The base pairing observed in DNA is due to which type of bonds between bases?

The base pairing observed in DNA is due to which type of bonds between bases?

• A. Hydrogen bonds
• B. Ionic bonds
• C. Covalent bonds
• D. Metallic bonds

Answer: (A)

Base pairing observed in DNA is due to hydrogen bonds between the bases. These are weak, noncovalent attractions that form between a hydrogen attached to a electronegative atom (like nitrogen or oxygen) and a lone pair on another electronegative atom. In DNA, adenine forms two hydrogen bonds with thymine, and guanine forms three hydrogen bonds with cytosine. This arrangement gives the precise A–T and G–C pairing and provides just the right balance of strength: stable enough to hold the two strands together, yet flexible enough to separate during replication and transcription. Covalent bonds would lock bases in place and prevent strand separation, ionic bonds aren’t the type of interaction that occurs between uncharged bases in the DNA interior, and metallic bonds aren’t relevant to biological molecules.

Base pairing observed in DNA is due to hydrogen bonds between the bases. These are weak, noncovalent attractions that form between a hydrogen attached to a electronegative atom (like nitrogen or oxygen) and a lone pair on another electronegative atom. In DNA, adenine forms two hydrogen bonds with thymine, and guanine forms three hydrogen bonds with cytosine. This arrangement gives the precise A–T and G–C pairing and provides just the right balance of strength: stable enough to hold the two strands together, yet flexible enough to separate during replication and transcription. Covalent bonds would lock bases in place and prevent strand separation, ionic bonds aren’t the type of interaction that occurs between uncharged bases in the DNA interior, and metallic bonds aren’t relevant to biological molecules.