So RNA polymerase catalyzes the formation of phosphodiasta bond. It brings the complementary nucleotide triphosphate this nucleotide that is complementary to this base into the mixture and then our RNA polymerase holds this in place and it catalyzes the formation of this bond as shown in the following diagram and the pyrophosphate is released as a result. Now, as I mentioned before the RNA polymerase reads the DNA template from the three to five end but it synthesizes that polynucleotide chain in the five to three end and this is the same exact method that DNA polymerase uses. Remember, DNA polymerase also reads that DNA template from the three to five end and it synthesizes that DNA molecule from the five to three in the same way that RNA polymerase does. Now, the difference between RNA polymerase and DNA polymerase is in RNA polymerase. Notice we do not need a primer sequence to actually initiate the process.