北师大细胞生物学 03.ppt

§3. The general structure and multiplicity of the  cells 1.Biogap The cell originated 3.5 billion years ago  The comparison of cellular and non-cellular  organism. 2. viruses, viroid and prion ? virus and diversity of virus  TMV( tobacco mosaic disease ), hoof-and-mouth disease in cattle, sap of them are infectious agent capable of transmitting disease and pass through filters. They cannot be grown in culture media. In 1935, (Wendell Stanley) TMV was crystallized. e.g. AIDS, polio, influenza, measles, a few types of cancer, bacteriopphages virion in a variety of shapes and sizes but all of them consist of single stranded or double stranded RNA or DNA, surrounded by a protein capsule (capsid) polyhedron as 20-sided icosahedron lipid-containing outer envelope. HIV( human immunodeficiency virus ) gp120 Lytic infection and lysogenic infection ( integrate, provirus ) Which often alter the activities of the host cell ( Lambda-a bacterial Virus, HIV-by badding, tumor virus--become malignant) ? ? Viruses are noncellular pathogens that can only reproduce when present within a living cell. ? Viruses are not considered to be organism and not described as being alive. ? Viruses are not a primitive life form, but rather have evolved secondarily from fragments of cellular chromosomes. ? Viruses are used as a research tool and means of biotechnique. Viroids 1971, T, Diener potato spindle-tuber disease only a naked RNA about 240-600 bp without protein Prion 1957 Carleton Gajdusek in New Guinea, kuru disease being infectious. 1959 William Hadlow Scrapie ( slow virus) ~kuru? 1968 Igor Klatzao Inherited Creutafeldt-Jakob disease(CJD) ~kuru? 1982 Stanley Prusiner 27-30KD protein prion (a proteinaceous particle) responsible for scr