[生物学]03 病毒学概论 微生物与免疫学.ppt

病毒（Virus）是在19世纪末才被发现的一类微小病原体。 复合对称的病毒粒子 很多能有效杀菌的消毒剂、防腐剂及抗生素却不能杀灭病毒。为什么？ 针对病毒复制的5个步骤，你能找出一些有希望成为防止或控制病毒感染的好方法吗？ 第二节——亚病毒 四、病毒形态结构和大小 Size and Shapes of Viruses 1. Size (see Fig. 1A, Fig. 1B, and Fig. 1C) Viruses are usually much smaller than bacteria and are submicroscopic (def). Most range in size from 5 to 300 nanometers (nm) (def), although some Paramyxoviruses can be up to 14,000nm long. For a comparison of the size of a virus, a bacterium, and a human cell, scroll down to how big is... on the CELLS ALIVE web page. 2. Shapes (see Fig. 1A, Fig. 1B, and Fig. 1C) a. Helical viruses (def) consist of nucleic acid surrounded by a hollow protein cylinder or capsid and possessing a helical structure (see Fig. 2A). b. Polyhedral viruses (def) consist of nucleic acid surrounded by a polyhedral (many-sided) shell or capsid, usually in the form of an icosahedron (def); (see Fig. 2B and Fig. 1E).- Scanning electron micrograph of poliomyelitis viruses; courtesy of Dennis Kunkels Microscopy. c. Enveloped viruses (def) consist of nucleic acid surrounded by either a helical or polyhedral core and covered by an envelope (see Fig. 2C, Fig. 2D, Fig. 1F and Fig. 1H, and Fig. 3A).- Scanning electron micrograph of herpes simplex viruses; courtesy of Dennis Kunkels Microscopy. d. Binal (complex) viruses (def) have neither helical nor polyhedral forms, are pleomorphic (irregular shaped), or have complex structures (see Fig. 2E). - Scanning electron micrograph of the bacteriophage coliphage T4; courtesy of Dennis Kunkels Microscopy. Size and Shapes of Viruses 1. Size (see Fig. 1A, Fig. 1B, and Fig. 1C) Viruses are usually much smaller than bacteria and are submicroscopic (def). Most range in size from 5 to 300 nanometers (nm) (def), although some Paramyxoviruses can be up to 14,000nm long. For a comparison of the size of a virus, a bacterium, and a human cell, scroll down to how big is... on the CELLS ALIVE web page. 2. Shapes (see Fig. 1A, Fig. 1B, and Fig. 1C) a. Heli