142,8nm Javob: B _____________________________ 186. 3 xil nomalum nukleotidli DNK malekulasi mavjud
bo`lsa.Ulardan oqsil sintezlanishi uchun jami 420 ta t-RNK
sarflangan. 2-DNK malekulasidan oqsil sintezlanishi uchun
sarflangan t-RNKlar soni 1-DNKdan oqsil sintezlanishi uchun
sarflangan t-RNKlar sonidan 0.75 marta kam, 3-DNKdan oqsil
sintezlanishi uchun sarf bo`lgan t-RNKlar sonidan 0.8 marta ko`p
bo`lsa, 3-DNK malekulasini uzunligini aniqlang.(10 ta nukleotid
oralig`I 3.4 nm hisoblanadi)
A)107.1 B)142.8
C)178.5 D)163.2
Ishlanishi: 1) 1-DNK=x*0,75; 2-DNK=x; 3-DNK=x/0,8;
2) x*0,75+x+x/0,8=420
0,6x+0,8x+x=336
2,4x=336
x=140 -bu 2-DNK dagi t-RNK lar soni
3) D3=D2/0,8 D3=140*0,8 D3=175 175*3=
525 4) 525*0,34nm=
178,5nm Javob: C _____________________________ 187. 3 xil nomalum nukleotidli DNK malekulasi mavjud. DNK
malekulalarida jami 798 ta adenin nukleotidi bor. DNK
malekulalaridagi adenin nukleotidlari foizlari quyidagicha 1-DNK
da jami nukleotidlarni 20% ni, 2- DNK da jami nukleotidlarni
30%ni, 3- DNK da jami nukleotidlarni 40% ni tashkil qiladi.
2-DNK malekulasidagi adenin nukleotidlar soni 1-DNK
malekulasidagi adenin nukleotidlari sonidan 0.5 marta kam, 3- DNK
malekulasidagi adeninlar sonidan 0.6 marta ko`p bo`lsa,1-DNK
malekulasidagi timin va sitozinlar sonini yig`indisini aniqlang
A)315 ta B)420 C)525 D)675
Ishlanishi: 1) 1-DNK=0,5x; 2-DNK=x; 3-DNK=x/0,6;
2) 0,5x+x+x/0,6=798
0,3x+0,6x+x=478,8
1,9x=478,8
x=252 -bu 2-DNK dagi A lar soni
3) D1=D2*0,5 D1=252*0,5 D1=126 A-20%=20%-A
4) 126---20%
x---30% x=(126*30)/20=189 S-30%=30%-G
5) S+T=126+189=
315 Javob: A
