Deoxyribonucleic acids

Deoxyribonucleic acids are high polymeric chain molecules that are composed of 4 different building blocks, the nucleotides. Each nucleotide consists of a phosphate residue, a C5 sugar ring (deoxyribose) and one of 4 nitrogen bases (adenine, thymine, guanine and cytosine). By esterification of the 5` phosphate group of each basic building block (see illustration) with the 3` hydroxyl group of the following nucleotide, unbranched biopolymers (chain molecules) are formed. Due to this linear arrangement of the 4 nucleotide basic building blocks:

• dAMP (2'deoxyadenosine-5`monophosphate)
• dCMP (2'deoxycytidine-5'-monophosphate)
• dGMP (2'Deoxyguanosine-5`monophosphate)
• dTMP (2'Deoxythymidine-5`monophosphate)

in a genetically determined order, the DNA can act as a carrier of genetic information.

The synthesis of DNA takes place in the cell under the catalytic action of several enzymes, including DNA polymerases, DNA ligases and DNA gyrases (DNA topoisomerases). The DNA is broken down hydrolytically by deoxyribonucleases.

Deoxyribonucleic acids are carriers of all genetic information. Their genetic code provides all the information necessary for the production of ribonucleic acids (RNA).

A special group of RNA, the mRNA, contains the information for the construction of the proteins that are necessary for the biological development of a living being and for the metabolism of a cell. Within the protein-coding genes, the sequence of the bases (adenine, thymine, guanine and cytosine) determines the order of the amino acids of the respective protein: In the genetic code, 3 bases define each for a certain amino acid.