The nucleic acids are the collective term for the two main macromolecular nucleotide polymers:
- DNA (deoxyribonucleic acid)
- RNA (ribonucleic acid)
Nucleotides, the constituent units of nucleic acids, are made up of simpler molecules called nucleosides and inorganic phosphate (H3PO4). Each nucleoside, in turn, is made up of a monosaccharide (D-ribose in RNA and 2-deoxy-D-ribose in DNA) and a heterocyclic base .
Heterocyclic bases, also known as nitrogenous bases, are divided into two main classes: purines and pyrimidines. Adenine (A) and guanine (G) belong to the purines; cytosine (C) and thymine (T) (replaced by uracil (U) in RNA) conversely belong to the pyrimidines.
DNA molecules are found in double helix form (A, B and Z-forms), while RNA molecules are typically single-stranded.
The main function of nucleic acids is the conservation and transmission of genetic information . In particular, the DNA of a cell and the information it contains represents the cellular genome.
In FLT PET imaging, a radiopharmaceutical similar in chemical composition to the nucleoside deoxythymidine is used, to which a hydroxyl group is replaced with a radioactive fluorine atom: [18F] -FLT.