Which type of bond holds the two strands of a DNA double helix together?
Answer and explanation
Correct answer: C. Hydrogen bonds between a purine on one strand and a pyrimidine on the other
- Step 1: The two strands run antiparallel and are linked across the helix by their bases.
- Step 2: Adenine pairs with thymine and guanine pairs with cytosine, each pairing a purine with a pyrimidine through hydrogen bonds.
Answer
hydrogen bonds between purine and pyrimidine bases.
Why not the others: Covalent bonds hold each strand's sugar-phosphate backbone, not the two strands together; peptide bonds join amino acids; phosphates are in the backbone, not paired with bases.
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