225. DNKning bir zanjirida 180 ta triplet kod bo’lib, shundan 30
tasi adeninli nukleotid. Shu DNK asosida transkripsiya bo’lgan i-
RNKda guaninli nukleotidlar soni DNKning o‘sha zanjirdagi
adeninli nukleotidlaridan 4 marta ko‘p, sitozinlar soni guanindan 2
marta kam bo’lsa, DNK qo‘sh zanjiridagi purin va pirimidin asoslar
nisbatini toping.
A) 1 purin (360A+180G) : 1 pirimidin (180C+360T)
B) 2 purin (360A+180G) : 1 pirimidin (90C+180T)
C) 5 purin (330A+120G) : 1 pirimidin (60C+30U)
D) 5 purin (330A+120G) : 1 pirimidin (60C+30T)
Ishlanishi:
1) N=AK*3 N=180*3=540N -1 ta ipdagi N lar
2) i-RNK da: G=4A G=4*30=
120
; S=G/2; S=120/2=
60
U=
30
; A=540-(G+S+U) A=540-210=
330
3) DNK da: U+A=A(T) 30+330=360A(360T)
G+S=G(S) 120+60=180G(180S)
4) Purin=A+G Purin=
360A+180G
Pirimidin=S+T Pirimidin=
180S+360T Javob: A
_____________________________
226. 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 pirimidin
asoslari sonini toping.
A) 600 B) 960
C) 1200
D) 320
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=960+240=1200N Purin
5) S+T=960+240=
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