In DNA, adenine pairs with thymine via how many hydrogen bonds?

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Multiple Choice

In DNA, adenine pairs with thymine via how many hydrogen bonds?

Adenine and thymine pair through two hydrogen bonds, a pattern that helps stabilize the DNA double helix while keeping the two strands complementary and regular in width. This two-bond pairing contrasts with guanine and cytosine, which form three hydrogen bonds, contributing extra stability to GC-rich regions. If A and T shared only one bond, the interaction would be much less stable; if they formed four, the pairing would be unusually strong and disrupt the balance of forces that enable strands to separate when needed. Thus, the correct number of hydrogen bonds between adenine and thymine is two.

Adenine and thymine pair through two hydrogen bonds, a pattern that helps stabilize the DNA double helix while keeping the two strands complementary and regular in width. This two-bond pairing contrasts with guanine and cytosine, which form three hydrogen bonds, contributing extra stability to GC-rich regions. If A and T shared only one bond, the interaction would be much less stable; if they formed four, the pairing would be unusually strong and disrupt the balance of forces that enable strands to separate when needed. Thus, the correct number of hydrogen bonds between adenine and thymine is two.

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