Which base always pairs with adenine in a DNA molecule?

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Multiple Choice

Which base always pairs with adenine in a DNA molecule?

Explanation:
Base pairing in DNA is determined by complementary hydrogen bonds and the need to keep the double helix width uniform. Adenine forms two hydrogen bonds with thymine, making this A–T pairing stable and specific. The geometry and bonding patterns don’t fit adenine pairing with cytosine or guanine, which pair with each other to form GC pairs. This specificity is why thymine is the partner for adenine in DNA. Note that in RNA, adenine pairs with uracil.

Base pairing in DNA is determined by complementary hydrogen bonds and the need to keep the double helix width uniform. Adenine forms two hydrogen bonds with thymine, making this A–T pairing stable and specific. The geometry and bonding patterns don’t fit adenine pairing with cytosine or guanine, which pair with each other to form GC pairs. This specificity is why thymine is the partner for adenine in DNA. Note that in RNA, adenine pairs with uracil.

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