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Viruses

Viruses. http://lbhsbio.files.wordpress.com/2008/01/bacteria-and-viruses-combo-2.ppt. STRUCTURE. Nonliving Composed of a nucleic acid and a protein coat Cause many diseases Virology – Study of Viruses Comparison of Viruses and Cells below. Structure of a Virus. Nucleic acid (DNA or RNA).

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Viruses

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  1. Viruses http://lbhsbio.files.wordpress.com/2008/01/bacteria-and-viruses-combo-2.ppt

  2. STRUCTURE • Nonliving • Composed of a nucleic acid and a protein coat • Cause many diseases • Virology – Study of Viruses • Comparison of Viruses and Cells below

  3. Structure of a Virus Nucleic acid (DNA or RNA) Protein Coat ( capsid)

  4. Characteristics of Viruses 2 essential features • 1. Nucleic Acid • May be DNA or RNA • Helical, closed loop, or long strand • 2. Protein Coat – called CAPSID • Some have ENVELOPE • Ex. Influenza, chickepox, herpes simplex, HIV • VIRAL SHAPE • Icosahedron – 20 triangular faces • Ex.) herpes, chickenpox, polio • Helix – Coiled spring • EX.)Rabies, measles, tobacco mosaic

  5. Grouping Viruses • Grouped according to: • Presence of capsid and envelope – shape • RNA or DNA, single or double stranded – structure

  6. Other Grouping of Viruses • Viroids- The smallest known particle that can replicate. • Disrupt plant cell metabolism • Can destroy entire crops • Prions – Abnormal forms of proteins that clump together inside cells. • Clumping eventually kills the cell • Examples • Scrapie – in sheep • Mad Cow Disease

  7. Viral Replication • Can replicate only by invading host cell and using its enzyme and organelles. • Bacteriophage – viruses that infect bacteria • Used to study viruses

  8. Lytic Cycle of Virus Replication • Lytic Cycle • Viral genome is released into the host cell • Replication follows immediately • Cellular components used to make new viruses • Viral enzyme kills cell. • Play animation

  9. Lysogenic Cycle of Virus Replication • Nucleic acid of virus becomes part of the host cell’s chromosome • Nucleic acid remains in the cell in this form for many generations • HIV follows this pattern • HIV infects WBC and remains as proviruses • As immune system fails, opportunistic infections occur = AIDS • Play animation • Play animation

  10. Viruses and Human Disease • Control and Prevention of spread. • Vaccination & Antiviral drugs • Ex.) chickenpox vaccine, AZT, Acyclovir, protease inhibitors. • Emerging Viruses – exist in isolated habitats • Do not usually infect humans unless environmental conditions favor contact. • Several viruses are now linked to cancers such as leukemia, liver cancer, Burkitt’s lymphoma, cervical cancer.

  11. PAPOVAVIRUSES

  12. ADENOVIRUSES

  13. HERPESVIRUSES

  14. POXVIRUSES

  15. PICORNAVIRUSES Polio

  16. After polio infections, the killer T-cell have destroyed the motor neurons that are producing the virus. The result is a loss of muscle control including the diaphragm. The iron lung changes the pressure to pump air in and out of the lungs.

  17. MYXOVIRUSES

  18. RHABDOVIRUSES

  19. RETROVIRUSES AIDS

  20. Research the following viruses

  21. Look at how the virus infects http://www.slic2.wsu.edu:82/hurlbert/micro101/pages/Chap11.html

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