Download
1 / 11
110 likes | 120 Views
This text provides an in-depth exploration of viruses, including their structure, replication, and interaction with host cells. Learn about the 2009 pandemic H1N1 influenza A virus, the tobacco mosaic virus, adenoviruses, bacteriophage T4, and more. Gain a comprehensive understanding of viral entry, uncoating, transcription, RNA synthesis, and self-assembly. Explore both the lytic and lysogenic cycles and discover the impact of viruses on host cells.
E N D
Viruses 0 17
Figure 17.8 1 m (a) 2009 pandemic H1N1 influenza A virus (b) 2009 pandemic screening
Figure 17.2 Membranous envelope Capsomere RNA RNA DNA Head DNA Capsid Capsomereof capsid Tailsheath Tailfiber Glycoprotein Glycoproteins 80 225 nm 70–90 nm (diameter) 80–200 nm (diameter) 18 250 nm 20 nm 50 nm 50 nm 50 nm (c) Influenza viruses (a) Tobacco mosaic virus (b) Adenoviruses (d) Bacteriophage T4
Figure 17.3 VIRUS DNA Entry anduncoating Transcription andmanufacture ofcapsid proteins 1 3 Capsid Replication 2 HOSTCELL Viral DNA mRNA Capsidproteins Viral DNA 4 Self-assembly ofnew virus particlesand their exit fromthe cell
Figure 17.4-5 1 Attachment 2 Entry of phageDNA anddegradationof host DNA 5 Release Phage assembly 3 4 Synthesis ofviral genomesand proteins Assembly Head Tailfibers Tail
Animation: Phage Lysogenic and Lytic Cycles Right click slide / Select play
Figure 17.5 Daughter cellwith prophage PhageDNA The phage injects its DNA. Many celldivisionscreate manyinfectedbacteria. Phage DNAcircularizes. Phage Bacterialchromosome Prophage exitschromosome. Lytic cycle Lysogenic cycle Prophage is copiedwith bacterialchromosome. The cell lyses, releasing phages. Prophage Phage DNA and proteins aresynthesized and assembled. Phage DNA integrates intobacterial chromosome.
Figure 17.6 Capsid RNA HOST CELL Envelope (withglycoproteins) Viral genome(RNA) Template mRNA Capsidproteins ER Copy of genome (RNA) Glycoproteins New virus
Animation: HIV Replicative Cycle Right click slide / Select play
Figure 17.7a Viral envelope Glycoprotein Capsid RNA (twoidenticalstrands) HOSTCELL HIV Reversetranscriptase Reversetranscriptase Viral RNA RNA-DNAhybrid DNA NUCLEUS Provirus ChromosomalDNA RNA genomefor the nextviral generation mRNA New virus
Figure 17.UN03 The phage attaches to ahost cell and injects its DNA. PhageDNA Bacterialchromosome Prophage Lytic cycle Lysogenic cycle • Temperate phage only• Genome integrates into bacterial chromosome as prophage, which (1) is replicated and passed on to daughter cells and (2) can be induced to leave the chromosome and initiate a lytic cycle • Virulent or temperate phage• Destruction of host DNA• Production of new phages• Lysis of host cell causes release of progeny phages
