nucleósidos

Nucleosides are organic molecules that serve as the building blocks of nucleic acids, DNA and RNA. Each nucleoside consists of two components: a nitrogenous base and a sugar molecule. The nitrogenous base is a heterocyclic aromatic compound that contains nitrogen. There are five main types of nitrogenous bases found in nucleosides: adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U). Adenine, guanine, and cytosine are found in both DNA and RNA, while thymine is specific to DNA, and uracil is specific to RNA.

The sugar molecule attached to the nitrogenous base is a pentose sugar, meaning it has five carbon atoms. In DNA, the sugar is deoxyribose, which lacks an oxygen atom at the 2' carbon. In RNA, the sugar is ribose, which has an oxygen atom at the 2' carbon. When a nitrogenous base is linked to a sugar molecule, it forms a nucleoside. For instance, adenine linked to ribose forms adenosine, and adenine linked to deoxyribose forms deoxyadenosine.

Nucleosides are crucial for cellular processes. They are not only precursors to DNA and RNA but also play roles in cell signaling, energy transfer, and as components of coenzymes like NAD+ and FAD. The modification of nucleosides can also lead to various important molecules, such as cyclic AMP (cAMP), which is a vital second messenger in many signaling pathways. Understanding nucleosides is fundamental to comprehending the structure and function of genetic material and cellular metabolism.