Index >>Viroids and Prions >>RNA Dependent Viroid Replication

RNA Dependent Viroid Replication - According to this scheme, synthesis of viroids is DNA independent, and is analogous to that of many viral RNAs.
A basic assumption for this would be that RNA dirsected RNA polymerases are present in normal cells to catalyse RNA directed RN A synthesis.
This appears to be against the concept that cellular.
RNAs are transcribed from DNA templates.
However, there is recent evidence that RNA directed RNA synthesis may occur to a limited extent in normal cells of some plants and in E. coli.
An alternate assumption is that RNA directed RNA polymerase is composed of polypeptides specified both by host cell RNA and viroid RNA, as in the RNA bacteriophage Qβ