Messenger RNA (mRNA) is used during translation to form polypeptides. Describe how mRNA is produced in the nucleus of a cell.

RNA polymerase scans the antisense DNA strand in the 3’ to 5’ direction, until it locates a promotor region. RNA polymerase then unwinds the DNA by breaking the hydrogen bonds between the complementary bases of the two separate strands- this is known as helicase activity. The exposed base will attract a free nucleotide from the nucleus using complementary base pairing. The RNA polymerase continues to do this for subsequent bases, pairing each base to the next via condensation reactions. The process ends when the RNA polymerase reaches a terminator region. The resulting molecule is known as pre-mRNA. The pre-mRNA is then spliced (involving the removal of introns) and capped and tailed before exiting the nucleus via pores.Things to note:1) Direction of DNA scanning is 3’-5’, but the mRNA is synthesised in the 5'-3' direction2) RNA polymerase has three roles; scanning the DNA for the promotor region, helicase activity, and forming bonds between bases3) this process takes place in three steps: initiation, elongation and termination