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Viruses are non- cellular , npn- living infectious agents that are composed of nucleoproteins which can multiply inside animals and plants or bacterial cells.It consists of both living and non- living properties
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LIVING_PROPERTIES OF VIRSUES
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NON_ LIVING PROPERTIES OF VIRUSES
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]1)They are obligate intracellular parasities,
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1)They can be crystallized and stored in bottles
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i.e<,cannot exists outside .
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2)They can multiply inside the living organisms
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2)They cannot multiply outside the host
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3)They contain a genetic material namely DNA or RNA
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3)They dont have the cells
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Spherical
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polio virus
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rod shaped
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TMV virus,influenza virus
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rectangular
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vaccinia virus
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polyhedral
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adeno virus, herpes virus,polio virus
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tadpole shaped
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bacteriophages
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Helical
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Rabies virus , TMV
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Generally plant virus consists of RNA but in cauliflower mosaic virus and dahila mosaic virusthe genetic material is double standard DNA
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Generally animal virus consists of DNA but in polio virus,flue virus it is single standard RNA
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A single standard DNA is present in bacteriophage M14 and coliphage S13
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A double standard RNA is present in Wound tumor virus ,Rice dwarf virus, Maize dwarf virus, Reo virus
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TMV VIRUS
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BACTERIOPHAGE
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POX VIRUS
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AIDS VIRUS
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TMV is most extensively studied plant virus.
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They are pathogenic virus infecting bacteria
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POX virus is aa casual agent of small pox.
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Acquired immune deficiency syndrome(AIDS)is an infectious diseases is caused by a virus known as human immunodeficiency virus (HIV)
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It is elongated rod-like,3000A0long ,180A0 in diameter, molecular weight being 39.4*106, 95%protein and 5% RNA by weight interwined to form helical ,grooved,cylinderical rods.
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Twort discovered the bacteriophages. The structure of T4 bacteriophage contains head and tail regions.
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pox virus are among the largest of animal virus ,have complex structure and rectangular shaped
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This virus also called as Human T lymphotropic virus 3 or AIDS related retrovirus (ARV)
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The walls of the cylinder are 70A0 thick.2130 capsomers are arranged helically to form aa capsid .
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Head is folded double standard DNA is packed in head.Head is hexagonal with around 2000 capsomeres.
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This is rectangular shaped (300*230mU) in size ,6% double standard DNA ,89% protein ,5% lipids.
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AIDS virus consists of single standard RNA surrounded by protein coat( core shell) the entire structure is wrapped around in an envelope.
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49 capsomers are present in 3 turns and 130 turns in complete virus capsid. Each capsomere has a molecular weight of 17,400 and is formed by condensation of 158 aminoacids
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Tail is helically symmetrical with a core tube surrounded by a protein tail sheath consists of 144 capsomeres arranged in 24 rings of 6 subunits. The sheath is connected to collar at its upper end and base plate at lower end.
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Genome is dumb bell shaped;central core has dsDNA.
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After entering the blood, AIDS virus infects the helper T-LYMPHOCYTES(not the suppressor T-cells) and destroy them. Helper T cell plays an essential role in antibody production.
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RNA strand is embeddedin furrow and therefore,it is helical;ssRNA consists of 6400 nucleotides.Thus , the approximate ratio of nucleotides and capsomers is 3:1
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basal plate is hexagonal with single pin or spike at each corner. A thin tail fibre is also given out of the corner . A enzyme lysozyme is responsible for dissolving the bacterial cell wall is present in tail fibers.
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The core contains two enzymes - RNA polymerase and **ATP-phosphohydralase.On both sides of the core lie lateral bodies one on each side.
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Thus, AIDS virus destroy an important link in immune defence rendering the individuals prone to infectious diseases and tumour formation.
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