Nucleosides and Nucleotides

Nucleosides and nucleotides and their derivatives are biologically ubiquitous substances that participate in nearly all biochemical processes. They form the monomeric units of nucleic acids and thereby play central roles in both the expression and storage of genetic information.

Nucleosides are glycosylamines obtained by chemical or enzymatic decomposition of nucleic acids and contain two components: a five-carbon sugar (ribose or 2’ deoxyribose) and nitrogen base. Examples of nucleosides include adenosine, cytidine, guanosine, and thymidine. They function as signaling molecules and are precursors for nucleotides needed for DNA and RNA synthesis. Nucleosides play an important role in medicine and molecular biology and are used as antiviral or anticancer agents.

As the building block of DNA and RNA, nucleotides are organic molecules composed of three components: a five-carbon sugar, nitrogen base and one or more phosphate groups. Examples of nucleotides include adenine, cytosine, guanine, thymine, and uracil. Nucleotides are not only the basic unit of genetic material in all living things, they also play a role in the energy, metabolism, and signaling in cells.