_____________________________ 248. i-RNK zanjirida 80 ta uratsil bor, shu RNK zanjiridan
teskari transkripsiyalangan DNK ning 1 ta zanjiridagi sitozinlar soni
RNK dagi uratsillar sonidan 2,5 marta ko‘p, guaninlar soni esa 2,5
marta kam. DNKning shu zanjiridagi timin miqdori undagi guanin
va sitozin nukleotidlar miqdorining o'rtachasiga teng bo’lsa DNK
molekulasidagi vodorod bog’lar sonini aniqlang.
A) 1052 B) 428 C) 1088 D) 856
Ishlanishi: 1) DNK da: A=80; S=2,5U=2,5*80=200; G=U/2,5=80/2,5=32;
T=(S+G)/2=(200+32)/2=116
i-RNK da: U=80; G=200; S=32; A=116
2) DNK da: A+S+G+T =>i-RNK da: U+G+S+A
80+200+32+116=428
2) A+T=A(T) -bitta zanjirdagi A va T yig’indisi A yoki T ga
teng: 80+116=196 A-T G+S=G(S) -bitta zanjirdagi G va S yig’indisi G yoki S ga
teng: 200+32=232 G-S 3) H=2A+3G H=2*196+3*232 H=392+696=1088 Javob: C _____________________________ 249. DNK molekulasining ma'lum qismida 1380 ta vodorod
bog’lari bo‘lib, undagi sitozinli nukleotidlar 90 juftni tashkil etadi.
Shu DNK bo’lagi asosida translyatsiya jarayonida hosil bo’lgan
polipeptid molekulasidagi monomerlar sonini aniqlang.
A) 400 B) 200 C) 460 D) 230
Ishlanishi: 1) 2A+3G=H => S=G => 2A+3*180=1380
2A=1380-540 2A=840 A=420
2) A+G=N => 180+420=600N DNK ni 1 ta ipi yoki i-RNK
dagi N lar
3) AK=N/3=600/=200AK Javob: B _____________________________ 250. 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 fosfodiefir
bog’lari sonini toping, (nukleotidlar o'zaro fosfodiefir bog‘ orqali
bog’lanadi)
A) 2400 B) 12398 C) 1199 D) 2398 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
4)A+G=N 240+960=1200N - Purin yoki Pirimidin DNK dagi
barcha N larning yarmini tashkil etadi.Bu esa DNK ning 1 ta ipidagi
yoki i-RNK dagi N larga teng bo’ladi. 5) 2N=2*1200=2400N –DNK dagi barcha N lar
6) F=N-2=2400-2=2398F Javob: D
