1. Tardigrade
  2. Question
  3. Biology
  4. Which one is true? (1) A = T , G = C (2) A = G , T = C (3) C = G , T = A (4) T = U , G = A

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. Which one is true?
(1) $A = T , G = C$
(2) $A = G , T = C$
(3) $C = G , T = A$
(4) $T = U , G = A$

BHUBHU 2005

Solution:

Nitrogen bases are of two types:
(1) Purines base - (a) Adenine (b) Guanine
(2) Pyrimidines - (a) Cytosin (b) Thymine
The specific pairing between purine and pyrimidine bases proposed by Watson and Crick not only fitted very well with the radius of DNA determined from X-ray diffraction pictures but also had necessary complementary lock and key shape for efficient hydrogen bonding, which happens to be two between $A$ and $T ( A = T )$ and three betwen $G$ and $C ( G \equiv C )$.