The single-stranded DNA is revealed and ready for transcription as soon as the RNA polymerase and its related transcription elements are in place. Afterwards, RNA polymerase will begin to move down the DNA template strand in the 3' to 5' direction, and as it does so, it ties together interrelated nucleotides. This action makes a new strand of mRNA that is arranged in the 5' to 3' direction because of complementary base-pairing. More nucleotides are affixed to the mRNA as the RNA polymerase continues down the strand of DNA, therefore building a developing longer chain of nucleotides. Which is called elongation.
