Nucleic Acids
In the Watson–Crick double helical model of DNA, which of the following base-pair combinations and number of hydrogen bonds is CORRECT?
Select the correct option:
Solution
A–T: 2 hydrogen bonds; G–C: 3 hydrogen bonds
According to Watson and Crick's model of B-DNA, complementary base pairing occurs between Adenine (A) and Thymine (T) via 2 hydrogen bonds, and between Guanine (G) and Cytosine (C) via 3 hydrogen bonds. Because G–C pairs have one additional hydrogen bond, DNA rich in G–C content has a higher melting temperature (Tm). This stronger G–C interaction is exploited in PCR primer design — primers with higher G–C content bind more stably. The two strands run antiparallel (one 5'→3' and the other 3'→5').
🔒 Solution Hidden from View
Submit your answer to unlock the detailed step-by-step solution.
More nucleic acids Practice Questions
About This Question
- Subject
- chemistry
- Chapter
- biomolecules
- Topic
- nucleic acids
- Difficulty
- Easy
- Year
- 2025
Solution
Correct Answer:
A–T: 2 hydrogen bonds; G–C: 3 hydrogen bonds
According to Watson and Crick's model of B-DNA, complementary base pairing occurs between Adenine (A) and Thymine (T) via 2 hydrogen bonds, and between Guanine (G) and Cytosine (C) via 3 hydrogen bonds. Because G–C pairs have one additional hydrogen bond, DNA rich in G–C content has a higher melting temperature (Tm). This stronger G–C interaction is exploited in PCR primer design — primers with higher G–C content bind more stably. The two strands run antiparallel (one 5'→3' and the other 3'→5').
This easy difficulty chemistry question is from the chapter biomolecules, covering the topic of nucleic acids. It appeared in the 2025 exam.
Looking for more practice? Explore all chemistry questions or browse biomolecules questions on RankGuru.