Pha 11.2 Lytic development sectio is controlled by a Phai taches to bacterium cascade acterium Ean mes for ynthesis are made Replication Figure 11.3 Lytic begins development takes place by Late development Genomes producing phage genomes heads. tails are made and protein particles that DNA packaged into heads tails attached are assembled into progeny pl ha ages 消当
Figure 11.3 Lytic development takes place by producing phage genomes and protein particles that are assembled into progeny phages. 11.2 Lytic development is controlled by a cascade
Early: phage genes are transcr bed by host RNA polymerase 11.2 Lytic development is controlled by a AAA cascade Types of gene product Regul ator gene(s) RNA polymerase gma factor or antiteminat on factor Middle: early product causes transcript on of middle genes Figure 11. 4 Phage lytic development Regul ator gene(s) proceeds by a regulatory sigma fa ctor or antite minat on factor cascade, in which a gene Structural genes Replicat ion enzymes etc product at each stage is Late: middle product causes transcription of late genes needed for expression of the genes at the next stage d. Structural genes 请莘大 Phage components
Figure 11.4 Phage lytic development proceeds by a regulatory cascade, in which a gene product at each stage is needed for expression of the genes at the next stage. 11.2 Lytic development is controlled by a cascade
EARLY INITIATION 11.2 Lytic development 入人A is controlled by a cascade EARLY TERMINATION Figure 9.31 Switches in Early region Next region transcriptional specificity can be RNA controlled at initiation ANTITERMINATION or termination 消当 Early/next joint mRI
Figure 9.31 Switches in transcriptional specificity can be controlled at initiation or termination. 11.2 Lytic development is controlled by a cascade
11.3 Functional Class Class I C|assⅢl clustering in phages T and T4 6 genes 7 genes 13 genes RNA polymerase ■■■■■■■ Host interference Figure 11. 5 Phage T7 contains thre ee classes DNA synthesis ■■■■■ of genes that are isozyme expressed sequentially. The Heads tails genome Is-38 kb DNA maturation 消当
Figure 11.5 Phage T7 contains three classes of genes that are expressed sequentially. The genome is ~38 kb. 11.3 Functional clustering in phages T7 and T4
11.3 Functional clustering in phages T7 and T4 F late RNA 55 The map of T4 late RNA 45 th thymidine kinase Is cIrcular de v endonucle ase v 42,43,62,44 iAl, ip. f internal proteins There is DNA polymerase etc e lysozyme 57 tail fiber extensive he ad 1 dNmP kin ase clustering of 3 sheath termin ator 58.61.41 2head completion genes coding DNA pr imase so head completion 65 head completion 5 baseplate plug components of topoisomerase 3 the phage and Ok b 6,7.8.9,10.12 rAn/8 processes such baseplate wedge topoisomerase aS dna wac,13.14.16. plication, but 837.363 head there is also tail fibers 120 dispersion of late RNA 18 sheath, 19tai d tMP synthetase genes coding 20.67,6.21,22,2 for a variety of DNA ligase 30 baseplate5982.51,2626 24. hoc inh he ad enzymatic and other functions baseplate plug Essential genes are indicated by numbers. Nonessential genes are identified by 请第大: I letters. Only some representative T.4 genes are shown on the map
Essential genes are indicated by numbers. Nonessential genes are identified by letters. Only some representative T4 genes are shown on the map. 11.3 Functional clustering in phages T7 and T4 Figure 11.6 The map of T4 is circular. There is extensive clustering of genes coding for components of the phage and processes such as DNA replication, but there is also dispersion of genes coding for a variety of enzymatic and other functions