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Chapter 18.2 Viruses and Prions - PowerPoint PPT Presentation


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Chapter 18.2 Viruses and Prions. “Viruses and prions are smaller and less complex than bacteria; they invade cells and can alter cellular functions.”. Chapter 18.2 Learning Targets. Illustrate the general structure of viruses.

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Chapter 18.2 Viruses and Prions


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    1. Chapter 18.2 Viruses and Prions “Viruses and prions are smaller and less complex than bacteria;they invade cells and can alter cellular functions.”

    2. Chapter 18.2 Learning Targets • Illustrate the general structure of viruses. • Compare and contrast the sequence of events in viral replication by the lytic cycle, the lyosgenic cycle, and retroviral replication. • Discuss the structure, replication, and action of prions in relationship to causing disease.

    3. Characteristics T-4 Virus - infects E. coli • non-living particles • invade living cells • pathogenic - named after the disease they cause or organ they infect • smallest of all organisms

    4. VIRUS - an obligate intracellular parasite INFECTIOUS MONONUCLEOSIS

    5. Origin of Viruses Wendell Stanley (1904 - 1971) first isolated TMV in 1935. • Viruses may have originated from host cells • 1935 - first seen by an electron microscope • Tobacco mosaic virus - first virus discovered - 1886

    6. 1886 - “Living Fluid Infectant” - the virus passed through filters that held bacteria.

    7. Viral Structure • Inner core - contains viral DNA or RNA (never both) • Capsid - outer coat of protein • Envelope - outer layer on larger viruses

    8. Various Shapes of Viruses

    9. Viral ReplicationLytic Cycle • 1. Attachment • 2. Injection • 3. Replication • 4. Assembly • 5. Lysis

    10. LYSOGENIC CYCLE 1. Attachment 2. Injection • Viral DNA integration (provirus) 4. Cell division 5. Replication 6. Assembly 7. Lysis

    11. L Y S O G E N I C L Y T I C

    12. VirusesBozeman Biology http://www.youtube.com/watch?v=L8oHs7G_syI 8:06 min.

    13. VIRUSESCHAPTER 18 Part 2

    14. Edward Jenner - discovered a vaccine for smallpox

    15. SmallpoxVariola (Major & Minor) • First virus to be studied in detail • Edward Jenner - 1798 • First vaccine - cowpox virus (vaccinia virus)

    16. Child with smallpox

    17. (Ali Maow of Merka, Somalia, contracted smallpox in 1977 at the age of 23. His was the last known case of smallpox in the world.) Last case of smallpox

    18. Icosahedral Virus(many sides) Wart virus Polio - Naked, small, icosahedral virus

    19. Enveloped Virus INFLUENZA VIRUS

    20. Children with measles (uncommon today)

    21. E-Coli Bacteria BACTERIOPHAGE

    22. Attachment of a phage to the cell wall of E-Coli

    23. Temperate vs. Virulent Viruses

    24. HERPES ZOSTER (“Shingles”)

    25. HERPES HERPESVIRUS

    26. HIV Retroviruses • RNA viruses • Reverse transcriptase - makes DNA from its RNA • Includes HIV, polio & some cancers

    27. Retrovirus Cycle

    28. The Immune SystemBozeman Biology http://www.youtube.com/watch?v=L8oHs7G_syI 13:47 min.

    29. HIV /AIDS

    30. When HIV Becomes AIDS (HIV #2) http://www.youtube.com/watch?v=68I7JlVhuhY 3:56 min

    31. Louis Pasteur -discovered a vaccine for rabies

    32. PATHWAY OF RABIES VIRUS

    33. Animal Rabies in U. S.1999