If A and C make 30% and 20% of DNA, respectively, what will be the percentage composition of T and G?
- T : 20%, G : 20%
- T : 20%, G : 30%
- T : 30%, G : 20%
- T : 30%, G : 30%
Answer
(3) T : 30%, G : 20%
Solution
According to Chargaff's rule, in double-stranded DNA the amount of adenine equals thymine and the amount of guanine equals cytosine.
⇒ T = A = 30%
⇒ G = C = 20%
Check: A + T + G + C = 30 + 30 + 20 + 20 = 100%
∴ T : 30%, G : 20%
Answer: (3)