AGRICULTURE MICROBIOLOGY Lecture Notes - Martinus Beijerinck, Tobacco Mosaic Virus, Virus
Document Summary
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Most viruses are too small to be seen directly with a light microscope. Viruses infect all types of organisms, from animals and plants to bacteria and archaea. Since the initial discovery of tobacco mosaic virus by martinus beijerinck in 1898, about 5,000 viruses have been described in detail though there are millions of different types. Viruses are found in almost every ecosystem on earth and are the most abundant type of biological entity. The study of viruses is known as virology, a sub-speciality of microbiology. The shapes of viruses range from simple helical and icosahedral forms to more complex structures. The average virus is about one one-hundredth the size of the average bacterium: every virus has 2 stages dormant, particulate, transmissible stage called the virion stage an active, intracellular stage called the infectious stage.
