III. HOAT DONG DAY - HOC
1. Tim hieu dot bien gen
+ Dot bidn tao coden mdi.
+ Tdn sd dot bidn.
+ Tdc nhan trong ngoai
CO the.
- Dai dien HS trinh bay -^ ldp nhan xet, bd sung.
Npi dung
1. Tim hieu dot bien gen
Hogt dpng cua GV - GV nhan xet, danh gia va yeu cdu HS khai quat kie'n thiic.
- GV giang giai ve gay dot bie'n nhan tao.
+ Diing hod chat lam thay ddi cap nucledtit trong gen theo y mud'n.
+ Tang tdn sd dot bidn d cay trdng, cdc chiing vi sinh vat tao sinh khd'i.
Hogt dpng cua HS - HS khai quat kidn thiic vd: Khai niem dot bidn.
dac didm, the dot bidn, tac nhan gay dot bidn.
- HS cho vf du: Nhdm mdu d ngudi:
Sodd
Npi dung
* Khai niem:
- Dot bidn gen la nhiing bidn ddi trong cau triic gen.
- Dot bidn diem la dot bidn lien quan tdi bidn ddi d mdt cap nucledtit trong gen.
* Dac didm:
- Mdi ldn bidn ddi gen tao ra mdt cap alen mdi - Tdn sd dot bidn gen thdp va phu thudc vdo tac nhan gay dot bidn.
* Tdc nhan gay dot bidn:
- Tac nhan hod hgc.
- Tac nhan vat If.
- Tac nhan sinh hgc.
* The dot bidn.
Cd the mang gen dot bidn da bidu hien ra kieu hlnh.
Hogt dpng cUa GV - GV neu yeu cdu:
+ Md ta cdc dang dot bie'n gen bdng so dd.
+ Bidu thi mdi quan he giiia gen va protein tren sodd.
Hogt dpng cUa HS
- GV nhan xet, danh gid va yeu cdu HS khai quat kidn thiic.
- GV sii dung thdng tin bd sung vd HbA va HbS dd minh hoa cho dang ddt bidn.
- HS viet trinh tu cdc nucledtit ciia gen ban ddu va bidu didn cdc dang dot bien gen.
- HS vidt so dd.
ADN -^ mARN ->
protein
HS khang dinh bidn ddi trong ADN se thay ddi d prdtein.
- Ldp theo doi nhan xet phdn trinh bay cua ban.
- HS ket hgp SGK trang 20 muc 2 va khdi quat kidn thiic vd cdc dang ddt bidn.
Npi dung
2. Cac dang dot bien gen
a) Thay the 1 cap nucledtit
- Mgt cap nucledtit trong gen dugc thay thd bdng 1 cap nucledtit khac lam thay ddi thanh phan axit amin trong protein.
- Protein bi thay ddi chiic nang.
b) Them hay mdt 1 cap nucledtit
- Dot bidn lam mdt hay theml cap nucledtit trong gen -> ma di
Hogt dpng cua GV
- GV bd sung them dang dot bien dao vi trf cap nucledtit.
- GV neu cau hdi:
Trong cac dang dot bidn tren, dang nao gay hau qua ldn hon? Giai thfch.
- GV neu vdn dd:
Dang dot bidn them hoac mdt 1 cap nucledtit 6 dau gen, giiia gen va gdn cud'i gen thi trudng hgp nao se gay anh hirdng nghiem trgng hem? VI sao?
Hogt dpng cua HS Npi dung
- HS van dung kidn thiic va thao luan nhanh trong nhdm dd tra ldi dugc.
+ Dang dot bidn thay thd cap nucledtit chi lam thay ddi 1 axit amin trong prdtein nao ft anh hudng.
+ Dang dot bidn them hay mdt 1 cap nucledtit thi khi dgc lech 1 nucledtit -^ codon khac thudng gay anh hudng tdi nhidu axit amin.
- HS tidp tuc thao luan va tra ldi dugc:
Trudng hgp dot bidn them hoac mdt cap xay ra d ddu gen la nghiem trgng vi ma di truydn se dgc sai tit vi trf dd va toan bd axit amin trong prdtein bi thay ddi.
truydn bi dgc sai tir vi trf dot bien.
- Thay ddi trinh tu axit amin trong chudi pdlipeptit -^ thay ddi chiic nang ciia prdtein.
Hogt dpng 2
TIM HIEU CO CHE PHAT SINH DOT BI^N GEN Muc tieu:
- HS lam ro ca chd phdt sinh dot bidn gen.
- Lien he vd van dd mdi trudng vdi dot bidn gen.
Hogt dpng cua GV - GV dat cau hdi ddn ddt.
+ Hoat ddng khdng binh thudng cua ADN thd hien nhu the nao?
Nguyen nhan ddn ddn hoat ddng khdng binh thudng la gl?
- GV khang dinh: Dot bie'n phat sinh do chfnh nguyen nhan tii mdi trudng hay ban than sinh vat.
- GV neu yeu cau:
Trinh bay co chd phat sinh dot bidn gen do su kdt cap khdng diing trong tai ban ADN.
Hogt dpng cua HS - HS van dung kidn thiic bai 1 tra ldi dugc.
+ Sao chep bi sai.
+ Bi diit doan khi tu sao.
+ Nguyen nhan do cdu triic gen hoac tir ydu td mdi trudng.
- HS hoat ddng nhdm.
+ Ca nhan nghien ciiu SGK muc 1 trang 20 va hlnh 4.1.
+ Thao luan nhdm thd'ng nhdt y kidn, yeu cdu:
+ Phan tfch dugc kdt cap khdng diing d vi trf xac dinh.
+ Nhan bidt dugc su kdt cap sai d nhiing vi trf khac ciia gen.
- Dai dien HS trinh bay
—>• ldp nhan xet.
Npi dung