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Viruses :Tiny Biological Particles Size video.

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Presentation on theme: "Viruses :Tiny Biological Particles Size video."— Presentation transcript:

1 Viruses :Tiny Biological Particles http://labtutorials.org/category/animation/ Size video

2 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

3 Viruses composed of:  1) Protein covering  2) Nucleic Acid either…  a) DNA (deoxyribonucleic acid)  b) RNA (ribonucleic acid)  ** no water

4 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

5 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

6  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

7  Steps proceed rapidly and end in lysing of cell Lytic pathway

8 Lytic cycle examples  1) Rhino virus…  common cold  2) Influenza virus…  flue virus

9  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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11 Lysogenic cycle examples  Herpes simplex I …  cold sores  Varicella…..  chicken pox (lytic) shingles (lysogenic)

12 Viruses we get immunized against  Measles  Mumps  Chicken pox can be fatal in adults  influenza

13 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!

14 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.

15 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

16 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

17  Between 1990 and 1995 in the UK,  0.00008% of cases. Only a tiny number of those were serious.

18 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

19 Subunit Vaccines  include only parts of virus protein  Much lower chances of reactions

20  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

21 Different infectious agents  http://www.susanahalpine.com/anim/KubyHTML/vaccine.htm http://www.susanahalpine.com/anim/KubyHTML/vaccine.htm


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