A DNA segment has a total of 1000 nucleotides, out ofwhich240 of them are adenine containing nucleotides. How many pyrimidine bases this DNA segment possesses?

Explanation

According to Chargaff.s rule, ratio of purines to pyrimidines is equal, i.e. A + G = C + T Since, the number of adenine {A) is equal to the number of thymine (T) and A = 240 (given)
Therefore, T = 240
Also, the number of guanine (G) is equal to cytosine (C) Thus, G+C = 1000-(A+ T)
G + C = 1000- 480 = 520 Hence, G = 260, C = 260
The number of pyrimidine bases, i.e.
C + T = 240 + 260 = 500