In a eukaryote, DNA never leaves the nucleus, so its information must be copied. This copying process is called transcription and the copy is mRNA. Transcription takes place in the cytoplasm (prokaryote) or in the nucleus (eukaryote). The transcription is performed by an enzyme called RNA polymerase. To make mRNA, RNA polymerase: 1  Binds to the DNA strand at a specific sequence of the gene called a promoter.  Unwinds and unlinks the two strands of DNA.