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.
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- Bd me tbiTcfng ma con liin cbitng to la dot bie'n trpi.
fl - Trir 2 trU"6ng hdp da c6 bd hoac me liln, con 8 triTdng hdp liin la c6 dot ^iS'n lun phat sinh trong giao tuT cua bd hoac me. - '
dm nang ti/ 6n va luygn thi Sinh hpc - Phung Duy Ddng
- Do do so'giao tu" mang dot bien lun la 8.
- Tong so giao tuT 100000 x 2 = 200000 (moi hdp tu^ diTdc tao ra tit 1 giao ty dvtc va 1 giao tiJcai).
g
Vay tan so dot bien gen la: = 4x10"^ 200000
Loai 4: Tim dang dot bien khi bie't su" thay doi ve ti le cac loai nucleotit.
Phrftfng phap giai:
- Ne'u dot bien khong lam thay doi so nucleotit (chieu dai gen khong thay ddi) thi dot bien thupc dang thay the cap nucleotit.
- Khi chieu dai gen khong ddi thi thay bao nhieu cap A - T se bang bay nhieu cSp G - X.
Vidu:
Bie't so'nucleotit mdi loai cija gen tru'dc dot bie'n la: A = T = 450 nucleotit, G = X = 1050 nucleotit. Sau dot bien ti 16 —=43,27% . G
Cho bie't dot bien da xay ra nhu'the'nao? Bie't rang chieu dai gen khong thay ddi.
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A 450
- Ti le cac loai nucleotit cua gen truTdc dot bie'n la: —= =42,86% G 1050
- Sau dot bien gen khong thay ddi chieu dai ma ti le — tang (43,27%) G
chtfng to dot bie'n thuoc dang thay cap G - X bang cSp A - T. - So cap G - X bi thay bang so cap A - T diTdc thay. Goi X la sd^ cap nucleotit thay the (x nguyen difdng)
A 450+x
Ta CO phu-dng trinh: —= = 43,27% = 0,4327 G 1050-x
Giai he phu'dng trinh ta c6: x = 3.
Vay dang dot bie'n la thay 3 cap G - X bang 3 cSp A - T. itAi,
Loai 5: Xac dinh kieu hinh cua gen dot bie'n Vidu:
d ngi/di, gen tdng hOp chuoi a - Hb do mot gen tren NST so 11 bi dot bien da
xuat hien nhieu alen. Trong do alen A tdng hdp HbA, alen S tdng hdp HbS
NgUdi CO kieu gen SS bi benh thie'u mau hong cau hinh liem.
Cho bie't:
- Ca the 1 cd: 98% HbA, 0% HbS, cac dang Hb khac cd 2%. - Ca the 2 cd: HbA = 0%, HbS = 90%, cac dang Hb khac cd 10%.
- Ca the 3 cd: HbA = 45%, HbS = 45%, cac dang Hb khac cd 10%.
Hay cho bie't nhffng ca the nao bi benh thie'u mau hong cau hinh liem.
100
Cty TNHH MTV DWH Khang Vigt
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