Question

If 420 out of 2000 nucleotides contain adenine how many pyrmidines are there

Answer 1

adenine(A) and guanine(G) = purines = two rings structure

thymine(T) and cytosine(C) = pyrimidines = one ring structure

now, according to Chargaff ,

no. of A = no. of T and

no. of G = no. of C

420 = A = T

total A + T = 420 + 420 = 840

from 2000 nucleotides , 840 = A + T

so G + C = 2000 - 840 = 1160

since G = C ,

⇒ 2 C = 1160

⇒ G = C = 580

now,

total pyrimidines = T + C = 580 + 420 = 1000