Wednesday, November 20, 2013

Hum 300 History And Mefthods Of Science

What is a computer computer virus ? Why be they so uncorrectable to controlViruses are microscopic particles of 20-300nm in size , truss intra cellular parasites they substructure throw up only by invading and winning over other cells as they wishing the cellular machinery for egotism reproduction . Host range includes a wide revolution of animal and plants There are viruses which can infect bacterium and they are called batceriophage . A complete virus particle is called virion consisting of its sincere nucleic acid (either ribonucleic acid or deoxyribonucleic acid ) and a protein rise up called mirid . Viruses with deoxyribonucleic acid as genetic significant are called DNA virus ( eg herpes virus or Adenovirus etc ) and those with RNA as genetic material are called RNA viruses ( e .g : Foot and Mouth unhealthiness virus , SARS virus HIV etc . Virus encoded proteins organise the capsid . The nucleic acid and the capsid together termed as nucleocapsid . sure viruses have a tissue layer or envelope covering the nucleoacpsid and they are called enveloped viruses . The envelope is normally of glycolipid and the lipid membrane itself and any carbohydrates present are merely host-coded (The Influenza virus and HIV use this strategy to table the repellent tuneful arrangementSince viruses use the machinery of a host cell to reproduce and continue within the host cell , they are rough to purloin without killing the host cell . Viruses used incompatible mechanisms to avoid the tolerant arrangement of the host cell . The around ordinarily used strategies include antigenic variation , antigenic slip and wave . Influenza virus uses both antigenic diversify and antigenic drift to evade the immune system .

antigenic variation can occur through trey in the main defined genetic processes : gene mutation , recombination , and slip results in pathogens that are immunologically distinct from the parental strains there by escaping the immune system of the host .Antigenic shift involves between ii contrary subtypes of the same virus coinfect a single cell and change RNA segments to form a new subtype . Antigenic drift is by changing the surface protein mainly haemagglutinin and Neuraminidase proteins in reference of influenza virus . Mutations in the RNA or DNA causes change in the surface protein and host immune system fails to identify the viral proteins and this will facilitate the viral constancy in the host cell and making it elusive to controlReferenceds Virology , David M .Knipe , Peter M Howley , Diane E Griffin , Robert A birth , Malcom A Martin , Bernard Roizman , Stephan E Stratus , Source Lippincott Williams Wilkins (LWW , fifth edn , 2007 . PAGEPAGE 1...If you penury to get a full essay, order it on our website:

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