A short DNA segment has 30 A–T base pairs and 7 G–C base pairs. How many hydrogen bonds hold the two strands together?
Answer and explanation
Correct answer: D.
- Step 1: A–T pairs have 2 hydrogen bonds and G–C pairs have 3. Step 2. 2 × 30 + 3 × 7 = 81. **Answer: . Why not the others:** is what you get if you swap the number of bonds per pair. is what you get if you count one bond per pair. is what you get if you count two bonds for every pair.
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