mononukleotid

A mononucleotide is the basic building block of nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Each mononucleotide consists of three components: a nitrogenous base, a five-carbon sugar, and one or more phosphate groups.

The nitrogenous bases are divided into two categories: purines and pyrimidines. Adenine (A) and guanine (G) are purines, while cytosine (C), thymine (T), and uracil (U) are pyrimidines. DNA contains adenine, guanine, cytosine, and thymine, whereas RNA contains adenine, guanine, cytosine, and uracil.

The five-carbon sugar in DNA is deoxyribose, and in RNA, it is ribose. The phosphate group is attached to the sugar molecule. When multiple mononucleotides link together, they form a polynucleotide chain, with the phosphate group of one mononucleotide forming a phosphodiester bond with the sugar of another. This repeating sugar-phosphate backbone is characteristic of DNA and RNA. Mononucleotides are also involved in cellular energy transfer, most notably adenosine triphosphate (ATP).