Cẩm nang tự ôn và luyện thi sinh học phần 2

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nang tij On vS luy$n thi Siiih hgc - Phung Duy £)6ng

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TOM

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Cty TNHH MTV DWH Khang Vigt

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

ChiTcfng 2.

I.

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NOI

DUNG

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 CO 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.

^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 ADN dan tdi cap doi nham (Vi du:
5 B U - A), lien ket sai (Vi 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
the kham.

in

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r;

+ 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 D W H 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.
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I. CAU HOI T i ; 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

Cty TNHH MTV D W H Khang Vi$t

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

nhU' v6 hai d o i v d i the dot bien.

Hudng

Hiidngddn
X e t d mitc do phan

nhieu dot bien d i e m 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.
-

chpn gid'ng.
C f i u 14: Giffa bie'n di to hdp va dot bien gen cd d i e m nao khdc nhau?
Hudng

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

-

Dang tien dot bien c6 the dtfcJc enzim suTa chffa nen khong gay tac hai g i .

-

M o t so dot bien geri c6 the l a m thay d d i chffc naijg cua protein theo hufdng

CO Idi cho the dot bien.
' -

*

"

TiJy to hdp gen va tiiy m o i triTdng dot bien c6 hai c6 the trd thanh c6 I d i .

C f i u 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.

truyen von cd d bo' me.
-

Dd^i v d i 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

- •

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

,

ddn

Chffa, V I con tiiy thuoc vao v i t r i 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

HUdng ddn
T a n so dot bien gen phu thuoc:

cap nucleotit l a m xuat hien ma ke't thuc d doan dau cua gen thi chudi polipeplit

-

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

cd the mat hau he't cac axit amin.

-

Dac d i e m cau true cua gen (ben vffng hoSc it ben vffng).

C f i u 9: L o a i dot bien nao c6 the xuat hien ngay trong d d i ca the?

Hudng

loai khac n h a u " . Theo em, cd dung khong?

CSu 10: T a i sao dot bie'n gen c6 tan so dot bie'n thap nhffng l a i 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.
C f i u 11: Trong hai loai dot bie'n trpi va iSn. L o a i nao cd vai tro quan trong hdn
doi v d i tien hoa? V i sao?

•

'

'

HUdngdhi
Dot bie'n iSn c6 vai trd quan trong hdn d o i v d i tie'n hda v i dot bie'n iSn i t
nghiem trpng hdn va lan tran trong qu^n the nhd qud trinh giao phoi.
C f i u 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?
i'

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

cd the l a m thay d d i trinh tff axit amin trong p r o t e i n " SGK Sinh hpc 12 - Nang
cao (trang 35) lai g h i : " N g u y e n nhan cua dot bie'n da bpi la do lai xa giffa hai

ddn

D o t bien xoma va dot bie'n tien phoi.

HUdngddn

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

N g u y e n 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

C f i u 15: N d i rang, dang mat hoac them mot cap nucleotit, l a m thay d d i nhieu

C&u 8: T a n so' dot bien gen phu thuoc vao yeu to nao?

:Jir>ii

ddn

Dot bien gen l a m thay ddi cau true cua gen, con bie'n di to hdp thi khong.

e n z i m sufa chffa.
"'

ddn

D e u la bie'n di di truyen, deu cung cap nguyen lieu cho qua trinh tien hda va

-

tiJT,

CSu 13: Dot bien g e n c o nhffng d i e m nao gidng v d i bien di to hdp?

Hudng

V i M i •:>•:>(!;

ddn

Dot bie'n thay the mot cap nucleotit khong lam dich khung dpc ma d i truyen
nen khong the l a m 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 b p i , 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) D o t bie'n gen k h o n g chi phu thuoc vao l o a i tac nhan, l i e u Iffdng, cffdng
dp cua l o a i tac nhan gay dot b i e n 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 l a m mat hoSc xen them mot cSp nucleotit tren A D N .
Hay phan tich cac y tren k h i ndi ve cd che dot bien.
t?

Hudng ddn

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 n d i den chat acridin la mot tac nhan gay dot bien mat hoac them mot cSp
nucleotit, khong he ndi g i ve cd che gay dot bie'n.

-


C^m nang tij On

Cty TNHH MTV D W H Khang Vi$t

luygn thi Sinh hpc - Phung Duy Dfi'ng

C a u 18: V e n g u y e n p h a n v a c d c h e ' p h a t s i n h d o t b i e n g e n , c a c sach c 6 nhiTng y

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

k i e n khac nhau:

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

-

Hitdng

V e n g u y e n p h a n : C o sach c h o r a n g : " N g u y e n n h a n g a y d o t b i e n g e n l a d o

-

^'

tac d o n g l i , h o a , h a y s i n h h p c d n g o a i c a n h h o a c r o i l o a n s i n h l i , h o a s i n h d t e

D o t b i e n ca'u t r i i c N S T CO v a i t r o nha't d i n h dd^i v d i tie'n h o a l a v i :

b a o " . C o sach c o n du'a t h e m m o t n g u y e n n h a n ni^a l a d o cac b a z d d a n g h i e m cap

-

-

V e c d c h e : C o sdch c h o r a n g : " C d che' p h a t s i n h d o t b i e n g e n l a : Su" k e t

c a p k h o n g d u n g t r o n g n h a n d o i v a tac d p n g cua c a c tac n h a n g a y d o t b i e ' n " . C o
sach k h i t r i n h b a y v e c d c h e p h a t s i n h d o t b i e n g e n d a d e c a p d e n 3 y :
l o a i tac n h a n g a y d o t b i e n m a con p h u thupc vao dac d i e m , c a u true cua gen.

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 s u n g v d i n h a u v a l a m p h a t
s i n h d o t bie'n.

t h a n h l o a i mdi. V i d u : N h i e u l o a i m u o i , q u a t r i n h d a o d o a n du'dc lap d i lap l a i
^ l i f t /'sStW'

IIAWJB

'J-i.'i^-'

D o t b i e n ca'u t r u e N S T c u n g c 6 v a i t r o 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 c a 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

-

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 r a y k i e n c u a m i n h .

N g i r d i t a CO t h e 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 .

dan
Sinh hoc Idp 10) v i v a y cho r a n g tac

-

(.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 c u a 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 g e n .

n h a n s i n h h p c l a v i r u t t h i chufa c h i n h xac.
+

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

khong m o n g muo'n.

3 - Chat 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 .

V i r u t k h o n g p h a i la sinh v a t ( S G K

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 t a o n e n n g u d n n g u y e n l i e u

t r d n c^c N S T d a gop p h a n t a o n e n l o a i m d i .

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

HiCdng

-

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

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 n h a n , l i e u l i f d n g , c i f d n g d p cua

+

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

>c4c a l e n m d i t r o n g q u a t r i n h t i e n h o a .

bo s u n g k h o n g d u n g k h i n h a n d o i .

B a z d d a n g h i e m k e t c a p 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 h o a h p c g a y d o t bie'n. C d che' g a y d o t

-

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 .

bie'n c u a b a z d d a n g h i e m l a d o c h i i n g c 6 nhiyng v i t r i H e n k e t h i d r o b i t h a y d o i

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 q u a k h a c n h a u

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 c u a

cho t h e d o t bie'n k h o n g ?

ADN

t h e o m a u l a p sai n a y m d i l a m p h a t s i n h d o t 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 t h e o 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 t h u p c v a o ye'u t o n a o . 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 g a y d o t b i e n . Nhu'ng v a n k h o n g d a y d u .

!,

ddn

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

Hitdng

ddn

• ' '

D o a n N S T b i dt?t g a y c d t h e x a y r a 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:
+

Co the dua ra nhu sau:

•^

D o a n d u t g a y d d a u m u t , c 6 t h e 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

i i y e n , t u y v a y luTdng v a t c h a t 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 q u a n g h i e m

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

' 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 k h i i

c a u t r u e c u a 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

i;nang b a o v e v a c 6 t h e l a m c h o N S T d i n h n h a u k h i b o a t d p n g g a y tac h a i c h o the

t r i n h n h a n d o i c u a A D N d a n de'n ke't c a p b d s u n g 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 t i a tuf n g o a i c 6 t h e l a m c h o 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 ) t a o r a cac d a n g t i e n d o t bie'n. C a c t i e n d o t bie'n t i e p tuc
, t

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 s i n h d o t bie'n.
C f i u 19: V i sao d o t bie'n c a u t r u e N S T thiTdng gay h a i c h o t h e d o t bie'n.
Hudng

+

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

+

D o t bie'n ca'u t r i i c 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
.s jjaaftt

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

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

dan

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 .

Jot bie^n.

iii:

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 t h e d o t bie'n thu'dng g i a m k h a n a n g s i n h s a n .
87


Cty TNHH MTV DVVH Khang Vigt

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

HUdng ddn

C a u 22: The da boi diTdc nhan bie't bang phu'dng phap nao?
Hudngddn
-

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

1. Gen quy dinh cau true ciia protein, tiif do quy dinh cac tinh trang (kieu
hinh). Co the mot gen hay nhieu gen quy dinh mot tinh trang.
2. Sir bieu hien kieu 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,

phat trien manh,...

con dai da so gen dong vai tro khac, khong quy dinh tinh trang nen khong bieu

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

hien thanh kieu hinh.
b) Trang thai cua gen: Trong te bao ciing c6 nhieu gen bat boat, khong boat
d6ng nen khong bieu hien thanh kieu hinh.

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.

c) V i tri 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 NST khac nhau, bieu hien k i e u hinh doc lap, gen nSm

b) Tac dong vao luc NST phan l i trong giam phan tao ra giao tuT 2n. Cho cac
giao tu^ 2n cijng loai ket hdp vdi nhau qua thu tinh tao ra the tiT da boi 4n.
c) Tac dong vao luc NST cua hdp tu" phan l i trong nhiJng Ian nguyen phan
dau tien tao ra dot bien ticn phoi, phat trien thanh cd the tu" da boi 4n.
d) Cho lai khac loai tao ra cd the lai xa roi gay dot bien 4n tao thanh c d the
song nhi boi (the dj da boi 4n).

tren NST thiTdng bieu hien khac gen nam trong NST 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 giai 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.

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

e) Cho lai giffa cd the 6n v d i 2n,...

, •

g) Cho the tiJboi 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

+

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 bd sung.

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

-

Tu'dng tac at che.

-

Tu'dng tac cpng gpp.

b) Tac dong vao luc NST phan l i trong giam phan tao thanh giao tuT 2n. Cho

c) Cho lai hifu tinh giffa cd the tu" boi vdi cd the lu'Sng boi.
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 vdi xac suat rat thap, v i tan so dot bien rat b6.

C a u 26: Hay trinh bay khai quat ve cd chephat sinh dot bien.
HUdngddn
Cac tac nhan gay dot bien tac dong va luc A D N nhan doi, luc N S T nhan doi,

<

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

Bang each:

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

lu! \

. •,

g) Sir tirdng tac v d i m o i tru'dng: Sir bieu hien k i e u hinh cua gen c6n chiu anh
hurdng ciia m o i tru'dng:
-

Ciing mot k i e u gen c6 the phan iJng thanh nhiTng k i e u hinh k h i c nhau

trong nhffng m o i tru'dng khac nhau.
-

M o i k i e u gen chi c6 the dieu chinh kieu hinh cua m i n h trong mot pham y i

nha't djnh (muTc phan uTng viTdt qua gidi han do, gen c6 the b i dot bien va bieu
hien k i e u hinh dot bien).
h) Bieu hien cua dot bien gen:

-

D o t bien xoma: Neu la dot bien trpi se bieu hien thanh the kham, neu la

dot bien Ian thi khong bieu hien.

•

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

-

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

cua A D N cua NST. TiT do phat sinh dot bien.

-

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

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

fifi

bieu hien 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 thi m d i bieu hien k i e u hinh.
Jki
i ) Gen binh thirdng hoac gen b i dot bien diTdc d i truyen qua cac the he va
dirpc bieu hien theo cac quy luat di truyen.
•

89


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

Cau 28: So sanh thiTdng bien va dot bien.
^ :tnK-ii QBti
oh Hi^ngddn
'
'
1
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
trinh chon loc).
^,,5.^
^.^.^.^
^
^
^
^
^
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.
b) Khac nhau:
- Bien di to hdp c6 sU to hdp lai vat cha't di truyen con dot bie'n c6 sir bien
(J6'i vat chat di truyen.
- Bien di to hdp luon xua't hien 6 the he sau. Dot bien c6 the xuat hien ngay
trong ddi ca the.
- Dot bien hen quan den moi tru-dng, con bien di to hdp thi khong lien quan
den moi triTdng, cd che phat sinh bien di to hdp la do sir phan li doc lap, hoan vi
va to hdp cua cac gen. Con cd che phat sinh dot bien la do tac nhan dot bien lam
bien doi cau triic cua gen ciaa NST, lam roi loan qua trinh nhan doi cua ADN,
qua trinh nhan doi, tiep hdp trao doi doan va phan li cua NST.
!: - 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.
">
B) Do sur chuyen doan cija NST.
91


Cty TNHH MTV DVVH Khang Vi^t

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

C ) Do cac tac nhan gay dot bien trong va ngoai cd the hoac do roi loan sinh
l i , sinh hoa trong te' bao.

D) Do N S T phan l i khong dong deu.

d'c^^jfi:'^

• ' •

CSu 4: Dot bien la gi?

'

f

gu 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.

i; ^

,

""

'' '

'

>

D) V i ca A , B va C.

A) La 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.

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

C ) La nhiyng bien ddi dot ngot ve cau true cua NST.

nguon nguyen lieu chu ye'u cua qua trinh tien hoa?

D) La nhi?ng bien ddi dot ngot, gian doan cua mot tinh trang.
CSu 5: The dot bien la gi?
A) L a nhiTng ca the mang dot bien da bieu hien tren k i e u hinh cua cd the.

(

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 td 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 NST.

B ) La nhi^ng bieu hien ra kieu hinh cua te'bao bi dot bien.

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

C ) La ca the b i dot bien.
D) La trang thai cd the cua ca the bi dot bien.

fl

moitri^ng.
D) V i ca 3 l i do tren.

CSu 6: T a n so dot bien la gi?
A) La tan so xuat hien cac ca the bi dot bien trong quan the giao phdi.

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 ) La ti le giao tuT mang dot bien tinh tren tdng so giao tuT diTdc sinh ra.

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

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

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

D) La t i le giffa ca the mang dot bien v d i tdng so ca the.

,

is.

D) M o t gen lan dot bien.

Cfiu 7: Dot bien xoma la loai dot bien:
A) X a y ra d te bao sinh diTdng.

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

B ) X a y ra tai cd quan sinh dxidng.

dpt bie'n thay the'mot cap nucleotit?

j

,, ,

C ) DiTdc nhan len nhd nguyen phan r d i bieu hien d mpt phan cd the.

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

D) Ca A , B va C deu dung.

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

,,

C) L u o n lam thay doi mot axit amin trong chuoi polipeptit.

CSu 8: Dot 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 giam phan.

C ) B i e u hien d giao tur.

D) Ca A , B va C deu dung.

D) Co the l a m cho chuoi polipeptit ngan l a i .
CSu 15: Dot bie'n nao sau day lam thay ddi ca'u true protein nhieu nha't?
B ) Ma't 2 cap nucleotit.

A) Dot bien xuaft hien vao giai doan dau cua sU phat trien phoi.
B ) D o t bien xuat hien d giai doan phoi phan hoa te' bao.

• -i ,
.n-'od'*^

i;;;;

')

D) Ma't 1 cap nucleotit ci v i tri cudi gen.
Cau 16: K h i noi ve dot bie'n NST dieu nao sau day la sai?
A) La nhu*ng bien ddi ve ca'u true NST, ve so lufdng cua mot cap N S T hoac tat

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

cacaccSpNST.

A) Dot bien gen k h i phat sinh diTdc k i e u hinh ngay ra k i e u hinh.

^'^

By Dot bie'n N S T la nhffng bie'n ddi ve cd scl vat chat di truyen d cap te'bao.

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

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

C ) Dot bien gen c6 the c6 Idi, c6 hai hay trung tinh.
D) Dot bie'n gen la loai dot bien xay ra d cap do phan tuT.

,\;':, a-i.

• C ) M a t 1 cap nucleotit d v i tri dau gen.

C ) Dot bien xua't hien trong nhi?ng Ian nguyen phan dau tien cua hdp tur.
D) Dot bien xua't hien trong qua trinh phat then cua phoi.

,

A) Ma't 3 cap nucleotit.

C a u 9: Dot bien tien phoi la gi?

^

I

doan, lech b o i , da boi.

D) Khong c6 cau nao sai.

oiii;.'

>


C a m n a n g lif o n va l u y Q n t h i S i n h h g c -

P h u n g Duy

Bdng

Cty T N H H

C a u 1 7 : K h i noi ve nguyen nhan gay ra dot bien NST d i c u nao sau day la chua
chinh xac?

,

; . .^sj^.

dSy khong dung?

'

B ) L a m thay d o i hinh dang, kich thu'dc cua NST. ' ' •
C) L a m thay d o i nhom gen Hen ke't cua NST.

D ) Tat ca A , B va C.

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

'

,

CSu 2 5 : H a u qua cua dot bien lap doan doi v d i ca'u true N S T la: ,

D ) Khong CO cau nao sai.
C a u 1 9 : K h i noi den dot bien mat doan, dieu nao sau day khong dung?
A ) Doan b i mat c6 the d dau mut, giffa canh hoSc mang tam dong.

>

i

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

; <>

B ) L a m thay d o i hinh dang kich thiTdc NST.

i., ^

C) Khong l a m thay d o i nhom lien ke't gen tren NST.

B ) X a y ra trong qua trinh N S T nhan d o i .

D ) Tat ca A, B va C.

CSu 2 6 : H a u qua cua dot bie'n dao doan d o i v d i cau true N S T la:

CSu 2 0 : 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 ) L a p doan l a m tang hay giam cu'dng do bieu hien cua tinh trang.

l\

A ) L a m cho cac gen tren N S T xa nhau hdn.

iI

B ) L a m cho cac gen tren N S T gan nhau hdn.

' -

C) Khong l a m thay d o i nhom lien ke't gen tren NST.

• -

D ) Tat ca A, B va C.

C ) H a u qua cua lap doan l a m thay d o i nhom gen l i e n ke't.

CSu 2 7 : H a u qua cua dot bie'n chuyen doan doi v d i cau true N S T la:

1
; i;

A ) L a m cho cac gen tren N S T xa nhau hdn, gan nhau hdn.

trong cap N S T ttfdng dong kep.

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

CSu 2 1 : Cau nao sau day khong dung?

C ) L a m thay d o i nhom lien ke't gen tren NST.

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

D ) Tat ca A , B va C.

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

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

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

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

B ) Cac doan trao d o i c6 the xay ra trong mot cap N S T 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.

i-.nr.:,;

1 8 0 " r 6 i dUWc n o i l a i .

D ) Tat ca A , B va C deu diing.
Cflu 2 2 : K h i de cap den dot bie'n chuyen doan N S T dieu nao sau day dung?

'' '•

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

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

dut v d i nhau.

•

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

trinh tu" nhan d o i cua NST.

,

.

C a u 2 4 : H a u qua ciia dot bie'n mat doan doi v d i cau true N S T la:

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

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

; v.^'

D ) Khong cau nao sai ca.

A ) Ccf che'gay dot bien NST la cac tac nhan gay dot bien l a m diJt gay NST.

D ) Doan b i mat, ne'u khong chiJa tam dong se b i thoai hoa.

•

C) D o N S T khong phan l i trong qua trinh phan bao.

hoc nhif 5 B U , acridin tac dong vao luc A D N nhan d o i .

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

Vigt

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

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

trinh phan l i cua N S T trong phan bao.

Khang

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

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

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

DVVH

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

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

D ) Cau C chtfa chinh xac.

MTV

B ) Doan N S T bj dao phai n l m d dau hay giiJa canh cua N S T va khong mang
f

tam dong.
C) Dao doan i t anh hu'dng de'n siJc song cua sinh vat do khong l a m ma't vat
chat d i truyen.
D ) Ddo doan l a m thay d o i trat tU s^p xep cac gen tren N S T nhiTng khong l a m
o

thay doi nhom gen l i e n ke't.

D ) Tat ca A , B va C deu dung.
'•

95


Ca'm nang l\f On va luy$n thi Sinh hpc - Phiing Duy Bfl'ng

Cty TIMHH MTV DWH Khang Vigt

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
B) SuT. moi, thiTa ngon, chet yeu.
C) Ngon tro dai hdn ngon giiJa, tai tha'p, ham be.

<

DAP

l.D
10. A

2. A
11.D

19. A

20. C
29. D

28. B

3. C
12. D
21. D
30. A

4. B

AN

13. B

5. A
14. C

6. B
15. C

7. D
16. D

8. D
17. D

9. C
18. D

22. D
31.D

23. D
32. D

24. D

25. D

27. D

33. D

34. D

26. D
35. D

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.
D)CaA,BvaC.

IV. B A I TAP

LUAN

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 TAX GTA GXT...5'
5' T A X ATG XAT XGA ... 3'
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'' "
k.,„.

97


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

Cty TIMHH MTV DVVH Khang \,|a)

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:
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.
.'^•v';.".

:';V'v v;v,, •

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.

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 tijpfStein 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?
Hiidngddn

f'

• '

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:
A= °

A=T^117 nucleotit
4
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
Loai 3: Xac djnh tan so' dot bie'n gen.
;
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

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.
g
- Ca the 3 cd mau chtfa HbA va HbS vdi ti le ngang nhau nen kieu gen la
Vay tan so dot bien gen la:
= 4x10"^
/vS. Do dd khong bi benh thie'u mau hong cau hinh Hem.
200000
- Ca the 1 cd mau chi chiJa HbA nen kieu gen la AA. Do dd cung khong

Loai 4: Tim dang dot bien khi bie't su" thay doi ve ti le cac loai nucleotit.
mac benh.
Phrftfng phap giai:
I - Ca the 2 cd mau chi chiJa HbS nen kieu gen la SS. Do dd bieu hien benh
- Ne'u dot bien khong lam thay doi so nucleotit (chieu dai gen khong thay Miig'u mau hong cau hinh liem.
ddi) thi dot bien thupc dang thay the cap nucleotit.
Lofli 6; Giai thich hien tufdng dot bien.
i
- Khi chieu dai gen khong ddi thi thay bao nhieu cap A - T se bang bay
Vidu:
nhieu cSp G - X.
Cho chuot di binh thtfdng (AA) giao phdi vdi chuot nhay van (aa) thi trong tat
Vidu:
ca cac Ma hau het la chuot binh thtfdng, nhiTng trong dd cd mot con nhay van.
Bie't so'nucleotit mdi loai cija gen tru'dc dot bie'n la:
Hien tiTdng tren du'dc giai thich nhiT the nao?
A = T = 450 nucleotit, G = X = 1050 nucleotit.
Sau dot bien ti 16 —=43,27% .
Hitdngddn
G
Cd the xay ra hai tru'dng hdp sau:
Cho bie't dot bien da xay ra nhu'the'nao? Bie't rang chieu dai gen khong thay ddi.
- Trudng hap J: Trong qua trinh giam phan cua kieu gen AA da phat sinh
HUdng ddn
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
A 450
ao thanh da tao ra thanh hdp tuT aa phat trien thanh chuot nhay van.
- Ti le cac loai nucleotit cua gen truTdc dot bie'n la: —=
=42,86%
Trudng hcfp 2: Cap NST chiJa cap gen AA cd mot NST bi mat doan trong

G 1050
6 chiJa gen A. Khi thu tinh NST ma't gen A ke't hdp vdi NST binh thudng chufa
- Sau dot bien gen khong thay ddi chieu dai ma ti le — tang (43,27%)
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.
^ ^
G
2. Ve dot bien NST
chtfng to dot bie'n thuoc dang thay cap G - X bang cSp A - T.
Loai 1: Xac dinh loai dot bien
- So cap G - X bi thay bang so cap A - T diTdc thay.
* Xac dinh loai dot bien tif ki hieu nhiem sac the
Goi X la sd^ cap nucleotit thay the (x nguyen difdng)
•
Phtftfng phap giai: So sanh vdi cau trijc ban dau cua NST de tun ra dang dot bie'n:
A
450+x
Vidu:
Ta CO phu-dng trinh: —=
= 43,27% = 0,4327
Mot cap NST tifdng ddng, mdi NST gdm 5 doan ttfdng (Jng: NST thu" nhat cd
G 1050-x
Itac cap vdi ki hieu Ian Imt la 1, 2, 3, 4 va 5. NST thuT hai cd cac doan vdi ki hieu
Giai he phu'dng trinh ta c6: x = 3.
Ian iifdt la a, b, c, d va e. Tif te bao cd cap NST dd thay xuat hien:
Vay dang dot bie'n la thay 3 cap G - X bang 3 cSp A - T.
itAi,
a) Giao tijT chufa NST vdi ki hieu 1, 2, 3, d va e.
;
Loai 5: Xac dinh kieu hinh cua gen dot bie'n

• b) Mot nhdm te bao chtfa NST vdi ki hieu 2, 3, 4, va 5.
Vidu:
c) Mot nhdm te bao chiJa cac NST vdi ki hieu la 1, 2, 3, 4, 5; 1, 2, 3, 4, 5 va a,
d ngi/di, gen tdng hOp chuoi a - Hb do mot gen tren NST so 11 bi dot bien da
, c, d, e. Hay cho bie't cac hien tu-dng tren la gi? Lay vi du d ngufdi ve tri/dng
xuat hien nhieu alen. Trong do alen A tdng hdp HbA, alen S tdng hdp HbS
hdp b va c.
NgUdi CO kieu gen SS bi benh thie'u mau hong cau hinh liem.
Cho bie't:
Cachothe
thebie't
cd:
98%ca=HbA,
0%
cacthie'u
dang
Hb hong
khac
cd 2%.
100Hay
-- Ca
231 cd:
nhffng
HbA
the
45%,
0%,nao
HbS
HbS
biHbS,

=benh
=90%,
45%,
cac
cacdang
mau
dang
Hb
Hbkhac
khac
cau
cdhinh
cd10%.
10%.
liem.
101
- 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
dvtc va 1 giao tiJcai).


Ca'm

n a i i q ii( oti vii

Cty TIMHH MTV DVVH Khang Vi^t

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 : lai : lAa : 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:
Ve alen A ta c6 he ph^dng trinh:

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

Ve alen a ta c6 he phuTdng trinh:

2A + 3G=3200
2A + 2G=240

A=480 nucleotit.

=> A=360 nucleotit.

! , 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 li 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

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 ra tu" kieu gen tren c6
ihe viet nhu" the' nao?
HUdng dan
a) Kieu gen:

Aa^X^X^
bd

Aa^X^X^
bD

(3)

Aa — X ' ^ X ' =
(2)
Aa—X'^X'^
bd
bD
b) Thanh phan gen trong moi loai giao tuf.

(4)

-

(1)

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^ AbDX''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?
HUdng ddn
a) Kieu gen cua te bao sinh due 2n d ngifdi dan ong:
^ X ^ ^ Y hay ^ X - ^ ^ Y
ab
aB
103

Cty TNHH MTV DVVH Khang Vi§t

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 t h t f 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 l i 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.
ri':.';
4
128 = 2'. Vay tirte'bao sinh due 2n dau tien da nguyen phan lien tiep 7 Ian.
2n =

—

^

= 38

(CO

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 X X 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.

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
b) Dot bien 4n lam cho te bao CO kieu gen A Aaa.
- Hay tinh so' lu'dng tijTng loai nucleotit cua kieu gen.
-

tijT.

^ ^ ^

^

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.
Hitdngddn
.

Gen co: ^ ^ ^ ^ xx2

2 = 1800 nucleotit
. 3,4 A "

« ''^^ J

-

Gen A co:

A = T = 20%.G = X = 30%
A = T = 1800x20% = 360 nucleotit
G = X = 1800x 30% = 540 nucleotit

Gen a co:

A = T = 15%.G = X = 35%
A = T = 1800x 15% = 270 nucleotit
G = X = 1800x 35% = 630 nucleotit

a) Dot bien 3n:
+ 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:
- Giaotu'Aacd: A = T = 360 + 270 = 630 nucleotit
G = X = 540 + 630= 1170 nucleotit
-

Giao tuf aaco: A = T = 270 + 270 = 540 nucleotit
G = X = 630 + 630 = 1260 nucleotit
Giao tuf A cd: A = T = 630 nucleotit
r'|*.i\
G = X = 540 nucleotit '

- Giao tufa cd:

A = T = 270 nucleotit
G = X = 630 nucleotit

"

«'ff'i**'

105


Cty TNHH MTV DWH Khang Vi|t

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
G = X = 540 + 540 = 1080 nucleotit
- Giaotu-Aaco: A = T = 360 + 270 = 630 nucleotit
G = X = 540 + 630 = 1170 nucleotit
- Giao tu: aa c6: A = T = 270 + 270 = 540 nucleotit
G = X = 630 + 630 = 1260 nucleotit
Lo^i 5: Lai ca the dot bien
Vidul:
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|
HUdng ddn
- Cay thap chie'm ti le:
^- = — . Ta c6: — — x —
• 27+8+1 36
36 6 6
- Kie'u gen Aaaj da giam phan 6 loai giao tu* vdi ti 16:
iAa:iAa,:iaa,:iA:ia:ia,

6 6 ' 6 ' 6 6 6
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:
36^:AAaa:—AAaa,:—AAajaj:—Aaaaj:—Aaa,a]:
6

' 3 6 ' ' 36
'36
1
2
2
2
2
2
—aaa,a,:—AAa:—AAa,:—Aaa:—Aaa,:—Aaia,:
36
' ' 236
36 ' 3 6
36 I ' 36
' '1
2
1 A A 2 ^ 2 .
2
: — A a 36
: — A a' |3: —6 a a :36
— a a '| :36
—ajaj
36raaa,:—aajaj:
' 36 ' ' —
36 A A 36
Ki6'u hinh: 27 cay cao: 8 cay trung binh: 1 cay thap
Ta nhan tha'y:
- 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.
106

Vidu2:
^
i
Co the 2n bi dot bien trd thanh cO the' 3n va cd the 4n, vi vay c^c gen dtfdc
xet trong cac cd the' do alen vdi nhau cijng quy dinh mot tinh trang.
1. Cho cac cay di hdp 4n giao pho'i vdi nhau drfdc Fj c6 cay kie'u hinh than
cao, cd cay kieu hinh than 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
AAaa
AAaa
P
1— AA:—:Aa:—aa
AA 4 ^ 1
1 AA 4^ 1
G(P)
6
6 6
— AA:-Aa:—aa
6 sau:6 6
vdi ti 16 nhir

F, . Co1 kie'u to hdp
1
- AAAA: —4 AAAa:—AAaa
36
36
36
4
16
J _
AAAa:—AAaa:—Aaaa
36
36
36
4
1
\_
36'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
p
:
Aaaa

x Aaaa
1 AAa:—aa
I ^
(I
4
1 ^ —
G(P) : —AA:—Aa:—aa x
16
6 6
2 2
1
1
4
F, • —AAAa:—AAaa:—AAaa
'
12
12
12
4
,
1
^
1
— Aaaa: — Aaaa:—aaaa
12
12
12
Kie'u hinh: — cay cao : cay tha'p
12
12

X

\

X


Cty TNHH MTV DVVH Khang Vi§t

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

4
2
2
4
— AAa: — A a a : — A A : — A a :
36
36
36
36
2
I
I
2
— Aaa:—aaa:—Aa:—aa.
'
36
36
36
36

,
7
33
3
^
i "
K i e u hinh: — cay cao : — cay thap.
36
^
36
^
'

2. Cac cay d i hdp 3n giao phoi v d i nhau diTdc F, c6 kieu hinh cay cao va kieu
hinh cay thap, k i e u gen la A A a , Aaa.
Co 3 sd do l a i :
*

P

:

G(P)

AAa

,>

AAa

1
— AA:—Aa:—A:—a
6
6
6
6

iAA3Aa:iA:ia
6

6

6

6

^-AAAA:—AAAa:—AAA:—AAaft
36
36
36
36

F,

2

4
4
2
-AAAa: — A A a a : — A A a : — A a :

36
36
36
36
2
4
4
2
— AAA: — A A a : — A A : -Aa:
36
36
36
3

K i e u hinh:

36 cay cao

i 36

P

Aaa

G(P)

^Aa:laa:lA:^a
6
6
6

6

F,

I'

X

cay thap.

. .

.

'"• ' '•'•
,
,

'

«

3:

Do dot bien nen cd the 2n trd thanh 4n. Cho Fi 4n tu" thu phan du'dc F2 gom 5
•>
1
loai kieu hinh phan l i theo ti 16 —
36

7
8
cay c6 kieu hinh cao 120 cm, — cay c6
3fi

•>
18
7
is
t
kieu hinh cao 115 cm, — cay c6 kieu hinh cao 110 cm, — cay c6 kieu hinh cao
36
^
36
'

t,

•

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

Ipiie'm t i le —. C d the 4n cho loai giao tuf chie'm t i le — phai c6 k i e u gen A A a a .

1
2
2
4
— AAaa:—Aaaa:—AAa:—Aaa:
36

3
36
36

2_

1
1
2
AAa:—Aaa:—AA:—Aa:
36
36
36
36
4_
2 ^
4
Aaas — a a a : — A a : — a a .
36'
36
36
36
27
9
K i e u hinh: — cay cao : — cay thap.
36
36
P
AAa
r

Aaa

1

—Aa:—aa:—A:—a
6
6
6
6

2
1
1
2
V
— AAAa:—AAaa: — AAA:—AAa ?
36
36
36
36
4
2
2
4
— AAaa: — A a a a : — A A a : — A a a :
36
36
36
36

Sddo lai:
F,

AAaa

:

G(F,) :

fl
-AA

16

—Aa:—aa
6
6
J

AAaa

X
X

1 A
A A
4 AA a : —1a a
—
A:—

6
6
6

1
4
1
— AAAA:—AAAa:—AAaa:
36
36
36
-iAAAa:l^AAaa:i-Aaaa:
36
36
36

•

— AAaa:—Aaaa:—aaaa.
36
36
36

'

1
1
8
18
8

K i e u gen:
—AAAA:—AAAa:—AAaa:—Aaaa:—aaaa
^
36
36
36
36
36
K i e u hinh: — cay cao 120 cm.
36
_8_
36
_18
36
_8_
36

108

'

.

•

Hudngddn

Aaa

— AA:—Aa:-A:—a'

6
6
6
6

-

1
1
1
Ta c6: — = — x —
36
6
6

-Aaaa:—-aaaa: — A a a : — a a a :
36
36
36
36

G(P)

- •

100 cm. Hay bien luan va vie't sd do lai cua Fi

^ - A A a : — A a a : — A a : —aa
36
36

36
36
35

Vidu

•

cay cao 115 cm.
cay cao 110 cm.
cay cao 105 cm.
109


Cty TNHH MTV DWH Khang Vij^

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

—

cay cao 100 cm.

,

,,:

,t^f^^„

3. Chuot di binh thiTdng giao phoi vdi chuot nhay van;
Trudng hap 1:

(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?

. ,

,

^

HU&ng ddn
1. Fi CO kieu hinh 75% chuot binh thi/dng : 25% chuot nhay van.
P

: Aa

X

: l A A : 2 A a : laa

^

Trudng hap 1: Dot bie'n ca'u true de ma't doan NST chtfa gen A.
Aa

G(P) : - a x A , a
Fi

'

.

'

,,,,,, ^

: l A - : l A a : laa : l a -

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)
P

:

Aa

X

G(P) : A ^ a . a
Fi

•

!«!

id

]

b) P : Aa X aa
G : -, a x a
Fi : l a - : laa (100% nhay van)
Aa X aa
c) P
A, - X a
G(P)
lAa : l a ;
F,

,

/.

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

Co 2 trudng h(fp:
X

.• .

Trudng hap 4: Dot bie'n gen A thanh gen a
A A X aa
a) P
A
-> a X a
G(P)

'

Kieu hinh: 3 di binh thiTdng : 1 nhay van

: Aa

' ^ b XK/:rii'yj^h:y-v

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

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

P

: A A X aa

G : A Xa
•>
F, : Aa (100% binh thirdng)
Trudng hap 2:
' r.
,
P : Aa X aa
G : A, a a
Fi : l A a : laa
it
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
^
;
''
G : A,-xa
x
Fi : l A a : l a Kieu hinh: 50% chuot di binh thirdng : 50% chuot nhay van.

Aa

G(P) : A, a A, a
Fi

P

Aa

A, a

'

: l A a : laa

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

b) P
G(P)
F,

Aa
A - > a, a

X

aa

X

a

, ,

aa (100% chuot nhay van), i

Vid^5:
"
Hai ca the c6 kieu gen khac nhau, nhiTng c6 mot nguon goc chung, v i vay cdc

ien cua chung da alen vdi nhau. Cac gen alen do ciing quy dinh mot tinh trang.
:ho 2 ca the Fi do giao phoi vdi nhau diTdc the he lai phan l i theo ti le 11 cay
sao : I cay tha'p. Hay bien luan va viet sd do lai.
HUdngddn
-

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


dm

Cty TNHH MTV DVVH Khang Vigt

nang lij On va luy$n thi Sinh hpc - Phung Duy Ddng

Ta CO cay thap chiem ti le: ~ =
= ^x— giao tur chiem ti le — c6
12 6 2 6 6
1 3^
the la giao tuf cua cay 2n, cung c6 the la giao tuf cua cSy da bpi
SPdo lai:
1. F,
X
AAaa
Aa
f
1

- A A : — A a : - a a X - A : 1- G(F,)
6
6 6
U 2
_1_
4
4
AAA:—AAa: —AAa:—j
The he lai —
12
12
12' '12'
12
12
Kieu hinh : 11 cay cao : 1 cay thap.
2. F|
:
AAa
x Aa
— AA:—Aa:—A:—a
iA:la
G(F,)
6
6 6 6
U2 2 , 2
1
1
2
2
1 1

The he lai : — A A A : — A A a : — A A a : — A a a : — A A : — A a : — A a : — a a
12
12
12
12 12 12 12 12
Kieu hinh : 11 cay cao : 1 cay thap.
3. F,
AAaa
: ^ 2 ^ 1 Aaa
x
1
^
2
1
1
— Aa:—aa:—A:—a
-AA:—Aa:—aa
G(F,)
16
6 6 ,
8
2
1
The" he lai 2
— A AAa:—AAaa:—Aaaa:—AAaa:
36
36
36 36
4
1

1
4
— Aaaa:—aaaa:—AAA:—AAa:
36
36
36 36
J_Aaa:AAAa:AAaa:-laaa.
36
36
36 36
Kieu hinh ^ cay cao : ^ cay thap = cay cao : ^ cay thap.
\

/

Aaa
X
AAa
1
1
^ AA 2^
2 1
— Aa:—aa:—A:-a
A
A
:
A
a
:
A:-a

6 6 6 6
6
6 6 6
2
4
4
2
The he lai: — A A A a:—A A aa:—A A a:—A aa:
36
36
36 36

4. F,
G(F,)

-LAAaa:AAaaa:AAaa:±aaa:
36

Kieu hinh

36

36

36

AAAa:±Aaa:i-Aa:i-aa.
36
36 36 36

33 cay
. cao : —
3 cay
. thap = —
11cay
^ cao : —1 cay thap.
—
36
36
1

^

AAaa
Aaaa x
3 3 ^ ^
4
1
—Aa:-aa
v6 6
— AA: —Aa:—aa
12 6 3 6 6
The he lai 3
— AAAa: — AAaa:—Aaaa
i!'!
36
36
36
3
12

3
— AAaa:—AAaa:—aaaa
36
36
36
^ cay thap. "'I'
Kieu hinh
12
33
3
^ 11 ^
— cay cao : — cay thap = — cay cao
6. F,
36
36
12 ^
^3 3 ^ x -AA:—Aa:—A:—a
Aaaa
x AAa 6
G(F,)
6 6 6
u- A a —aa
6 y
5. F,
G(F,)

A A

A

The he lai — AAAa:—AAaa:—AAa:—Aaa
36
36
36 36
—AAaa:—Aaaa:—Aaa:—aaa.
36
36
36 36
33 ,
3
11 cay cao : — cay thap.
cay cao : — cay thap = —
Kieu hinh —
36 '
36
12
12

Vidu6:

Cho bie't A: Qua ngot, a: Qua chua. Dem lai cac cay ti? bpi vdi nhau cho ket
qua d F| nhiT sau:
a) Tmyng hap 1: Phan li kieu hinh 3 qua ngot: 1 qua chua.
b) Tmyng hap 2: Xuat hien 350 cay qua ngot trong to'ng so' 420 cay.
'

HUdngddn

a) TriTdng hPp 1: Cay qua chua chiem
Do do: P : Aaaa x Aaaa

b) Tru'ctng hPp 2: Cay qua ngot chiem ti 16

^ ^^

=7
420 6
Do do cay qua chua chiem ti le - = - x 1
q ;
6 6 :,
=> P : AAaa x aaaa
Liiu y: Ve lai cac the dot bien c6 ra't nhieu bai tap, nhifng deu thupc 2 loai:
1. Loai thvtnhdt: Biet cong thiJc lai, tim kel qua lai.
PhiTdng phap giai loai toan nay nhU" sau:
a) TriTdc het phai xac dinh du-pc kieu gen cua bo me (P) tCf do xac dinh c6 bao
nhieu sP do lai.
,
(r r; ;G: ' 113


dm

nang tij On va luygn thi Sinh hgc - Phung Duy oa'ng

Cty TNHH MTV DWH Khang Vigt

b) X a c dinh so loai giao tu" c6 kha nang song va thanh phan gen cua m o i loaj

Sadolail:

giao tur diTOc h m h thanh tu" bo va me (Cd the 4n chi c6 giao tit 2n m d i c6 kha

nang song. C d the 3n thi giao tu" n va 2n deu c6 kha nang song).
c) Cho cac loai giao tuT cua bo', me ket hdp v d i nhau (lap bang). TCf do suy

P

X"X"

X^Y

G(P)

x"x^ox^Y

^

F,

IX^X^Y : I X ^ X ^ X " : 1 X ^ 0 : 1 0 Y .

,v..-^
'

,

(Con trai X^X^Y CO bieu hien benh m i l mau).

u" phan l i k i e u gen va k i e u hinh.

Vidu 2: M o t cap v d chong sinh d^dc 2 ngu'di con:

2. Lr^a/?M/ia/.-Bie't ke't qua l a i , t i m cong thi?c l a i .

Dtfa thiJ nhat c6 kieu hinh binh thiTdng, difa thu" hai c6 bieu hien benh Dao.

Phu"dng phap giai loai toan nay nhu" sau:

Cap v d chong nay c6 nhCng ban khoan:

a) X a c dinh so k i e u hinh lap chiem t i le bao nhieu ( V i du 6). HoSc t i m xem

1. T a i sao l a i sinh ra diJa con thu" hai nhu* vay? D o v d hay chong?

CO k i e u hinh nao chi chiem mot phan trong tdng so cac phan k i e u hinh dtfdc sinh

2. N e u sinh con ni^a thi diJa tre sinh ra c6 bieu hien bdnh Dao hay khong?

ra (xem v i du 3)

3. Ngu'di b i benh Dao c6 kha nang sinh con hay khong? N e u c6 thi con hp se

b) Xac dinh nhi?ng k i e u gen nao sinh ra t i le giao tu'tren.

nhiT the nao? Hay giai dap ban khoan noi tren.

c) Tu" do suy ra cac sd do lai va giai tijfng sd do l a i .

Hudngddn

Loai 6: G i a i thich cac hien ttfdng dot bien.

'

1. DiJa con binh thudng la do sif tai to hdp gii?a triJng b i n h thifdng (n) v d i tinh

Vi du 1: Do dot bien nen- c6 nhiJng cd the c6 NST g i d i tinh la X O hoSc X X Y .

trung binh thtfdng (n).

^ Cung do dot bien, c6 nguTdi c6 gen Ian nam tren N S T g i d i tinh X va bieu hien

DiJa con khong binh thiTdng (bieu hien benh Dao) la do trong qua trinh giam

thanh benh m u mau.
1. M o t cap v d chong, ca 2 c6 k i e u hinh binh thtfdng hp sinh mot dtfa con gai

phan phat sinh giao tuT cap NST thur 21 khong phan l i nen da tao thanh 2 loai giao
tuf: M o t loai c6 ca 2 chiec cua cap 21 (n + 1). mot loai

X O , bieu hien benh m i i mau.

khong

chuTa chiec nao cua

Hay giai thich hien tu'dng nay.

cap 21 (n - 1). K h i thu tinh, giao tuf thifa 1 chiec cua cSp 21 ket hdp giao tuf binh

2. M o t phu nff bieu hien benh mu mau, ket hon v d i mot ngiTdi c6 k i e u hinh

thirdng tao thanh hdp tuf cap 21 cd 3 chiec phat trien thanh benh Dao.
Su" g i a m phan khong binh thu'dng c6 the tijf te bao sinh tinh triing hay te bao

binh thu^dng. Hp sinh drfdc mot dtfa con trai. Neu diJa con trai nay c6 N S T gidi
tinh la X X Y , khong bieu hien benh m i i m ^ u hoac c6 bieu hien m i l mau thi giai

sinh triJng. V i vay nguyen nhan gay ra benh c6 the do v d ho^c chong.

thich ra sao?

T u y nhien, nhiTng nghien ciJu tren the gidi cho bie't t i le b i benh Dao tang len
'

Hudngddn

1. G i a i thich hien tu'dng:
Quy urdc X'^: K h o n g bieu hien benh m i i mau.
X^• Bieu hien benh m i i mau.
Con gai X O nhan X " tCf me va O turbo.
Bo me CO k i e u hinh binh thiTcfng. Sif giam phan te bao sinh due cua b d c6
hien tu'dng dot bien the d i b p i .
Sddolai:
P

:

G(P)
F,

X^X"xX^Y

:X^rxX^Y,0

: I X ^ X ^ Y : I X ^ ^ Y : I X ^ O : I X ' O (con gai bieu hien benh).

2. Con trai X X Y cd va khong bieu hien bpnh m i i mau.
Co the giai thich bang sd do sau:
Saddlail:
^

P

: X^X^xX^Y

G(P)

: X" x X ^ Y , 0

F,

: I X ^ X ' - Y : IX^O.

(Con trai X ' ^ X ' Y khong bieu hien benh m i i mau)
114

X

,.

Cling

f

vdfi tuoi ngu'di me do sif giam phan d ngtfcli phu nif l<3n tuoi de xay ra khong

binh thtfdng.
2. N e u sinh diJa con niJa thi cung c6 kha nang b i benh Dao, nhu'ng ra't hiem,

vi tan so' dot bien rat be.
3. Ngu'di bi benh Dao thtfdng v6 sinh, do sir giam phan gSp nhieu trd ngai trong

qua trinh tiep hdp, phan l i . Tuy nhien cung c6 the c6 kha nang sinh con. TnTdng hdp
nay k h i giam phan se hinh thanh cac loai giao tuf: n, n + 1, n + 2, n - 1.
Chi CO giao tu" n ket hdp v d i giao tuf binh thiTdng se sinh con binh thu'dng, con
cac loai giao tufkhac se khong tao ra con binh thifdng diTdc (bi dot bien lech bpi).
Nhtf vay con cua hp c6 den 75% bi dot bien lech b p i .
Vi du 3: M e n Hb^ g a y benh thie'u m a u hong cau h i n h l i e m alen H b ' quy
\h k i e u h i n h b i n h thifdng. K i e u gen d i hdp H b ^ H b ' g a y benh thie'u m a u
\g cau h i n h l i e m nhe.
1. M o t cap v d chong sinh diTdc mot diJa con bieu hipn benh thie'u mdu hong
cau hinh l i e m nhe. K i e u gen cua b d me c6 the nhuf the' nao?
2. N e u cap v d chong sinh diTdc mot dtfa con c6 k i e u hinh binh thtfdng, k i e u
I hinh cua cap v d chong do c6 the nhU the nao?

115


Ca'm nang ti; 6n

luygn thi Sinh hge - Phung Duy D8'ng

3. M o t cap vd chong sinh difrtc mot diJa con bi thieu mau hong cau Mnh l i e m
bi chet luc 2 tuoi. K i e u gen ciia cap vd chong do nhif the nao?
4. Ba n o i va ba ngoai deu bieu hien benh thieu mau hong cau hinh Hem
nhc, ong ngoai va ong noi c6 kieu hinh binh thu'dng, bo me sinh diTcfc 2 ngiTdi
con, diJa thiJ nhat che't v i benh hong cau hinh l i e m , du'a thiJ hai b i benh hong
cau hinh l i e m nhe.

Vi du 4:

6 ruoi

dain gen n tren NST

thu'dng, gen dot bien N tren NST gidi tinh X quy dinh canh c6 mau nho.
K h i l a i ruoi diTc hoang dai c6 canh binh thiTdng ( X " Y ) v d i rudi cai dot bien
(X^X") canh CO nhiyng mau nho thi:
1. F| xua't hien kieu hinh theo t i le: - ruoi di/c c6 cdnh binh thu'dng, - ruoi
3
3
c^i c6 canh binh thu'dng va ^ rudi cdi c6 canh c6 nhffng mau nho.

-

M o i du'a con da thijfa hiTdng gen cua bo me nhu' the' nao?

-

Neu bo me tic'p tuc sinh con nu"a thi kha nang c6 the xuat hien duTa tre c6

kieu hinh binh thu'dng khong? Giai thich?

2. T i le giffa rudi difc va rudi cai d F, la 1 diTc : 2 cai. Cf F2 la 3 di/c : 4 cai.
3. T i le dang hoang dai va dang dot bien d F , la 1 dot bien : 2 hoang dai. 6 F2

HUdng dan

la: 1 dot bie'n : 6 hoang dai.

1. DiJa con c6 bieu hien benh thieu mau hong cau hinh \\idi l i e m nhe. K i e u

Hay giai thich cac hien tU'(?ng tren.

gen ciia du'a con do la: Hb^Hb' nhan mot giao i\i cua bo va mot giao tuf cua me.
Kieu gen cua bo'me c6 the nhtf sau:

tinh X quy dinh dang canh binh

gidi

,,

'

HUdngddn

..

1. L a i ruoi difc hoang dai (X"Y) vdi ruoi cai dot bien (X^X")

a) P: Hb'Hb^ (me) x Hb'Hb^ (bo)

P

: X"Y

b) P: Hb'Hb^ (me) x Hb^Hb^ (bo)

G(P)

: X",Y

c) P: Hb^^Hb' (me) x H b ' H b ' (bo)

F,

: 1 X ^ X M X " X M X " Y : IX'^Y (chet)

(khong CO kieu gen Hb'^Hb^ vi bi benh thieu mau nang thiTdng chft't tru'dc 2 tuoi).

Rudi diTc X^Y bi chet, nen Fj chi xuat hien 3 loai hinh:

X

X^X"
X^X"
*

'

2. Du'a con c6 kieu hinh binh thu'dng.

oj

K i e u gen cua du'a con d6 la H b ' H b \n cua m o i bo me giao tur H b ' . Do do:

^X^X"

(rudi cai c6 mau) (1 dot bien)

_^

^ X"X"

(ruoi cai canh binh thifdng) (hoang dai)

iv

K i e u gen cua bo me c6 the nhU' sau:
a) P: H b ' H b ' x H b ' H b ' ( K i e u hinh bo me binh thifdng).
b) P: Hb^Hb' x H b ' H b ' ( M o t ngu'di binh thiTdng mot ngiTdi thieu mau nhe).
^ X " Y (ruoi diTc canh binh thiTdng) (hoang dai)

c) P: H b ^ H b ' ; Hb'Hb" (Ca 2 deu thieu mau nhe)
3. Con b i thieu mau hong cau hinh l i e m b i chet luc 2 tuoi, c6 kieu gen la
H b ' H b ' . Do do b d me deu phai c6 gen Hb^ => P: Hb^Hb'x Hb^Hb^
binh thu'dng c6 kieu gen Hb^Hb' truyen cho me gen Hb'. DuTa con chet c6 kieu gen
Hb^Hb^ nhan cua moi b d me 1 giao tur Hb^. V i vay b d me deu c6 gen Hb^.
Du'a con thiJ hai b i thie'u mau hong cau hinh l i e m nhe c6 kieu gen Hb^Hb'
5. Neu b d me tiep tuc sinh con ni^a thi c6 kha nang xuat hien tre c6 kieu hinh
,,^
'

I

X^X"
x^x"

: x"Y

b) F,

X

, ( M l

'ifM

/ , , •^'::v:^>>;,.:
'

x-x"
X"

y .

; /;

; .''^

•/-%fp/,;''

-I'^ii'-jy'

: I X " X " : 1X"Y

F2

Chung

cho ca 2 phep lai ta c6:

;
;

'

•

; >

3X"X" ( ? hoang dai): 3X"Y {S hoang dai): I X ^ X " ( $ dot bien)
Dod6liledF2la:3dirc:4cai
1 dot bidn : 6 hoang dai.

Hb'.Hb'

: IHb'Hb^ 2Hb^HbMHbW.

x

: ^ X ^ X " : ^ X " X " : ^ X " Y (X'^Ybjchet)

Tinh

binh thu'dng Hb*Hb' xac sua't 25% theo sd do sau:

^^u.|J,,^

: X"Y

G(F,):X",Y

G(F,):X",Y

nhan giao tuf Hb^ hoac cua me hoac cua bd.

: Hb^Hb'

a) F ,
F2

Do do kieu gen cua P: Hb^Hb'xHb^Hb'

, , B d m e : H b ' H b ' x Hb^Hb*

'

3. 6 Fi xay ra 2 phep lai:

4. Ong noi binh thu'dng c6 kieu gen H b ' H b ' truyen cho b d gen H b ' . Ong ngoai

G

2. V i i CO ti le 1 difc : 2 cai. 1 dot bie^n : 2 hoang dai.

:''p'Sir^^ •


cam nang tij on va Iuy6n Ihi Sinh hpc - Phting Duy Pgng

Cty T N H H M T V D W H Khang Vigt

Vi du 5: 6 tarn dau (2n = 28) gidi tinh cai difdc quy dinh bdi cap NST X Y ,
gidi tinh diTc dtfcJc quy dinh bdi cap NST X X . Gen quy dinh mau sac trijrng nam
tren cap NST so 10. M e n A xac dinh trtfng mau trang, alen a quy dinh tru-ng mau
xam den. Tit 2 noi tam triJng trang va triJng xam den, ngu'di' ta da tao diTOc 2 noi
tam ma khi lai vdi nhau se cho ^ so triJng mau xam den, nd toan tam cai va -

2. Do'i vdi noi tnJng mau x i m den.
X''
d6t bien
a) 9 ^ ^
^

i.\

so triJng c6n lai cd mau trang nd ra toan llm d\ic. (Ken tam dufc cd nang sua't td
tang trung binh 30% so vdi ken tam cai vi vay ngiTdi ta chi suf dung ken tam di/c
de siin xua't td). Hay giai thich ngiTdi ta da tao ra 2 dong tam nay nhu" the nao?

HMngddn

+

Y

chuyfin doan

Y

TCf loai ca the nay se cho triJng mang NST X ' va NST so 10 khong mang
en a ( - X").
2^

dot

b) c5

bie'n

X"

;—'-r~,
a

X

chuytn doan

-

> —=•

^

^

TuT loai ca the nay se cho tinh trung mang X" va NST so' 10 khong mang
en a (-X").
va

Hal noi tam ma khi cho lai vdi nhau cho: - so trtog mau trang nd ra toan

2
tam du-c va - con lai mau xam den, nd ra toan tam cai. Chtfng td tinh trang mau

2
sac triJng lien ke't vdi gidi tinh => gen xac dinh nd nam tren NST gidi tinh.

c) Cho tnJng (-X") ket hdp vdi tinh trilng (-X") se tao thanh hdp tu^ =

—
X"
iii tren thanh con diTc cd NST so 10 khong mang gen quy djnh mau s^c ma cd
T X mang gen a quy dinh mau xam den.
XA A
P3. Cho lai noi tam cai trtfng trang dot bien
vdi noi tam di/c trtfug

+ T i le 1 : 1 nay la ket qua cua phep lai phan tich.

P

: $ X^Y

cJX" X"

X

G(P) : - X ^ , - Y

X"

+ V i gen quy dinh mau sac trtfng n^m tren NST thtf 10. Do vay, de cd diTdc
2 noi tam tren, ta phai gay dot bien chuyen doan NST mang gen xac dinh mau
sac tru-ng tiT NST thu" 10 sang NST gidi tinh X, nhif sau:
1. Doi vdi noi tam tri^ng trang:
N O — —

gay d6l bien

'

chuyd'n doan

^

Y

2^

^

_ 2^

^

A Y

Tam cai dot bien nay se cho triJng mang NST Y va NST so 10 khong
mang gen A ( - Y )
A
b)

A

X

g ay doi

bia'ii

^ _

=

=

gay noi Dieii ^

^

^

c h u y e n doan

_

X

Tam difc dot bien nay se cho tinh trung mang NST X^ va NST so 10
khong mang gen A (-X'*').
c) Cho tnJng ( - Y ) ket hdp vdi tinh trung ( - X'^) se tao thanh hdp t^ =

18

ch hien tu-dng tren.
1^
HUdngddn
• O loai nay, nhieu phan tren mot NST cd cMc nang tu-dng tiT nhU" tam dong.
phdng xa lam dut NST thanh nhieu doan nhd, cac doan nho cd chiJa chi^c
'ng nhu- tam dong trd thanh NST doc lap, lam cho so Itfcfng NST trong te bao
Ig ma khong lam thay doi ham lu-dng A D N trong te bao do.
J TAP VAN DVNG
Hay van dung cac phu-dng phap giai cua tijfng loai toan da de cap de'n d tren,
i ciic bai tap sau:

X^
Y

phat trien thanh con cai cd chtfa cap NST so 10 khong mang gen quy dinh m^u
sac, ma cd NST X mang gen A quy dinh mau trtfug trang.

den dot bien se cho — so' triJng mau xam den nd ra toan tam cai va — so'
2
2
g mau xam den nd ra toan tam difc nhu" sd do lai d tren.
Vidu6:
Mot loai cay cd bo NST Itfdng boi 2n = 24. Ng^di ta phdng xa hat cua loai
y do khi trong phoi mam cac NST trong te bao con chtfa ti/ nhan doi.
Quan sat diTdi kinh hien vi cac phien trung k i cua Ian phan bao dau tien cua
bao phoi mam ngu-di ta thay so lifdng NST Idn hdn 24, tuy nhien ham Itfdng
p N trong te bao khong doi so vdi te bao chiJa bo NST lu-dng boi 2n. Hay giai

2
i 1: Mot gen chi huy tong hdp chuoi pohpeptit gom 498 axit amin cd — = - .
G 3
bie't dot bie'n xay ra khong lam thay doi so nucleotit cua gen.
1. Mot dot bie'n xay ra lam cho gen sau dot bien cd ti le — = 66,48%. Dot
G
In thuoc dang nao cua dot bie'n gen?
119


d m nang tij 6n

Cty TNHH MTV D W H Khang V i g t ^

luygn thi Sinh hpc - Phung Duy D6ng

2. M o t dot bien xay ra l a m cho gen sau dot bien c6 t i Ic — = 66,85% • Dpt
G
bien noi tren da l a m cho cau true cua gen b i thay ddi nhU' the" nao, thupc dang

nao cua dot bien gen?

D o t bien xay ra trong gen B l a m ma't mot axit amin chtfng to dot bien dang

mat 3 cap nucleotit ke tiep nhau chiJa trpn trong 1 bp ba ma hoa.
-

A x i t amin thu" hai iJng v d i bp ba ma hoa thii: ba tren mach ma go'c.

V a y dot bien l a m mat bp ba ma hoa d v i t r i thiir ba cua gen.

Hudng dan
1. Gen' ban dau chi tong hdp chuoi polipeptit gom 498 axit amin, chiJng to
gen do CO so'nucleotit la:
[(498 X 3) + 3 (nucleotit cua bo ba m d dau) + 3 (nucleotit cua bo ba k e t thijc]
X 2 = 3000
So'nucleotit tufng loai cija gen:
A + G = 3 0 0 0 : 2 = 1500
Ta CO he phu"cfng trinh:

HUdng ddn
-

' "

''^^

A_2

B a i 3: Gen A quy dinh mat mau do, alen dot bien a quy dinh mau mat hong. K h i

2 gen n o i tren ciJng tai ban 4 Ian thi m o i triTdng noi bao cung cap cho gen mat do
nhieu hPn gen quy dinh mat mau hong 90 nucleotit tiT do.

D o t bien gen da cho t i le: ^='^=66,61%

g i a m xuong thanh 66,48% v i so

3

It/dng nucleotit trong gen khong thay ddi nen so loai nucleotit loai A giam cung
bang so' nucleotit loai G tang.
Gpi X la so nucleotit loai A giam d i do dot bien, ta c6 phiTdng trinh:

Trong gen dot bien c6 the xay ra cac tru'cfng hdp sau:

;

Giai phufdng trinh ta c6 x = 1.

+

Ba cap nam trpn v e n trong 1 bp ba ma hoa.

+

Ba cap thupc hai bp ba ke tiep nhau tren mach ma goc. N e u xet thiJ tif

tijr trai sang phai thi c6 the xay ra hai triTdng hdp:
- H a i nucleotit cua bp ba ben trai con 1 nucleotit cua bp ba ben phai.
-

M o t nucleotit d bp ba ben trai, con 2 nucleotit cua bp ba ben phai.

b) Ma't 3 cap nucleotit nam trong 3 bp ba ke" tiep nhau: dan den mat 1 axit
amin, xuat hien 2 axit amin m d i .
c) Ma't 3 cap nucleotit nam r a i rac d cac v i t r i khac nhau trong gen dan den

Al^ = ^
= 66,48% = 0,6648
G +x
900 + x

dich khung doc ma d i truyen tai nhieu v i t r i khac nhau, gay hau qua tai hai hdn
1 ''

cdc tru'dng hdp tren.
B a i 4: Gen A ma hoa 498 axit amin. M o t dot bien xay ra l a m cho gen nay mat

Nhir vay dot bien da l a m thay ddi 1 cap A - T bang 1 cap G - X .

mot doan g o m 6 nuclcolit. K h i tdng hdp A R N thong tin tiJT gen da b i dot bien m o i

Dot bien dang thay the 1 cap nucleotit nay bang 1 cap nucleotit khac.

triTdng noi bao da cung ca'p 7485 ribonucleotit tuf do. Gen dot bie'n da sao ma bao

2. D o t bien l a m cho t i le — tiT 66,67% tang len 66,85%. Chi?ng to so
G
nucleotit loai A tang. Tat nhien so nucleotit A tang len bang so nucleotit G giam

nhieu Ian?
Hiidng ddn
-

..oK ft. X ;

•

S d b p ba cua gen A : 498 + 2 = 500

nu;

Suy ra so nucleotit cua gen bang: 500 x 3 x 2 = 3000 nucleotit

di, nen ta c6 phu'dng trinh:
600+x
900-x
'

,

a) M a t 3 cap nucleotit ke tiep nhau gom:

G = X = 900 nucleotit

G

M o i gen dot bien b i mat: 90 : (2^ - 1) = 90 : 15 (gen) = 6 nucleotit

hay mat 3 cap nucleotit

Giai he phiTdng trinh ta c6: A = T = 600 nucleotit

-

_

Hiidng ddn
-

-G~3

^

Hay xac dinh nhffng k i e u bien d d i c6 the xay ra trong gen dot bien.

= 66,85% = > x - l

Nhir vay dot bien da lam thay ddi mot cSp G - X bang mot cSp A - T . Dpt

bien dang thay the" cap nucleotit nay bkng cSp nucleotit khac.
B a i 2: Dot bien xay ra trong gen B lam mat axit amin thu" 2 cua chuoi pohpeptit do
gen do tdng hpp. Hay xac dinh dang dot bien va v i tri dot bien xay ra trong gen do.

-

r,iv

Gen mat mot doan gom 6 nucleotit. Suy ra mach mang ma gdc mat 3 nucleotit

ke tiep nhau. Do do mach mang ma gdc ciia gen dot bien c6 1500 - 3 = 1497
nucleotit hay mach m A R N do gen phien ma c6 1497 ribonucleotit. So Ian sao
ma (phien ma) tir gen dot bien la: 7485 : 1497 = 5 Ian.
B a i 5: Gen A quy dinh mau mat do l a m mat 3 cap nucleotit va tao thanh alen a
hoac a|.

^^^./•=v^,:•*.;^..^^^.;v

1. Gia thie't alen a difdc tao thanh bang mot trong 3 con diTcJng sau day t h i
phan tuT protein tu'dng iJng se khdc v d i so protein do gen A tdng hdp nhtf the nao?
121


Cty TNHH MTV DWH Khang Vigt

Ca'm nang tg 6n va luy$n thi Sinh hgc - Phung Duy Dfl'ng

Cho rang trong triTdng hdp nay moi axit amin chi do mot bp ba xac dinh, va
dot bien khong lien quan den codon ket thiic.
a) Ba cap nucleotit bi mat chiJa trpn trong mot bp ba ma hoa.
b) Hai nucleotit thupc mpt bp ba ma hoa, con mot nucleotit ke tiep thupc bp
ba ke'tiep.
c) Hau qua cua dot bien d a va b c6 giong nhau hay khong? Tai sao?
2. Gia thiet alen ai tao thanh do dot bien mat ba nucleotit d cac vi tri khac
nhau cua gen A thi phan tuT protein do gen bi dot bien tong hdp khac vdi protein
do gen A tong hdp nhu" the nap?
Cho biel phan tuf protein do gen A tdng hdp c6 198 axit amin va cac axit amin
tu'dng i^ng vdi cac vi tri bi bien ddi trong gen chi do mpt bp ba ma hoa quy dinh.
a) Mat cap nucleotit so 4, so 7 va so 12.
b) Mat cap nucleotit so 591, so 594 va so 597.

HUdngddn
,,, 1. Sir khac nhau giffa phan tuT protein do gen A va do alen a tdng hdp.
a) protein dot bien khac protein binh thiTdng 1 axit amin.
b) protein dpi bien kem protein binh thrfdng 1 axit amin va c6 mpt axit amin
bi thay the.
j ; c) Khong. V i 2 codon diTdc hinh thanh sau dpt bien cua hai trrfdng hdp la khac nhau.
a a) Tru'dng hdp 3 cap nucleotit bi mat nam 5 3 vi tri khac nhau:
V i tri so 4 thupc codon thu" 2, vi tri so" 7 thupc cpdpn thu' 3, vj tri so 12
thupc codon thi? 4.
Tru-dng hdp nay, phan tuT protein do alen ai tdng hdp kem phan tu" protein
do gen A tdng hdp mpt axit amin va c6 2 axit amin d dau chuoi polipeptit khac
vdi 2 axit amin tu'dng vtng ciia chuoi polipeptit do gen A tdng hdp.
b) Tru-tJng hdp 3 cap nucleotit bj mat nam d cac vi tri 591, 594 va 597:

HUdng ddn
*'
1. Them 1 cap nucleotit 6 giffa cap so 6 va so 7 se lam thay ddi cac bp ba ma
6a tir codon thuT 3 trd di. Vay protein do gen dot bien tdng hdp chi c6 axit amin
1? nhait gidng vdi axit amin tiTdng ufng tren phan tuT protein do gen A tdng hdp.
2. Them mpt cap nucleotit d giiJa cap so 594 va 595 thi se lam thay ddi codon
thuf 2 ke tur codon ket thuc.
i"V i vay protein do gen dot bien tdng hdp c6 mpt axit amin cud'i cung khdc vdi
axit amin tu'dng iJng cua protein do gen A tdng hdp.
Bai 7: Mpt gen chi huy tdng hdp chudi polipeptit gdm 198 axit amin, c6 ti le
X = 0,6 . Mpt dot bien xay ra tuy khong lam thay ddi so' lu'dng nucleotit cua
X
en nhvfng da lam thay ddi ti le ndi tren.
\. Khi ti le — trong gen dot bien = 60,43% hay cho biet:
_

+ Dot bien thupc dang nao?
+ So lien ket hidro trong gen dpt bien thay ddi nhtf the nao?
+ Chuoi polipeptit cua gen dpt bien khac vdi chupi polipeptit cua gen binh
.tfdng nhu" the nao?
2. Khi ti le —=59,57%, hay cho biet:

+ Cau triic cua gen da thay ddi nhiT the nao?
'">' *
';«''>^
+ So' lien ket hidro trong gen thay ddi nhiT the' nao?
>• • •
Hitdngddn
'
1. Chuoi polipeptit cua gen do c6 198 axit amin, chiJng to mach mang ma
B'ccp 198 + 2 = 200bpba
S P nucleotit ciia gen (N) la: 200 x 3 x 2 = 1200 nucleotit
Ap dung cong thufc: T + X = - N . Khi T = 0,6X.
2

Chuoi polipeptit do gen a i tdng hdp it hdn chuoi polipeptit do gen A tdng
hdp mpt axit amin v a c6 2 axit amin d cudi chuoi khac vdi 2 axit amin tiTdng iJng
tren chudi polipeptit do gen A tdng hdp.

Ta c6: 0,6X + X = ^ N = 600=>X = 375; T = 225.

Bai 6: Gen A chi huy tdng hdp phan tu" protein gdm 198 axit amin.

Trong gen dpt bien c6: —=60,43% .

1. Dot bien gen lam them 1 cap nucleotit d giiJa cap sd'6 va cap so 7 thi phan

i\i protein do gen dot bien tdng hdp khac vdi phan tuT protein do gen A tdng hdp
nhq thenao?

T
T
Ti 16 — cua gen binh thiTdng la — = 0,6.
X
X

2. Dpt bien lam them 1 cap nucleptit d khoang gii?a cap 594 va 595 thi phan
tur protein do gen dot bien tdng hdp khac vdi phan tuT protein do gen A tdng hdp
nhU'the'nao?
Gia thiet r^ng dot bien khong anh hiTdng den chtfc n^ng cua codon ke't thuc
cua gen.
122

t

,|
«'
r,VT' i!lf>^!f'Km

T

It'
'n M

'H.I

i\

' Nhir vay ti le — tang chiJng to c6 sir thay the cap G - X b^ng cap A - T.
X
Goi X la SP cap nucleptit bi thay the, ta ce phtfdng trinh:
' ' " •'
T-.X
225 + x ^ ^ ^ j
X+x

375-x


Ca'm nang tir 6n va luy^n thi Sinh hoc - Phung Duy Pgng

Cty TNHH MTV DWH Khang Vigt

+

V a y dot b i e n thuoc dang thay the' 1 cap G - X bkng cap A - T .

+

So lien k e t h i d r o s e b i thay d o i nhiTsau:

HUdng ddn

.;

a) So' N S T cua l o a i do k h i bi dot bie'n:

Gen dot bien k e m gen binh thi/cfng 1 lien ke't hidro.
+

Chuoi polipeptit cua gen dot bien c6 the khac chuoi polipeptit cua gen

bmh thu'dng ve thanh phan 1 axit amin hoac dot bien khong l a m thay doi chuoi
polipeptit tijy theo codon trufdc dot bien va codon sau dot bien ma hoa 2 axit
amin khac nhau hay cung ma hoa 1 axit amin.

v* ;

T
T
2. T i le — = 5 9 , 5 7 % . So vdi t i le — = 0,6 (cua gen binh thi/cJng) la giam,
X
X
chiJng to CO sirthay the cap A - T b a n g cap G - X .

;

Goi X la so' cap nucleotit bj thay the'.
,

Ta CO phirong trinh:

The khong (2n = 8); the mot (2n = 9); the ba (2n = 11); the ba kep
(2n = 12); the bon (2n = 13); the bon kep (2n = 14).
b) The 3n (5

X

3 = 15); the 4n (5

X

4 = 20); the 5n (5

X

5 = 25).

c) B o N S T CO 2n = 12 la bo N S T cua loai do d the ba kep hay the bon.
d) Bat k i cap N S T tuTOng dong nao cung c6 the them mot N S T va hinh thanh
the ba. D o vay d loai tren (2n = 10) so l o a i the ba khac nhau c6 the dtfdc hinh
thanh la 5.

. •

B a i 1 0 : Gia sv! rang d cay ca doc diTcfc ba nhiem doi v d i N S T A , sif phoi hcJp va
phan l i giffa cac N S T xay ra hoan toan ngau nhien (tiJc la to' hdp giffa A A va A

= 59,57%

du'dc tao thanh v d i t i le ngang nhau).
Co bao nhieu cay con va m o i loai chie'm t i le bao nhieu se dtfdc sinh ra k h i

Giai phu'Ong trinh ta c6: x = 1

cay nhU" vay difdc thu phan bang phan cua cay lufdng b o i binh thiTdng.

V a y dot bien thuoc dang thay mot cap A - T bang mot cap G - X . D o do so
Hen ke't hidro trong gen dot bien tang them 1 lien ke't hidro.

HUclngddn
Ca. doc difdc the ba d o i v d i NST A , tufc la trong bp NST cua cay n^y c6 3 NST

B a i 8 : Gen A va gen B nam ke tie'p nhau tren NST. protein do gen A chi huy
tong hop CO 48 axit amin. Con protein do gen B chi huy tong hdp c6 96 axit
amin. M o t dot bie'n da lam cho 2 gen noi tren thanh gen C. Protein do gen C chi
huy tong hcfp co 144 axit amin.

A (AAA).
Cay lirdng b o i binh thu'dng c6 2 NST A ( A A ) . Ta c6 sd do sau:
AA
P
:
AAA
X
G(P)

1. D o t bien lien quan de'n bao nhieu cap nucleotit va thuoc dang nao cua dot

^iAA:iA
2
2

A
t .1 , )

bien gen?

-AAA:-AA
2
2

2. Xac dinh chieu dai cua gen C.

1
NhiT vay, c6 2 l o a i cay con, moi loai chiem t i le ^ , tufc la c6 ^ so cay con la

HUdng dan
1. Protein do gen C tong hcJp c6 so axit amin bang tong so' axit amin cua
protein do gen A va gen B tong hOp. D i e u do chtfng to dot bie'n gen lien quan tdi

the ba, va -

6 cap nucleotit. Trong do c6 3 cap nucleotit la bo ba ket thuc cua gen A va 3 cap

2

la bo ba m d dau cua gen B bi mat.

: ..^o

2. Chieu d ^ i cua gen C: [(144 x 3) + 6] x 3,4 A " = 1489,2 A "
B a i 9 : M o t loai c6 bo NST 2n = 10. Co bao nhieu NST c6 the diTdodn d:

•

•

AIS:''], -AJ

B a i 1 1 : Nhi?ng phan tich d i truyen te bao hoc cho hay r^ng, c6 hai l o a i chuoi

D a y la dang mat mot so' cap nucleotit ke' tie'p nhau va n o i 2 gen ke' can thanh
mot gen m d i .

so cay con la lifdng boi binh thifdng.

khac nhau: Chuoi rCfng liTdng b o i va chuoi nha tam b o i . 6 nhiTng l o a i nay gen A
Xiic dinh than cao, troi hoan toan so v d i alen a (than tha'p)
K h i gay dot bie'n nhan tao ngiTdi ta da thu diTdc mot so dang tiJ b o i va cac
dang nay chi tao cac giao tijTlu^dng boi c6 kha nang song.

»'

' '

a) The khong, the mot, the mot kep, the ba, the ba kep, the bon, the bon kep.

1. Xac dinh ket qua phan linh ve kieu gen va kieu hinh cua cac phep lai sau:

b) T h e 3 n , 4 n , 5n.

a) P: Aaaa X Aaaa

c) Neu bo N S T cua loai do b i dot bie'n c6 2n = 12. D o la dot b i e n dang nao?

2. Hay cho biet mot so dSc d i e m quan trong khac nhau giu-a chuo'i nha va

d) Co bao nhieu loai the ba khac nhau, c6 the diTdc hinh thanh.

b) P: Aaaa x A A a a

chuo'i rijfng.
3. G i a i thich nguon goc va qua trinh xuat hien chuoi nha.


Cty TNHH MTV DWH Khang Vigt

Ca'm nang ti/ On va luy$n thi Sinh hgc - Phung Duy DO'ng

Nhiyng cay c6 kieu gen dong hdp tuT chi cho 1 loai giao tur nhiTng cay dong

4. K h i ket qua cua phep lai cho ti le:
a) 1 cao : 1 thap

b ) 3 cao : 1 thap

c ) 1 1 cao : 1 thap

d) 35 cao : 1 thap

T h i k i e u gen cua P c6 the nhu" the nao?

hdp t ^ troi khong the c6 sir phan tinh k h i l a i . Do d d , chi c6 c i c cay aa, aaa, aaaa
la phii hdp. Tijf do, ta thay muon c6 ke't qua lai phan tinh 1 cao : 1 thap thi kieu
gen cua P CO the nhiT sau: P:

Aa

x

aa

Hoac P:

Aa

x

aaa

Hoac P:

Aa

x

aaaa

Hitdng dan
1. Xac dinh ket qua phep l a i :
a) P
G(P)

:

Aaaa x Aaaa

: A a , aa

A a , aa

l A A a a : 2Aaaa: laaaa

Aaaa

m\:

G(P)

x

—AA:—Aa:—aa
6
6
6

AAaa
4
1 ^
-AA:—Aa:—aa
6
6
6
y

f l A A A A : 8 A A A a : 18 A A a a : 8 Aaaa: laaaa

[35 cao: 1 tha'p
2. Chuol nha so v d i chuoi riifng c6 lufdng A D N cao hdn, tong hdp chat hint cri
khong CO kha nang sinh giao tuT binh thtfcfng nen khong cd hat nhtf chuoi r t o g .
3. Co the cho rang chuol nha c6 nguon goc tuT chuoi r t o g : Trong truTdng hdp
dac biet, do tac nhan gay dot bien tac dong vao luc giam phan, l a m te liet sir
hinh thanh thoi v6 sac, dan den cac cap NST khong phan li tao thanh giao tuT 2n.
L o a i giao tuT nay k e l hdp v d i giao tuT binh thiTdng (n) trong thu tinh se tao ra hdp
tu^ 3n phat trien thanh cay chuol 3n. NhSng cay chuoi 3n c6 qua to, ngon, khong
hat da diTdc con ngiTdi giff lai trong va nhan len bKng sinh san sinh diTSng tao nen
chuol nha ngay nay.

'

aa

K M

Hoac P: Aaaa x

aaa

<,

Hoac P: Aaaa x

aaaa

Ta CO cay than chiem t i le — = — x -i- =^ x 1
4
2 2

4
NhiTng k i e u gen c6 giao tur chiem ti le ^ la: A a , Aaa, Aaaa. C^c cay 2n,
3n, 4n khong the c6 giao tu" chiem t i le ^ . D o do de c6 ket qua lai phan tinh
3 cao : 1 thap t h i k i e u gen cua P c6 the nhiT sau:

P:

Aa

x

Aa

Hoac P:

Aa

x

Aaaa

Hoac P: Aaaa x

Aaaa

c) K e t qua phep lai cho 11 cao : 1 thap
1
1 1 3
1
Cay thap chiem t i le: — " ^ T ^ ^ r ^ T ^ T

12
6 2
6 6
Giao tijT chiem t i 1^ - la giao tur sinh ra tur cay A A a , Aaa, A A a a . Giao tur
6
chiem ti le -

cd the giao tur cua cay A a , Aaaa.

P: Aaaa x

a) K e t qua phep lai cho 1 cao : 1 thap
1

Nhffng k i e u gen c6 giao tijf chiem ti le ^ la: A a , A A A a , Aaaa. Nhiftig cay
c6 k i e u gen A A A a se cho 2 loai giao tuT: ^ A A : ^ A a n6n ket qua cua phep lai
khong the phan tinh, do do chi c6 cay cd kieu gen A a hoSc Aaaa m d i cho ket

Aa

Hoac P: Aaa

x

Aa

£;

Hoac P: Aaa

x

AAaa

Hoac P: Aaa

x AAa

Hoac P: Aaaa x

AAaa

Hoac P: Aaaa x

AAa

,

viiivf'

'iicr, yyn

'j

'

.<-ik-:^\t:.r'^'

s

d) Ket qua cua ph6p l a i phan tinh 35 cao : 1 thap ta c6 cay thap chiem t i 1$:
36

6

6

rv

Giao tur chiem t i le - la giao tur sinh ra tif cay A A a , Aaa, A A a a . D o do de
6
cd ket qua lai phan tich 35 cao : 1 thap thi sd do lai cd the nhur sau:

126

. M,

Hoac P: Aaaa x

Do d6 de cd ket qua phan tinh 11 cao: 1 thap thi kieu gen cua P c6 the nhiT sau:

4. Xac dinh kieu gen cua P.

qua lai phan tinh 1 : 1 .

>,
'

dien ra manh hdn, te' bao va cd quan sinh dtfdng to hdn, phat trien kh6e hdn,

Ta CO cay thap chiem t i le ^ ~

v

b) K e t qua phep lai cho 3 cao : 1 thap.

3cao: Ithap
b)

,


Cty TNHH MTV DWH Khang Vi^t

Cam iiang tu on va luyen thi Sinh hgc - Phung Duy B6ng

P: Aaa x AAa
Hoac P: Aaa x Aaa
^'v-'f'' '''^
"
Hoac P: Aaaa X AAaa iUuff ;S;:,;« ••
Hoac P: Aaa x Aaa
Hoac P: Aaa x AAa
Hoac P: Aaa x AAaa
'
.!
Hoc sinh tiT chiJng minh bkng each giai cu the cac sd do lai.
Bai 12: O ruoi gia'm, doan 16A tren NST gidi tinh X bi lap doan thi lam giam so
mat ddn trong mat kep cua ruoi giam, lam cho mat loi thanh mat det.
Hien t^dng lap 2 doan, roi 3 doan 16A tren NST gidi tinh X xay ra nhxi the

nao? Hinh dang m^t thay ddi nhu- the nao?

Hitdngddn

a) Giai thich qua trinh tao thanh NST X c6 2 doan 16A.
Binh thu'dng d ruoi giam cai c6 2 NST X, moi chiec c6 1 doan 16 A, con d
ruoi diTc chi c6 mot NST X mang 1 doan 16A.
O ruoi giam, trao ddi cheo chi xay ra d gidi cai. Do trao ddi cheo khong can,
da tao ra mot NST X khong mang doan 16A va mot NST X c6 2 doan 16A.
Ruoi cai dot bien nay kh? giam phan se cho trihig mang NST X c6 2 doan 16A.
Sy phd'i hdp giffa trtfng mang NST X c6 chtfa 2 doan 16A vdi tinh trung Y se
tao thanh ruoi diTc c6 NST X mang 2 doan 16A (mat det).
Ruoi diTc nay khi giam phan se cho tinh triing X c6 chiJa 2 doan 16A.
Sir phdi hdp giffa trffng c6 NST X chufa 2 doan 16A vdi tinh trung c6 NST X
chffa 2 doan 16A vdi tinh trung c6 NST X chffa 2 doan 16A se tao thanh ruoi cai
CO 2 NST X, mdi NST deu chffa 2 doan 16A (mat det).
Sff phdi hdp giffa trffng c6 NST X chffa 2 doan 16A vdi tinh Irilng binh thffdng
(NST X chffa 1 doan 16A) se tao thanh ruoi cai di hdp (mot NST X c6 2 doan
16A va mot NST X c6 1 doan 16A).
Ruoi cai nay mat cung det nhffng khong gid'ng het ruoi cai chffa 2 NST X deu
mang 2 doan 16A.
b) Sff hinh thanh NST X c6 3 doan 16A.

'

- Sff phol hdp giffa tinh trung va trffng deu mang NST X c6 3 doan 16A se
hinh thanh rudi cai dong hdp, trong te bao sinh dffdng cua no c6 6 doan 16A
(mat ra't det).
I7K

IIJ ) ' '<
i

' i

Bai 13: Gia thiet 2 cap NST tffdng ddng mang cac cap alen bieu thi bang cac con

I

so'nhffsau:
1

2

4

6

7

8 9

r

2' 3' 4'

6'

7'

8' 9'

.-'ife

3

a) Hay vie't cd che dan den sff bien ddi vi tri ciia gen tren NST.
b) Sff bien ddi v i tri cua gen tren NST cd phai chi do dot bien cau trffc NST
hay khong? Tai sao?

HUdngddn

a) Vie't cd che dan den sff bien ddi v i tri cua gen tren NST.
+ Bie'n ddi lien quan de^n mot NST:
- Dao doan: Doan bi dao CO chffa hoSc khong chffa tam dong:
1 2 3 4 hoac 1' 2' 3' 4'
-

Chuyen vi tri cua gen: 4

2

3

1 hoSc 4" 2'

3'

1' , ,

,

- Ma't doan d ben trong cua canh lam cho 2 gen trffdc dSy c^ch xa nay
nhich lai gan nhau tren mot NST:1 3 4, 1 2 4. 1 4 hay 1' 3' 4', 1' 4'.
-

Trao ddi cheo khong can giffa 2 cromatit cua mot NST kep: .
1 2 2 3 4 . 1 34 hoac r 2 ' 2 ' 3 ' 4 M ' 3 ' 4 '
+ Bien ddi lien quan den 2 hoSc nhieu NST:
-'^
-

Trao ddi cheo khong can giffa 2 cromatit ciia 2 NST tffdng ddng:,'
1
y

2

3 4
2' 3' 4' ^

1

r

2 2' 3' 4'
3 4

-

Chuyen doan tffdng hd:

-

Chuyen doan khong tffdng ho: 1 2 3; 6 7 8 9 4

•

1 2 3 9; 6 7 8 4
•

+ Bien ddi khong phai la dot bien ca'u true.
Trao ddi cheo ddng deu xay ra giffa hai NST tffdng ddng:
1

-

- Ruoi cai mang 2 NST X, mdi chiec chffa 2 doan 16A da xay ra trao ddi
cheo khong can tao ra NST X c6 3 doan 16A va mot NST X c6 1 doan 16A.
Ruoi cai dot bien nay se tao thanh trffng X c6 chffa 3 doan 16A. Loai trffng nay
ket hdp vdi tinh trung Y se tao thanh rudi dffc mang NST X c6 chffa 3 doan 16A
(mat rat det).

I'llA

- Sff phdi hdp giffa trffng chffa NST X c6 3 doan 16A vdi tinh trung X c6 1
doan, hay 2 doan 16A se tao thanh rudi c^i di hdp, m^t ra't det nhUng khong
gidiig het trffdng hdp ca 2 NST X deu c6 3 doan 16A.

r

2 3 4
2' 3' 4"

r 2 3 4
" ^ 1
2' 3' 4'

Sff bien ddi vi tri cua gen tren NST khong chi do dot bien cau true NST ma
con do trao ddi cheo ddng deu (can) giffa 2 cromatit cua mot NST k6p hoSc giffa
cac cromatit thuoc 2 NST tffdng ddng.
Bai 14: Gia thie't c6 mot NST mang cac gen c6 chieu dai bang nhau. Do bi chieu
xa, phan tff A D N tao nen NST nay bi dfft mot doan tffdng ffng vdi 20 ARN thong
tin va lam ma't di 5% tdng so gen cua NST 66.
Khi phan tff A D N bi dot bien tff nhan doi da doi hoi moi trffdng n6i bao cung
cap 38000 nucleotit tff do.

•

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