Rebecca DavenportWednesday 10:35-1:159/25/16Ch 19 blueprint1. Virusesa. Characteristics?i. Smaller than cellsii. More simple than cellsiii. Lack the structures and machinery found in cells1. Obligate intracellular parasiteiv. Debate if viruses are “alive” or not- 1. Not considered living cause they are A-cellular.v. Host range: a virus can only infect a limited number of host species1. Evolution of recognition systems by the virusb. Structure?i. ~20 nmii. Made up of nucleic acid and protein coat (aka capsid)iii. Classify viruses based on nucleic acid & capsid structureiv. Some viruses have accessory proteins1. Membranous envelopec. Types?i. Helical Virus (looks like a slinky)1. Rod shaped2. Capsomeres arranged in helical shape3. Ex: tobacco mosaic virus4.ii. Icosahedral virus 1. Polyhedral capsid w/20 trianglular facets (isohedron)2. Ex: Adenovirus3.iii. Bacteriophage1. Viruses infect bacteria2. Ex: Bacteriophage T43.iv. Accessory structures1. Help infect hosts2. Mainly made of host cell membrane3. Ex: Influenza Virusd. Genetic makeup-i. Double strandedii. Single strandediii. Double stranded RNA (Mutate)iv. Single stranded RNA (Mutate) e. Capsid- protein coat that surrounds and protects genetic material. f. Viral Replicative Cyclei.1. Don’t have to know step 3, what transcription means.ii. Lytic phages:1. Results in host cell death.2.3. JUST the DNA is injected into the host. iii. Lysogenic phages1. Allow replication of phage genome without destroying
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