What do viruses and bacteria have in common

 Bacteria and viruses can infect many species unrelated to each other. Rabies as a viral example, and staphylococcus as a bacterial example. Both can cause disease. 
They are able to mutate within a short period of time (few generations). 
Neither bacteria or viral organisms have a nucleus.  Hope that helped

The basic repeating unit of nucleic acids are known as nucleotides. a nucleotide consists of three distinct chemical groups.