Ribonucleic acid

The ribonucleic acid is a chemical compound made up of phosphoric acid, ribose and 4 organic bases, a nucleic acid, i.e. a molecular chain (polynucleotide) consisting of many nucleotides.

Ribonucleic acid is similar in structure to deoxyribonucleic acid (DNA). The nitrogen bases adenine, guanine, cytosine and uracil are each bound to a sugar residue (the ribose). The sugar is in turn esterified with a phosphate residue in two places and forms a bridge with this residue. The sugar and phosphate residues alternate and form a chain. Three consecutive nitrogen bases are called a triplet and contain the genetic code for a specific amino acid. Several triplets in a row encode a polypeptide or protein chain. RNA thus plays an essential role in protein biosynthesis.

In contrast to DNA (deoxyribonucleic acid), the sugar (ribose) contains a hydroxyl group at the 2'-position instead of a hydrogen atom. In addition, the nitrogen base thymine is exchanged for uracil in RNA. Due to these chemical differences, RNA, unlike DNA, is usually only single-stranded.

Furthermore, the hydroxyl group of ribose causes molecular instability of the molecule (which is important for the proper transcription of genetic information). RNA differs from DNA also by this molecular instability. This is functionally important because different transcripts are needed at different points in time during translation. The ribonucleic acid therefore has no long-term storage function for the genetic code.

RNA occurs in different forms and also fulfils different tasks.

An essential function of RNA in the cell is the conversion of genetic information into protein structures. The RNA is involved here both as an information carrier (mRNA = messenger RNA) and as a catalyst in the translation of this genetic information into a protein structure (rRNA).

The mRNA copies the information located on a gene and transports it to the ribosome. There, protein synthesis takes place based on the information stored in the mRNA. In the process, 3 adjacent nucleotides form a so-called codon, which represents a specific amino acid. Thus, a polypeptide chain of amino acids is built up step by step.

The mRNA (messenger RNA), for example, only serves as a buffer for the genetic information until the transfer and translation is completed.

Shorter RNA molecules have no genetic code at all. The transfer RNA (tRNA) transports the individual amino acids to the ribosome where the protein synthesis takes place.

As another RNA molecule, rRNA (ribosomal RNA) is involved in the construction of the ribosomes. Further examples are asRNA (antisense RNA) for the regulation of gene expression, hnRNA (heterogeneous nuclear RNA) as a precursor to mature mRNA, ribowitches for gene regulation, ribozymes for the catalysis of biochemical reactions, etc.

In connection with diseases, ribonucleic acids play a role in that many viruses (RNA viruses) have only one RNA as a genetic material. When an RNA virus comes into contact with body cells, the genetic information of its RNA is activated. By means of the enzyme reverse transcriptase, the genetic information of the RNA is transcribed into the DNA. This DNA is incorporated into the DNA of the host cell and its genetic code is changed. This reprogramming leads to the constant creation of new viruses. The viruses are in turn discharged from the cell and thus infect other cells. The process is repeated until the cell dies.

In the cosmetic field, RNA is used as an active ingredient against skin ageing. The RNA is supposed to slow down the aging process of the skin.