nucléotides

Nucleotides are the fundamental building blocks of nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Each nucleotide consists of three components: a phosphate group, a five-carbon sugar (either ribose or deoxyribose), and a nitrogenous base. The nitrogenous bases are classified into two groups: purines (adenine and guanine) and pyrimidines (cytosine, thymine, and uracil). In DNA, adenine pairs with thymine, and guanine pairs with cytosine. In RNA, adenine pairs with uracil, and guanine pairs with cytosine.

The sequence of these nitrogenous bases along the DNA or RNA molecule carries the genetic information. DNA, with its double-helix structure, stores the genetic blueprints for all living organisms. RNA, typically single-stranded, plays various roles, including protein synthesis (messenger RNA), ribosomal structure (ribosomal RNA), and transport of amino acids (transfer RNA).

Beyond their role in genetic material, nucleotides also function as energy carriers, most notably adenosine triphosphate (ATP), which is the primary energy currency of the cell. They are also involved in cell signaling and as components of coenzymes essential for metabolic reactions. The synthesis and breakdown of nucleotides are tightly regulated processes within cells, ensuring the availability of these crucial molecules for cellular function and replication.