How many hydrogen bonds are present between a cytosine-guanine pair?

A cytosine-guanine pair in DNA is stabilized by three hydrogen bonds. This specific pairing is crucial for maintaining the structure of the DNA double helix. In terms of base pairing, cytosine (C) forms three hydrogen bonds with guanine (G), making it a stronger and more thermodynamically stable interaction compared to pairs like adenine-thymine, which only have two hydrogen bonds.

The three hydrogen bonds between cytosine and guanine occur as follows: one hydrogen bond forms between the carbonyl oxygen of cytosine and the amine hydrogen of guanine, and the other two hydrogen bonds form between the amine group of cytosine and two different nitrogen atoms in guanine. This triple bonding is significant for the overall stability and integrity of the DNA molecule, emphasizing the importance of these base pairs during processes such as DNA replication and transcription. Understanding this specific number of hydrogen bonds is fundamental in genetics and molecular biology as it plays a key role in base pairing and DNA structure.