How many hydrogen bonds form between a guanine and a cytosine base pair in the Watson-Crick DNA double helix?
Answer and explanation
Correct answer: B. 3 hydrogen bonds
Watson-Crick base pairing specifies 3 hydrogen bonds between Guanine and Cytosine (one C=O...H-N, one N-H...N, one N-H...O=C), whereas Adenine and Thymine form only 2 hydrogen bonds. High GC-content confers higher melting temperature (Tm).
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