nucléotide

A nucleotide is a molecule consisting of a nucleoside and a phosphate group. Nucleosides are composed of a nitrogenous base and a sugar. The nitrogenous bases found in nucleotides are adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U). The sugars are either ribose, in the case of RNA, or deoxyribose, in the case of DNA. Therefore, the building blocks of DNA are deoxyadenosine monophosphate (dAMP), deoxyguanosine monophosphate (dGMP), deoxycytidine monophosphate (dCMP), and deoxythymidine monophosphate (dTMP). The building blocks of RNA are adenosine monophosphate (AMP), guanosine monophosphate (GMP), cytidine monophosphate (CMP), and uridine monophosphate (UMP).

Nucleotides are the monomers that polymerize to form nucleic acids, namely DNA and RNA. DNA, or deoxyribonucleic acid, serves as the genetic blueprint for all living organisms. RNA, or ribonucleic acid, plays various roles in gene expression and regulation, including messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). The sequence of nucleotides within a nucleic acid carries the genetic information.

Beyond their role in nucleic acids, nucleotides also function as energy carriers. Adenosine triphosphate (ATP) is the primary energy currency of the cell, powering numerous cellular processes through the hydrolysis of its phosphate bonds. Other nucleotides, such as guanosine triphosphate (GTP), also participate in energy transfer and signaling pathways. Furthermore, cyclic AMP (cAMP) and cyclic GMP (cGMP) act as important second messengers in cellular signal transduction. The structure and function of nucleotides are fundamental to understanding molecular biology and genetics.