_____________________________ 251.
AUGCGAAUCCGACGGCUU
nukleotidlar
ketma-
ketligiga ega i-RNK molekulasiga komplementar DNK qo‘sh
zanjiridagi A, G, C, T nukleotidlar sonini (a), vodorod bog‘lar sonini
(b) aniqlang.
A) a-A va T 8 ta, G va C 10 ta; b-46
B) a-A va T 4 ta, G va C 15 ta; b-26
C) a-A va T 20 ta, G va C 8 ta; b-44
D) a-A va T 16 ta, G va C 20 ta; b-46 Ishlanishi: 1) i-RNK da: AUGSGAAUSSGASGGSUU
DNK 1-ipda: TA
SGST TAGGSTGSS
GAA
DNK 2-ipda: ATGSGAAT
S
SGASGGSTT
2) 1 ta ipda: A+T=16N; G+S=20N 3) F=2N-2 F=36-2=34F 4) H=2A+3G H=2*8+3*10=16+30=46H Javob: D _____________________________ 252. DNK ning qo'sh zanjirida G nukleotidlari 40%ni tashkil
etadi. DNK dagi gen asosida sintezlangan oqsil 400 ta
aminokislotadan iborat bo‘lsa, shu DNK qo‘sh zanjiridagi adenin
nukleotidlari sonini toping.
A) 240 B) 140 C) 600 D) 960
Ishlanishi: 1) N=AK*3 N=400*3=1200N*2=2400N -2 ta ipdagi N lar
2) 2400---100%
G-x---40% G-x=(2400*40)/100=960N G-960=960-S
3) 960----40%
A-x---10% A-x=(960*10)/40=240 A-240=240-T Javob: A _____________________________ 253. 5000 nukleotiddan iborat DNK fragmentining markaziy
qismiga 8000 juft nukleotiddan iborat bo’lgan regulyator gen birikdi.
Shu DNK asosida sintezlangan i-RNK zanjiridagi fosfodiefir bog’ini
aniqlang?
A) 10500 B) 6499 C) 10499 D) 20999
Ishlanishi: 1) 2500+8000=10500N -DNK ning 1 ta ipidagi yoki i-RNK dagi
N lar.
2) F=N-1=10500-1=10499F Javob: C _____________________________ 254. Ximoptirsinogen fermenti 245 ta aminokislotadan iborat
bo’lib, uni sintezlagan DNK molekulasi tarkibida A 20 %. Ushbu
fragmentdagi G-S orasidagi vodorod bog’larni A-T orasidagi
vodorod bog’lariga nisbati nechiga teng.
A) 3,25 B) 1,5 C) 2,5 D) 2,25 Ishlanishi: 1) N=AK*3 N=245*3=735N*2=1470N -2 ta ipdagi N lar
2) 1470---100%
A---20% A=(1470*20)/100=294N A-294=294-T
3) 294----20%
G---30% G=(294*30)/20=441 G-441=441-S
4)H=2A+3G H=2*294+3*441=588+1323=1911
5) 3G/2A=1323/588=2,25 Javob: D
