The enzyme RNA polymerase produces strands of RNA from DNA templates. This is the first step in protein synthesis, known as transcription.
The RNA polymerase enzyme requires several cofactors to bind and form the RNA complex before it can transcribe the DNA. The DNA is unwound by DNA helicase enzymes to form a ‘bubble’ of open DNA. The transcription complex forms in this bubble, progressing along the DNA. The complex ‘reads’ each DNA base and matches it to the complementary mRNA base, synthesising a growing complimentary copy of the DNA sequence in the mRNA molecule.
DNA and RNA are chemically very similar, but have a few key differences. One is that RNA contains the bases Adenine, Guanine, Cytosine and Uracil whereas DNA contains Adenine, Guanine, Cytosine and Thymine.