RNA
Chains
Starts
with
pppG
or
pppA - The first base of RNA is always purine, either pppG or pppA. In
E. coli most chains start with pppG, while φx174 and T7 bacteriophage chains start with pppA. After synthesis, however, the terminal triphosphate group or nucleotides may be cleaved by endonucleases.
This results in RNA chains without terminal triphosphate groups, or chains starting with pyrimidine nucleotides. It should be noted that RNA chains can be formed de novo and do not require primers, in contrast to DNA replication
