<Li> The RNA may remain in the nucleus or exit to the cytoplasm through the nuclear pore complex . </Li> <P> The stretch of DNA transcribed into an RNA molecule is called a transcription unit and encodes at least one gene . If the gene encodes a protein, the transcription produces messenger RNA (mRNA); the mRNA, in turn, serves as a template for the protein's synthesis through translation . Alternatively, the transcribed gene may encode for either non-coding RNA (such as microRNA), ribosomal RNA (rRNA), transfer RNA (tRNA), or other enzymatic RNA molecules called ribozymes . Overall, RNA helps synthesize, regulate, and process proteins; it therefore plays a fundamental role in performing functions within a cell . </P> <P> In virology, the term may also be used when referring to mRNA synthesis from an RNA molecule (i.e., RNA replication). For instance, the genome of a negative - sense single - stranded RNA (ssRNA -) virus may be template for a positive - sense single - stranded RNA (ssRNA +). This is because the positive - sense strand contains the information needed to translate the viral proteins for viral replication afterwards . This process is catalyzed by a viral RNA replicase . </P> <P> A DNA transcription unit encoding for a protein may contain both a coding sequence, which will be translated into the protein, and regulatory sequences, which direct and regulate the synthesis of that protein . The regulatory sequence before ("upstream" from) the coding sequence is called the five prime untranslated region (5'UTR); the sequence after ("downstream" from) the coding sequence is called the three prime untranslated region (3'UTR). </P>

During transcription the sense strand of dna is copied to mrna