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VIRUSES CHAPTER 18. Part 1. 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. VIRUS - an obligate intracellular parasite. INFECTIOUS MONONUCLEOSIS.
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VIRUSESCHAPTER 18 Part 1
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
VIRUS - an obligate intracellular parasite INFECTIOUS MONONUCLEOSIS
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
1886 - “Living Fluid Infectant” - the virus passed through filters that held bacteria.
Viral Structure • Inner core - contains viral DNA or RNA (never both) • Capsid - outer coat of protein • Envelope - outer layer on larger viruses
Viral ReplicationLytic Cycle • 1. Attachment • 2. Injection • 3. Replication • 4. Assembly • 5. Lysis
LYSOGENIC CYCLE 1. Attachment 2. Injection • Viral DNA integration (provirus) 4. Cell division 5. Replication 6. Assembly 7. Lysis
L Y S O G E N I C L Y T I C
VIRUSESCHAPTER 18 Part 2
SmallpoxVariola (Major & Minor) • First virus to be studied in detail • Edward Jenner - 1798 • First vaccine - cowpox virus (vaccinia virus)
Last case of smallpox (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.)
Icosahedral Virus(many sides) Wart virus Polio - Naked, small, icosahedral virus
Enveloped Virus INFLUENZA VIRUS
BACTERIOPHAGE E-Coli Bacteria
HERPESVIRUS HERPES
Retroviruses HIV • RNA viruses • Reverse transcriptase - makes DNA from its RNA • Includes HIV, polio & some cancers
PATHWAY OF RABIES VIRUS