Nukleotidia

Nukleotidia are the basic building blocks of nucleic acids, including DNA and RNA. Each nucleotide consists of three components: a nitrogenous base (purine or pyrimidine), a five-carbon sugar (ribose in ribonucleotides or deoxyribose in deoxyribonucleotides), and one or more phosphate groups. Nucleotides polymerize through their phosphate and sugar moieties to form polynucleotides, creating the sugar-phosphate backbone with the bases protruding to store genetic information.

The bases are categorized as purines (adenine and guanine) and pyrimidines (cytosine, thymine in DNA, and uracil in RNA). In DNA, thymine replaces uracil and pairs with adenine, while in RNA uracil pairs with adenine. Nucleotides can exist as ribonucleotides (RNA) or deoxyribonucleotides (DNA), reflecting the presence of ribose or deoxyribose sugars. They also include nucleotide derivatives such as the energy-carrying triphosphates ATP and GTP, and nucleotide-based signaling molecules like cyclic AMP and cyclic GMP.

Nukleotidia are synthesized by cells through de novo pathways or via salvage pathways that recycle nucleosides and phosphate groups. Deoxyribonucleotides, required for DNA, are produced from ribonucleotide precursors and undergo reduction in specific steps. The balance of nucleotide pools is tightly regulated to support DNA replication, transcription, RNA processing, and overall cellular metabolism.

In addition to their roles in heredity and information transfer, nucleotides function as energy carriers, cofactors, and signaling molecules, and they participate in a wide range of enzymatic reactions. They are ubiquitously present in all living cells, reflecting their essential roles in biology.