What happens during the synthesis of mRNA?

Synthesis of mRNA from DNA happens in 3 steps: initiation, elongation, and termination. Initiation occurs when RNA polymerase binds to a promoter sequence signaling DNA to unwind. RNA polymerase then uses one of the DNA strands as a template to create a new mRNA molecule using complementary bases. This step is known as elongation. The last step is termination, where the RNA polymerase reaches a termination sequence which signals transcription to stop. The synthesis of an mRNA strand is complete and it detaches from the DNA.