BIOL 1406 Lecture 17: Biology notes Ch. 19
Document Summary
Viruses lead a borrowed life between life-forms and chemicals. Viruses can infect and set in motion a genetic takeover of cells. Change the behavior of the cells and use the cells machinery to reproduce. In the late 1800s, researchers hypothesized that particles smaller than bacteria caused some diseases. Tobacco mosaic disease stunts growth of tobacco plants and gives their leaves a mosaic coloration. In 1935, wendell stanley confirmed this hypothesis identifying the tobacco mosaic virus (tmv) Viruses are: infectious particles consisting of nucleic acid enclosed in a protein coat (capsid) and, in some cases, a membranous envelope. A virus is thus called a dna virus or an rna virus. A capsid is the protein shell that encloses the viral genome built from protein subunits. Some viruses have membranous envelopes that help them infect hosts. Viral envelopes are derived from the host cell"s membrane and contain a combination of viral and host cell molecules.
