cytozínom

Cytosine is one of the four main nucleobases found in DNA and RNA. Along with adenine, guanine, and thymine (in DNA) or uracil (in RNA), cytosine forms the building blocks of genetic material. It is a pyrimidine derivative, meaning its chemical structure is based on a single six-membered heterocyclic aromatic ring with two nitrogen atoms.

In DNA, cytosine always pairs with guanine through three hydrogen bonds. This specific pairing is crucial for the stable double-helix structure of DNA and for accurate replication of genetic information. In RNA, cytosine also pairs with guanine. The sequence of these bases along the DNA or RNA molecule encodes the genetic instructions for the development, functioning, growth, and reproduction of all known organisms.

Cytosine can undergo certain chemical modifications, such as methylation, which plays a significant role in gene regulation without altering the underlying DNA sequence. These epigenetic modifications can affect gene expression, influencing various cellular processes and even contributing to disease development. The study of cytosine and its roles is fundamental to molecular biology, genetics, and medicine.