BIOL 230 Lecture Notes - Lecture 13: Martinus Beijerinck, Tobacco Mosaic Virus, Rna Virus
Document Summary
A glimpse of history: virus means poison , d. iwanowsky, martinus beijerinck determined that tobacco mosaic disease (1890s) was caused by a different infectious material. This was filterable and too small to be seen with light microscope: w. twort and f. d"herelle discovered filterable virus that destroyed bacteria. Inert particles: no metabolism, replication, and motility outside the host cell. Inert outside cells; inside, direct activities of cell. Classified based on type of cell they infect: eukaryotic viruses and prokaryotic viruses: bacteriophages (phages) infect prokaryotes, may provide alternative to antibiotics. Virion (viral particle) is a nucleic acid surrounded by a protein coat: protein coat is capsid - carries required enzymes, capsid- protects nuvleic acids, composed of identical subunits called capsomeres, capsid + na = nucleocapsid. Enveloped viruses have acquired the envelop from the host cell and modified with viral proteins. Enveloped viruses have a lipid bilayer envelope - not a membrane. Non-enveloped (naked) viruses lack envelope, more resistant to disinfectants.
