第四章 噬菌体（Fourth chapter bacteriophage）.docVIP

第四章 噬菌体（Fourth chapter bacteriophage） Phages can be divided into two types: one is the ability to replicate and proliferate in host cells, and to produce a number of progeny phages, and ultimately to lyse bacteria, known as virulent phage. The other is a phage gene and host chromosome integration, does not produce offspring phage, phage DNA but can with bacterial DNA replication, and with bacteria divide and subculture, called temperate phage (temperate phage) or lysogenic phage (lysogenic phage). The toxic phage can proliferate in the susceptible bacteria by replication, and the proliferation process includes several stages of adsorption, penetration, biosynthesis, maturation and release. From the release of phage adsorption to bacteria dissolved progeny phage, called phage replication cycle or lytic cycle. Adsorption and adsorption are the process of specific binding of bacteriophages to bacterial surface receptors (Fig. 4-3), and their specificity depends on the complementarity of the molecular structures of phage proteins with the host surface receptors. Different phage adsorption methods were different. The silk phage was adsorbed at its terminal, and the tail phage was adsorbed by tail silk and tail thorn. Silk like phages, such as M13, F1, and microsphere phages, such as MS2, are sexually attached to bacterial pili, so only F + bacteria that infect sexually pilus are infected. As long as the bacteria have specific receptors, whether live or dead, the phage can adsorb, but the phage cannot enter the host of death. Through the end of adsorption of phage host bacteria, with a similar tail end of the material containing lysozyme solution, a hole in the cell wall, and then through the contraction of the tail sheath, the head of DNA injection of bacteria, and the bacteria in the extracellular protein capsid (Fig. 4 - 4). Tailless phages and silk phages can enter the bacterial cell by shelling. Biosynthesis of phage nucleic acids into bacterial cells, on the one han