LESSION—2 Viruses, Viroids and Prions VIRUSES The name virus (Latin virus=venom of poisonous fluid) was given by Pasteur to the causative agents of infectious diseases. Adolph Mayer (1885), a Dutch scientist, and D....
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B.Sc. BOTANY PART I LESSION 1 Main Groups of Microorganisms Microorganisms show a great diversity in their cell structure and function. Some broad groups of Microorganisms are as follows. [I] Prions Prions are small proteinaceous infectious particles that do not contain nucleic acid. They were first identified by American neurobiologist Stanley Prusiner in 1982 in sheep affected by neurobiological disease. These are the only disease causing organisms which do not have nucleic acids. The major portion of this infectious agent is a protein called PrP (prion protein). The prion protein exists in two configuration. One is a normal cellular from (PrP c ) that is found in the brains of all adult mammals and does not cause disease and is found only in infected cells. The infected form is given a symbol consisting of PrP with a superscript that indicates the sourc...
ZOLOOGY LESSION-4 MONOCYSTIS MONOCYSTIS Monocytis (Gr., Mono=Single+kystis=bladder) is a gregarine parasite of sporozoa. Its life cycle is completed in one host only. There are two forms of gregarines are recognized, which exhibits sexual reproduction only i.e., acephaline and cephaline. In acephaline forms, the body is not divided in to chambers and anterior in does not bear and organ for attachment. Thus, the monocytis is an but the cephaline forms possesses the chambered body as well as the organ for attachment. Thus, the monocystis is an acephaline gregarine. The various species of Monocystis are M. agilis; M. pheretimi; M.lumbrici; M.lloidi; M.beddardi and M...