Question

Which one of the following is correct for DNA?

• A. A + T = G + C
• B. A - T = G - C
• C. A + C = G + T
• D. A + G = T + C

Hint:

Remember Chargaff's rules: In DNA, the amount of adenine equals thymine, and the amount of cytosine equals guanine. Additionally, the total purines equal the total pyrimidines.

Answer 1

The Correct Option is D

Step 1: Understanding DNA structure.
In DNA, the base pairing follows Chargaff's rules, where adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). The total amount of purines (A and G) is equal to the total amount of pyrimidines (T and C). Hence, A + G = T + C is correct. Step 2: Analyzing the options.
(A) A + T = G + C: This is incorrect, as the sum of A and T does not equal the sum of G and C.
(B) A - T = G - C: This is incorrect, as there is no such relationship in DNA structure.
(C) A + C = G + T: This is incorrect; it does not follow Chargaff's rules.
(D) A + G = T + C: This is correct, as it follows Chargaff's rule that purines equal pyrimidines. Step 3: Conclusion.
The correct answer is (D) A + G = T + C.