General

The RNA (ribonucleic acid)


Structure of ribonucleic acid

The RNA (ribonucleic acid), like the DNA, is a nucleotide strand. It is of central importance in protein biosynthesis (transcription and translation).
A single nucleotide consists of a phosphate acid residue, a ribose (monosaccharide with 5 C atoms -> pentose), and an organic base. These may be adenine, cytosine, guanine or uracil. Compared to DNA, thymine in RNA is thus replaced by uracil.
As a rule, the ribonucleic acid consists of only one strand. This is mainly due to their function. During transcription, the DNA is transcribed (transferred) to the messenger RNA and read again in translation for the synthesis of proteins. The process works so effectively and economically, because the RNA has only one strand compared to the DNA on which all the information is included as well. For by complementarity of bases the sequence of a genetic code is established also on one-stranded RNA.
Additional Knowledge: The so-called RNA World Hypothesis implies that our present civilization is a successor to a world based on ribonucleic acid as a general building block for information storage and catalysis of chemical processes. Accordingly, RNA molecules have been the first precursors of organisms. This hypothesis can be explained by the ability of the RNA to store, transmit and reproduce genetic information and to influence it as a ribozyme (catalytically active RNA) reaction. The deoxyribonucleotide, which is responsible for the assembly of DNA, is originally made from building blocks of RNA. Demensprechend DNA can only be generated, if previously constructed RNA in the form of ribonucleotides.

Selection of different RNA variants (non-exhaustive list)

mRNA (messenger RNA) transports the genetic information from the cell nucleus to the ribosomes, the site of protein biosynthesis
tRNA (transfer RNA) transports amino acids from the cytoplasm to the ribosomes (does not encode genetic information!)
rRNA (ribosomal RNA) is responsible for the structure of ribosomes (does not encode genetic information!)