AP Biology ? Chapter 19 Viruses ? Overview: A Borrowed Life ? Viruses:???????? Basically just genes packaged in protein coats. ??????????????????????? They lack the structures and metabolic machinery found in cells ? ? Are viruses living or nonlinving? -??????????? They cannot reproduce or carry out metabolic activities outside of a host cell ? so they are kind of between living and non-living (hence ?A borrowed life?. ? ? A lot of what we know about molecular biology comes from the study of viruses ? a lot of the information about genes and nucleic acids. ? ??????????? The ability to manipulate genes and transfer them comes from the study of viruses ??????????? Viruses are used as the agents of gene transfer in gene therapy. ? ? ? ?