Introduction to Medical Microbiology Exam #2 Study Guide[ CORRECT QUESTION AND ANSWERS GRADED A+]

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Introduction to Medical Microbiology Exam #2 Study Guide Chapter 6 – Acellular Pathogens 1. Know the basic characteristics and components of Viruses and the definition of Virion  Obligate int... racellular parasites - non-living, infectious agents, can’t live w/o host  work by: invading, taking over cell functions & directing it to produce more viruses  use structures & enzymes of cells to support own reproduction  Can infect all forms of life: Bacteria, Archaea, and Eukarya  Considered ultramicroscopic- electron microscope  2000 viruses could fit into an average bacterial cell  Viruses have nucleic acid (DNA or RNA) surrounded by a protective protein coat (capsid) or called nucleocapsid  Virion – fully formed virus that can establish an infection in a host cell 2. Know the basic structure of the viral Capsid and be able to distinguish between the 3 common shapes  Outer protein shell made of repeating protein subunits known as capsomeres. 3 Common shapes:  Helical - composed of rod-shaped capsomeres arranged into hollow discs  Icosahedral - flat and rounded capsomeres arranged into a 20-sided figure  Complex - have an icosahedral head, helical tail, and attachment fibers 3. Know the basic structure of the viral Envelope, including the definition of Naked Viruses and Spikes  Double layer of lipid that surrounds the capsid  Found on mostly animal viruses  Naked viruses - viruses lacking an envelope  Created from portions of the host cell membrane  Spikes - viral proteins that protrude from the surface and help virus attach to host cell 4. Know the makeup and possible arrangements of viral Nucleic Acid  Can be DNA or RNA but not both  DNA may be linear/circular or double-stranded/single-stranded  RNA can be double-stranded/single-stranded 5. Know the steps of Bacteriophage and Animal virus multiplication, be able to describe what happens during each step, and be able to identify differences between the two types Viral Multiplication: Bacteriophage (virus that infect bacteria) Viral Model Viral Multiplication: Animal Virus Model  Attachment - virus & host cell come together - use tail fibers  Penetration - bacteriophage injects nucleic acid into the host o protein coat remains on the outside  Biosynthesis - virus shuts down host cell machinery and directs the host to produce new viral components  Maturation - viral components assemble into new bacteriophages  Release o Lytic cycle - viral enzyme digests the host cell wall resulting in cell lysis(rupture) and virus release o Lysogeny – viral DNA inserts into bacterial chromosome and enters inactive prophage state  can re- enter lytic cycle  can carry toxins  Attachment -virus attaches to specific host cell receptors o spikes instead of tail fibers  Penetration –entire virion taken into cell o Endocytosis – engulfment by host cell o Membrane fusion – viral envelope fuses with host cell membrane  Uncoating - the envelope (if present) & capsid are separated from nucleic acid o viral nucleic acid released into cytoplasm  Biosynthesis and Maturation o Virus stops host function & makes duplication of DNA or RNA to produce the components for new viruses o New viruses assemble themselves  Release o Enveloped viruses - released by budding & exocytosis o Naked viruses - released when the cell lyses o DNA viruses can integrate into the host chromosomes to form a provirus 6. Know the basic Nomenclature rules for viruses and be able to match the virus families with examples of virus members listed *only know disease it cause and not if RNA or DNA? Common DNA Viruses Common RNA Viruses  Poxviridae – Smallpox virus  Herpesviridae o Herpes simplex type I (HSV-1) o Herpes simplex type II (HSV-2) o Varicella-zoster virus o Epstein-Barr virus o Cytomegalovirus (CMV)  Papillomaviridae – Human Papillomavirus (HPV)  Hepadnaviridae – Hepatitis B virus  Parvoviridae – Parvovirus B19  Adenoviridae - Adenovirus  Picornaviridae – Poliovirus, Rhinovirus and Hepatitis A virus  Togaviridae – Encephalitis viruses and Rubella virus  Rhabdoviridae – Rabies virus  Reoviridae – Rotavirus  Retroviridae – Human Immunodeficiency virus (HIV)  Filoviridae – Ebola, Marburg virus  Orthomyxoviridae – Influenza virus 7. Know the difference between Acute versus Persistent infections and Latent versus Chronic infections Acute infections - short duration  host may develop long-lasting immunity Persistent infections - persist for years, often without disease symptoms  Latent infection - virus can remain silent in the host cell & reactivate o Ex. Herpes Simplex, Chicken Pox  Chronic infection – recurrent symptoms over a long time o Ex. Hepatitis C, HIV 8. Be able to define Oncoviruses, Cytopathic Effects, and Syncytia  Oncoviruses – cause the host cell to become cancerous o Virus don’t kill the host cell but causes it to change its properties (transformation)  Cytopathic Effects (CPE) - virus-induced damage to the cell that alters its microscopic appearance  Syncytia – fusion of multiple host cells into single large cells with multiple nuclei [Show More]

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