i truyen

D ) Ddo doan l a m thay doi trat tU s^p xep cac gen tren NST nhiTng khong lam

thay doi nhom gen lien ke't o

' • 95

Cau 29: Cac the dot bien nao sau day d ngUdi la hau qua cua dot bien l$ch bpi

dang2n+ 1?

A) Hoi chuTng TdcncJ, ClaiphentcJ, Dao ' r < v i ^

B) SuT moi, thiTa ngon, chet yeu

C) Ngon tro dai hdn ngon giiJa, tai tha'p, ham be <

D) Tat ca A, B va C

Cau 30: Cac the dot bien d nguTdi phat sinh do dot bien cau true NST la:

A) Benh ung thu" mau B) Benh mau kho dong

C) Benh bach tang D) Benh mii mau

Cfiu 31: Cac the dot bien d ngUdi do dot bien gen 1^:

A) Benh mau kho dong, benh mu mau

B) Benh bach tang, di tat dinh ngon 2 va 3 bang mot mang noi

C ) Benh hong cau hinh liidi liem

D) Tat ca A, B va C

Cau 32: Cac the dot bien d ngifdi phat sinh do dot bien di boi la:

A) Hoi chiJng 3X, hoi chiJng Tdcnd, hoi chiJng Dao

B) Hoi chiJng Claiphentcj

C ) D i tat thtjfa ngon tay, tai thap, ham be

D) Ca A, B va C

Cau 33: Loai dot bien nao sau day lien quan den NST gidi tinh?

A) Benh mau kho dong, benh mil mau

B) Hoi chiJug 3X, hoi chu-ng Tdcnd

C ) Hoi chtfug Claiphentcf, di tat dinh ngon 2 va 3

D) Tat ca A, B va C

Cfiu 34: The dot bien nao chi xuaft hien d nam gidi?

A) Hoi churng Claiphentcf "

B) Di tat dinh ngon 2 va 3 bang mot mang noi

C ) Benh mau kho dong, b^nh mu mau iio;?<3:!>'

D) Tat ca A, B

Cfiu 35: Hien tiTdng bien di xay ra doi vdi mot cSp NST ti/dng dong?

A) Hoan vi gen dan deh bien di to hdp, trao doi doan khong can dan den dot

: bien lap doan

B) NST bi dut gay dan den dot bien mat, dao, chuyen doan

i C ) cap NST tiTdng dong kh6ng phan li dan den dot bien lech bpi

1 Ve dot bien gen ,

Loai 1: Xac dinh su" bien d^i cua protein khi bie't loai dot bien va vi tri xay ra

dot bien

HUdng dan

+ Dot bien xay ra d bp ba md dau va bp ba ke't thuc thuTdng dtfdc enzim sijfa chiya nen khong lam bien doi cau true cua protein

+ Dot bien thay the mot cap nucleotit: Can cxi vao bang ma di truyen de xac

dinh: Neu bp ba dot bien la ma ke't thuc thi chuoi polipeptit bi ngan lai, ne'u bp

ba dot bien va bp ba ban dau deu ma hoa mot axit amin thi cau true cua protein khong bi bien doi, neu bp ba dot bie'n ma hoa axit amin khac vdi bp ba ban dau (tru'dc dot bie'n) thi c6 the xac dinh eu the axit amin bi thay the

+ Ne'u mat hoac them mot cap niicleotit thi khung dpe ma di truyen bi chuyen dich Can ciJ vao bang ma di truyen de xac dinh cu the nhiJng axit amin bj thay the

Vidul:

Mot doan gen cau triic vdi cdc cap nucleotit chifa hoan ehinh nhuT sau: ' ^

3' ATG T A X GTA G X T 5 ' 5' T A X ATG X A T XGA 3' <i • -

1 Khi xay ra dot bie'n thay cap thuf 7 G - X bkng T - A thi cau true protein tufdng tfng se thay doi nhu" the nao? (thay histidin b^ng tirozin)

2 Khi dot bie'n mat 1 cap nucleotit thu" 5 la A - T chuoi polipeptit cd gi thay doi (toan bp axit amin bi thay doi)

3 Tru-dng hdp nucleotit thi? 10 la G - X bi thay thebdi A - T Hau qua gi se Xay ra trong protein du'dc tong hdp (chuoi polipeptit ngan lai)

4 Ma't 3 cap nucleotit d 3 bp ke'tic'p nhau thi cau true protein se thay doi nhir the' nao? (mat 1 axit amin va xua't hien 2 axit amin mdi)

Vidu2: V

Mot gen quy dinh tong hdp protein cd trinh tif:

Met - Gly - Glu - Thr - Lys ) i'

gen do bi dot bie'n da quy dinh protein c6 trinh trf:

Met - Arg - Glu - Thr - Lys

Day la dang dot bien nao? Hau qua vai tro cua no? ' t r ' ' "

Ca'm nang ti; On va luygn thi Sinh hpc - Phung Duy Dfl'ng

HUcfng ddn

+ Cap thu'4 la A - T bi thay the bang cap G - X

+ Tijy thupc vao vi tri va tinh cha't cua loai axit amin bi thay the': Ne'u axit

amin nSm d vi tri trung tam phan iJng thi enzim bi mat boat tinh Ne'u nam ct vi

tri khac ihi boat tinh ciia enzim van khong thay doi

Loai 2: Cac dang dot bien lien quan den lien ket hidro

HUdng ddn

+ Khi mat mot cap nucleotit c6 the giam 2 hoac 3 lien ket hidro

+ Khi thay the' mot cap nucleotit c6 the lam tang, giam mot lien ket hidro

+ Khi thay the cac cap nucleotit c6 the lam tang, giam hoac khong doi so

hen ke't hidro

+ Ne'u sau dot bien, chieu dai 2 gen b^ng nhau va so' lien ke't hidro khong

thay doi, thi chi c6 the xay ra dot bien thay the'nhieu cap nucleotit

+ Ne'u sau dot bie'n gen c6 chieu dai, so Wdng tilfng loai nucleotit, so' lien ke't

hidro deu khong doi nbiTng cau true protein lai thay doi thi do la dot bien thay

the cac eSp nucleotit

Vidu 1:

Gen dot bien gay benh thie'u mau binb lu"3i liem hdn gen binh tbtfcfng mot

lien ke't hidro nhu'ng 2 gen c6 chieu dai bang nhau Hoi dot bie'n lien quan den

bao nhieu cSp nucleotit va thuoc dang nao?

HUdng ddn

Vi chieu dai 2 gen bang nhau nen khong the xay ra ma't, hoac them cac cap

nucleotit Gen dot bie'n hdn gen binh tbiTcfng 1 hen ke't hidro chtfog to 1 cSp A =

T bi thay the bang 1 cap G = X

Vidu 2:

O ruoi gia'm, phan tuT protein bieu hien tinh trang dot bie'n m^t trang so vdi

protein bieu bien tinh trang mat do thi kem 1 axit amin va c6 2 axit amin mdi

Hay cho biet: '^•v';." :';V' v v ; v , , • ^^,<y

a) Nhi?ng bien doi xay ra trong gen quy dinh m^t do?

b) Gen quy dinh mat do dai bdn gen quy dinh m^t tr^ng la bao nhi6u A"?

c) Ne'u gen mat trang it bdn gen m^t do 8 lien ke't hidro tiT nhan doi 4 Ian thi

nhu cau tirng loai nucleotit doi hoi moi tru'dng noi bao cung ca'p giam di bao

nhieu so vdi gen m^t do

Hitdngddn

a) Nhi?ng bie'n doi xay ra trong gen quy dinh m^t do: Mat 3 cSp nucleotit

trong bo ba ke tie'p nhau

b) Chieu dai 1 cSp nucleotit tren gen bang 3,4A" tfif do c6 the suy ra chieu d^i

bdn kem nhau gii?a 2 gen

Cty TIMHH MTV DVVH Khang \,|a)

c) Gen mat trang it hrtn gen mat do 8 lien ke't hidro chiJng to gen mat tranj,

;n gen mat do 2 cap G = X va mot cSp A = T Tiir do c6 the suy ra nhu ciu ttrng

jjii nucleotit giam di bao nhieu

Vidu 3:

Gen CO 1170 nucleotit va A = -^G Gen nay bi dot bie'n tdng hdp mot phan

tij-pfStein giam xuo'ng mot axit amin va c6 2 axit amin mdi

t a) Tinh chieu dai cua gen bi dot bie'n?

b) Dot bie'n gen thuoc dang nao?

c) Ne'u so' lien ket hidro cua gen dot bie'n la 1630 thi gen dot bie'n c6 bao n|ii6u nucleotit moi loai?

f' Hiidngddn • '

a) Phan tijf protein do gen dot bie'n tdng hdp giam 1 axil amin cbiJng to da mat

3 cap nucleotit Suy ra:

- So nucleotit cua gen dot bie'n la: 1170 - 6 = 1164 nucleotit

- Chieu dai cua gen dot bien: (1164 : 2) x 3,4 = 1978,8 A"

b) Dang dot bie'n: Mat 3 cap nucleotit trong ba bo ba ma boa lien tie'p nhau

c) So nucleotit cua moi loai gen ban dau:

G = X=468 nucleotit

A + G=1170:2=585

So Hen ke't hidro cua gen ban dau: (117 x2) + (468 x 3) = 1638 lidn ket hidro

So lien ke't hidro giam: 1638 - 1630 = 8 hen ket hidro

| | => Ba cap nucleotit ma't di phai la: 2 cap G - X va 1 cap A - T

Do do so nucleotit moi loai cua gen dot bie'n la: ^ 'V*'

A = T = 1 1 7 - 1 = 116 nucleotit

G = X = 466 - 2 = 464 nucleotit ' T

PhiMng phap giai: f;

- Tim so' giao tiJf mang dot bien gen

- Tim tdng so giao tuf difde sinh ra Tiir d6 suy ra tan so dot bie'n gen

Widu:

Theo doi 100000 tre em sinh ra d mot nha ho sinh, ngiTcfi ta tha'y c6 10 em

'^n bam sinh, trong do c6 2 em c6 bd hoac me liin, cac em con lai bd me deu bmh tbuTcfng (sinh ra trong mot dong ho khong c6 ngi/cfi lun) Tinh tan so dot bie'n gen

HUdng ddn

- Bd me tbiTcfng ma con liin cbitng to la dot bie'n trpi

fl - Trir 2 trU"6ng hdp da c6 bd hoac me liln, con 8 triTdng hdp liin la c6 dot

^iS'n lun phat sinh trong giao tuT cua bd hoac me - '

dm nang ti/ 6n va luygn thi Sinh hpc - Phung Duy Ddng

- Do do so'giao tu" mang dot bien lun la 8

- Tong so giao tuT 100000 x 2 = 200000 (moi hdp tu^ diTdc tao ra tit 1 giao ty

- Ne'u dot bien khong lam thay doi so nucleotit (chieu dai gen khong thay

ddi) thi dot bien thupc dang thay the cap nucleotit

- Khi chieu dai gen khong ddi thi thay bao nhieu cap A - T se bang bay

nhieu cSp G - X

Vidu:

Bie't so'nucleotit mdi loai cija gen tru'dc dot bie'n la:

A = T = 450 nucleotit, G = X = 1050 nucleotit

Sau dot bien ti 16 —=43,27% G

Cho bie't dot bien da xay ra nhu'the'nao? Bie't rang chieu dai gen khong thay ddi

- So cap G - X bi thay bang so cap A - T diTdc thay

Goi X la sd^ cap nucleotit thay the (x nguyen difdng)

A 450+x

Ta CO phu-dng trinh: —= = 43,27% = 0,4327

G 1050-x Giai he phu'dng trinh ta c6: x = 3

Vay dang dot bie'n la thay 3 cap G - X bang 3 cSp A - T. itAi,

Loai 5: Xac dinh kieu hinh cua gen dot bie'n

Vidu:

d ngi/di, gen tdng hOp chuoi a - Hb do mot gen tren NST so 11 bi dot bien da

xuat hien nhieu alen Trong do alen A tdng hdp HbA, alen S tdng hdp HbS

NgUdi CO kieu gen SS bi benh thie'u mau hong cau hinh liem

Cho bie't:

- Ca the 1 cd: 98% HbA, 0% HbS, cac dang Hb khac cd 2%

- Ca the 2 cd: HbA = 0%, HbS = 90%, cac dang Hb khac cd 10%

- Ca the 3 cd: HbA = 45%, HbS = 45%, cac dang Hb khac cd 10%

Hay cho bie't nhffng ca the nao bi benh thie'u mau hong cau hinh liem

100

Cty TNHH MTV DWH Khang Vigt

HUdng ddn

- Gen nkm tren NST so 11, ti^c la NST thiTdng nen kieu gen cua moi ci the

ve gen nay phai cd 2 alen

- Ca the 3 cd mau chtfa HbA va HbS vdi ti le ngang nhau nen kieu gen la /vS Do dd khong bi benh thie'u mau hong cau hinh Hem

- Ca the 1 cd mau chi chiJa HbA nen kieu gen la AA Do dd cung khong

mac benh

I - Ca the 2 cd mau chi chiJa HbS nen kieu gen la SS Do dd bieu hien benh

Miig'u mau hong cau hinh liem

Lofli 6; Giai thich hien tufdng dot bien i

Vidu:

Cho chuot di binh thtfdng (AA) giao phdi vdi chuot nhay van (aa) thi trong tat

ca cac Ma hau het la chuot binh thtfdng, nhiTng trong dd cd mot con nhay van

Hien tiTdng tren du'dc giai thich nhiT the nao?

Hitdngddn

Cd the xay ra hai tru'dng hdp sau:

- Trudng hap J: Trong qua trinh giam phan cua kieu gen AA da phat sinh

dot bie'n giao tuf: A -> a Giao tiJf dot bie'n a ke't hdp vdi giao tuf a, d o kieu gen aa

ao thanh da tao ra thanh hdp tuT aa phat trien thanh chuot nhay van

Trudng hcfp 2: Cap NST chiJa cap gen AA cd mot NST bi mat doan trong

6 chiJa gen A Khi thu tinh NST ma't gen A ke't hdp vdi NST binh thudng chufa

gen a se tao thanh cap NST khong cd gen ttfdng tfng cua a ('la) vi vay, chi can

cd 1 alen Ian, tinh trang nhay van cung diTdc bieu hien ^ ^

2 Ve dot bien NST

•

Loai 1: Xac dinh loai dot bien

* Xac dinh loai dot bien tif ki hieu nhiem sac the

Phtftfng phap giai: So sanh vdi cau trijc ban dau cua NST de tun ra dang dot bie'n:

Vidu:

Mot cap NST tifdng ddng, mdi NST gdm 5 doan ttfdng (Jng: NST thu" nhat cd

Itac cap vdi ki hieu Ian Imt la 1, 2, 3, 4 va 5 NST thuT hai cd cac doan vdi ki hieu

Ian iifdt la a, b, c, d va e Tif te bao cd cap NST dd thay xuat hien:

• b) Mot nhdm te bao chtfa NST vdi ki hieu 2, 3, 4, va 5

c) Mot nhdm te bao chiJa cac NST vdi ki hieu la 1, 2, 3, 4, 5; 1, 2, 3, 4, 5 va a, , c, d, e Hay cho bie't cac hien tu-dng tren la gi? Lay vi du d ngufdi ve tri/dng hdp b va c

101

Ca'm n a i i q i i ( o t i v i i Uiyen thi Sinh hgc - Phung Duy 06'ng

Hxtdng dan

a) Do la giao tu" liinh thanh do trao doi cheo giffa cac cap NST ttfcfng dong

b) Do la hien tiTdng dot bien cau true NST dang ma't doan V I du NST so' 2]

mat doan gay ung thu" mau

c) Do la hien ttfdng dot bien di boi V i du: Cap 21 c6 3 chiec gay ra benh Dao

* Xdc dinh loai dot hien tCt ti le cue loai giao till

Phifdng phap giai: Tijf kieu gen c6 the biet ti le cac loai giao tur dtfdc hinh

thanh qua giam phan va ngu'dc lai

Vidu: Kieu gen Aaa khi giam phan phat sinh cac loai giao tu" c6 ti le nhu" sau:

l A : 2a : 2Aa : laa Do do khi bie't ti le cac giao tu' nhu" tren ta biet dot bien la

the lech boi dang Aaa ,

Tuang tu nhu tren:

- T i le cac loai giao tu": l A : la : l a i : l A a : l A a , : laai suy ra the dot bien

dang Aaa|

- T i le 2A : l A A : 2Aa : l a - > dot bien dang AAa

- T i le l A A : l A a -> dot bien dang AAAa

- T i 16 1 Aa : laa —> dot bien dang Aaaa

- T i le 1 AA : 4Aa : laa -> dot bien dang AAaa

* Xdc dinh loai dot bien tiC soluc/ng nucleotit moi loai ciia the dot bien

Phil'dng phap giai: Tim so' Itfdng nucleotit m6i loai cua gen ban dau roi so

sanh vdi so nucleotit moi loai cua the dot bien

Vidu:

• ' Mot cap alen Aa dai 0,408fim Alen A c6 3120 hen ket hidro, alen a c6 3240

lien ket hidro Do dot bien da lam xuat hien the dot bien c6 A = 1320 va G = 2280

nucleotit Hay cho biet do la the dot bien nao Kieu gen dot bien do

Hiidng dan

Gen dai 0,480^m => 2A + 2G = 2400

Dodo:

'2A + 2G=2400 2A + 3G=3120

! , So nucleotit cua A cua the dot bien la: 1320 = 2 x 480 + 360

i Do do: Dot bien la the lech boi

Loai 2: Xac dinh thanh phan gen trong moi loai giao tuT cua the dot bien lech boi

Phtfofng phap giai:

Neu c6 1 cap NST khong phan l i trong giam phan thi thanh phan NST trong

giao tuf tfng vdi cap do c6 the c6 ca 2 chiec hoac khong c6 chiec nao Tu" do suy

thanh phan gen cua giao tu"

102

Cty TIMHH MTV DVVH Khang Vi^t

Vi du 1: Xet 3 cap NST trfdng dong d ngifdi: cap NST thu" 21 chuTa 1 cap gen

di hdp; cap NST thiir 22 chtJa 2 cap gen di hdp va cap NST thiJ 23 chtfa mot cap gen dong hdp

a) Kieu gen tren 3 cap NST ttfdng dong do c6 the viet nhiT the' nao

b) Khi giam phan c6 hien tu'dng dot bien the di boi cap NST thii' 23, thanh

phan gen trong moi loai giao tuf khong binh thUdng sinh r a tu" kieu gen tren c6

ihe viet nhu" the' nao?

- Kie'ugenAa — X ^ X ^ v a A a — X ' ^ X ' ^

^ bd bD Cho cac loai giao tu" khong binh thu'cJng gio'ng nhau:

ABDX'^X^ AbdX^X^ aBDX'^X^ abdX''X^

AbdX'^X^ AbDX'^X^ A b D X ' ' X ^ aBdX''X^ ; ABDO, AbdO, aBDO, abdO, ' '

AbdO, AbDO, aBdO, abDO

- Kieu gen: Aa — X'^X'-' va Aa — X'^X'^ , ,

^ bd bD Cho cac loai giao tu' khong binh thu-dng giong nhau:

ABDX'-•X^ AbdX'''X^ aBDX^X", abdX'^X^

A B d X ' X ^ AbDX'••X^ aBdX'X^ abDX'-•X^

ABDO, AbdO, aBDO, abdO, AbdO, AbDO, aBdO, abDO

Vi du 2: Xet 2 cap NST thi? 22 va 23 trong te bao sinh due 2n d mot ngufdi

dan ong ngu^di ta thay c6 2 cap gen di hdp nam tren cap NST thuf 22 va 2 gen troi nam tren NST gidi tinh X Gia thiet NST Y khong mang alen

a) Neu qua trinh giam phan xay ra binh thu'dng thi c6 the hinh thanh nhieu nhat bao nhieu loai tinh trung? Vie't thanh phan gen cua cac loai tinh trijng do

b) Neu CO hien tiTdng dot bien di bpi cap NST thu* 23 thi thanh phan gen trong moi loai tinh triing viet nhtf the nao?

Ca'm nang tij fln va luygn thi Sinh hpc - Phung Duy Pa'ng

Ca 2 kieu gen khi c6 hoan vi gen d c&p NST thtf 22 se cho so loai tinh

trung nhieu nhaft va thanh phan gen viet trong cac loai tinh triJng do nhiT sau:

ABX°''.AbX"''\^ abX°^ ABY, AbY, aBY, abY

b) Dot bien di boi cap 23 thanh phan gen trong moi loai tinh triing la:

ABX^'^Y, AbX^'^^Y, aBX^^Y, abX'"'T, ABO, abO, aBO, abO

''^ Loai 3: Xac dinh kha nang hinh thanh so loai giao tiJT cua the dot bien

PhrfoTng p h a p g i a i :

Bict so" loai giao tuT = 2" (n la so'cap NST c6 cau true khac nhau, hoac so'cap

gen di help) Neu trong bo NST c6 n cap NST, trong do c6 I cap NST c6 cau true

giong nhau thi so lu-cfng giao tuT = 2 " " N e u co 1 cap NST tiTcfng dong c6 trao

ddi doan tai 1 diem sc cho 4 ca'u true NST Neu 1 cap NST khong phan li se cho

2 loai giao tu-doi vdi cap do, TiTdo suy ra kha nang hinh thanh cac loai giao tu-

Vidii:

d 1 loai, te bao sinh due 2n thifc hien nguyen phan lien tiep mot so Ian, doi

hoi moi tru^dng noi bao cung cap nguyen de hinh thanh nen 4826 NST dcfn mdi

Cac te bao con sinh ra tir nguyen phan cuo'i cung deu giam nhiem binh thu'dng

cho 256 tinh triing chiJa NST Y

a) Neu moi cap NST tUdng dong deu gom 2 NST c6 cau true khac nhau (triT

cap XX) thi kha nang cd the cai cho bao nhieu loai trtfng, ca the diTc c6 kha nang

cho bao nhieu loai tinh trCing?

b) Khi CO sir trao ddi doan xay ra mot cap NST tu'dng dong tai mot diem va sir

dot bien di boi xay ra d cap NST gidi tinh thi kha nang ca the cai c6 the cho bao

nhieu loai triJng, ca the diTc co kha nang cho bao nhieu loai tinh trung?

HUdng dan

a) So tinh triing chiJa NST Y bang so tinh triing chiJa NST X, nen so tinh

trung du-dc hinh thanh la: 256 + 256 = 512

- So' te bao 2n du^dc hinh thanh tu" Ian nguyen phan cuo'i ciang:

512 ' = 128 te bao con r i ' : ' ;

4

128 = 2' Vay tirte'bao sinh due 2n dau tien da nguyen phan lien tiep 7 Ian

2n = — ^ = 38 ( C O 19 cap NST)

- Ca the cai co kha nang cho 2"* loai giao tiif

- Ca the diro>c6 kha nang cho 2''-* loai giao tuT

b) Khi CO trao do'i doan va dot bien:

Cap NST tu'dng dong trao do'i doan tai 1 diem cho 4 cau true NST, cSp NST

gidi tinh d ca the cai (Idn) la XX dot bien dj boi cho 2 to hdp la XX va O Cap

NST d ca the di/c la XY cho 2 to' hdp la XY va O Do do: Ca the c6 kha nang

cho: 2'^ X 4 X 2 loai triJng Ca the diTc cd kha nang cho: 2'^ x 4 x 2 loai tinh trung

Cty TNHH MTV DVVH Khang Vi§t

Loai 4: Xac dinh so' lu-dng nucleotit mSi loai cua gen trudc dot bien tijr do suy

ra so' lirdng nucleotit mSi loai cua gen dot bie'n, cua giao tuT, hdp tuT tao thanh

Vidv:

Mot cap gen di hdp dai 3060 A", gen A co 20% Adenin, gen a co 15% Adenin

a) Dot bien 3n lam cho te bao co kieu gen Aaa

- Hay tinh so lu'dng tirng loai nucleotit cua kieu gen

- Te bao do giam phan cho bao nhieu loai giao tuT vdi th^nh phan gen vie't

nhu" the nao? Biet rang co 2 loai giao tuf 2n va n

- Tinh so lu'dng tijfng loai nucleotit cua moi kieu giao tijT ^ ^ ^

b) Dot bien 4n lam cho te bao CO kieu gen A Aaa ^

- Hay tinh so' lu'dng tijTng loai nucleotit cua kieu gen

- Te bao do giam phan cho bao nhieu loai giao tuT? Thanh phan gen vie't nhu the' nao? Biet rang chi cd loai giao tuT 2n

- Tinh so liTdng tiTng loai nucleotit cua moi giao tuT

+ So lu'dng tiJng loai nucleotit cua kieu gen Aaa

A = T = 360 + 270 + 270 = 900 nucleotit

" ' G = X = 540 + 630 + 630 = 1800 nucleotit

Cac loai giao tuT: 2Aa, aa, 2a, A ,,

So lu'dng tiJfng loai nucleotit cua moi loai giao tuf:

Cam nang t i / on va hiyen Ihi Sinli hoc - Phung Duy DS'ng

b) Dot bien 4n: So ItfOng tijfng loai nucleotit cua kieu gen AAaa

A = T = 360 + 360 + 270 + 270 = 1260 nucle6tit

G = X = 540 + 540 + 630 + 630 = 2340 nucleotit

+ So loai giao tiJ: lAA, 4Aa, laa

+ So' lu'Ong tifng loai nucleotit cua mSi giao tu"

- Giao tu" AA c6: A = T = 360 + 360 = 720 nucleotit

Do dot bien gen troi da tao thanh 2 alen tu'dng phan mdi la a va ai Gen A troi

so vdi gen a, gen a troi so vdi gen a| Do dot bien the di boi da tao ra cd the lai

Fi CO kieu gen Aaaj Cho cd the F, do tu" thu phan du'dc F2 phan li theo ti 16 27

cay cao: 8 cay cao trung binh: 1 cay tha'p

Hay bien luan va vie't sd do lai cua F|

Str ke't hdp giiya cac giao tijT difc va cai cho 36 kie'u to hdp (lap bang) trong do

19 kieu gen vdi ti 16 nhu" sau:

- Cac cay c6 kie'u gen chiJa A at cac gen a v& aj cho kieu hinh cay cao

- Kieu gen khong c6 A, gen a at cac gen ai va cho kieu hinh cay cao trung binh

- Ki6'u gen ajai quy dinh kie'u hinh thap

2 Cho cac cay di hdp 3n giao phoi vdi nhau du'dc F, c6 cay ki^u hinh than

cao, CO cay ki6'u hinh than thap

Bie't rang than cao la tinh troi so vdi than thap Hay vie't sd do lai

HUdng ddn

1 Quy ufdc A - Than cao a: Than tha'p

Kie'u gen cua cay 4n di hdp la AAAa, AAaa, Aaaa Khi giao phoi vdi nhau cay AAAa se cho F, toan than cao, vi vay cay di hdp 4n giao phoi vdi nhau c6 kie'u hinh than cao va than thap ki6'u gen la:

AAaa va Aaaa - Do do ta CO 3 sd do lai: 1

P G(P)

AAaa:—Aaaa:—aaaa 36 36 Kie'u hinh: — cay cao : — cay thap 36 36

P : Aaaa x Aaaa G(P) : Aa, aa x Aa, aa F| : lAaaa : 2Aaaa : 1 aaaa Ki6'u hinh: 3 cay cao : 1 cay tha'p

4 , 1 ^ 1

— Aaaa: — Aaaa:—aaaa

12 12 12 Kie'u hinh: — cay cao : cay tha'p 12 12

Ca'm nang tij 6n vSi luygn thi Sinh hpc - PhiJng Duy DO'ng

2 Cac cay di hdp 3n giao phoi vdi nhau diTdc F, c6 kieu hinh cay cao va kieu

hinh cay thap, kieu gen la A A a , Aaa

36

36

36 cay thap

i Fi giam phan cho cac loai giao tu" chia lam 6 phan Trong do c6 loai giao tuf

Ipiie'm ti le — Cd the 4n cho loai giao tuf chie'm ti le — phai c6 kieu gen AAaa

^ 36 36 36 36 36 Kieu hinh: — cay cao 120 cm

36 _8_

36 _18

36 _8_

ca'm nang tu On va luygn thi Sinh UQC - Phung Duy Pa'ng

— cay cao 100 cm , ,,: ,t^f^^„

(Cay thap nhat, khong c6 gen A, c6 mot gen A chieu cao tang them 5 cm, cay

cao nhat CO 4 gen A cao 120 cm) •

Vidu4:

O chuot nhat, gen A troi hoan toan lam cho chuot di binh thufdng Do dot bien

cau true mat di mot doan chiJa alen A lam cho chuot c6 kieu gen - a (dau " - " chi

gen da mat) Kieu hinh difde bieu hien la chuot di dUdng vong (nhay van) Cung

CO the do hien tu'dng dot bien gen A thanh gen a gay ra hien tu'dng do

1 Cho chuot bo' me c6 kieu hinh binh thiTdng, khong c6 hien tu'dng dot bien

giao pho'i vdi nhau du^dc F, c6 kieu hinh 75% la chuot binh thiTcJng, 25% la chuot

nhay van Hay vie't sd do lai

2 Chuot bo me eo kieu hinh binh thu"dng nhU'ng c6 hien tu'dng dot bien te'bao

sinh due cai trong giam phan nen cac chuot con F; sinh ra 50% c6 kieu hinh la

chuot binh thiTdng, 50% c6 kieu hinh la chuot nhay van

Giai thich va viet sd do lai

3 Cho chuot CO kieu hinh binh thiTdng giao pho'i vdi chuot nhay van Sd do lai

CO the viet nhU'the nao? , , ^

Kieu hinh: 3 di binh thiTdng : 1 nhay van

2 Chuot bo me binh thtfdng, c6 hien tifdng dot bien trong giam phan ,

-Kieu hinh: 50% chuot di binh thiTdng : 50% chuot nhay van

Trudng hap 2: Dot bie'n gen A thanh a, trong giam phan (dot bie'n giao tuT)

G(P) : A ^ a a A, a '

Fi : l A a : laa

Kieu hinh: 50% chupt di binh thiTdng : 50% chuot nhay van

Cty TNHH MTV DWH Khang Vij^

3 Chuot di binh thiTdng giao phoi vdi chuot nhay van;

Kieu hinh: 50% chuot di binh thifdng : 50% chuot nhay van

Trudng hap 3: Dot bie'n ma't doan:

a) P : A A x aa ^ ; ''

Fi : l A a : l a Kieu hinh: 50% chuot di binh thirdng : 50% chuot nhay van

-Trudng hap 4: Dot bie'n gen A thanh gen a

a) P G(P)

F,

A A X aa

A -> a X a

l A a : laa Kieu hinh: 50% chuot di binh thiTdng : 50% chuot nhay van.;

Aa X aa

A - > a, a X a , ,

aa (100% chuot nhay van), i

b) P G(P)

- Cac gen alen ciing quy dinh mot tinh trang, c6 nghla la phep lai chiu siT

i phoi cua quy luat tinh troi Quy iTdc: A: Cay cao; a: Cay tha'p

111