RNA synthesis:         

The general mechanism of RNA synthesis through these eukaryotic RNA polymerases is the similar as for the prokaryotic enzyme that is:

-   the initiation  of RNA synthesis  through RNA polymerase  is directed  through the presence of a promoter site on the 5' side of the transcriptional  begin site;

-   the RNA polymerase  transcribes  one strand, the antisense  (-) strand of the DNA sample;

-   RNA is synthesis that does not need a primer;

-   the RNA  synthesis occurs  in  the  5' → 3'  direction  with  the  RNA  polymerase catalyzing  a nucleophilic that attack through the 3' -OH of the growing  RNA chain on the phosphorus atom on an incoming ribonucleoside 5 -triphosphate.