文档介绍：Bacterial Viruses
Main types of bacterial viruses.
Sizes are approximate scale
Schematic representations of the main types of bacterial viruses
Tailed bacteriophage :
Genome: DNA, double-stranded. Virion: complex shape, binary symmetry, variable number of capsomers. The tails of the phage are long and contractile in group A , long and noncontractile in group B, and very short in group C. Example: T-even coliphages.
Cubic bacteriophage:
Group 1 Genome:DNA, single-stranded. Virion: icosahedral, cubic symmetry, 12 capsomers. Example: X174
Group 2 Genome: DNA, double-stranded. Virion: cubic symmetry, enveloped. Example: PM-2.
Group 3 Genome: RNA, single-stranded. Virion: icosahedral, cubic symmetry, 32 capsomers.
Group 4 Genome: RNA, double-stranded. Virion: cubic symmetry, enveloped. Example: 06.
Filamentous bacteriophage:
Genome: DNA, single-stranded. Virion: rod-shaped, helical symmetry. Example: fd.
Temperate Bacterial Viruses: Lysogeny and Lambda
Virulent Viruses
Temperate Viruses
Lysogeny (溶原性):Viruses can enter a state called lysogeny, where most phage genes are not expressed, and the phage genome is replicated in synchrony with the host chromosome
Prophage or provirus
Can be induced (lysogenic induction) by UV radiation, nitrogen mustards or X-ray.
Temperate Bacterial
Viruses: Lysogeny and
Lambda
Temperate Phage: Lambda
Linear double-stranded DNA
Single-stranded tail of 12 nucleotides long at the 5’-terminus
These single-stranded ends plementary (cohesive)
The two ends can associate and form a double-stranded circle containing 48,502 base pairs.
Electron Micrograph of Lambda particles
ic and Molecular Map of Lambda
PR: Lytic cycle
PL: Lysogeny
Lytic Growth of Lambda
DNA damage is caused by UV, X-ray, Chemicals etc.