Portage Learning, Microbiology Module 6 Complete Solutions

virus a small, non-cellular particle that cannot replicate unless inside a living host cell obligate intracellular parasites unable to replicate on their own 00:0201:29 2 components of a virus genomic material comp ...

virus a small, non-cellular particle that cannot replicate unless inside a living host cell obligate intracellular parasites unable to replicate on their own 00:0201:29 2 components of a virus genomic material comprised of either DNA or RNA and a capsid capsid a membrane-like protective structure that contains the genetic material, similar to the nucleus of a eukaryotic cell are viruses prokaryotic or eukaryotic? Neither, they are acellular Viral genomes can be either ___________-stranded and may be found in _________ arrangement double- or single- / circular or linear envelope an additional layer around the capsid, derived from the host cell membrane and serves as an additional barrier to the external environment naked (non-enveloped) virus a virus simply surrounded by the protein capsid The overwhelming majority of animal viruses are __________________ whereas the majority of plant or bacteria-infecting viruses are not. Enveloped Differences in ________________ can also significantly influence the shape and appearance of the virus. virion composition smallpox virus an enveloped, ~ 200 nm long and has a distinct dumbbell shaped viral capsid poliovirus non-enveloped and only ~30 nm in diameter 00:0201:29 Differences between viruses are best visualized via an ____________. electron microscope paramyxoviruses and orthomyxoviruses both enveloped, spherical and ~100-150 nm in diameter but vary drastically in composition and function paramyxoviruses the causative agent of measles and mumps, contain a single-stranded linear genome and fuses with the host cell membrane to initiate entry and viral replication orthomyxoviruses the causative agent of the flu, contain eight segments of RNA and enters the host cell via endocytosis Viruses also require ___________________ in order to successfully replicate host cell enzymes Outside of a host cell viruses have no metabolism and are essentially ___________. dormant viral envelope often required to interact with and promote successful entry into the host cell Any _______________ required for cell entry must be present on the outer surface of the viral envelope. proteins As the envelope is derived from the _________________________, this camouflages the virus and lowers the likelihood of immune detection by making it appear similar to the normal biological host cell. host cell membrane Ror all viruses, the genome is replicated following ________________, never before. attachment and entry first step in viral life cycle virus must first attach to the host cell second step in viral life cycle virus quickly penetrates and enters the cell third step in viral life cycle the capsid disintegrates (uncoating), as it enters the cytoplasmic space fourth step in viral life cycle the viral genome then undergoes transcription/translation to produce new viral proteins fifth step in viral life cycle the virus also duplicates its entire genome sixth step in viral life cycle new viruses are then assembled seventh step in viral life cycle new viruses are released bacteriophage the type of virus that infects bacteria structure of bacteriophage an icosahedral (20-sided polygon) capsid head group containing the viral genome, and a helical tail In bacteriophages, once the tail fibers have mediated binding, the ______________ penetrates the host cell wall and the viral genome is effectively 'injected' through the hollow helical tail and into the cytoplasm. helical tail 2 forms of bacteriophage replication lytic and lysogenic (temperate) ________________ bacteriophages replicate within the host bacteria until it lyses, or ruptures, effectively destroying the host bacterial cel