guaninu

Guanine is one of the four main nucleobases found in DNA and RNA, along with adenine, cytosine, and thymine (or uracil in RNA). It is a purine derivative, meaning it has a double-ring structure composed of a pyrimidine ring fused to an imidazole ring. In DNA and RNA, guanine pairs specifically with cytosine through three hydrogen bonds, forming a critical component of the genetic code. Its molecular formula is C5H5N5. Guanine is also a key component of guanosine and deoxyguanosine, which are nucleosides. These nucleosides, when phosphorylated, form nucleotides, the building blocks of nucleic acids. Beyond its role in genetics, guanine is also involved in energy transfer as part of guanosine triphosphate (GTP), a molecule similar to ATP. Guanine can be synthesized de novo or through the degradation of nucleic acids. Defects in guanine metabolism can lead to certain metabolic disorders. It is also found in the pigment guanine, which gives fish their iridescent sheen and is used in cosmetics.