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'''Transcription''' is the biological process by which [[prokaryotic]] and [[eukaryotic]] cells generate single stranded [[RNA]]  

'''Transcription''' is the biological process by which [[prokaryotic]] and [[eukaryotic]] cells generate single stranded [[RNA]]  

through the enzymatic action of a specific isoform of [[RNA polymerase]]. It is the intermediary step in the production of [[protein|proteins]], and the final step for non-protein coding RNAs. Protein-coding genes are transcribed into mRNA which are then translated by the [[ribosome]] to create a nascent [[polypeptides|polypetide]] chain. In eukaryotes, the transcription process is however more complex than in prokaryotes because of the presence of three distinct RNA polymerases, each responsible for the transcription of a different class of RNA.<ref>{{cite web |author=Jerard Hurwitz |title=The Discovery of RNA Polymerase |publisher=JBC, The Journal of Biological Chemistry |url=http://www.jbc.org/content/280/52/42477 |accessdate=17 January 2015 |quote=In all organisms, genes coding for proteins are transcribed by the multisubunit complex, DNA-dependent RNA polymerase. In prokaryotes, this is accomplished by the core RNA polymerase linked to a number of sigma factors that specify its binding to different promoter elements. In eukaryotes, this process is more complex because of the presence of three distinct RNA polymerases, each responsible for the transcription of a different class of RNA.}}</ref>

through the enzymatic action of a specific isoform of [[RNA polymerase]]. It is the intermediary step in the production of [[protein]]s, and the final step for non-protein coding RNAs. Protein-coding genes are transcribed into mRNA which are then translated by the [[ribosome]] to create a nascent [[polypeptides|polypetide]] chain. In eukaryotes, the transcription process is however more complex than in prokaryotes because of the presence of three distinct RNA polymerases, each responsible for the transcription of a different class of RNA.<ref>{{cite web |author=Jerard Hurwitz |title=The Discovery of RNA Polymerase |publisher=JBC, The Journal of Biological Chemistry |url=http://www.jbc.org/content/280/52/42477 |accessdate=17 January 2015 |quote=In all organisms, genes coding for proteins are transcribed by the multisubunit complex, DNA-dependent RNA polymerase. In prokaryotes, this is accomplished by the core RNA polymerase linked to a number of sigma factors that specify its binding to different promoter elements. In eukaryotes, this process is more complex because of the presence of three distinct RNA polymerases, each responsible for the transcription of a different class of RNA.}}</ref>

In virally-infected cells, both RNA and DNA can be transcribed, and the resulting double-stranded RNA is an alarm signal for infection, as it is captured by the [[RNA interference]] pathway, imported into the [[endplasmic reticulum]] and then displayed on the cell surface in a specific subtype of MHC class II molecules. These short interfering RNAs (siRNAs) cause the production of [[interferon]]s, and the activation of the immune system.

In virally-infected cells, both RNA and DNA can be transcribed, and the resulting double-stranded RNA is an alarm signal for infection, as it is captured by the [[RNA interference]] pathway, imported into the [[endplasmic reticulum]] and then displayed on the cell surface in a specific subtype of MHC class II molecules. These short interfering RNAs (siRNAs) cause the production of [[interferon]]s, and the activation of the immune system.