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Viruses :Tiny Biological Particles http://labtutorials.org/category/animation/ Size video
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Viruses are abiotic Do not meet all 5 characteristics of living things…. 1) can not obtain energy a) do not exchange gasses b) do not take in nutrients/water 2) can not reproduce on own a) host cell makes the copies of viruses 3) viruses are not cells
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Viruses composed of: 1) Protein covering 2) Nucleic Acid either… a) DNA (deoxyribonucleic acid) b) RNA (ribonucleic acid) ** no water
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Host cells Cells that have been invaded by viruses or virus DNA/RNA Host cell is forced to make virus DNA/RNA Host cell is forced to make virus proteins These parts are assembled in the host cell to create new virus particles
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2 methods of viral attack 1) lytic cycle: immediate take over of cell a) destruction of host cells cause disease symptoms 2) lysogenic cycle: covert attack a) virus DNA blends in with host cell DNA b) when host cell divides the virus divides too c) stress or illness cause virus to switch to lytic cycle and cause disease symptoms
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1) Attachment – virus finds host & locks on 2) Penetration- entire virus or virus DNA/RNA enters host cell 3) Replication & protein synthesis of Viral genes makes viral proteins and DNA/RNA 4)Assembly – new viruses put together 5) Release – new viruses leave host cell Viral Multiplication Steps
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Steps proceed rapidly and end in lysing of cell Lytic pathway
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Lytic cycle examples 1) Rhino virus… common cold 2) Influenza virus… flue virus
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1) Viral DNA becomes part of host DNA 2) Viral DNA copied each time host cell divides 3) Latent period = no symptoms but more and more host cells are becoming infected 4) Stimulus causes switch to lytic cycle and symptoms appear Lysogenic Pathway
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Lysogenic cycle examples Herpes simplex I … cold sores Varicella….. chicken pox (lytic) shingles (lysogenic)
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Viruses we get immunized against Measles Mumps Chicken pox can be fatal in adults influenza
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Vaccinations Activate our acquired immune system https://app.discoveryeducation.com/learn/videos/2D21C2FF-648A-4187-82B5-C3DAA38D3224?hasLocalHost=true https://app.discoveryeducation.com/learn/videos/2D21C2FF-648A-4187-82B5-C3DAA38D3224?hasLocalHost=true Cause creation of memory cells Prevent us from showing symptoms of disease even if we are exposed to it Prevent us from transmitting disease to others http://www.vaccines.com/spread-of-disease.cfm http://www.vaccines.com/spread-of-disease.cfm Can eradicate disease causing agents from the face of the earth!
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Smallpox virus wiped off the face of the earth, except for samples held in labs in the U. S. & Russia scientists declared world small pox free in 1979. U.S. hasn't vaccinated for smallpox since 1972. 1 OR 2 PEOPLE IN 1 MILLION vaccinated may die because this is a LIVE VACCINE of a pox similar to small pox (.000000002 %) fears remain about the smallpox samples being used as bioweapons.
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How we make vaccinations Viruses identified & isolated from host Host cells found in which viruses can reproduce ( eggs, tissue culture) millions of viruses are produced Viruses are purified Viruses are either killed or weakened http://content.time.com/time/video/player/0,3206 8,60312463001_1951560,00.html http://content.time.com/time/video/player/0,3206 8,60312463001_1951560,00.html
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Live Attenuated vaccinations living microbes weakened = no symptoms. closest to natural infection, so strong immune responses often confer lifelong immunity The remote possibility that attenuated microbes could mutate back to disease causing
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Between 1990 and 1995 in the UK, 0.00008% of cases. Only a tiny number of those were serious.
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Inactivated Vaccinations Produced by killing the virus with chemicals, heat, or radiation. More stable Dead microbes can’t mutate Stimulate weaker immune response booster shots needed
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Subunit Vaccines include only parts of virus protein Much lower chances of reactions
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Chances are you don’t know anyone who has had diphtheria, whooping cough (pertussis), measles, mumps, or German measles (rubella). In the 19th and early 20th centuries, these illnesses struck hundreds of thousands of people in the U. S. each year, mostly children, and tens of thousands of people died. Now vaccinations have all but wiped them out
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Different infectious agents http://www.susanahalpine.com/anim/KubyHTML/vaccine.htm http://www.susanahalpine.com/anim/KubyHTML/vaccine.htm
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