virus powerpoint
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CHARACTERISTICS OF VIRUSES
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Are Viruses Living or Non-living?
Biologists consider viruses to be non-living because:– Are not cells– Do not grow or respond to their surroundings– Cannot make food, take in food, or produce wastes– Viruses do not respond to stimuli.
They can only multiply if in another living cell
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What are Viruses?Definition-
Viruses are noncellular particles made up of genetic material and protein that can invade living cells.
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Discovery of Viruses
Beijerinck (1897) coined the Latin name “virus” meaning poison
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Tobacco Mosaic Virus
Wendell Stanley (1935) discovered viruses were made of nucleic acid and protein
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Smallpox
Edward Jenner (1796) developed a smallpox vaccine using milder cowpox viruses
Smallpox has been eradicated in the world today
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How Big is a Virus?
Viruses are very small – smaller than the smallest cell.
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Characteristics
Non living structuresNon-cellularContain a protein coat called the
capsidHave a nucleic acid core containing
DNA or RNA (one or the other - not both)
Capable of reproducing only when inside a HOST cell
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Characteristics
Some viruses are enclosed in an protective envelope
Some viruses may have spikes to help attach to the host cell
Most viruses infect only SPECIFIC host cells
CAPSID
ENVELOPE
DNA
SPIKES
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CharacteristicsOutside of host cells, viruses are inactiveViruses cause many common illnesses/ diseases
Some viruses may cause some cancers like leukemia
EBOLA VIRUSHIV VIRUS
MEASLES
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Characteristics
Viruses cause many common illnesses diseases
Some viruses may cause some cancers like leukemia
MEASLES
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What do Viruses look like?
Viruses are unusual and different from other things in nature.
Viruses come in a variety of shapes
Some may be helical shape like the Ebola virusSome may be polyhedral shapes like the influenza virusOthers have more complex shapes like bacteriophages
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Types of Viruses: Helical Viruses
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Polyhedral Viruses
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Complex Viruses
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Viral Taxonomy
Family names end in -viridaeGenus names end in -virus Viral species: A group of viruses
sharing the same genetic information and ecological niche (host).
Common names are used for species
Subspecies are designated by a number
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Morophology– RNA or DNA Virus– Do or do NOT have an envelope– Capsid shape– HOST they infect
Used for Virus Identification
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Herpes Virus
SIMPLEX I and II
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Adenovirus
COMMON COLD
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Influenza Virus
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Chickenpox Virus
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Papillomavirus – Warts!
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HOST SPECIFICITY
All kingdoms can be infected by viruses
Viruses are kingdom specific but they may or may not be species specific
Spread is specific to the type of virus
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PARASITISM
Viruses are parasites.– A parasite is an organism that depends
upon another living organism for its existence in such a way that it harms that organism.
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Bacteriophages
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Cylces
Lysogenic Cycle– Viral DNA– May stay inactive in host for long periods of
time– Long lasting – Example Mono or chickenpox
Lytic Cylce– Short and can be over come – Example flu virus
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Vaccine
Is a weaken form of the virus – To expose your immune system to the virus which
will allow your body to better fight off the virus when exposed to the full blow virus.
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Vector Control
This is controlling the vectors that are carrying the virus.
Examples:– We stay home when sick, cover our mouth when
we cough etc. – We control the mosquito population in order to
control the West Nile virus
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Other Drug Treatments
Specific to certain viruses.
They don’t cure the virus but they can slow down and inhibit the multiplication of the virus.
copyright cmassengale
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Reducing the RiskThey can’t be treated but they can be prevented!
Cover mouth/nose when you sneeze of cough
Wash hands frequently Avoid contact with the body fluids Not foolproof but reduces the risks