+ Bien ddi khong phai la dot bien ca'u true.
Trao ddi cheo ddng deu xay ra giffa hai NST tffdng ddng:
1 2 3 4 r 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.
Cam nang tif on va luyen thi Sinh hoc - Phung Duy Ddng
a) Dot bie'n noi tren thuoc loai dot bien gi? b) Xac dinh so" gen tren NST do.
c) X^c dinh chieu dai trung binh cua gen.
Hitdngddn
a) Dot bien noi tren la dot bien cau true NST dang mat doan vi doan bi diJt tiTdng u-ng vcti 20 ARN thong tin hay 20 gen.
b) Xac dinh so' gen tren NST: Doan bi mat gom 20 gen ke" tiep nhau va chiem 5% tdng so gen cua NST. Do do NST c6.(20 : 5) x 100 = 400 gen.
c) So gen cua NST sau khi bi dut la: 400 - 20 = 380 gen
So nucleotit do moi trifdng noi bao cung cap cho 380 gen tu" nhan doi la 38000 nucleotit. Do do so nucleotit cua moi gen la: 38000 : 380 = 100 nucleotit
Vay chieu dai trung binh cua mot gen la: 3,4 A" X 50 = 170 A".
Bai 15: Bie't cac bp ba ma sao da ma hoa cac axit amin nhu" sau: UXU: Xerin; AXA: Treonin; UAU: Tirozin; AAG: Lizin; GUU: Glixin; XXX: Prolin; GXA: Alanin; AUA: Izolcfxin; GAA: Glutamic; UGG: Triptofan.
Mot doan gen binh thu'dng da dieu khien tdng hdp mot doan cua chuoi polipeptit CO trat tU" cac axit amin la: Xerin - Treomin - Prolin - Lizin - Tirozin - Glixin - Alanin - Glutamic - Izoldxin - Triptofan.
Gia thiet rang riboxom luon luon tru'cJt tren phan tu^ mARN theo chieu tuf trai sang phai.
1. Hay viet trat tif cac nucleotit cua doan gen ttfdng iJng.
2. Khi CO hicn tu'rfng dot bien dao doan NST chuTa doan gen noi tren thi dao doan polipeptit tu'dng iJng c6 cac axit amin sap xe'p theo trat tiT nao?
Hudng dan
1. Trat tir sap xcp cac ribonucleotit cua doan mARN: UXU - AXA - XXX - AAG - UAU - GGU - GXA - GAA - AUA - UGG
- Trat tiT sap xe'p cac nucleotit trong mach mang ma goc:
TAT - TGT - TTX - ATA - XXA - XGT - XTT - TAT - AXX - Trat tuf sap xe'p cac nucleotit trong mach bd sung:
ATA - AXA - XXX - AAG - TAT - GGT - GXA - GAA - ATX - TGG 2. Dot bie'n dao doan lam cho trat tif cac nucleotit trong mach mang ma goc dao ngu'dc. Vi vay trat tu" cac ribonucleotit trong mARN cung bi dao ngUdc, dan tdi trat tiT cac axit amin bi dao ngu'dc:
Triptofan - Isoldxin - Glutamic - Alanin - Glixin - Tirozin - Lizin - Prolin - Treomin - Xerin.
Bai 16: Doan khdi dau cua mot gen binh thiTdng chiJa cac nucleotit trong mach khuon nhU" sau:
ATG GXA TGX AXT X GAT
1. Gia su" rang trong qua trinh dot bien nucleotit thu" 5 la X bi thay thebdi A. Hoi CO bao nhieu axit amin bi thay ddi d phan tu" protein diTdc tdng hdp?
Cty TIMHH MTV DVVH Khang Vigt
2. Gia sij" nucleotit thu" 5 ay bi mat di thi c6 bao nhieu axit amin bi thay ddi d phan tu* protein du'dc tdng hdp?
3. Ne'u them vao sau nucleotit thi? 3 la A mot nucleotit X thi hau qua the hien nhif the nao d phan tuf protein diTdc tdng hdp?
Gia thiet rang qua trinh dich ma xay ra theo hu'dtng tiif trai sang phai d phan tu" mARN du'dc sao ra tijf gen do.
HUdng ddn
1. Nnucleotit thu" 5 la X nam trong bo ba thu" hai la GXA bi thay thebSi A thi
chi bp ba thuf 2 bi bie'n ddi thanh GAA. Do do chi mot axit amin bi thay ddi 6 phan tuT protein du'dc tdng hdp.
2. Nucleotit thi? 5 bi ma't di se dan de'n thay ddi khung dich ma tiif nucleotit thiJ 5. Do do tiJf axit amin thiJ hai trd di trong chuoi polipeptit se bi thay ddi.
3. Ne'u them A vao sau nucleotit thu* 3 thi khung dich ma bi thay ddi tuT
nucleotit thiJ 4. Do do tiJT axit amin thi? hai trd di trong chudi polipeptit bi thay ddi. Nhifng sir thay ddi khong gidng nhau d thanh phan cic axit amin so vdi trUdng hdp tren.
Bai 17: Gia thiet NST thi? nhat c6 7 gen, NST thu" hai c6 5 gen. Cac gen tren
NST ke tiep nhau lam thanh mot phan tuT ADN. Cac gen deu dai 5100 A". Phan
X\i ADN CO trong NST thtf nhat chtfa 20% Adenin, phan tuT ADN c6 trong NST
UhiJhai chiJa 15% Adenin.
j Do dot bie'n cau true NST, moi phan tuT ADN da dut mot doan dai bang nhau va chuyen doan cho nhau de trd thanh hai phan tuf ADN mdi. Phan tuT ADN mdi va chuyen doan cho nhau de trd thanh hai phan tuf ADN mdi. Phan tuT ADN mdi ' ma phan Idn vat chat di truyen c6 nguon goc tif NST thi? nhat da cd so lien ket
hidro cua mot loai nucleotit giam di la 2100 so vdi so lien ket hidro cua mot loai nucleotit do trong phan ttjf ADN nkm d NST thi? nhat khi chifa dot bie'n.
1. Tinh chieu dai cua moi phan tuf ADN khi chtfa dot bien. " S" 2. So lU'dng tufng loai nucleotit trong mdi phan i\i ADN khi chu'a dot bie'n la bao nhieu?
3. So lufdng tufng loai nucleotit trong moi phan tuf ADN mdi diTdc hinh thanh sau dot bie'n la bao nhieu?
HUdngddn
1. Chieu dai cua mdi phan tufADN khi chu'a dot bien: n
- Phantu'ADNtrongNSTthi?nhat:5100A"x7 = 35700A" Mi<r \
- Phan tuf ADN trong NST thi? hai: 5100 A"X 5 = 25500 A"
2. So lufdng ti?ng loai nucleotit trong moi phan tuf ADN khi chiTa dpt bie'n:
- Phan tuf ADN trong NST thur nhat: (35700 A") : 3,4 A" X 2 = 21000 nucleotit A = T = 21000 X 20% = 4200 nucleotit
dm nang tij 6n va luy$n thi Sinh hgc - Phung Duy Ddng