Pathogen

Viruses, Prokaryotes, Protists, and Fungus Study Guide Discovery of Viruses : ? While studying the tobacco mosaic disease that affects tobacco plants, scientist Dmitri Ivanovsky passed extracts of diseased tobacco leaves through filter pores small enough to strain out bacteria ( which was thought of as being pathogens) ? After realizing that the strained substance (thought to be disease free) could STILL pass on the disease, it lead him to believe that the pathogen was NOT bacteria?but what was it? Structure of Viruses : ? Basic viral structure includes genetic material (either DNA or RNA ? not both) surrounded by a protein called capsid. ? In some viruses, the capsid is surrounded by a lipid envelope that surface from which