Question

Which of following is not correct according to Chargaff's rule?

• A. $\frac{A}{T}=1$
• B. $A+T=G+C$
• C. $G+A=T+C$
• D. $\frac{C}{G}=1$

Answer 1

Answer: (B)

$A+T=G+C$

Erwin Chargaff did a biochemical analysis of DNA isolated from a number of organisms. Based on his biochemical analysis, he arrived at a conclusion that, in DNA, the quantity of purines is equal to the quantity of pyrimidine; Content of adenine is equal to the content of thymine and content of guanine is equal to the content of cytosine. Thus A:T ratio as well as C:G ratio will be one and the total content of A+G will be equal to the total content of T+C. But no equivalence was observed in the total content of A+T and G+C.
So, the correct answer is option B.