While the bacteria RNA transcription directly synthesized DNA of eukaryotes most transcripts are processed in the nucleus that is modified before they are transported to the cytoplasm as differential mRNA, which would serve as carriers of information for protein synthesis. Unlike bacteria which Transcription and translation take place virtually at the same time, the eukaryotic these processes in terms of time but also the spatial are divided. The envelope of the nucleus possesses the subsequent role of the ribosome link to transcripts, before this becomes elaborated and functional molecule RNA.
In the nuclei of eukaryotic cells there are three types of RNA polymerase, RNA polymerase I, RNA polymerase II and III ARNpolimeraza.
Each of these enzymes consist of large number of subnjësive: two large and 12 small. As bacterial enzymes, and eukaryotic RNA polymerases are molecules with an irregular shape, the channel through which passes DNA. Bacterial RNA polymerase, however, unlike eukaryotic enzymes, is very active in vitro system. For its activity is essential presence of DNA, whereas eukaryotic enzyme activity depends on the presence of a range of additional factors.
This was the reason, for which up to 1979 it was not possible to investigate in vitro mechanism of eukaryotic transcription. Besides nuclear RNA polymerase, eukaryotic cells contain RNA polymerase in organelles, such as mitochondria and chloroplasts. Enzymes distinct from nuclear organelles.
Each of the three nuclear RNA polymerases and eukaryotic cells _transkripton different sets of genes. RNA polymerase II transcribed structural genes are translated into proteins. Two other polymerases synthesize RNA that are translatues cellular apparatus: RNA polymerase I synthesizes large ribosomal subunit RNA (18s and 28S).
