The gene to be transcribed s unwound and unzipped using the enzyme DNA helicase which breaks the hydrogen bonds between complementary bases. Activated RNA nucleotides then bind to the exposed complementry bases forming hydrogen bonds. RNA polymerase is used to make the sugar-phosphate backbone of the mRNA strand. The mRNA produced is complementary to the template strand of DNA therefore is a copy of the base sequence of the coding DNA strand. The mRNA strand is then released through the nuclear pore and travels to the ribosome, ready for translation.