分子生物学第十一章噬菌体的战略Phagestrategies.ppt
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1、Chapter 11Phage strategies11.1 Introduction11.2 Lytic development is divided into two periods11.3 Lytic development is controlled by a cascade11.4 Functional clustering in phages T7 and T411.5 Lambda immediate early and delayed genes are needed for both lysogeny and the lytic cycle11.6 The lytic cyc
2、le depends on antitermination11.7 Lysogeny is maintained by repressor protein11.8 Repressor maintains an autogenous circuit11.9 The repressor and its operators define the immunity region11.10 The DNA-binding form of repressor is a dimer 11.11 Repressor uses a helix-turn-helix motif to bind DNA11.12
3、Repressor dimers bind cooperatively to the operator11.13 Repressor at OR2 interacts with RNA polymerase at PRM11.14 The cII and cIII genes are needed to establish lysogeny11.15 PRE is a poor promoter that requires cII protein11.16 Lysogeny requires several events11.17 The cro repressor is needed for
4、 lytic infection11.18 What determines the balance between lysogenic and the lytic cycle?Episome is a plasmid able to integrate into bacterial DNA. EpistasisImmunity in phages refers to the ability of a prophage to prevent another phage of the same type from infecting a cell. It results from the synt
5、hesis of phage repressor by the prophage genome.Induction refers to the ability of bacteria (or yeast) to synthesize certain enzymes only when their substrates are present; applied to gene expression, refers to switching on transcription as a result of interaction of the inducer with the regulator p
6、rotein.Lysogeny describes the ability of a phage to survive in a bacterium as a stable prophage component of the bacterial genome.Lytic infection of bacteria by a phage ends in destruction of bacteria and release of progeny phage.Plasmid is an autonomous self-replicating extrachromosomal circular DN
7、A.Prophage is a phage genome covalently integrated as a linear part of the bacterial chromosome.11.1 IntroductionFigure 11.1 Lytic development involves the reproduction of phage particles with destruction of the host bacterium, but lysogenic existence allows the phage genome to be carried as part of
8、 the bacterial genetic information. 11.1 IntroductionFigure 11.2 Several types of independent genetic units exist in bacteria. 11.1 IntroductionFigure 11.3 Lytic development takes place by producing phage genomes and protein particles that are assembled into progeny phages. 11.2 Lytic development is
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