Ribonucleotides

In biochemistry, a ribonucleotide or ribotide is a nucleotide containing ribose as its pentose component. It is considered a molecular precursor of nucleic acids. Nucleotides are the basic building blocks of DNA and RNA. The monomer itself from ribonucleotides forms the basic building blocks for RNA. However, the reduction of ribonucleotide, by enzyme ribonucleotide reductase (RNR), forms deoxyribonucleotide, which is the essential building block for DNA. There are several differences between DNA deoxyribonucleotides and RNA ribonucleotides. Successive nucleotides are linked together via phosphodiester bonds by 3'-5'.

Ribonucleotides are also utilized in other cellular functions. These special monomers are utilized in both cell regulation and cell signaling as seen in adenosine-monophosphate (AMP). Furthermore, ribonucleotides can be converted to adenosine triphosphate (ATP), the energy currency in organisms. Ribonucleotides can be converted to cyclic adenosine monophosphate (cyclic AMP) to regulate hormones in organisms as well. In living organisms, the most common bases for ribonucleotides are adenine (A), guanine (G), cytosine (C), or uracil (U). The nitrogenous bases are classified into two parent compounds, purine and pyrimidine.

The general structure of a ribonucleotide consists of a phosphate group, a ribose sugar group, and a nucleobase, in which the nucleobase can either be adenine, guanine, cytosine, or uracil. Without the phosphate group, the composition of the nucleobase and sugar is known as a nucleoside. The interchangeable nitrogenous nucleobases are derived from two parent compounds, purine and pyrimidine. Nucleotides are heterocyclic compounds, that is, they contain at least two different chemical elements as members of its rings.

...
Wikipedia