In DNA bases, CG is one pair and AT is another pair because the double ring bonds with the single ring. Why can't Guanine bond with Thymine?

The reason guanine (G) cannot form a direct bond with thymine (T) in DNA is because of the difference in their chemical structure. Guanine is one of the four nitrogenous bases found in DNA, while thymine is a separate nitrogenous base.

Guanine and thymine are each paired with a complementary base to ensure stability and proper functioning of the DNA molecule. In DNA, guanine is always paired with cytosine (C), forming a G-C base pair, while thymine is always paired with adenine (A), forming an A-T base pair.

The specific pairing between G and C and between A and T is based on hydrogen bonding. Hydrogen bonds occur between specific nitrogenous bases that have compatible structures, allowing them to connect to each other. Guanine and cytosine can form three hydrogen bonds with each other, creating a stronger bond compared to adenine-thymine, which only forms two hydrogen bonds.

Therefore, G and C are complementary bases that can form a stable bond, while G and T cannot form the necessary hydrogen bonds to create a stable base pair. The specific pairing of nucleotides in DNA is vital for its accurate replication and transcription into RNA.