In base pairing, adenine always pairs with thymine, and guanine always pairs with cytosine.

Why does adenine always pair with thymine?

Base pairing. Base pairing between adenine and thymine can be found in DNA only. There are two hydrogen bonds holding the two nitrogenous bases together. ... The hydrogen bonds between adenine and thymine are important for DNA to maintain a double helix structure.

Does DNA thymine pair with adenine?

Adenine is one of the four building blocks of DNA. It's the A of the A, C, G, and T that's in DNA. Adenine has the property that, when it's in the double helix, it is always found opposite of thymine, so adenine and thymine pair one on each strand.