Variety of Non-Coding RNAs in Eukaryotic Genomes

The genomes of large multicellular eukaryotes mainly consist of DNA that encodes not proteins, but RNAs. The unexpected discovery of approximately the same number of protein genes in Homo sapiens and Caenorhabditis elegans led to the understanding that it is not the number of proteins that determines the complexity of the development and functioning of an organism. The phenomenon of pervasive transcription of genomes is finding more and more confirmation. Data are emerging on new types of RNA that work in different cell compartments, are expressed at different stages of development, in different tissues and perform various functions. Their main purpose is fine regulation of the main cellular processes. The presence of a rich arsenal of regulators that can interact with each other and work on the principle of interchangeability determines the physiological complexity of the organism and its ability to adapt to changing environmental conditions. An overview of the currently known functional RNAs expressed in eukaryotic genomes is presented here. There is no doubt that in the near future, using high-tech transcriptome technologies, many new RNAs will be identified and characterized. But it is likely that many of the expressed transcripts do not have a function, but are an evolutionary reserve of organisms.