How many hydrogen bonds are formed between an adenine-thymine pair?

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An adenine-thymine pair in DNA forms two hydrogen bonds. This pairing is due to the specific complementary base pairing rules established by the structure of DNA. Adenine, a purine, contains an amino group and can form hydrogen bonds with thymine, which is a pyrimidine.

The formation of these two hydrogen bonds occurs between certain functional groups: one hydrogen bond is formed between the carbonyl group of thymine and an amino group of adenine, while the second hydrogen bond is formed between an amino group of thymine and the carbon-nitrogen double bond of adenine. This specific two-bond pairing helps ensure the stability of the DNA double helix, influencing the overall structure and function of genetic material.

In contrast, guanine and cytosine pairs form three hydrogen bonds, which contribute to their stronger binding compared to adenine-thymine pairs, but that context is separate from the question regarding adenine-thymine.